The role of occipital condyle and atlas anomalies on occipital cervical fusion outcomes in Chiari malformation type I with syringomyelia: a study from the Park-Reeves Syringomyelia Research Consortium

OBJECTIVE

Congenital anomalies of the atlanto-occipital articulation may be present in patients with Chiari malformation type I (CM-I). However, it is unclear how these anomalies affect the biomechanical stability of the craniovertebral junction (CVJ) and whether they are associated with an increased incidence of occipitocervical fusion (OCF) following posterior fossa decompression (PFD). The objective of this study was to determine the prevalence of condylar hypoplasia and atlas anomalies in children with CM-I and syringomyelia. The authors also investigated the predictive contribution of these anomalies to the occurrence of OCF following PFD (PFD+OCF).

METHODS

The authors analyzed the prevalence of condylar hypoplasia and atlas arch anomalies for patients in the Park-Reeves Syringomyelia Research Consortium database who underwent PFD+OCF. Condylar hypoplasia was defined by an atlanto-occipital joint axis angle (AOJAA) ≥ 130°. Atlas assimilation and arch anomalies were identified on presurgical radiographic imaging. This PFD+OCF cohort was compared with a control cohort of patients who underwent PFD alone. The control group was matched to the PFD+OCF cohort according to age, sex, and duration of symptoms at a 2:1 ratio.

RESULTS

Clinical features and radiographic atlanto-occipital joint parameters were compared between 19 patients in the PFD+OCF cohort and 38 patients in the PFD-only cohort. Demographic data were not significantly different between cohorts (p > 0.05). The mean AOJAA was significantly higher in the PFD+OCF group than in the PFD group (144° ± 12° vs 127° ± 6°, p < 0.0001). In the PFD+OCF group, atlas assimilation and atlas arch anomalies were identified in 10 (53%) and 5 (26%) patients, respectively. These anomalies were absent (n = 0) in the PFD group (p < 0.001). Multivariate regression analysis identified the following 3 CVJ radiographic variables that were predictive of OCF occurrence after PFD: AOJAA ≥ 130° (p = 0.01), clivoaxial angle < 125° (p = 0.02), and occipital condyle-C2 sagittal vertical alignment (C-C2SVA) ≥ 5 mm (p = 0.01). A predictive model based on these 3 factors accurately predicted OCF following PFD (C-statistic 0.95).

CONCLUSIONS

The authors' results indicate that the occipital condyle-atlas joint complex might affect the biomechanical integrity of the CVJ in children with CM-I and syringomyelia. They describe the role of the AOJAA metric as an independent predictive factor for occurrence of OCF following PFD. Preoperative identification of these skeletal abnormalities may be used to guide surgical planning and treatment of patients with complex CM-I and coexistent osseous pathology.

Approaches to ventriculoperitoneal shunt scalp erosion: countersinking into the calvarium. Illustrative case

BACKGROUND

Ventriculoperitoneal shunting (VPS) is a standard procedure for the treatment of hydrocephalus, and the management of its complications is common in the practice of pediatric neurosurgery. Shunt exposure, though a rare complication, can occur because of thin, fragile skin, a young patient age, protuberant hardware, poor scalp perfusion, and a multitude of other patient factors.

OBSERVATIONS

The authors report a complex case of VPS erosion through the scalp in a young female with Pfeiffer syndrome treated with external ventricular drainage, empirical antibiotics, and reinternalization with countersinking of replaced shunt hardware into the calvarium to prevent internal skin pressure points, reduce wound tension, and allow wound healing.

LESSONS

Recessing the shunt hardware, or countersinking the implant, into the calvarium is a simple technique often used in functional neurosurgical implantation surgeries, providing a safe surgical strategy to optimize wound healing in select cases in which the skin flap is unfavorable.

Cervical corpectomy in a pediatric patient with chondrodysplasia punctata and C5 dysplasia with spinal cord compression: illustrative case

BACKGROUND

Chondrodysplasia punctata (CDP) describes skeletal dysplasia secondary to a variety of genetic underpinnings characterized by cartilaginous stippling from abnormal calcium deposition during endochondral bone formation. Approximately 20%-38% of patients with CDP have cervical spine abnormalities, resulting in stenosis and cord compression. However, approaches to management differ among patients.

OBSERVATIONS

The authors present an 18-year-old male with a known history of CDP and cervical kyphosis with worsening paresthesias and increased spasticity. Imaging confirmed dysplastic C4 and C5 vertebra with focal kyphosis, bony retropulsion, spinal cord compression, and myelomalacia. To treat the stenosis and deformity, the patient underwent C4 and C5 vertebrectomies with C3 to C6 anterior fusion with resolution of symptoms.

LESSONS

Despite many CDP patients having cervical deformities with spinal cord compression and associated neurological symptoms, there is a paucity of data on surgical management and outcomes. There are only scattered reports, and most authors recommend initial conservative management because of the high risk of operative morbidity and mortality secondary to comorbidities. When surgery is performed, long-term follow-up is recommended because of the high rates of progression of deformity, requiring subsequent operations. The authors hope that their experience adds to the literature describing the surgical management of cervical deformities in these patients.

Pediatric pineal region tumors: institutional experience of surgical managements with posterior interhemispheric transtentorial approach

PURPOSE

Resecting pineal region tumors in children is often challenging. Several approaches have been proposed and practiced. A personal series of pediatric pineal region tumors resected through craniotomy with posterior interhemispheric occipital transtentorial (OT) approach are reviewed. We present the surgical techniques, pitfalls, and their results.

MATERIAL AND METHODS

Eighty patients ranging in age from 3 months to 21 years old, and treated over 3 decades were reviewed. Hydrocephalus caused the main presenting symptoms and was noted in 74 patients. It was treated prior to the craniotomy for tumor resection with endoscopic third ventriculostomy (ETV) in 33, external ventricular drainage in 26, and precraniotomy shunt in 15. Nine patients had ETV together with endoscopic biopsy. All patients had a parieto-occipital craniotomy in a prone position. Through a tentorial section, a gross total resection of the tumor was attempted except for germinomas.

RESULTS

The tumor pathology showed 32 germ cell tumors (GCT), 22 benign astrocytomas, 13 pineal parenchymal tumors, 5 ATRTs, 3 papillary tumors, and 5 others. Of GCTs, 18 were teratomas. The extent of resection consisted of 55 gross total resections, 13 subtotal resections, 10 partial, and 2 biopsies with one postoperative death. Hemiparesis in 2, cerebellar ataxia in another 2, and hemiballismus in 1 were transient and improved over time. One had permanent hemisensory loss and another patient had bilateral oculomotor palsy. Postoperative homonymous hemianopia occurred in 2 patients but subsided over a short period of time. Parinaud's sign was noted in 24 patients, of which 16 were transient.

CONCLUSION

The posterior interhemispheric OT approach provides a safe route and comfortable access to the pineal region in children. A great majority of postoperative neurological complications are the results of direct manipulations of the midbrain at tumor resection. Identification and preservation of the tumor-brain interface are of paramount importance. GCTs other than teratomas are treated with neoadjuvant chemotherapy and may eliminate the need for craniotomy. Exophytic midbrain JPAs are amenable to resection.

An adolescent case of sellar osteochondromyxoma in the setting of spondyloepiphyseal dysplasia

PURPOSE

Osteochondromyxomas (OMX) are rare congenital bone tumors that have only been described in the context of Carney complex syndrome (CNC). Data on OMX as a separate entity and in association with other disorders remain limited, making both diagnosis and treatment difficult.

METHODS

A case report of a 17-year-old female diagnosed with sellar OMX is presented in the setting of spondyloepiphyseal dysplasia (SED). We discuss the radiographic and histopathological interpretations in addition to reviewing the current literature on OMX.

RESULTS

A successful gross total resection of the tumor was achieved via an endonasal endoscopic transsphenoidal approach. A diagnosis was established radiographically and pathologically.

CONCLUSION

The diagnosis and treatment of OMX are best achieved via tissue biopsy. Following confirmed osteochondromyxoma cases long term for recurrence and outcomes will be essential in understanding its natural tumor history and in establishing standard treatments.

Endoscopic endonasal optic nerve decompression: treatment of fibrous dysplasia in a pediatric population

OBJECTIVE

Patients with fibrous dysplasia (FD) of the anterior skull base can experience progressive visual loss and impairment. The authors reviewed their experience with endonasal decompression of the optic nerve (ON) in this patient population. Endoscopic ON decompression (EOND) is a feasible surgical approach for children with FD and visual deficit due to structural ON compression.

METHODS

Electronic medical records of children between 1 and 17 years of age with unilateral FD of the anterior skull base and concomitant ON compression, who required EOND between 2017 and 2022 (n = 4), were reviewed for demographic data, both pre- and postoperative imaging, and evaluations by an otolaryngologist, neurosurgeon, and ophthalmologist in a multidisciplinary fashion.

RESULTS

EOND was found to be a safe and effective surgery for children with FD. Visual acuity was stable in 80% of the eyes postoperatively. Visual fields improved in 40% of the eyes and remained stable in the rest.

CONCLUSIONS

EOND is beneficial for progressive optic neuropathy that is unresponsive to steroid therapy and can prevent permanent disability if performed prior to irreversible damage to the nerve. EOND can decompress the edematous ON with proper exposure of the optic canal and orbital apex, without any major complications.

Pediatric Endoscopic Endonasal Skull Base Surgery: A Retrospective Review Over 11 Years

OBJECTIVE

To show the safety and efficacy of the endoscopic endonasal approach (EEA) for skull base surgery in pediatric patients through descriptive analysis of cases over an 11-year period.

METHODS

The study comprised 94 patients undergoing EEA for skull base surgery, between January 2007 and June 2018, at 2 tertiary pediatric hospitals. Descriptive statistics are presented regarding the presentation, intraoperative details, and complications.

RESULTS

Over the study period, 130 surgeries were performed in 94 patients: 94 primary surgeries and 36 reoperations. The mean patient age was 13.8 years and 48.9% of patients were female. Presenting signs/symptoms included endocrinopathies (56.4%), vision abnormalities (37.2%), and cranial nerve deficits (20.2%). EEA alone was used in 95.7% of primary surgeries and 91.7% of reoperations. Diseases treated included craniopharyngioma (18.1%), pituitary adenoma (17.0%), Rathke cleft cyst (13.8%), chordoma (9.6%), osteosarcoma (5.3%), juvenile nasopharyngeal angiofibroma (4.3%), skull base fracture (4.3%), and encephalocele (3.2%). A lumbar drain was used in 20.2% of primary surgeries and 25% of reoperations. A nasoseptal flap was used in 36.2% of primary surgeries and 25% of reoperations. Postoperative complications included cerebrospinal fluid leak (12.8%), sinusitis (7.4%), bacterial meningitis (3.2%), and carotid artery injury in 1 reoperation.

CONCLUSIONS

EEA for anterior cranial base disease is safe and efficacious in pediatric patients and can be used to treat many of the rare and heterogenous diseases that arise in this anatomic location. Management strategies and rates of sinonasal and intracranial complications including cerebrospinal fluid leak rate are similar to those reported in adult cohorts.

Pediatric benign triton tumor of trigeminal nerve: a case report and literature review

PURPOSE

Benign triton tumors (BTTs) in the pediatric population are extremely rare occurrences. Paucity of data on BTTs poses both diagnostic and therapeutic challenges, particularly when found intracranially.

METHODS

A case report of a 10-year-old male diagnosed with incidental maxillary trigeminal (V2) BTT is presented. We discuss radiographic and histopathological interpretations. Furthermore, we provide a brief review of current literature and historical background on pediatric trigeminal BTT diagnosis, histopathology, and management.

RESULTS

Successful gross total resection of the tumor was achieved via Dolenc approach to the cavernous sinus. Management options with consideration of outcomes from the few prior cases reported in the literature are presented.

CONCLUSION

Treatment of trigeminal nerve tumors requires a broad differential diagnosis and understanding rare tumors is essential in the diagnosis and treatment algorithm.

Middle meningeal artery embolization in pediatric patient

PURPOSE

There is paucity of data in management of recurrent and expanding subdural hematomas (SDH) within the pediatric population, who are otherwise not surgical candidates. Middle meningeal artery (MMA) embolization has been utilized minimally in this population and here, we explore the utility of this procedure in a 15-month-old-child, along with review of the literature.

METHODS

A case report of a 15-month-old child who underwent MMA embolization for recurrent and expanding SDH in the setting of anticoagulation for cardiac condition. A literature review of MMA embolization in pediatric patients was conducted.

RESULTS

Initially stabilization of SDH was noted on serial imaging; however, recurrent hemorrhages were noted with subsequent boluses of antiplatelet and anticoagulating agents. There are only 5 total reported cases, included ours, of MMA embolization in pediatrics with an overall success rate of 80%.

CONCLUSION

Treatment of chronic or recurrent subdural hematoma by MMA embolization in the pediatric population is understudied. Our case notes limitation of this procedure and impact on long-term success, specifically in patients with systemic illness and ongoing anticoagulation.

Presentation, management and outcome of surgically managed pediatric thoracic outlet syndrome

PURPOSE

Thoracic outlet syndrome (TOS) is a rare disorder involving compression of the brachial plexus, subclavian artery, and subclavian vein. There is a paucity of data for this pathology's surgical treatment within pediatrics. The objective of this study is to explore the presentation, management, and outcome of pediatric TOS.

METHODS

A retrospective chart review was conducted for 44 patients at a single institution undergoing surgery for TOS. Data was collected on demographics, pre- and postoperative factors, and outcomes.

RESULTS

Forty-four patients underwent 50 surgeries (8 bilaterally). The average age was 15.5 years with 72% female. The most common symptoms were numbness (72%) and pain (66%), with a normal exam in 58%. The average symptom duration prior to surgery was 35.2 months. A supraclavicular approach was performed in all patients, with anterior scalene section (90%), rib resection (72%), neurolysis (92%), and intraoperative EMG (84%) commonly used. Two patients had a lymphatic leak. All patients reported subjective improvement of preoperative symptoms of numbness (26%), pain (22%), and weakness (6%). Differences between vTOS (n = 9) and nTOS (n = 35) included higher preop swelling (p < 0.012), decreased symptom duration (p < 0.022), higher venogram usage (p < 0.0030), and higher preoperative thrombolytics/angioplasty (p < 0.001) in vTOS compared to nTOS. A comparison of soft tissue and soft tissue with bone decompression did not reveal any outcome differences.

CONCLUSION

Pediatric TOS benefits from a multidisciplinary approach, showing good outcomes in postoperative symptom resolution. In our cohort, a supraclavicular approach provided an effective window for decompression with a low complication rate.

The role of neurosurgery in the management of tuberous sclerosis complex–associated epilepsy: a systematic review

OBJECTIVE

Tuberous sclerosis complex (TSC) is an autosomal dominant, multisystem neurocutaneous disorder associated with cortical tubers, brain lesions seen in nearly all patients with TSC, which are frequently epileptogenic. Seizures are often the earliest clinical manifestation of TSC, leading to epilepsy in over 70% of patients. Medical management with antiepileptic drugs constitutes early therapy, but over 50% develop medically refractory epilepsy, necessitating surgical evaluation and treatment. The objective of this study was to summarize the literature and report seizure outcomes following surgical treatment for TSC-associated epilepsy.

METHODS

A systematic literature review was performed in accordance with the PRISMA guidelines. The PubMed and Embase databases were searched for journal articles reporting seizure outcomes following epilepsy surgery in TSC patients. Included studies were placed into one of two groups based on the surgical technique used. Excellent and worthwhile seizure reductions were defined for each group as outcomes and extracted from each study.

RESULTS

A total of 46 studies were included. Forty of these studies reported seizure outcomes following any combination of resection, disconnection, and ablation on a collective 1157 patients. Excellent and worthwhile seizure reductions were achieved in 59% (683/1157) and 85% (450/528) of patients, respectively. Six of these studies reported seizure outcomes following treatment with neuromodulation. Excellent and worthwhile seizure reductions were achieved in 34% (24/70) and 76% (53/70) of patients, respectively.

CONCLUSIONS

Surgery effectively controls seizures in select patients with TSC-associated epilepsy, but outcomes vary. Further understanding of TSC-associated epilepsy, improving localization strategies, and emerging surgical techniques represent promising avenues for improving surgical outcomes.

Complications and outcomes of posterior fossa decompression with duraplasty versus without duraplasty for pediatric patients with Chiari malformation type I and syringomyelia: a study from the Park-Reeves Syringomyelia Research Consortium

OBJECTIVE

The aim of this study was to determine differences in complications and outcomes between posterior fossa decompression with duraplasty (PFDD) and without duraplasty (PFD) for the treatment of pediatric Chiari malformation type I (CM1) and syringomyelia (SM).

METHODS

The authors used retrospective and prospective components of the Park-Reeves Syringomyelia Research Consortium database to identify pediatric patients with CM1-SM who received PFD or PFDD and had at least 1 year of follow-up data. Preoperative, treatment, and postoperative characteristics were recorded and compared between groups.

RESULTS

A total of 692 patients met the inclusion criteria for this database study. PFD was performed in 117 (16.9%) and PFDD in 575 (83.1%) patients. The mean age at surgery was 9.86 years, and the mean follow-up time was 2.73 years. There were no significant differences in presenting signs or symptoms between groups, although the preoperative syrinx size was smaller in the PFD group. The PFD group had a shorter mean operating room time (p < 0.0001), fewer patients with > 50 mL of blood loss (p = 0.04), and shorter hospital stays (p = 0.0001). There were 4 intraoperative complications, all within the PFDD group (0.7%, p > 0.99). Patients undergoing PFDD had a 6-month complication rate of 24.3%, compared with 13.7% in the PFD group (p = 0.01). There were no differences between groups for postoperative complications beyond 6 months (p = 0.33). PFD patients were more likely to require revision surgery (17.9% vs 8.3%, p = 0.002). PFDD was associated with greater improvements in headaches (89.6% vs 80.8%, p = 0.04) and back pain (86.5% vs 59.1%, p = 0.01). There were no differences between groups for improvement in neurological examination findings. PFDD was associated with greater reduction in anteroposterior syrinx size (43.7% vs 26.9%, p = 0.0001) and syrinx length (18.9% vs 5.6%, p = 0.04) compared with PFD.

CONCLUSIONS

PFD was associated with reduced operative time and blood loss, shorter hospital stays, and fewer postoperative complications within 6 months. However, PFDD was associated with better symptom improvement and reduction in syrinx size and lower rates of revision decompression. The two surgeries have low intraoperative complication rates and comparable complication rates beyond 6 months.

Chiari malformation type 1 presenting as isolated unilateral foot drop with rapid recovery following posterior fossa decompression

BACKGROUND

Chiari malformation (CM) type 1 is characterized by descent of the cerebellar tonsils resulting from crowding of the posterior fossa. In 30% of cases, it is associated with syringomyelia. When symptomatic, it may result in a classic constellation of symptoms.

CASE PRESENTATION

Here we describe a case of a 16-year-old male who presented with isolated, unilateral foot drop due to CM type 1 and holosyrinx. This unique presentation is extremely rare, and we additionally present a review of all other reported cases in the literature. After undergoing posterior fossa decompression with C1 laminectomy and duraplasty, our patient made a complete neurological recovery within 2 weeks postoperatively and his MRI entire spine at 3 months postoperatively demonstrated a nearly complete resolution of the holosyrinx with significant decompression of the foramen magnum.

CONCLUSION

This rare presentation highlights the importance of maintaining a broad differential, particularly in pediatric patients, and expediting the workup in order to offer a surgical decompression within 1-2 months of foot weakness to maximize the probability of a full neurological recovery.

Upper extremity nerve transfers for acute flaccid myelitis: a systematic literature review

BACKGROUND

Acute flaccid myelitis (AFM) is a rare disease that commonly affects young children. AFM's pathophysiology involves loss of lower motor neurons following a viral infection and induces acute asymmetric flaccid paralysis most commonly in the upper extremities. Nerve transfers have emerged as a treatment option for these patients with permanent motor deficits.

OBJECTIVE

To summarize the literature and report safety and efficacy outcomes following nerve transfers for recovery of shoulder abduction and external rotation, and elbow flexion and extension in pediatric patients with AFM. Recovery of at least antigravity function was defined as a successful outcome. This systematic review was performed according to the PRISMA guidelines. The PubMed, Embase and Cochrane databases were utilized.

RESULTS

Five studies comprising 44 patients (median age 2.95 years; 71% male), and 93 upper extremity nerve transfers were included. Thirty-eight patients received 65 nerve transfer procedures aiming for recovery of shoulder abduction and/or external rotation with a transfer to the axillary and/or suprascapular nerve. The recovery of shoulder abduction and external rotation was achieved in 40.7% (n = 11/27) and 60% (n = 6/10) of patients, respectively. Time from injury to surgery showed an inverse relationship with the odds for successful recovery (OR: 0.81; 95% CI: 0.64-1.02; p = 0.07); however, statistical significance was not reached. Successful recovery of elbow flexion with a transfer to the musculocutaneous was reported at a rate of 92.3% (n = 12/13). Successful re-innervation of the radial nerve with recovery of elbow extension was found in 75% (n = 6/8) of patients. No complications were reported.

CONCLUSIONS

Upper extremity nerve transfers appear to be promising and safe for AFM patients. Shoulder abduction is the most challenging upper extremity function to recover. Further studies are warranted to identify whether nerve transfers are associated with superior outcomes when performed earlier.

Pediatric spinal intramedullary anaplastic myxopapillary ependymoma: a case report

A 6-year-old girl presented with a 1-week history of progressive upper and lower extremity weakness and bilateral upper extremity dysesthesia. Imaging demonstrated a 4.7 × 1.2-cm enhancing intramedullary lesion in the cervical spine from level C2 to C5 with associated cystic components and syringomyelia. The patient underwent a C2-C5 laminoplasty, with gross total resection of the intramedullary lesion. Histological analysis showed small to medium-sized epithelioid cells, with predominantly a solid architecture focally infiltrating into the adjacent spinal cord tissue. Focal papillary differentiation was present along with peri-vascular pseudorosettes, mucin microcysts, and globules of dense collagen. Focal anaplasia was noted with mitosis (5/10 HPF), focal necrosis, and elevated Ki67 10-15%. These findings were consistent with a myxopapillary ependymoma with anaplastic features. CSF cytology was negative for tumor cells. MYCN amplification was not present. She was treated with targeted proton-beam radiation therapy. This is the fourth case of an intramedullary anaplastic myxopapillary ependymoma to date, and the first case in the cervical spine reported in the literature.

Socioeconomic and demographic factors in the diagnosis and treatment of Chiari malformation type I and syringomyelia

OBJECTIVE

The goal of this study was to assess the social determinants that influence access and outcomes for pediatric neurosurgical care for patients with Chiari malformation type I (CM-I) and syringomyelia (SM).

METHODS

The authors used retro- and prospective components of the Park-Reeves Syringomyelia Research Consortium database to identify pediatric patients with CM-I and SM who received surgical treatment and had at least 1 year of follow-up data. Race, ethnicity, and insurance status were used as comparators for preoperative, treatment, and postoperative characteristics and outcomes.

RESULTS

A total of 637 patients met inclusion criteria, and race or ethnicity data were available for 603 (94.7%) patients. A total of 463 (76.8%) were non-Hispanic White (NHW) and 140 (23.2%) were non-White. The non-White patients were older at diagnosis (p = 0.002) and were more likely to have an individualized education plan (p < 0.01). More non-White than NHW patients presented with cerebellar and cranial nerve deficits (i.e., gait ataxia [p = 0.028], nystagmus [p = 0.002], dysconjugate gaze [p = 0.03], hearing loss [p = 0.003], gait instability [p = 0.003], tremor [p = 0.021], or dysmetria [p < 0.001]). Non-White patients had higher rates of skull malformation (p = 0.004), platybasia (p = 0.002), and basilar invagination (p = 0.036). Non-White patients were more likely to be treated at low-volume centers than at high-volume centers (38.7% vs 15.2%; p < 0.01). Non-White patients were older at the time of surgery (p = 0.001) and had longer operative times (p < 0.001), higher estimated blood loss (p < 0.001), and a longer hospital stay (p = 0.04). There were no major group differences in terms of treatments performed or complications. The majority of subjects used private insurance (440, 71.5%), whereas 175 (28.5%) were using Medicaid or self-pay. Private insurance was used in 42.2% of non-White patients compared to 79.8% of NHW patients (p < 0.01). There were no major differences in presentation, treatment, or outcome between insurance groups. In multivariate modeling, non-White patients were more likely to present at an older age after controlling for sex and insurance status (p < 0.01). Non-White and male patients had a longer duration of symptoms before reaching diagnosis (p = 0.033 and 0.004, respectively).

CONCLUSIONS

Socioeconomic and demographic factors appear to influence the presentation and management of patients with CM-I and SM. Race is associated with age and timing of diagnosis as well as operating room time, estimated blood loss, and length of hospital stay. This exploration of socioeconomic and demographic barriers to care will be useful in understanding how to improve access to pediatric neurosurgical care for patients with CM-I and SM.

Extradural decompression versus duraplasty in Chiari malformation type I with syrinx: outcomes on scoliosis from the Park-Reeves Syringomyelia Research Consortium

OBJECTIVE

Scoliosis is common in patients with Chiari malformation type I (CM-I)-associated syringomyelia. While it is known that treatment with posterior fossa decompression (PFD) may reduce the progression of scoliosis, it is unknown if decompression with duraplasty is superior to extradural decompression.

METHODS

A large multicenter retrospective and prospective registry of 1257 pediatric patients with CM-I (tonsils ≥ 5 mm below the foramen magnum) and syrinx (≥ 3 mm in axial width) was reviewed for patients with scoliosis who underwent PFD with or without duraplasty.

RESULTS

In total, 422 patients who underwent PFD had a clinical diagnosis of scoliosis. Of these patients, 346 underwent duraplasty, 51 received extradural decompression alone, and 25 were excluded because no data were available on the type of PFD. The mean clinical follow-up was 2.6 years. Overall, there was no difference in subsequent occurrence of fusion or proportion of patients with curve progression between those with and those without a duraplasty. However, after controlling for age, sex, preoperative curve magnitude, syrinx length, syrinx width, and holocord syrinx, extradural decompression was associated with curve progression > 10°, but not increased occurrence of fusion. Older age at PFD and larger preoperative curve magnitude were independently associated with subsequent occurrence of fusion. Greater syrinx reduction after PFD of either type was associated with decreased occurrence of fusion.

CONCLUSIONS

In patients with CM-I, syrinx, and scoliosis undergoing PFD, there was no difference in subsequent occurrence of surgical correction of scoliosis between those receiving a duraplasty and those with an extradural decompression. However, after controlling for preoperative factors including age, syrinx characteristics, and curve magnitude, patients treated with duraplasty were less likely to have curve progression than patients treated with extradural decompression. Further study is needed to evaluate the role of duraplasty in curve stabilization after PFD.

Occipital-Cervical Fusion and Ventral Decompression in the Surgical Management of Chiari-1 Malformation and Syringomyelia: Analysis of Data From the Park-Reeves Syringomyelia Research Consortium

BACKGROUND

Occipital-cervical fusion (OCF) and ventral decompression (VD) may be used in the treatment of pediatric Chiari-1 malformation (CM-1) with syringomyelia (SM) as adjuncts to posterior fossa decompression (PFD) for complex craniovertebral junction pathology.

OBJECTIVE

To examine factors influencing the use of OCF and OCF/VD in a multicenter cohort of pediatric CM-1 and SM subjects treated with PFD.

METHODS

The Park-Reeves Syringomyelia Research Consortium registry was used to examine 637 subjects with cerebellar tonsillar ectopia ≥ 5 mm, syrinx diameter ≥ 3 mm, and at least 1 yr of follow-up after their index PFD. Comparisons were made between subjects who received PFD alone and those with PFD + OCF or PFD + OCF/VD.

RESULTS

All 637 patients underwent PFD, 505 (79.2%) with and 132 (20.8%) without duraplasty. A total of 12 subjects went on to have OCF at some point in their management (PFD + OCF), whereas 4 had OCF and VD (PFD + OCF/VD). Of those with complete data, a history of platybasia (3/10, P = .011), Klippel-Feil (2/10, P = .015), and basilar invagination (3/12, P < .001) were increased within the OCF group, whereas only basilar invagination (1/4, P < .001) was increased in the OCF/VD group. Clivo-axial angle (CXA) was significantly lower for both OCF (128.8 ± 15.3°, P = .008) and OCF/VD (115.0 ± 11.6°, P = .025) groups when compared to PFD-only group (145.3 ± 12.7°). pB-C2 did not differ among groups.

CONCLUSION

Although PFD alone is adequate for treating the vast majority of CM-1/SM patients, OCF or OCF/VD may be occasionally utilized. Cranial base and spine pathologies and CXA may provide insight into the need for OCF and/or OCF/VD.

Dural augmentation approaches and complication rates after posterior fossa decompression for Chiari I malformation and syringomyelia: a Park-Reeves Syringomyelia Research Consortium study

OBJECTIVE

Posterior fossa decompression with duraplasty (PFDD) is commonly performed for Chiari I malformation (CM-I) with syringomyelia (SM). However, complication rates associated with various dural graft types are not well established. The objective of this study was to elucidate complication rates within 6 months of surgery among autograft and commonly used nonautologous grafts for pediatric patients who underwent PFDD for CM-I/SM.

METHODS

The Park-Reeves Syringomyelia Research Consortium database was queried for pediatric patients who had undergone PFDD for CM-I with SM. All patients had tonsillar ectopia ≥ 5 mm, syrinx diameter ≥ 3 mm, and ≥ 6 months of postoperative follow-up after PFDD. Complications (e.g., pseudomeningocele, CSF leak, meningitis, and hydrocephalus) and postoperative changes in syrinx size, headaches, and neck pain were compared for autograft versus nonautologous graft.

RESULTS

A total of 781 PFDD cases were analyzed (359 autograft, 422 nonautologous graft). Nonautologous grafts included bovine pericardium (n = 63), bovine collagen (n = 225), synthetic (n = 99), and human cadaveric allograft (n = 35). Autograft (103/359, 28.7%) had a similar overall complication rate compared to nonautologous graft (143/422, 33.9%) (p = 0.12). However, nonautologous graft was associated with significantly higher rates of pseudomeningocele (p = 0.04) and meningitis (p < 0.001). The higher rate of meningitis was influenced particularly by the higher rate of chemical meningitis (p = 0.002) versus infectious meningitis (p = 0.132). Among 4 types of nonautologous grafts, there were differences in complication rates (p = 0.02), including chemical meningitis (p = 0.01) and postoperative nausea/vomiting (p = 0.03). Allograft demonstrated the lowest complication rates overall (14.3%) and yielded significantly fewer complications compared to bovine collagen (p = 0.02) and synthetic (p = 0.003) grafts. Synthetic graft yielded higher complication rates than autograft (p = 0.01). Autograft and nonautologous graft resulted in equal improvements in syrinx size (p < 0.0001). No differences were found for postoperative changes in headaches or neck pain.

CONCLUSIONS

In the largest multicenter cohort to date, complication rates for dural autograft and nonautologous graft are similar after PFDD for CM-I/SM, although nonautologous graft results in higher rates of pseudomeningocele and meningitis. Rates of meningitis differ among nonautologous graft types. Autograft and nonautologous graft are equivalent for reducing syrinx size, headaches, and neck pain.

Factors associated with syrinx size in pediatric patients treated for Chiari malformation type I and syringomyelia: a study from the Park-Reeves Syringomyelia Research Consortium

OBJECTIVE

Factors associated with syrinx size in pediatric patients undergoing posterior fossa decompression (PFD) or PFD with duraplasty (PFDD) for Chiari malformation type I (CM-I) with syringomyelia (SM; CM-I+SM) are not well established.

METHODS

Using the Park-Reeves Syringomyelia Research Consortium registry, the authors analyzed variables associated with syrinx radiological outcomes in patients (< 20 years old at the time of surgery) with CM-I+SM undergoing PFD or PFDD. Syrinx resolution was defined as an anteroposterior (AP) diameter of ≤ 2 mm or ≤ 3 mm or a reduction in AP diameter of ≥ 50%. Syrinx regression or progression was defined using 1) change in syrinx AP diameter (≥ 1 mm), or 2) change in syrinx length (craniocaudal, ≥ 1 vertebral level). Syrinx stability was defined as a < 1-mm change in syrinx AP diameter and no change in syrinx length.

RESULTS

The authors identified 380 patients with CM-I+SM who underwent PFD or PFDD. Cox proportional hazards modeling revealed younger age at surgery and PFDD as being independently associated with syrinx resolution, defined as a ≤ 2-mm or ≤ 3-mm AP diameter or ≥ 50% reduction in AP diameter. Radiological syrinx resolution was associated with improvement in headache (p < 0.005) and neck pain (p < 0.011) after PFD or PFDD. Next, PFDD (p = 0.005), scoliosis (p = 0.007), and syrinx location across multiple spinal segments (p = 0.001) were associated with syrinx diameter regression, whereas increased preoperative frontal-occipital horn ratio (FOHR; p = 0.007) and syrinx location spanning multiple spinal segments (p = 0.04) were associated with syrinx length regression. Scoliosis (HR 0.38 [95% CI 0.16-0.91], p = 0.03) and smaller syrinx diameter (5.82 ± 3.38 vs 7.86 ± 3.05 mm; HR 0.60 [95% CI 0.34-1.03], p = 0.002) were associated with syrinx diameter stability, whereas shorter preoperative syrinx length (5.75 ± 4.01 vs 9.65 ± 4.31 levels; HR 0.21 [95% CI 0.12-0.38], p = 0.0001) and smaller pB-C2 distance (6.86 ± 1.27 vs 7.18 ± 1.38 mm; HR 1.44 [95% CI 1.02-2.05], p = 0.04) were associated with syrinx length stability. Finally, younger age at surgery (8.19 ± 5.02 vs 10.29 ± 4.25 years; HR 1.89 [95% CI 1.31-3.04], p = 0.01) was associated with syrinx diameter progression, whereas increased postoperative syrinx diameter (6.73 ± 3.64 vs 3.97 ± 3.07 mm; HR 3.10 [95% CI 1.67-5.76], p = 0.003), was associated with syrinx length progression. PFD versus PFDD was not associated with syrinx progression or reoperation rate.

CONCLUSIONS

These data suggest that PFDD and age are independently associated with radiological syrinx improvement, although forthcoming results from the PFDD versus PFD randomized controlled trial (NCT02669836, clinicaltrials.gov) will best answer this question.

Infratentorial choroid plexus tumors in children

OBJECTIVE

Choroid plexus tumors (CPTs) are rare pediatric intracranial neoplasms, and mostly occur in the lateral ventricle. CPTs located in the infratentorial location are considered to be rare in the pediatric population. We present a series of eight patients treated in the last decade at our institution focusing on clinical presentations and their outcome after excision.

METHODS

We performed an institutional retrospective review of patients who underwent surgical resection of infratentorial CPTs during the period from 2008 to 2017. Patients' charts were reviewed for demographic data, clinical presentation, surgical treatment, and follow-up.

RESULTS

There were eight patients (6 females and 2 males), with mean age for the cohort at presentation was 9.0 years. They represent 75% of 12 CPTs of all locations treated at the same period in our institution. These 8 infratentorial CPTs were in the fourth ventricle in seven, and in the cerebellopontine angle (CPA) in one. Seven patients had choroid plexus papillomas (WHO grade I) and 1 had an atypical choroid plexus papilloma (WHO grade II). Gross total resection was attempted in all patients. However, two of 3 patients with fourth ventricle floor invasion had subtotal resection with a thin layer of tumor left on the floor. The remaining 6 had a gross total resection. Six patients with preoperative hydrocephalus had a perioperative external ventricular drainage but none required permanent shunting after tumor resection. None showed recurrence/tumor progression without adjuvant therapy during the follow-up period of 20 months to 11 years.

CONCLUSION

Infratentorial dominance among pediatric CPTs in this series contradicts previous reports. Infratentorial CPTs are amenable to surgical resection. Unresected small residuals due to invasion to the fourth ventricle floor showed no regrowth during 2 to 3 years follow-up without adjuvant therapy. However, these patients with incomplete resection need watchful observations.

Nasal dermoid cysts with intracranial extension: avoiding coronal incision through midline exposure and nasal bone osteotomy

OBJECTIVE

Up to 10% of midline nasal dermoid cysts have intracranial extension. Previous techniques of excision include frontal and frontonasal craniotomies via a coronal approach, combined with a direct cutaneous excision of the dermoid cyst. While the coronal incision allows for wide visualization, it carries significant risks of transfusion, blood loss, and scarring. The authors present an alternative technique in which access is gained through a midline extension of the dermoid cyst excision that provides direct access for a keyhole frontal craniotomy.

METHODS

The authors utilize a nasal bone osteotomy, pericranial flap, and keyhole-type craniotomy performed through a nasal midline incision for the treatment of nasal dermoid cysts with intracranial extension. They performed a retrospective chart review of all patients with nasal dermoid cysts treated at the Ann & Robert H. Lurie Children's Hospital of Chicago from 2009 to 2017. Patient demographic data, operative data, and in- and outpatient complication data were collected.

RESULTS

In 10 patients with cyst extension near or into the intracranial cavity (7 with true intracranial extension), the nasal osteotomy technique was performed. The mean blood loss was 13 ml, with a 0% transfusion rate. The mean length of inpatient stay was 1 day. A durotomy was made and repaired as part of the dermoid cyst dissection in 3 patients. One patient underwent intraoperative placement of a lumbar drain. The mean operative time was 228 minutes. There were no intraoperative or postoperative complications, including the need for a reoperation. No patients had any long-term complications, and no patients have had dermoid cyst recurrence. The appearance of the scar was acceptable in all cases.

CONCLUSIONS

The midline approach to nasal dermoid cysts with intracranial extension is safe and results in limited blood loss, short operative times, and short lengths of inpatient hospital stay. This is a viable technique for the treatment of this challenging pathology.

Radiological and clinical predictors of scoliosis in patients with Chiari malformation type I and spinal cord syrinx from the Park-Reeves Syringomyelia Research Consortium

OBJECTIVE

Scoliosis is frequently a presenting sign of Chiari malformation type I (CM-I) with syrinx. The authors' goal was to define scoliosis in this population and describe how radiological characteristics of CM-I and syrinx relate to the presence and severity of scoliosis.

METHODS

A large multicenter retrospective and prospective registry of pediatric patients with CM-I (tonsils ≥ 5 mm below the foramen magnum) and syrinx (≥ 3 mm in axial width) was reviewed for clinical and radiological characteristics of CM-I, syrinx, and scoliosis (coronal curve ≥ 10°).

RESULTS

Based on available imaging of patients with CM-I and syrinx, 260 of 825 patients (31%) had a clear diagnosis of scoliosis based on radiographs or coronal MRI. Forty-nine patients (5.9%) did not have scoliosis, and in 516 (63%) patients, a clear determination of the presence or absence of scoliosis could not be made. Comparison of patients with and those without a definite scoliosis diagnosis indicated that scoliosis was associated with wider syrinxes (8.7 vs 6.3 mm, OR 1.25, p < 0.001), longer syrinxes (10.3 vs 6.2 levels, OR 1.18, p < 0.001), syrinxes with their rostral extent located in the cervical spine (94% vs 80%, OR 3.91, p = 0.001), and holocord syrinxes (50% vs 16%, OR 5.61, p < 0.001). Multivariable regression analysis revealed syrinx length and the presence of holocord syrinx to be independent predictors of scoliosis in this patient cohort. Scoliosis was not associated with sex, age at CM-I diagnosis, tonsil position, pB-C2 distance (measured perpendicular distance from the ventral dura to a line drawn from the basion to the posterior-inferior aspect of C2), clivoaxial angle, or frontal-occipital horn ratio. Average curve magnitude was 29.9°, and 37.7% of patients had a left thoracic curve. Older age at CM-I or syrinx diagnosis (p < 0.0001) was associated with greater curve magnitude whereas there was no association between syrinx dimensions and curve magnitude.

CONCLUSIONS

Syrinx characteristics, but not tonsil position, were related to the presence of scoliosis in patients with CM-I, and there was an independent association of syrinx length and holocord syrinx with scoliosis. Further study is needed to evaluate the nature of the relationship between syrinx and scoliosis in patients with CM-I.

Pediatric primary spinal atypical teratoid rhabdoid tumor: a case series and review of the literature

Atypical teratoid rhabdoid tumors (ATRTs) are rare malignant central nervous system tumors, commonly occurring before 3 years of age. Median overall survival (OS) of patients with these tumors is about 1 year, despite aggressive multimodal therapy. Pediatric primary spinal ATRTs are even more rare, with fewer than 50 cases reported. The authors present a series of four patients who were treated at Ann and Robert H. Lurie Children's Hospital of Chicago in the period from 1996 to 2017.These patients, with ages 2-11 years, presented with pain and a decline in motor functions. They were found to have lesions in the lumbar, thoracic, and/or cervical spine. One patient's tumor was intramedullary with exophytic components, while another patient's tumor had both intra- and extradural components. All patients underwent resection followed by chemotherapy (systemic and intrathecal). Two patients had fractionated radiation therapy and one had an autologous stem cell transplant. Three patients are known to be deceased (OS 8.5-45 months). The fourth patient was in remission 19 years after her initial diagnosis. To the authors' knowledge, this is the largest series of pediatric primary spinal ATRTs documented at a single institution. These cases illustrate a variety of presentations of spinal ATRT and add to the body of literature on this aggressive pathology.A systematic MEDLINE search was also conducted using the keywords "atypical teratoid rhabdoid tumor," "pediatric spinal rhabdoid tumor," and "malignant rhabdoid tumor spine." Reports were included for patients younger than 21 years, without evidence of intracranial or systemic disease at the time of diagnosis. Clinical characteristics and outcomes of the four institutional cases were compared to those in the literature. This review yielded an additional 48 cases of primary pediatric spinal ATRTs reported in the English-language literature. Patients (ages 2 months to 19 years) presented with symptoms of pain, regression of motor function, and spinal cord compression. The majority of tumors were intradural (14 extramedullary, 8 intramedullary, 1 both). Eleven cases in the literature described tumors limited to extradural structures, while 10 tumors involved the intra- and extradural spine. Four reports did not specify tumor location. Although rare, spinal ATRT should be considered in the differential diagnosis of pediatric patients presenting with a new spinal mass.

Recommendations for the management of MPS IVA: systematic evidence- and consensus-based guidance

INTRODUCTION

Mucopolysaccharidosis (MPS) IVA or Morquio A syndrome is an autosomal recessive lysosomal storage disorder (LSD) caused by deficiency of the N-acetylgalactosamine-6-sulfatase (GALNS) enzyme, which impairs lysosomal degradation of keratan sulphate and chondroitin-6-sulphate. The multiple clinical manifestations of MPS IVA present numerous challenges for management and necessitate the need for individualised treatment. Although treatment guidelines are available, the methodology used to develop this guidance has come under increased scrutiny. This programme was conducted to provide evidence-based, expert-agreed recommendations to optimise management of MPS IVA.

METHODS

Twenty six international healthcare professionals across multiple disciplines, with expertise in managing MPS IVA, and three patient advocates formed the Steering Committee (SC) and contributed to the development of this guidance. Representatives from six Patient Advocacy Groups (PAGs) were interviewed to gain insights on patient perspectives. A modified-Delphi methodology was used to demonstrate consensus among a wider group of healthcare professionals with experience managing patients with MPS IVA and the manuscript was evaluated against the validated Appraisal of Guidelines for Research and Evaluation (AGREE II) instrument by three independent reviewers.

RESULTS

A total of 87 guidance statements were developed covering five domains: (1) general management principles; (2) recommended routine monitoring and assessments; (3) disease-modifying interventions (enzyme replacement therapy [ERT] and haematopoietic stem cell transplantation [HSCT]); (4) interventions to support respiratory and sleep disorders; (5) anaesthetics and surgical interventions (including spinal, limb, ophthalmic, cardio-thoracic and ear-nose-throat [ENT] surgeries). Consensus was reached on all statements after two rounds of voting. The overall guideline AGREE II assessment score obtained for the development of the guidance was 5.3/7 (where 1 represents the lowest quality and 7 represents the highest quality of guidance).

CONCLUSION

This manuscript provides evidence- and consensus-based recommendations for the management of patients with MPS IVA and is for use by healthcare professionals that manage the holistic care of patients with the intention to improve clinical- and patient-reported outcomes and enhance patient quality of life. It is recognised that the guidance provided represents a point in time and further research is required to address current knowledge and evidence gaps.

Recommendations for the management of MPS VI: systematic evidence- and consensus-based guidance

Introduction

Mucopolysaccharidosis (MPS) VI or Maroteaux-Lamy syndrome (253200) is an autosomal recessive lysosomal storage disorder caused by deficiency in N-acetylgalactosamine-4-sulfatase (arylsulfatase B). The heterogeneity and progressive nature of MPS VI necessitates a multidisciplinary team approach and there is a need for robust guidance to achieve optimal management. This programme was convened to develop evidence-based, expert-agreed recommendations for the general principles of management, routine monitoring requirements and the use of medical and surgical interventions in patients with MPS VI.

Methods

26 international healthcare professionals from various disciplines, all with expertise in managing MPS VI, and three patient advocates formed the Steering Committee group (SC) and contributed to the development of this guidance. Members from six Patient Advocacy Groups (PAGs) acted as advisors and attended interviews to ensure representation of the patient perspective. A modified-Delphi methodology was used to demonstrate consensus among a wider group of healthcare professionals with expertise and experience managing patients with MPS VI and the manuscript has been evaluated against the validated Appraisal of Guidelines for Research and Evaluation (AGREE II) instrument by three independent reviewers.

Results

A total of 93 guidance statements were developed covering five domains: (1) general management principles; (2) recommended routine monitoring and assessments; (3) enzyme replacement therapy (ERT) and hematopoietic stem cell transplantation (HSCT); (4) interventions to support respiratory and sleep disorders; (5) anaesthetics and surgical interventions. Consensus was reached on all statements after two rounds of voting. The greatest challenges faced by patients as relayed by consultation with PAGs were deficits in endurance, dexterity, hearing, vision and respiratory function. The overall guideline AGREE II assessment score obtained for the development of the guidance was 5.3/7 (where 1 represents the lowest quality and 7 represents the highest quality of guidance).

Conclusion

This manuscript provides evidence- and consensus-based recommendations for the management of patients with MPS VI and is for use by healthcare professionals that manage the holistic care of patients with the intention to improve clinical- and patient-reported outcomes and enhance patient quality of life. It is recognised that the guidance provided represents a point in time and further research is required to address current knowledge and evidence gaps.

Electronic supplementary material

The online version of this article (10.1186/s13023-019-1080-y) contains supplementary material, which is available to authorized users.

Standardized Evaluation of Cerebral Arteriovenous Malformations Using Flow Distribution Network Graphs and Dual-venc 4D Flow MRI

BACKGROUND

Cerebral arteriovenous malformations (AVMs) are pathological connections between arteries and veins. Dual-venc 4D flow MRI, an extended 4D flow MRI method with improved velocity dynamic range, provides time-resolved 3D cerebral hemodynamics.

PURPOSE

To optimize dual-venc 4D flow imaging parameters for AVM; to assess the relationship between spatial resolution, acceleration, and flow quantification accuracy; and to introduce and apply the flow distribution network graph (FDNG) paradigm for storing and analyzing complex neurovascular 4D flow data.

STUDY TYPE

Retrospective cohort study.

SUBJECTS/PHANTOM

Scans were performed in a specialized flow phantom: 26 healthy subjects (age 41 ± 17 years) and five AVM patients (age 27-68 years).

FIELD STRENGTH/SEQUENCE

Dual-venc 4D flow with varying spatial resolution and acceleration factors were performed at 3T field strength.

ASSESSMENT

Quantification accuracy was assessed in vitro by direct comparison to measured flow. FDNGs were used to quantify and compare flow, peak velocity (PV), and pulsatility index (PI) between healthy controls with various Circle of Willis (CoW) anatomy and AVM patients.

STATISTICAL TESTS

In vitro measurements were compared to ground truth with Student's t-test. In vivo groups were compared with Wilcoxon rank-sum test and Kruskal-Wallis test.

RESULTS

Flow was overestimated in all in vitro experiments, by an average 7.1 ± 1.4% for all measurement conditions. Error in flow measurement was significantly correlated with number of voxels across the channel (P = 3.11 × 10^-28 ) but not with acceleration factor (P = 0.74). For the venous-arterial PV and PI ratios, a significant difference was found between AVM nidal and extranidal circulation (P = 0.008 and 0.05, respectively), and between AVM nidal and healthy control circulation (P = 0.005 and 0.003, respectively).

DATA CONCLUSION

Dual-venc 4D flow MRI and standardized FDNG analysis might be feasible in clinical applications. Venous-arterial ratios of PV and PI are proposed as network-based biomarkers characterizing AVM nidal hemodynamics.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;50:1718-1730.

Choroidal artery embolization in the management of cerebrospinal fluid overproduction: case report and review of the literature

Diffuse villous hyperplasia of the choroid plexus (DVHCP) is a rare cause of communicating hydrocephalus. DVHCP may be diagnosed radiographically and through histological evaluation. It may be associated with genetic abnormalities, particularly involving chromosome 9. Due to CSF overproduction, patients with DVHCP often fail management with shunting alone and may require adjuvant interventions. The authors present the case of a child with partial trisomy 9p and delayed diagnosis of hydrocephalus with radiographic evidence of DVHCP who was successfully managed with ventriculoperitoneal shunt (VPS) placement, adjuvant bilateral endoscopic choroid plexus coagulation (CPC), and the novel application of anterior choroidal artery embolization. In addition, a systematic MEDLINE search was conducted using the keywords "diffuse villous hyperplasia," "choroid plexus hypertrophy," and "idiopathic cerebrospinal fluid overproduction." Clinicopathological characteristics and outcomes of the present case were reviewed and compared to those in the literature.A 14-month-old girl with partial trisomy 9p presented with macrocephaly and radiographic evidence of communicating hydrocephalus and DVHCP. Ventriculoperitoneal shunting resulted in distal failure due to inadequate CSF absorption, and ventriculoatrial shunt (VAS) placement was not possible due to multiple cardiac anomalies. Daily CSF production was reduced via endoscopic third ventriculostomy and bilateral CPC, followed by distal choroidal artery embolization, enabling VPS re-internalization. The embolization was complicated by radiographic evidence of an iatrogenic cerebral infarct, but this was clinically occult. Thirty-two additional cases of communicating hydrocephalus due to DVHCP are reported in the literature: 27 pediatric, 3 adult, and 2 postmortem. Genetic abnormalities were noted in 14, with 7 (50%) involving chromosome 9. Twelve patients underwent plexectomy (9 bilateral, 2 unilateral, 1 partial), and 10 underwent CPC (4 bilateral, 3 unilateral, and 3 unspecified), with or without shunting. Eight patients were successfully managed with shunting alone (6 VASs, 2 VPSs), and none underwent arterial embolization.DVHCP is a rare cause of communicating hydrocephalus that may be associated with genetic abnormalities. A thorough review of the literature highlights diagnostic criteria and interventional options involved in managing this cause of CSF overproduction. The present case demonstrates that angiographic confirmation of prominent choroidal arteries may contribute to the diagnosis DVHCP. In addition, embolization of the distal choroidal arteries may be considered as a potential adjuvant treatment in patients for whom conventional treatments have failed or are not feasible.

Safety and outcome of combined endovascular and surgical management of low grade cerebral arteriovenous malformations in children compared to surgery alone

PURPOSE

To evaluate the outcomes of combined preoperative embolization and microsurgical resection in comparison with microsurgical resection alone as the current standard of care for low-grade cerebral arteriovenous malformations (AVM) in the pediatric population.

MATERIALS & METHODS

We performed a single-center retrospective study of pediatric patients presenting with Spetzler-Martin (SM) grade I and II cerebral AVMs at a high-volume tertiary pediatric hospital between January 2005 and September 2016. Low grade AVM patients were divided into two groups: pre-operative embolization with subsequent microsurgical resection or microsurgical resection alone. Patient demographics, clinical and imaging presentations, AVM morphological characteristics, post-operative complications, and mid to long-term clinical outcomes were studied. Post-embolization and post-surgical outcomes were assessed prior to and after treatment, at 3 months and at final follow-up using the modified Rankin Scale (mRS) to compare both final independent (mRS 0-2) and favorable (no change or improved mRS) clinical outcomes for comparison between study groups. Statistical associations of patient demographics, AVM characteristics/SM grading, and treatment modality group with post-operative complications were performed using univariate logistic regression analysis.

RESULTS

Thirty-four patients with low grade cerebral AVMs met the study inclusion criteria (mean age 10.6 ± 3.4 years; range 3-16 years, 22M:12 F). Twenty patients (59%) presented with ruptured AVMs. Twenty-five patients (73.5%) underwent combined treatment with embolization and microsurgical resection, while 9/34 (26.5%) underwent microsurgical resection alone. A total of 35 embolization procedures performed in 25 patients (Mode, 1; Range, 1-7) were associated with two minor post-embolization and 7 subsequent post-surgical (28%) complications, resulting in clinical deterioration in a single patient. Microsurgical resection alone was associated with 3 post-surgical complications (33%), resulting in permanent neurological disability in a single patient. There was no significance association of post-operative complications with either treatment modality group, combined treatment versus surgical resection alone [OR:1.13; 95% CI:0.23-5.62; p-value 0.88]. SM Grade II and eloquent locations were found to be significantly associated with post-surgical complications of low grade pediatric cerebral AVMs [OR 13.2 and OR 8 respectively, p-value 0.004 and 0.005). On mean follow-up time of 35.7 months, final clinical outcome was favorable in the majority of both treatment arms with no dependent (mRS>2) patients in the combined endovascular and surgical cohort. Two patients in the surgical cohort failed to achieve independent functional status, primarily due to a pre-operative morbid status (p-value 0.015). However, there was no significant difference in favorable outcomes between the treatment groups [p-value 0.14].

CONCLUSION

Our study suggests equivalent safety and favorable clinical outcomes related to combined endovascular embolization and microsurgical resection of low grade pediatric cerebral AVMs in comparison to microsurgical resection alone. On long term clinical follow-up, the vast majority of patients achieved an independent and favorable functional status irrespective of pre-operative embolization.

MynxGrip vascular closure device use in pediatric neurointerventional procedures

OBJECTIVE The aim of this paper was assess the efficacy and safety of using the MynxGrip arterial closure device in pediatric neuroendovascular procedures where the use of closure devices remains off-label despite their validation and widespread use in adults. METHODS A retrospective review of all pediatric patients who underwent diagnostic or interventional neuroendovascular procedures at the authors' institution was performed. MynxGrip use was predicated by an adequate depth of subcutaneous tissue and common femoral artery (CFA) diameter. Patients remained on supine bedrest for 2 hours after diagnostic procedures and for 3 hours after therapeutic procedures. Patient demographics, procedural details, hemostasis status, and complications were recorded. RESULTS Over 36 months, 83 MynxGrip devices were deployed in 53 patients (23 male and 30 female patients; mean age 14 years) who underwent neuroendovascular procedures. The right-side CFA was the main point of access for most procedures. The mean CFA diameter was 6.24 mm and ranged from 4 mm to 8.5 mm. Diagnostic angiography comprised 46% of the procedures. A single device failure occurred without any sequelae; the device was extracted, and hemostasis was achieved by manual compression with the placement of a Safeguard compression device. No other immediate or delayed major complications were recorded. CONCLUSIONS MynxGrip can be used safely in the pediatric population for effective hemostasis and has the advantage of earlier mobilization.

Peripherally derived T regulatory and γδ T cells have opposing roles in the pathogenesis of intractable pediatric epilepsy

Xu et al. provide the first study in patients with intractable epilepsy showing a direct correlation between the phenotype, activation state, cytokine profiles, and ability to cause neuronal apoptosis of brain-infiltrating peripherally derived immune cells with seizure severity using an unbiased flow cytometric approach.

The pathophysiology of drug-resistant pediatric epilepsy is unknown. Flow cytometric analysis of inflammatory leukocytes in resected brain tissues from 29 pediatric patients with genetic (focal cortical dysplasia) or acquired (encephalomalacia) epilepsy demonstrated significant brain infiltration of blood-borne inflammatory myeloid cells and memory CD4⁺ and CD8⁺ T cells. Significantly, proinflammatory (IL-17– and GM-CSF–producing) γδ T cells were concentrated in epileptogenic lesions, and their numbers positively correlated with disease severity. Conversely, numbers of regulatory T (T reg) cells inversely correlated with disease severity. Correspondingly, using the kainic acid model of status epilepticus, we show ameliorated seizure activity in both γδ T cell– and IL-17RA–deficient mice and in recipients of T reg cells, whereas T reg cell depletion heightened seizure severity. Moreover, both IL-17 and GM-CSF induced neuronal hyperexcitability in brain slice cultures. These studies support a major pathological role for peripherally derived innate and adaptive proinflammatory immune responses in the pathogenesis of intractable epilepsy and suggest testing of immunomodulatory therapies.

The rare case of a large complex intraosseous cranial arteriovenous malformation with successful multidisciplinary management

Intraosseous cranial arteriovenous malformations (AVMs) are very rare, challenging entities. The authors report the case of an extracranial parietooccipital vascular lesion. A 12-year-old boy presented with accelerated growth of a right scalp lesion over a few months. Digital subtraction angiography showed a large, right parietooccipital intraosseous AVM with multiple complex arterial feeders. Treatment of these lesions is difficult and can necessitate a multidisciplinary approach. In the featured case, 6 embolization procedures were performed over 1 year, including both transarterial and transvenous approaches, followed by total resection. The authors describe what is thought to be the second case of an AVM originating in the cranial bones and the first case with successful multidisciplinary management.

Surgical management of neurological manifestations of mucopolysaccharidosis disorders

The mucopolysaccharidosis (MPS) disorders are ultra-rare lysosomal storage disorders associated with progressive accumulation of glycosaminoglycans (GAGs) in cells and tissues throughout the body. Clinical manifestations and progression rates vary widely across and within the different types of MPS. Neurological symptoms occur frequently, and may result directly from brain damage caused by infiltration of GAGs, or develop secondary to somatic manifestations such as spinal cord compression, hydrocephalus, and peripheral nerve entrapment. Management of secondary neurological manifestations often requires surgical correction of the underlying somatic cause. The present review discusses the surgical management of neurological disease in patients with MPS, including diagnostic imaging. Background information is derived from presentations and discussions during a meeting on the brain in MPS, attended by an international group of experts (April 28-30, 2016, Stockholm, Sweden), and additional literature searches.

Seizure Outcomes in Children Following Electrocorticography-Guided Single-Stage Surgical Resection

BACKGROUND

In children with abnormal imaging, single-stage epilepsy surgery is an attractive alternative to the two-stage approach that relies on invasive recording of seizures. Implanted electrodes carry risks of their own and extend hospitalization, but the efficacy of one-stage resections in a variety of pathologies and cerebral locations is not well established. We report our center's experience with single-stage epilepsy surgery guided by intraoperative electrocorticography (ECoG).

METHODS

We retrospectively analyzed 130 consecutive patients who underwent single-stage epilepsy surgery before age 19 years and had at least a two-year follow-up. Intraoperative ECoG was available for review in 113. Patients were considered seizure-free if they were continuously Engel Class I up to the two-year postoperative mark. ECoG findings were classified according to the presence of interictal attenuation, spikes, both, or neither. Complications and hospital length of stay were evaluated.

RESULTS

Eighty percent of 130 patients were seizure-free at two years. All but one had an abnormal MRI. Patients with tumor had a better seizure outcome than patients with cortical malformation. Frontal resections had worse outcome, especially among tumors. Intraoperative ECoG revealed both attenuation and spikes in 48%, attenuation only in 23%, spikes only in 20%, and neither in 9%. The complication rate was 6.9%, with no major neurological complications. The average length of stay was 5.7 nights.

CONCLUSIONS

With ECoG-guided single-stage surgery, we achieved results comparable with other pediatric surgical series and with a low complication rate. An extensive two-stage approach may not be required when there is a lesion on imaging and other information is concordant, even when the MRI abnormality is subtle and unclearly delineated. Frontal foci may present a challenge because of their proximity to "eloquent" nonresectable cortex or critical structures.

Familial incidence of the congenital torcular dural arteriovenous shunt: Case report and review of the literature

Congenital dural sinus malformations are rare but can be major causes of mortality and morbidity in the pediatric population if not detected and managed urgently. Lesions involving large draining sinus structures such as superior sagittal sinus and torcular herophili can result in significant intracranial circulation impairment mostly due to venous drainage disturbance. Early detection plays a pivotal role in the outcome of the patients. Rarely familial incidence of some types of arteriovenous malformations in isolation from other congenital hereditary disorders has been reported. Knowledge of the familial association of congenital dural sinus malformations may raise the awareness for considering the possibility of occurrence of these lesions in the relatives of index cases. Herein, we describe the occurrence of giant torcular dural shunt in two pediatric cousins treated with endovascular embolization.

Pediatric skull base reconstruction: case report of a tunneled temporoparietal fascia flap

The authors of this report present a pediatric case involving the use of a tunneled temporoparietal fascia flap to reconstruct a skull base defect for a multiply recurrent clival chordoma and cerebrospinal fluid leak, demonstrate the surgical technique through illustrations and intraoperative photos, and review the pertinent literature. A 9-year-old female patient underwent extensive clival chordoma resection via both the endoscopic and open approaches, which ultimately exhausted the bilateral nasoseptal flaps and other intranasal reconstructive options. Following proton beam radiation and initiation of chemotherapy, tumor recurrence was managed with further endoscopic resection, which was complicated by a recalcitrant cerebrospinal fluid leak. A tunneled temporoparietal fascia flap was used to provide vascular tissue to augment an endoscopic repair of the leak and reconstruction of the skull base. While the nasoseptal flap remains the workhorse for many pediatric and adult endoscopic skull base reconstructions, the tunneled temporoparietal fascia flap has a demonstrated efficacy in adults when the nasoseptal flap and other intranasal flaps are unavailable. This report documents a pediatric case, serving as a step toward establishing this technique in the pediatric population.

Focal stenosis of the sigmoid sinus causing intracranial venous hypertension: Case report, endovascular management, and review of the literature

Regardless of the underlying pathology, elevated intracranial pressure is the endpoint of any impairment in either cerebrospinal fluid (CSF) absorption (including arachnoid villi) or intracranial venous drainage. In all age groups, the predominant final common pathway for CSF drainage is the dural venous sinus system. Intracranial venous hypertension (ICVH) is an important vascular cause of intracranial hypertension (and its subsequent sequelae), which has often been ignored due to excessive attention to the arterial system and, specifically, arteriovenous shunts. Various anatomical and pathological entities have been described to cause ICVH. For the second time, we present a unique case of severe focal stenosis in the distal sigmoid sinus associated with concurrent hypoplasia of the contralateral transverse sinus causing a significant pressure gradient and intracranial hypertension, which was treated with endovascular stent placement and angioplasty.

Squamosal Suture Craniosynostosis Due to Hyperthyroidism Caused by an Activating Thyrotropin Receptor Mutation (T632I)

BACKGROUND

Congenital hyperthyroidism can be a cause of failure to thrive, hyperactivity, developmental delay, and craniosynostosis during infancy. Most commonly, the condition occurs in the setting of maternal autoimmune thyroid disease. Rarely, congenital hyperthyroidism can also occur secondary to activating mutations within the thyrotropin (TSH) receptor.

PATIENT FINDINGS

A Hispanic male infant presented at age 6 months with severe thyrotoxicosis. At the time of presentation he was being evaluated for squamosal suture synostosis and he was noted to have significant developmental delays.

SUMMARY

The patient's thyrotoxicosis was initially treated with antithyroid medication, and he subsequently underwent craniosynostosis repair leading to neurodevelopmental improvement. DNA from the patient and his parents was submitted for mutational analysis of exons 9 and 10 of the TSH receptor. He was found to carry a monoallelic transition 1895C>T in exon 10 that resulted in the substitution of threonine at position 632 by isoleucine (T32I). This mutation resulted in constitutive activation of the TSH receptor. Neither parent carried this mutation indicating that the child has acquired a de novo germline mutation.

CONCLUSIONS

We report the first case of squamosal suture craniosynostosis in a patient with non-autoimmune hyperthyroidism. Squamosal suture craniosynotosis is rare, often has a subtle presentation, and should be considered in all patients with this condition because prompt treatment of hyperthyroidism and craniosynotosis repair can lead to normalization of neurodevelopment.

Endoscopic endonasal surgery for sinonasal and skull base lesions in the pediatric population

Endoscopic endonasal skull base surgical techniques, initially developed in adult patients, are being utilized with increasing frequency in pediatric patients to treat sinonasal and skull base lesions. This article reviews the current state of endoscopic endonasal approaches to the skull base to both treat disease and reconstruct the skull base in pediatric patients. Sinonasal and skull base embryology and anatomy are reviewed as a foundation for understanding the disease processes and surgical techniques. Selected skull base pathologies and conditions that involve the pediatric skull base are also reviewed.

Diagnostic evaluation, monitoring, and perioperative management of spinal cord compression in patients with Morquio syndrome

Mucopolysaccharidosis IVA is an autosomal recessive condition caused by mutations in the GALNS gene, which encodes N-acetylgalactosamine-6-sulfatase, also called galactosamine-6-sulfatase (GALNS). A reduction in or absence of effective GALNS leads to faulty catabolism of keratan sulfate and chondroitin-6-sulfate within the lysosome; their accumulation causes cell, tissue, and organ dysfunction. The connective tissue, cartilage, ligaments, and bone of patients with Morquio A syndrome are particularly affected. Patients with Morquio A syndrome are at high risk of neurological complications because of their skeletal abnormalities; many patients are in danger of cervical myelopathy due to odontoid hypoplasia and ligamentous laxity leading to atlantoaxial subluxation. The multisystemic involvement of patients with Morquio A syndrome requires treatment by multidisciplinary teams; not all members of these teams may be aware of the potential for subluxation and quadriparesis. A multinational, multidisciplinary panel of 10 skeletal dysplasia or Morquio A syndrome specialists convened in Miami, FL on December 7 and 8, 2012 to develop consensus recommendations for early identification and effective management of spinal cord compression, for anesthesia and surgical best practices, and for effectual cardiac and respiratory management in patients with Morquio A syndrome. The target audience for these recommendations includes any physician who may encounter a patient with Morquio A syndrome, however doctors who do not have access to the full spectrum of specialists and resources needed to support patients with Morquio A syndrome should attempt to refer patients to a center that does. Physicians who manage Morquio A syndrome or comorbid conditions within specialty centers should review these expert panel recommendations and fully understand the implications of spinal cord instability for their own practices.

Endovascular management of pediatric high-flow vertebro-vertebral fistula with reversed basilar artery flow. A case report and review of the literature

Vertebral artery arteriovenous fistula (VAVF) is mostly known as a post-traumatic and/or iatrogenic arteriovenous complication. However, spontaneous high-flow VAVF associated with flow reversal in the basilar artery has not been reported in children. We describe a unique asymptomatic presentation of a spontaneous high-flow VAVF associated with flow reversal in the basilar artery in a pediatric patient. The literature for classification, pathophysiology, treatment strategies, and post-procedural complications is also reviewed.

Onyx embolization of intracranial arteriovenous malformations in pediatric patients

OBJECT

The authors undertook this study to assess the safety and efficacy of Onyx embolization in the treatment of intracranial arteriovenous malformations (AVMs) in pediatric patients.

METHODS

All pediatric Onyx embolization of intracranial AVM cases performed consecutively at a single children's hospital over a 5-year period were collected and evaluated.

RESULTS

Twenty-five patients (mean age 10.5 years) underwent a total of 38 procedures. An aggregate of 56 pedicles were embolized (mean 1.47 per session). The Spetzler-Martin grade was determined in all cases. Onyx embolization resulted in complete obliteration of the AVM in 3 cases (12%) and partial obliteration in 22 cases (88%). A total of 23 patients underwent surgical treatment. The mean preoperative AVM devascularization in these cases was 72%. One patient was treated with radiosurgery following Onyx embolization. Overall, 10 complications occurred in a total of 38 procedures (26.3%). None of the complications resulted in permanent neurological morbidity. The rate of transient neurological complications was 10.5% (4 of 38 procedures) and the rate of transient nonneurological complications was 5.3% (2 of 38 procedures). The remaining 4 complications were clinically silent (rate of 10.5%). There were no procedure-related deaths in this study population. There was no significant difference in patients with and without complications in terms of demographic characteristics, AVM grade, or embolization features (p ≥ 0.2). Deep venous drainage was associated with higher complication rates (p = 0.03).

CONCLUSIONS

Onyx utilization is feasible for preoperative or primary embolization in the treatment of pediatric intracranial AVMs; however, the spectrum of complications encountered is broad, and attention must be paid to the technical nuances of and indications for its use to avoid many potential dangerous effects. Although the overall complication rates were higher than expected, all were either clinically silent or had only transient clinical effects. Thus, this experience suggests that Onyx embolization can be performed safely with a low rate of permanent morbidity in pediatric patients harboring these difficult lesions.

The influence of secondary gain on surgical outcome: a comparison between cervical and lumbar discectomy

Although the expectation of monetary compensation has been associated with failures in lumbar discectomy, the issue has not been investigated in patients undergoing cervical disc surgery. The authors analyzed the relationship between economic forms of secondary gain and surgical outcome in a group of patients with a common pay scale, retirement plan, and disability program. All procedures were performed at the Portsmouth Naval Medical Center between 1993 and 1995; active-duty military servicepersons treated for cervical radiculopathy were prospectively included. Clinical, demographic, and financial factors were analyzed to determine which were predictive of outcome. Financial data were used to create a compensation incentive, which is proportional to the patient's rank, years of service, potential disability, retirement eligibility, and base pay and reflects the monetary incentive of disability. The results of cervical surgery were compared to a previously reported companion population of patients treated for lumbar disc disease. A good outcome was defined as a return to active duty, whereas a referral for disability was considered a poor surgical result. A 100% follow-up rate was obtained for 269 patients who underwent 307 cervical operations. Only 16% (43 of 269) of patients who underwent cervical operation received disability, whereas 24.7% (86 of 348) of patients who underwent lumbar discectomy obtained a poor result (p = 0.0082). Although economic forms of secondary gain were not associated with a poor outcome in cervical disease, both the rank (p = 0.002) and duration (p = 0.03) of an individual's military career were significant factors (p = 0.02). Of the medical variables tested, multilevel surgery (p = 0.03) and revision operations at the same level (p = 0.03) were associated with referral for medical discharge. Secondary gain in the form of economic compensation influences outcome in lumbar but not cervical disc surgery patients; the increased rate of disability referral in patients who underwent lumbar discectomy may reflect an expectation of economic compensation. Social factors that are independent of the anticipation of economic compensation seem to influence the outcome in cervical disc surgery patients.

Safety and Efficacy of Onyx Embolization for Pediatric Cranial and Spinal Vascular Lesions and Tumors

BACKGROUND:

Although Onyx is widely used to embolize vascular lesions in adults, the safety and efficacy of this liquid embolic agent for use in children are not well studied.

OBJECTIVE:

To report our experience using Onyx in pediatric patients for a variety of cranial and spinal vascular lesions and tumors to determine its procedural complication rates, types, and clinical consequences and to highlight the indications for and principles of Onyx embolization in pediatric patients.

METHODS:

All pediatric Onyx embolization cases performed consecutively by the neuroendovascular services at our 2 institutions over a 5-year period were collected retrospectively and analyzed.

RESULTS:

Over the study period, 105 Onyx embolization procedures were performed in 69 pediatric patients with a mean follow-up of 112 days. Fifty-two patients harbored “primary” vascular lesions (malformations, fistulas, etc), whereas 17 patients had tumors. Complications occurred in 25 of 105 procedures (23.8%) and included ischemic infarct (7), asymptomatic nontarget embolization (4), intracerebral hemorrhage (3), microcatheter-related vessel perforation (3), retained microcatheter (2), cerebral edema (2), dimethyl sulfoxide-induced pulmonary edema (2), facial ischemia (1), and contrast-induced bronchospasm (1). Neurological morbidity occurred transiently after 10 procedures (9.5%) and permanently after 2 procedures (1.9%). There were no procedure-related deaths. Statistical analysis revealed no predictors of complications among the multiple potential risk factors evaluated.

CONCLUSION:

Our experience suggests that Onyx can be used effectively for embolization of pediatric cranial and spinal vascular lesions and tumors with low permanent morbidity; however, attention must be paid to the technical nuances of and indications for its use to avoid potential complications.

A multinational, multidisciplinary consensus for the diagnosis and management of spinal cord compression among patients with mucopolysaccharidosis VI

Cervical cord compression is a sequela of mucopolysaccharidosis VI, a rare lysosomal storage disorder, and has devastating consequences. An international panel of orthopedic surgeons, neurosurgeons, anesthesiologists, neuroradiologists, metabolic pediatricians, and geneticists pooled their clinical expertise to codify recommendations for diagnosing, monitoring, and managing cervical cord compression; for surgical intervention criteria; and for best airway management practices during imaging or anesthesia. The recommendations offer ideal best practices but also attempt to recognize the worldwide spectrum of resource availability. Functional assessments and clinical neurological examinations remain the cornerstone for identification of early signs of myelopathy, but magnetic resonance imaging is the gold standard for identification of cervical cord compression. Difficult airways of MPS VI patients complicate the anesthetic and, thus, the surgical management of cervical cord compression. All patients with MPS VI require expert airway management during any surgical procedure. Neurophysiological monitoring of the MPS VI patient during complex spine or head and neck surgery is considered standard practice but should also be considered for other procedures performed with the patient under general anesthesia, depending on the length and type of the procedure. Surgical interventions may include cervical decompression, stabilization, or both. Specific techniques vary widely among surgeons. The onset, presentation, and rate of progression of cervical cord compression vary among patients with MPS VI. The availability of medical resources, the expertise and experience of members of the treatment team, and the standard treatment practices vary among centers of expertise. Referral to specialized, experienced MPS treatment centers should be considered for high-risk patients and those requiring complex procedures. Therefore, the key to optimal patient care is to implement best practices through meaningful communication among treatment team members at each center and among MPS VI specialists worldwide.