What to do with an incidental finding of a fused sagittal suture: a modified Delphi study

OBJECTIVE

As many as 5% of normocephalic children may have a prematurely fused sagittal suture, yet the clinical significance and best course of management of this finding remain unclear. Providers in the Synostosis Research Group were surveyed to create a multicenter consensus on an optimal treatment and monitoring algorithm for this condition.

METHODS

A four-round modified Delphi method was utilized. The first two rounds consisted of anonymous surveys distributed to 10 neurosurgeons and 9 plastic surgeons with expertise in craniosynostosis across 9 institutions, and presented 3 patients (aged 3 years, 2 years, and 2 months) with incidentally discovered fused sagittal sutures, normal cephalic indices, and no parietal dysmorphology. Surgeons were queried about their preferred term for this entity and how best to manage these patients. Results were synthesized to create a treatment algorithm. The third and fourth feedback rounds consisted of open discussion of the algorithm until no further concerns arose.

RESULTS

Most surgeons preferred the term "premature fusion of the sagittal suture" (93%). At the conclusion of the final round, all surgeons agreed to not operate on the 3- and 2-year-old patients unless symptoms of intracranial hypertension or papilledema were present. In contrast, 50% preferred to operate on the 2-month-old. However, all agreed to utilize shared decision-making, taking into account any concerns about future head shape and neurodevelopment. Panelists agreed that patients over 18 months of age without signs or symptoms suggesting elevated intracranial pressure (ICP) should not undergo surgical treatment.

CONCLUSIONS

Through the Delphi method, a consensus regarding management of premature fusion of the sagittal suture was obtained from a panel of North American craniofacial surgeons. Without signs or symptoms of ICP elevation, surgery is not recommended in patients over 18 months of age. However, for children younger than 18 months, surgery should be discussed with caregivers using a shared decision-making process.

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.

Developing a hippocampal neural prosthetic to facilitate human memory encoding and recall of stimulus features and categories

Objective

Here, we demonstrate the first successful use of static neural stimulation patterns for specific information content. These static patterns were derived by a model that was applied to a subject's own hippocampal spatiotemporal neural codes for memory.

Approach

We constructed a new model of processes by which the hippocampus encodes specific memory items via spatiotemporal firing of neural ensembles that underlie the successful encoding of targeted content into short-term memory. A memory decoding model (MDM) of hippocampal CA3 and CA1 neural firing was computed which derives a stimulation pattern for CA1 and CA3 neurons to be applied during the encoding (sample) phase of a delayed match-to-sample (DMS) human short-term memory task.

Main results

MDM electrical stimulation delivered to the CA1 and CA3 locations in the hippocampus during the sample phase of DMS trials facilitated memory of images from the DMS task during a delayed recognition (DR) task that also included control images that were not from the DMS task. Across all subjects, the stimulated trials exhibited significant changes in performance in 22.4% of patient and category combinations. Changes in performance were a combination of both increased memory performance and decreased memory performance, with increases in performance occurring at almost 2 to 1 relative to decreases in performance. Across patients with impaired memory that received bilateral stimulation, significant changes in over 37.9% of patient and category combinations was seen with the changes in memory performance show a ratio of increased to decreased performance of over 4 to 1. Modification of memory performance was dependent on whether memory function was intact or impaired, and if stimulation was applied bilaterally or unilaterally, with nearly all increase in performance seen in subjects with impaired memory receiving bilateral stimulation.

Significance

These results demonstrate that memory encoding in patients with impaired memory function can be facilitated for specific memory content, which offers a stimulation method for a future implantable neural prosthetic to improve human memory.

Long-term outcomes of mesial temporal laser interstitial thermal therapy for drug-resistant epilepsy and subsequent surgery for seizure recurrence: a multi-centre cohort study

BACKGROUND

Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a minimally invasive alternative to surgical resection for drug-resistant mesial temporal lobe epilepsy (mTLE). Reported rates of seizure freedom are variable and long-term durability is largely unproven. Anterior temporal lobectomy (ATL) remains an option for patients with MRgLITT treatment failure. However, the safety and efficacy of this staged strategy is unknown.

METHODS

This multicentre, retrospective cohort study included 268 patients consecutively treated with mesial temporal MRgLITT at 11 centres between 2012 and 2018. Seizure outcomes and complications of MRgLITT and any subsequent surgery are reported. Predictive value of preoperative variables for seizure outcome was assessed.

RESULTS

Engel I seizure freedom was achieved in 55.8% (149/267) at 1 year, 52.5% (126/240) at 2 years and 49.3% (132/268) at the last follow-up ≥1 year (median 47 months). Engel I or II outcomes were achieved in 74.2% (198/267) at 1 year, 75.0% (180/240) at 2 years and 66.0% (177/268) at the last follow-up. Preoperative focal to bilateral tonic-clonic seizures were independently associated with seizure recurrence. Among patients with seizure recurrence, 14/21 (66.7%) became seizure-free after subsequent ATL and 5/10 (50%) after repeat MRgLITT at last follow-up≥1 year.

CONCLUSIONS

MRgLITT is a viable treatment with durable outcomes for patients with drug-resistant mTLE evaluated at a comprehensive epilepsy centre. Although seizure freedom rates were lower than reported with ATL, this series represents the early experience of each centre and a heterogeneous cohort. ATL remains a safe and effective treatment for well-selected patients who fail MRgLITT.

Magnetic resonance imaging-guided stereotactic laser ablation therapy for the treatment of pediatric epilepsy: a retrospective multiinstitutional study

OBJECTIVE

The authors of this study evaluated the safety and efficacy of stereotactic laser ablation (SLA) for the treatment of drug-resistant epilepsy (DRE) in children.

METHODS

Seventeen North American centers were enrolled in the study. Data for pediatric patients with DRE who had been treated with SLA between 2008 and 2018 were retrospectively reviewed.

RESULTS

A total of 225 patients, mean age 12.8 ± 5.8 years, were identified. Target-of-interest (TOI) locations included extratemporal (44.4%), temporal neocortical (8.4%), mesiotemporal (23.1%), hypothalamic (14.2%), and callosal (9.8%). Visualase and NeuroBlate SLA systems were used in 199 and 26 cases, respectively. Procedure goals included ablation (149 cases), disconnection (63), or both (13). The mean follow-up was 27 ± 20.4 months. Improvement in targeted seizure type (TST) was seen in 179 (84.0%) patients. Engel classification was reported for 167 (74.2%) patients; excluding the palliative cases, 74 (49.7%), 35 (23.5%), 10 (6.7%), and 30 (20.1%) patients had Engel class I, II, III, and IV outcomes, respectively. For patients with a follow-up ≥ 12 months, 25 (51.0%), 18 (36.7%), 3 (6.1%), and 3 (6.1%) had Engel class I, II, III, and IV outcomes, respectively. Patients with a history of pre-SLA surgery related to the TOI, a pathology of malformation of cortical development, and 2+ trajectories per TOI were more likely to experience no improvement in seizure frequency and/or to have an unfavorable outcome. A greater number of smaller thermal lesions was associated with greater improvement in TST. Thirty (13.3%) patients experienced 51 short-term complications including malpositioned catheter (3 cases), intracranial hemorrhage (2), transient neurological deficit (19), permanent neurological deficit (3), symptomatic perilesional edema (6), hydrocephalus (1), CSF leakage (1), wound infection (2), unplanned ICU stay (5), and unplanned 30-day readmission (9). The relative incidence of complications was higher in the hypothalamic target location. Target volume, number of laser trajectories, number or size of thermal lesions, or use of perioperative steroids did not have a significant effect on short-term complications.

CONCLUSIONS

SLA appears to be an effective and well-tolerated treatment option for children with DRE. Large-volume prospective studies are needed to better understand the indications for treatment and demonstrate the long-term efficacy of SLA in this population.

Above the Clavicle: A Simplified Screening Method for Asymptomatic Blunt Cerebral Vascular Injury

INTRODUCTION

Blunt cerebrovascular injury (BCVI) is an increasingly detected pattern in trauma with significant morbidity, putting patients at risk for subsequent stoke. Complex screening protocols exist to determine who should undergo CT angiography of the neck (CTAN) to evaluate for BCVI. Once identified, stroke incidence may be reduced with appropriate treatment across grades. We hypothesize that an expanded and simplified method for identifying patients with clinical suspicion for BCVI based upon injury above the clavicle (ATC) will illustrate a previously undiagnosed cohort of patients.

METHODS

A single-institution retrospective review of adult (age ≥18 years) blunt trauma patients with BCVI from January 1, 2010 to December 31, 2019 was conducted at a tertiary academic medical center. Patients undergoing CTAN were divided into 2 groups based upon qualification by either the expanded Denver criteria or clinical evidence of any injury ATC.

RESULTS

A total of 219 patients were diagnosed with BCVI (25 566 blunt trauma admissions, .9% incidence). Seventeen patients (8%) who did not satisfy expanded Denver were diagnosed with BCVI by ATC, most commonly undergoing CTAN due to facial trauma (n = 8). There were no differences in distribution of carotid artery injuries (CAI) and vertebral artery injuries (VAI) in the expanded Denver criteria group compared to the ATC group.

CONCLUSIONS

CTAN for blunt trauma with any injury ATC is an easy-to-use screening tool and may be seamlessly included with initial whole-body imaging.

Patterned Hippocampal Stimulation Facilitates Memory in Patients With a History of Head Impact and/or Brain Injury

Rationale: Deep brain stimulation (DBS) of the hippocampus is proposed for enhancement of memory impaired by injury or disease. Many pre-clinical DBS paradigms can be addressed in epilepsy patients undergoing intracranial monitoring for seizure localization, since they already have electrodes implanted in brain areas of interest. Even though epilepsy is usually not a memory disorder targeted by DBS, the studies can nevertheless model other memory-impacting disorders, such as Traumatic Brain Injury (TBI). Methods: Human patients undergoing Phase II invasive monitoring for intractable epilepsy were implanted with depth electrodes capable of recording neurophysiological signals. Subjects performed a delayed-match-to-sample (DMS) memory task while hippocampal ensembles from CA1 and CA3 cell layers were recorded to estimate a multi-input, multi-output (MIMO) model of CA3-to-CA1 neural encoding and a memory decoding model (MDM) to decode memory information from CA3 and CA1 neuronal signals. After model estimation, subjects again performed the DMS task while either MIMO-based or MDM-based patterned stimulation was delivered to CA1 electrode sites during the encoding phase of the DMS trials. Each subject was sorted (post hoc) by prior experience of repeated and/or mild-to-moderate brain injury (RMBI), TBI, or no history (control) and scored for percentage successful delayed recognition (DR) recall on stimulated vs. non-stimulated DMS trials. The subject’s medical history was unknown to the experimenters until after individual subject memory retention results were scored. Results: When examined compared to control subjects, both TBI and RMBI subjects showed increased memory retention in response to both MIMO and MDM-based hippocampal stimulation. Furthermore, effects of stimulation were also greater in subjects who were evaluated as having pre-existing mild-to-moderate memory impairment. Conclusion: These results show that hippocampal stimulation for memory facilitation was more beneficial for subjects who had previously suffered a brain injury (other than epilepsy), compared to control (epilepsy) subjects who had not suffered a brain injury. This study demonstrates that the epilepsy/intracranial recording model can be extended to test the ability of DBS to restore memory function in subjects who previously suffered a brain injury other than epilepsy, and support further investigation into the beneficial effect of DBS in TBI patients.

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.

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.

Comparison of 2 Sagittal Craniosynostosis Repair Techniques: Spring-Assisted Surgery Versus Endoscope-Assisted Craniectomy With Helmet Molding Therapy

INTRODUCTION

This study compares anthropometric outcomes of 2 sagittal synostosis repair techniques: spring-assisted surgery and endoscope-assisted craniectomy with molding helmet therapy.

METHODS

Patients undergoing spring-assisted surgery (n = 27) or endoscope-assisted craniectomy with helmet therapy (n = 40) at separate institutions were retrospectively reviewed. Pre- and 1-year postoperative computed tomography (CT) or laser scans were analyzed for traditional cranial index (CI), adjusted cranial index (aCI), and cranial vault volume (CVV). Nine patient-matched scans were analyzed for measurement consistency.

RESULTS

The spring-assisted group was older at both time points (P < .050) and spring-assisted group CVV was larger preoperatively and postoperatively (P < .01). However, the change in CVV did not differ between the groups (P = .210). There was no difference in preoperative CI (helmet vs spring: 70.1 vs 71.2, P = .368) between the groups. Postoperatively, helmet group CI (77.0 vs 74.3, P = .008) was greater. The helmet group also demonstrated a greater increase in CI (6.9 vs 3.1, P < .001). The proportion of patients achieving CI of 75 or greater was not significantly different between the groups (helmet vs spring: CI, 65% vs 52%, P = .370). There was no detectable bias in CI between matched CT and laser scans. Differences were identified between scan types in aCI and CVV measurements; subsequent analyses used corrected CVV and aCI measures for laser scan measures.

CONCLUSIONS

Both techniques had equivalent proportions of patients achieving normal CI, comparable effects on cranial volume, and similar operative characteristics. The study suggests that there may be greater improvement in CI in the helmet group. However, further research should be performed.

Hippocampal CA1 and CA3 neural recording in the human brain: validation of depth electrode placement through high-resolution imaging and electrophysiology

OBJECTIVE

Intracranial human brain recordings typically utilize recording systems that do not distinguish individual neuron action potentials. In such cases, individual neurons are not identified by location within functional circuits. In this paper, verified localization of singly recorded hippocampal neurons within the CA3 and CA1 cell fields is demonstrated.

METHODS

Macro-micro depth electrodes were implanted in 23 human patients undergoing invasive monitoring for identification of epileptic seizure foci. Individual neurons were isolated and identified via extracellular action potential waveforms recorded via macro-micro depth electrodes localized within the hippocampus. A morphometric survey was performed using 3T MRI scans of hippocampi from the 23 implanted patients, as well as 46 normal (i.e., nonepileptic) patients and 26 patients with a history of epilepsy but no history of depth electrode placement, which provided average dimensions of the hippocampus along typical implantation tracks. Localization within CA3 and CA1 cell fields was tentatively assigned on the basis of recording electrode site, stereotactic positioning of the depth electrode in comparison with the morphometric survey, and postsurgical MRI. Cells were selected as candidate CA3 and CA1 principal neurons on the basis of waveform and firing rate characteristics and confirmed within the CA3-to-CA1 neural projection pathways via measures of functional connectivity.

RESULTS

Cross-correlation analysis confirmed that nearly 80% of putative CA3-to-CA1 cell pairs exhibited positive correlations compatible with feed-forward connection between the cells, while only 2.6% exhibited feedback (inverse) connectivity. Even though synchronous and long-latency correlations were excluded, feed-forward correlation between CA3-CA1 pairs was identified in 1071 (26%) of 4070 total pairs, which favorably compares to reports of 20%-25% feed-forward CA3-CA1 correlation noted in published animal studies.

CONCLUSIONS

This study demonstrates the ability to record neurons in vivo from specified regions and subfields of the human brain. As brain-machine interface and neural prosthetic research continues to expand, it is necessary to be able to identify recording and stimulation sites within neural circuits of interest.

Magnetic resonance-guided stereotactic laser ablation therapy for the treatment of pediatric brain tumors: a multiinstitutional retrospective study

OBJECTIVE

This study aimed to assess the safety and efficacy of MR-guided stereotactic laser ablation (SLA) therapy in the treatment of pediatric brain tumors.

METHODS

Data from 17 North American centers were retrospectively reviewed. Clinical, technical, and radiographic data for pediatric patients treated with SLA for a diagnosis of brain tumor from 2008 to 2016 were collected and analyzed.

RESULTS

A total of 86 patients (mean age 12.2 ± 4.5 years) with 76 low-grade (I or II) and 10 high-grade (III or IV) tumors were included. Tumor location included lobar (38.4%), deep (45.3%), and cerebellar (16.3%) compartments. The mean follow-up time was 24 months (median 18 months, range 3-72 months). At the last follow-up, the volume of SLA-treated tumors had decreased in 80.6% of patients with follow-up data. Patients with high-grade tumors were more likely to have an unchanged or larger tumor size after SLA treatment than those with low-grade tumors (OR 7.49, p = 0.0364). Subsequent surgery and adjuvant treatment were not required after SLA treatment in 90.4% and 86.7% of patients, respectively. Patients with high-grade tumors were more likely to receive subsequent surgery (OR 2.25, p = 0.4957) and adjuvant treatment (OR 3.77, p = 0.1711) after SLA therapy, without reaching significance. A total of 29 acute complications in 23 patients were reported and included malpositioned catheters (n = 3), intracranial hemorrhages (n = 2), transient neurological deficits (n = 11), permanent neurological deficits (n = 5), symptomatic perilesional edema (n = 2), hydrocephalus (n = 4), and death (n = 2). On long-term follow-up, 3 patients were reported to have worsened neuropsychological test results. Pre-SLA tumor volume, tumor location, number of laser trajectories, and number of lesions created did not result in a significantly increased risk of complications; however, the odds of complications increased by 14% (OR 1.14, p = 0.0159) with every 1-cm3 increase in the volume of the lesion created.

CONCLUSIONS

SLA is an effective, minimally invasive treatment option for pediatric brain tumors, although it is not without risks. Limiting the volume of the generated thermal lesion may help decrease the incidence of complications.

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.

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.

A Pivotal Randomized Clinical Trial Evaluating the Safety and Effectiveness of a Novel Hydrogel Dural Sealant as an Adjunct to Dural Repair

BACKGROUND

A watertight dural repair is critical to minimizing the risk of postoperative complications secondary to cerebrospinal fluid (CSF) leaks.

OBJECTIVE

To evaluate the safety and efficacy of a novel hydrogel, Adherus Dural Sealant, when compared with control, DuraSeal Dural Sealant System, as an adjunct to standard methods of dural repair.

METHODS

In this 17-center, prospective, randomized clinical trial designed as a noninferiority, single-blinded study, 124 patients received Adherus Dural Sealant (test sealant) and 126 received DuraSeal (control). The primary composite endpoint was the proportion of patients who were free of any intraoperative CSF leakage during Valsalva maneuver after dural repair, CSF leak/pseudomeningocele, and unplanned retreatment of the surgical site. Each component was then analyzed individually as a secondary endpoint. Patients were followed for 4 mo after surgery.

RESULTS

The primary composite endpoint at the 120-d follow-up was achieved in 91.2% of the test sealant group compared with 90.6% of the control, thus showing that the test sealant was statistically significantly noninferior to DuraSeal ( P = .0049). Post hoc analysis of the primary composite endpoint at 14 d demonstrated superiority of the test sealant over the control ( P = .030). Primary endpoint failures in the control group tended to occur early in follow-up period, while a majority of test dural sealant failures were identified through protocol-required radiographic imaging at the 120-d follow-up visit.

CONCLUSION

The test sealant, Adherus Dural Sealant, is a practical, safe, and effective adjunct to achieving a watertight dural closure after primary dural closure in cranial procedures.

Effects of surgical targeting in laser interstitial thermal therapy for mesial temporal lobe epilepsy: A multicenter study of 234 patients

OBJECTIVE

Laser interstitial thermal therapy (LITT) for mesial temporal lobe epilepsy (mTLE) has reported seizure freedom rates between 36% and 78% with at least 1 year of follow-up. Unfortunately, the lack of robust methods capable of incorporating the inherent variability of patient anatomy, the variability of the ablated volumes, and clinical outcomes have limited three-dimensional quantitative analysis of surgical targeting and its impact on seizure outcomes. We therefore aimed to leverage a novel image-based methodology for normalizing surgical therapies across a large multicenter cohort to quantify the effects of surgical targeting on seizure outcomes in LITT for mTLE.

METHODS

This multicenter, retrospective cohort study included 234 patients from 11 centers who underwent LITT for mTLE. To investigate therapy location, all ablation cavities were manually traced on postoperative magnetic resonance imaging (MRI), which were subsequently nonlinearly normalized to a common atlas space. The association of clinical variables and ablation location to seizure outcome was calculated using multivariate regression and Bayesian models, respectively.

RESULTS

Ablations including more anterior, medial, and inferior temporal lobe structures, which involved greater amygdalar volume, were more likely to be associated with Engel class I outcomes. At both 1 and 2 years after LITT, 58.0% achieved Engel I outcomes. A history of bilateral tonic-clonic seizures decreased chances of Engel I outcome. Radiographic hippocampal sclerosis was not associated with seizure outcome.

SIGNIFICANCE

LITT is a viable treatment for mTLE in patients who have been properly evaluated at a comprehensive epilepsy center. Consideration of surgical factors is imperative to the complete assessment of LITT. Based on our model, ablations must prioritize the amygdala and also include the hippocampal head, parahippocampal gyrus, and rhinal cortices to maximize chances of seizure freedom. Extending the ablation posteriorly has diminishing returns. Further work is necessary to refine this analysis and define the minimal zone of ablation necessary for seizure control.

Corpus callosotomy via laser interstitial thermal therapy: a case series

Corpus callosotomy has been used as a form of surgical palliation for patients suffering from medically refractory generalized seizures, including drop attacks. Callosotomy has traditionally been described as involving a craniotomy with microdissection. MR-guided laser interstitial thermal therapy (MRg-LITT) has recently been used as a minimally invasive method for performing surgical ablation of epileptogenic foci and corpus callosotomy. The authors present 3 cases in which MRg-LITT was used to perform a corpus callosotomy as part of a staged surgical procedure for a patient with multiple seizure types and in instances when further ablation of residual corpus callosum is necessary after a prior open surgical procedure. To the authors' knowledge, this is the first case series of corpus callosotomy performed using the MRg-LITT system with a 3.3-year average follow-up. Although MRg-LITT is not expected to replace the traditional corpus callosotomy in all cases, it is a safe, effective, and durable alternative to the traditional open corpus callosotomy, particularly in the setting of a prior craniotomy.

Incidental durotomy in the pediatric spine population

OBJECTIVESpine surgery is less common in children than adults. These surgeries, like all others, are subject to complications such as bleeding, infection, and CSF leak. The rate of incidental durotomy in the pediatric population, and its associated complications, has scarcely been reported in the literature.METHODSThis is a retrospective chart review of all pediatric patients operated on at Wake Forest Baptist Health from 2012 to 2017 who underwent spine surgeries. The authors excluded any procedures with intended durotomy, such as tethered cord release or spinal cord tumor resection.RESULTSFrom 2012 to 2017, 318 pediatric patients underwent surgery for a variety of indications, including adolescent idiopathic scoliosis (51.9%), neuromuscular scoliosis (27.4%), thoracolumbar fracture (2.83%), and other non-fusion-related indications (3.77%). Of these patients, the average age was 14.1 years, and 71.0% were female. There were 6 total incidental durotomies, resulting in an overall incidence of 1.9%. The incidence was 18.5% in revision operations, compared to 0.34% for index surgeries. Comparison of the revision cohort to the durotomy cohort revealed a trend toward increased length of stay, operative time, and blood loss; however, the trends were not statistically significant. The pedicle probe was implicated in 3 cases and the exact cause was not ascertained in the remaining 3 cases. The 3 durotomies caused by pedicle probe were treated with bone wax; 1 was treated with dry Gelfoam application and 2 were treated with primary repair. Only 1 patient had a persistent leak postoperatively that eventually required wound revision.CONCLUSIONSIncidental durotomy is an uncommon occurrence in the pediatric spinal surgery population. The majority occurred during placement of pedicle screws, and they were easily treated with bone wax at the time of surgery. Awareness of the incidence, predisposing factors, and treatment options is important in preventing complications and disability.

Intraventricular recurrence of a craniopharyngioma: case report

Craniopharyngiomas frequently recur locally or less commonly along the path of prior resection. Ectopic recurrence is rare, although cases are reported along the neuraxis spanning from the subgaleal space down to the S1 nerve root. This case reports on a girl with a history of craniopharyngioma first resected at 23 months of age with two local suprasellar recurrences managed with repeat craniotomy and external beam radiation therapy. At age 14 she complained of worsening headaches and brain MRI demonstrated an enhancing 1.2-cm cystic lesion in the posterior body of the left lateral ventricle. Pathology following endoscopic resection of the lesion was consistent with an adamantinomatous craniopharyngioma. This case report serves to describe the first reported recurrence of a craniopharyngioma in the lateral ventricle and emphasizes the need for a high index of suspicion along with long-term follow-up of patients with a history of craniopharyngioma.

A review of Big Data analytics and potential for implementation in the delivery of global neurosurgery

Global access to neurosurgical care is still a work in progress, with many patients in low-income countries not able to access potentially lifesaving neurosurgical procedures. “Big Data” is an increasingly popular data collection and analytical technique predicated on collecting large amounts of data across multiple data sources and types for future analysis. The potential applications of Big Data to global outreach neurosurgery are myriad: from assessing the overall burden of neurosurgical disease to planning cost-effective improvements in access to neurosurgical care, and collecting data on conditions which are rare in developed countries. Although some global neurosurgical outreach programs have intelligently implemented Big Data principles in their global neurosurgery initiatives already, there is still significant progress that remains to be made. Big Data has the potential to drive the efficient improvement of access to neurosurgical care across low- and medium-income countries.

Cerebral Abscess in Young Adult with Hypoplastic Left Heart Syndrome

BACKGROUND

Cerebral abscesses are rare, potentially life-threatening entities that result from local spread or hematogenous dissemination to the brain. Prompt diagnosis and initiation of treatment is key in lowering morbidity and preventing mortality associated with cerebral abscesses. Congenital heart diseases with right-to-left intracardiac shunts can be complicated by brain abscesses via paradoxical embolism of infected microthrombi. Hypoplastic left heart syndrome (HLHS) is a rare congenital heart disease characterized by an underdeveloped left heart that uses intracardiac shunting to achieve adequate systemic circulation. We present the first reported case of a cerebral abscess in a patient with HLHS. The pathophysiology of HLHS and how it predisposes patients to development of cerebral abscesses is discussed.

CASE DESCRIPTION

A 25-year-old male was transferred to our institution complaining of headache, nausea, and vomiting. The patient was not an intravenous (IV) drug user, and serologic testing was negative for human immunodeficiency virus. Magnetic resonance imaging revealed a 2.6-cm left occipital abscess, which was surgically resected without complication, and the patient was treated with IV antibiotics.

CONCLUSION

HLHS is a rare congenital cardiac malformation. The long-term outcome of patients with this condition continues to improve as treatment paradigms evolve. As such, patients with HLHS are living longer, and their potential to develop cerebral abscesses secondary to their unique systemic circulation is increasing with improved life expectancy. Surgeons and physicians should maintain a high index of suspicion for cerebral abscess in the setting of HLHS.

Developing a hippocampal neural prosthetic to facilitate human memory encoding and recall

OBJECTIVE

We demonstrate here the first successful implementation in humans of a proof-of-concept system for restoring and improving memory function via facilitation of memory encoding using the patient's own hippocampal spatiotemporal neural codes for memory. Memory in humans is subject to disruption by drugs, disease and brain injury, yet previous attempts to restore or rescue memory function in humans typically involved only nonspecific, modulation of brain areas and neural systems related to memory retrieval.

APPROACH

We have constructed a model of processes by which the hippocampus encodes memory items via spatiotemporal firing of neural ensembles that underlie the successful encoding of short-term memory. A nonlinear multi-input, multi-output (MIMO) model of hippocampal CA3 and CA1 neural firing is computed that predicts activation patterns of CA1 neurons during the encoding (sample) phase of a delayed match-to-sample (DMS) human short-term memory task.

MAIN RESULTS

MIMO model-derived electrical stimulation delivered to the same CA1 locations during the sample phase of DMS trials facilitated short-term/working memory by 37% during the task. Longer term memory retention was also tested in the same human subjects with a delayed recognition (DR) task that utilized images from the DMS task, along with images that were not from the task. Across the subjects, the stimulated trials exhibited significant improvement (35%) in both short-term and long-term retention of visual information.

SIGNIFICANCE

These results demonstrate the facilitation of memory encoding which is an important feature for the construction of an implantable neural prosthetic to improve human memory.

Laser Interstitial Thermal Therapy for Mesial Temporal Lobe Epilepsy

Approximately one-third of patients with epilepsy do not achieve adequate seizure control through medical management alone. Mesial temporal lobe epilepsy (MTLE) is one of the most common forms of medically refractory epilepsy referred for surgical management. Stereotactic laser amygdalohippocampotomy using magnetic resonance-guided laser interstitial thermal therapy (MRg-LITT) is an important emerging therapy for MTLE. Initial published reports support MRg-LITT as a less invasive surgical option with a shorter hospital stay and fewer neurocognitive side effects compared with craniotomy for anterior temporal lobectomy with amygdalohippocampectomy and selective amygdalohippocampectomy. We provide a historical overview of laser interstitial thermal therapy development and the technological advancements that led to the currently available commercial systems. Current applications of MRg-LITT for MTLE, reported outcomes, and technical issues of the surgical procedure are reviewed. Although initial reports indicate that stereotactic laser amygdalohippocampotomy may be a safe and effective therapy for medically refractory MTLE, further research is required to establish its long-term effectiveness and its cost/benefit profile.

Management of idiopathic pediatric syringohydromyelia

OBJECT

Syringohydromyelia is frequently identified on spinal imaging. The literature provides little guidance to decision making regarding the need for follow-up or treatment. The purpose of this study was to review the authors' experience in managing pediatric syringohydromyelia of unknown cause.

METHODS

A single-institution retrospective review of all cases involving pediatric patients who underwent spinal MRI from 2002 to 2012 was conducted. Patients with idiopathic syringohydromyelia (IS) were identified and categorized into 2 subgroups: uncomplicated idiopathic syrinx and IS associated with scoliosis. Clinical and radiological course were analyzed.

RESULTS

Ninety-eight patients (50 female, 48 male) met the inclusion criteria. Median age at diagnosis of syrinx was 11.9 years. Median maximum syrinx size was 2 mm (range 0.5-17 mm) and spanned 5 vertebral levels (range 1-20 vertebral levels). Thirty-seven patients had scoliosis. The most common presenting complaint was back pain (26%). Clinical follow-up was available for 78 patients (80%), with a median follow-up of 20.5 months (range 1-143 months). A neurological deficit existed at presentation in 36% of the patients; this was either stable or improved at last follow-up in 64% of cases. Radiological follow-up was available for 38 patients (39%), with a median duration of 13 months (range 2-83 months). There was no change in syrinx size in 76% of patients, while 16% had a decrease and 8% had an increase in syrinx size. Thirty-six patients had both clinical and radiological follow-up. There was concordance between clinical and radiological course in 14 patients (39%), with 11 patients (31%) showing no change and 3 patients (8%) showing clinical and radiological improvement. No patients had concurrent deterioration in clinical and radiological course. One patient with scoliosis and muscular dystrophy underwent direct surgical treatment of the syrinx and subsequently had a deteriorated clinical course and decreased syrinx size.

CONCLUSIONS

There remains a paucity of data regarding the management of pediatric IS. IS in association with scoliosis can complicate neurosurgical decision making. There was no concordance between radiological syrinx size increase and clinical deterioration in this cohort, indicating that surgical decision making should reflect clinical course as opposed to radiological course.

Localization of interictal epileptiform activity using magnetoencephalography with synthetic aperture magnetometry in patients with a vagus nerve stimulator

Magnetoencephalography (MEG) provides useful and non-redundant information in the evaluation of patients with epilepsy, and in particular, during the pre-surgical evaluation of pharmaco-resistant epilepsy. Vagus nerve stimulation (VNS) is a common treatment for pharmaco-resistant epilepsy. However, interpretation of MEG recordings from patients with a VNS is challenging due to the severe magnetic artifacts produced by the VNS. We used synthetic aperture magnetometry (g2) [SAM(g2)], an adaptive beamformer that maps the excessive kurtosis, to map interictal spikes to the coregistered MRI image, despite the presence of contaminating VNS artifact. We present a series of eight patients with a VNS who underwent MEG recording. Localization of interictal epileptiform activity by SAM(g2) is compared to invasive electrophysiologic monitoring and other localizing approaches. While the raw MEG recordings were uninterpretable, analysis of the recordings with SAM(g2) identified foci of peak kurtosis and source signal activity that was unaffected by the VNS artifact. SAM(g2) analysis of MEG recordings in patients with a VNS produces interpretable results and expands the use of MEG for the pre-surgical evaluation of epilepsy.

Efficacy of passive helmet therapy for deformational plagiocephaly: report of 1050 cases

OBJECT

There has been a tremendous increase in the incidence of deformational plagiocephaly in children throughout the world. Therapeutic options include observation, active counterpositioning, external orthotics, and surgery. The current treatment in the US is highly debated, but it typically includes external orthotic helmets in patients with moderate to severe plagiocephaly presenting between 4 and 10 months of age or in children with significant comorbidities limiting passive (no-pressure) therapy. The present study was designed to evaluate 3 key issues: 1) the accuracy of the Argenta classification in defining a progressive degree of severity, 2) identification of an upper age limit when treatment is no longer effective, and 3) the effectiveness of an off-the-shelf prefabricated helmet in correcting deformational plagiocephaly.

METHODS

An institutional review board-approved retrospective study was conducted of all patients at the authors' clinic in whom deformational plagiocephaly was assessed using the Argenta classification system over a 6-year period; the patients underwent helmet therapy, and a minimum of 3 clinic visits were recorded. Inclusion criteria consisted of an Argenta Type II-V plagiocephalic deformity. Patients' conditions were categorized both by severity of the deformity and by patients' age at presentation. Statistical analysis was conducted using survival analysis.

RESULTS

There were 1050 patients included in the study. Patients with Type III, IV, and V plagiocephaly required progressively longer for deformity correction to be achieved than patients with Type II plagiocephaly (53%, 75%, and 81% longer, respectively [p < 0.0001]). This finding verified that the Argenta stratification indicated a progressive severity of deformity. No statistically significant difference in the time to correction was noted among the different age categories, which suggests that the previously held upper time limit for correction may be inaccurate. An overall correction rate to Type I plagiocephaly of 81.6% was achieved irrespective of severity and degree of the original deformity. This suggests that an inexpensive off-the-shelf molding helmet is highly effective and that expensive custom-fitted orthoses may not be necessary. The patients in the older age group (> 12 months) did not have a statistically significant longer interval to correction than the patients in the youngest age group (< 3 months). The mean length of follow-up was 6.3 months.

CONCLUSIONS

Patients treated with passive helmet therapy in the older age group (> 12 months) had an improvement in skull shape within the same treatment interval as the patients in the younger age group (< 3 months). This study supports the use of passive helmet therapy for improvement in deformational plagiocephaly in infants from birth to 18 months of age and verifies the stratification of degree of deformity used in the Argenta classification system.

Definitive treatment of vein of Galen aneurysmal malformation with stereotactic radiosurgery

Vein of Galen aneurysmal malformations (VGAMs) are uncommon congenital malformations arising from fistulous communication with the median vein of the prosencephalon, a primitive precursor of midline cerebral venous structures. Angiographic embolization is the primary modality for treatment given historically poor microsurgical outcomes. Only a few reports of treatment by Gamma Knife radiosurgery (GKRS) exist in the literature, and the results are variable. The authors present 2 cases of VGAM in which GKRS provided definitive treatment with good outcome: one case involving antenatal presentation of a high-output, mural-type VGAM with complex clinical course refractory to multiple embolic procedures, and the other a choroidal-type VGAM presenting with hemorrhage in an adult and without a feasible embolic approach. With discussion of these cases and review of the literature, the authors advocate inclusion of GKRS as a therapeutic option for treatment of these complex lesions.

Time-dependent perioperative anesthetic management and outcomes of the first 100 consecutive cases of spring-assisted surgery for sagittal craniosynostosis

BACKGROUND

  The anesthetic risks and outcomes of the first 100 consecutive spring-assisted surgeries (SAS) for cranial expansion from a single institution are reported. The effect of number of procedures was also tested on hematocrit postoperative day 1 (POD1), anesthesia time, and surgery time of the first procedure.

METHODS

  The records of 100 consecutive patients undergoing SAS were reviewed. Anesthesia management and related complications are presented. Time series linear regression analysis was performed on hematocrit POD1, anesthesia time, and surgery time of the first procedure.

RESULTS

  The average age of the first insertion procedure was 4.4 and 9.0 months for the second removal procedure. Two patients were inadvertently extubated during positioning. Thirty-eight children had a decrease in blood pressure >20% from baseline. No child was admitted to the intensive care unit. No patient received any blood or blood product transfusion. Anesthesia time, surgery time, and hematocrit POD1 were correlated with procedure number or experience.

CONCLUSIONS

Changes in anesthetic management resulted from changing the procedure. The reduction in volume resuscitation reduces the need for invasive monitoring. Facility and comfort with the surgical procedure increase with time and number of procedures performed. This experience further reduces blood loss and risk of transfusion.

Effects of antibiotic-impregnated external ventricular drains on bacterial culture results: an in vitro analysis

OBJECT

Treatment of ventriculoperitoneal shunt infections frequently requires placement of an external ventricular drain (EVD). Surveillance specimens obtained from antibiotic-impregnated (AI) EVDs may be less likely to demonstrate bacterial growth, potentially resulting in undertreatment of an infection. The purpose of this study was to assess whether AI EVDs had any significant effect on bacterial culture results compared with nonantibiotic-impregnated (NAI) EVDs.

METHODS

In vitro assays were performed using AI EVDs containing minocycline and rifampin (VentriClear II, Medtronic) and NAI EVD controls (Bioglide, Medtronic). The presence of antibiotics was evaluated via capillary electrophoresis of sterile saline drawn from AI and NAI EVDs after predefined incubation intervals. Antimicrobial activity was assessed by evaluating zones of inhibition created by the catheter aspirates on plates inoculated with a quality control strain of Staphylococcus epidermidis (American Type Culture Collection strain 12228). To determine the effects of cultures drawn through AI compared with NAI EVDs, the quality control strain was then incubated within 4 new AI and 4 new NAI EVDs for predefined intervals before being plated on culture media. Spread and streak plate culture results from each type of catheter were compared at each time interval.

RESULTS

Capillary electrophoresis showed that more minocycline than rifampin was eluted from the AI EVDs. Sterile saline samples incubated within the AI EVDs demonstrated zones of growth inhibition when placed on plates of S. epidermidis at all time intervals tested. No zones of inhibition were noted on NAI EVD control plates. When a standardized inoculum of S. epidermidis was drawn through AI and NAI EVDs, antimicrobial effects were observed after incubation in the AI EVD group only. Colony counting demonstrated that significantly fewer colonies resulted from samples drawn through AI compared with NAI EVDs at the multiple time intervals. Similarly, streak plating yielded a statistically significant number of false-negative results from AI compared with NAI EVDs at 2 time intervals.

CONCLUSIONS

The findings in the current study indicate that the risk of a false-negative culture result may be increased when a CSF sample is drawn through an AI catheter. In the management of a known shunt infection, a false-negative result from an EVD culture specimen may lead to an inappropriately short duration of antibiotic therapy. These data have significant clinical implications, particularly given the widespread use of AI drains and the current high rates of shunt reinfection after EVD use worldwide.

Posterior lumbar interbody fusion with bioabsorbable spacers and local autograft in a series of 27 patients

Object

The goal of this prospective study was to review a series of 27 patients who underwent bilateral posterior lumbar interbody fusion with instrumented pedicle fixation and two HYDROSORB (known generically as 70:30 poly[L-lactide-co-D,L-lactide]) rectangular cages packed with locally harvested autograft at a total of 48 levels, and to assess the safety and efficacy of this novel technique. This analysis, conducted at a mean of 26 months of follow up, is the first report of a long-term evaluation of this technique. Fusion rates and clinical outcomes are presented.

Methods

A prospective clinical and radiographic review of findings in 27 consecutive patients was performed. Fusion rates and clinical outcome were assessed at 6-month intervals up to the 32-month follow-up end point. Two patients with four corresponding fusion levels were lost to follow up.

Radiographic evidence of satisfactory fusion was achieved in 42 (95.5%) of 44 levels fused. Satisfactory fusion at all levels was achieved in 23 (92%) of 25 patients. Two patients required repeated operations for treatment of symptomatic pseudarthrosis during the study period. The likelihood of all levels attaining fusion in a given patient decreased as the number of levels treated increased, which is consistent with previously published studies. Nonetheless, fusion rates per treated level were similar for patients in whom one to three levels were treated. No significant surgical complication occurred.

Conclusions

Posterior lumbar interbody fusion in which the HYDROSORB bioabsorbable implant packed with locally harvested autograft and segmental internal fixation are used appears to be an interbody fusion alternative whose efficacy is comparable with previously reported procedures.

Anemia, testosterone, and pituitary adenoma in men

OBJECT

Older men with clinically nonfunctioning pituitary tumors have been noted to be anemic, to have hypopituitarism, and to have low serum levels of testosterone. The authors hypothesized that men with pituitary adenomas and hypogonadism have a physiologically related decrease in hematocrit.

METHODS

A retrospective analysis was conducted of 216 patients older than 50 years of age who harbored pituitary adenomas. In 100 men serum testosterone levels and a complete blood (cell) count (CBC) were obtained before treatment; a CBC was also acquired in a series of women with pituitary adenomas. Using clinical laboratory standards, anemia was defined as a hematocrit less than 40% in men and less than 35% in women. Thirty-one (46.3%) of 67 men with low serum concentrations of testosterone were anemic. In men with low levels of testosterone, the average hematocrit was 39.9%, compared with 45.6% for men with normal testosterone levels (p < 0.001). Men with macroadenomas were most likely to have both anemia and a low serum concentration of testosterone. Anemia was associated with a low level of testosterone, adjusting for tumor size (odds ratio 19, 95% confidence interval 4.86-77.03). Of patients with anemia, 84% were men and 16% were women (p < 0.001). The prevalence of anemia in women was low and was not correlated with tumor size. Men receiving testosterone replacement therapy had a significantly higher hematocrit value than men with low or normal testosterone levels.

CONCLUSIONS

These findings support a direct relationship between serum testosterone levels and hematopoiesis in men, and demonstrate that hematopoiesis is compromised in men who have low concentrations of testosterone due to a pituitary adenoma.

Blood use in cerebrovascular neurosurgery

BACKGROUND AND PURPOSE

This study reviews the perioperative use of red blood cell transfusion in cerebrovascular neurosurgery. The current algorithm for preoperative ordering of red cells is historical and dated. More blood is ordered than is actually transfused, and considerable variability exists between different institutions. We determine the use of blood transfusion in cerebrovascular surgery to develop a rational blood ordering practice.

METHODS

Records of 301 patients undergoing cerebrovascular neurosurgery at the University of Virginia were reviewed to quantitatively evaluate red blood cell transfusion practices. The amount and reason for transfusion were noted in each case.

RESULTS

In 126 patients undergoing carotid endarterectomy, there were no preoperative or intraoperative transfusions and 5 postoperative transfusions (4.0%). In 71 ruptured aneurysm patients, there were 2 preoperative blood transfusions (2.8%), 4 intraoperative transfusions (5.6%), and 15 postoperative transfusions (21.1%). Forty-seven patients underwent surgery for unruptured aneurysms, with no preoperative transfusions, 2 intraoperative transfusions (4.3%), and 8 postoperative blood transfusions (17.0%). Of the 54 patients undergoing surgery for arteriovenous malformations, 5 patients (9.3%) were transfused preoperatively, 4 were transfused intraoperatively (7.4%), and 22 were transfused postoperatively (40.7%). None of the 3 patients undergoing surgery for concomitant arteriovenous malformations and aneurysms received intraoperative blood transfusions, but 1 received blood both preoperatively and postoperatively, and another received a transfusion postoperatively only. The overall ratio of perioperative cross-match to transfusion in this series is 41.4.

CONCLUSIONS

In vascular neurosurgery at our institution, blood has routinely been ordered excessively. We recommend an ABO-Rh type and antibody screen for aneurysm and arteriovenous malformation surgery and no screen for carotid endarterectomy to efficiently utilize transfusion therapy in cerebrovascular surgery.