Spring-Assisted Remodeling for Ventricular Shunt-Induced Cranial Deformity

Craniocerebral Disproportion Corrected With Biparietal Distraction Osteogenesis

Ventriculoperitoneal shunt therapy represents a lifesaving neurosurgical intervention in pediatric patients with hydrocephalus. Although necessary, research indicates that shunting may be associated with a spectrum of craniocerebral disproportion from frank craniosynostosis to later presenting neurofunctional symptoms and headaches. The surgical management of craniosynostosis is generally treated according to provider and institutional preference; however, shunt therapy presents difficulties for typical vault remodeling procedures. In this report, we describe the utility of a biparietal distraction osteogenesis configuration for the treatment of craniocerebral disproportion in 2 patients. A parallel arrangement of an anterior and a posterior set of 2 distractors allows for a doubling of the typical expansion of the parietal diameter. This method effectively alleviates the scaphocephaly without disruption of the shunt site. We propose our repair for the indication of sagittal craniosynostosis in the shunted patient.

Neonatal hydrocephalus: an atypical presentation of malignant infantile osteopetrosis

PURPOSE

Autosomal recessive osteopetrosis has a variable presentation, most commonly including failure to thrive, hypocalcemia, seizures, hepatosplenomegaly, hydrocephalus, vision or hearing loss, and cytopenias. Multiple symptoms are usually seen at presentation. The variability of presentation often delays diagnosis and subsequent treatment. Here, we present a case of an infant with this condition who initially presented with triventricular hydrocephalus with Chiari I malformation. This alone is not a common presentation of this disease, and we present this case to highlight autosomal recessive osteopetrosis as a potential diagnosis in infants presenting with hydrocephalus and discuss the other associated symptoms, management, and prognosis of this condition.

CASE REPORT

The patient was a full-term infant with a routine newborn period. At 6 months, the infant had macrocephaly and frontal bossing with a bulging fontanelle. She was found to have hydrocephalus with moderate ventriculomegaly involving the third and lateral ventricles with an associated Chiari 1 malformation. The infant was asymptomatic at the time. The infant was promptly referred to neurosurgery and underwent an uncomplicated ventriculoperitoneal shunt placement. Post-operative X-rays showed increased density of the skull with other bone changes suggestive of autosomal recessive osteopetrosis. Subsequent lab work and imaging studies were consistent with this condition. The diagnosis was confirmed by genetic testing, and the patient has undergone treatment with hematopoietic stem cell transplant.

CONCLUSION

Hydrocephalus is a common feature of this condition, typically seen in conjunction with other systemic symptoms and laboratory findings. Our patient had a limited initial presentation of triventricular hydrocephalus with Chiari I malformation and was otherwise clinically asymptomatic. There is limited literature of such a presentation, and we highlight this case to increase awareness, as timely diagnosis of these patients is critical for treatment and future outcomes.

Craniosynostosis Develops in Half of Infants Treated for Hydrocephalus with a Ventriculoperitoneal Shunt

BACKGROUND

Craniosynostosis following placement of a ventriculoperitoneal shunt for hydrocephalus has been sporadically described. The purpose of this investigation was to determine the general risk of developing craniosynostosis in this patient population.

METHODS

The authors retrospectively reviewed records and radiographs of infants who underwent ventriculoperitoneal shunt placement for hydrocephalus from 2006 to 2012. Recorded variables included date of shunt placement, demographics, comorbidities, cause of hydrocephalus, shunt type, and number of shunt revisions. Axial computed tomographic images obtained before and immediately after shunt placement and 2 to 4 years after shunt placement were evaluated by a panel of clinicians for evidence of craniosynostosis. Patients with preshunt craniosynostosis, craniosynostosis syndromes, or poor-quality computed tomographic images were excluded. Data were analyzed using STATA Version 15.1 statistical software.

RESULTS

One hundred twenty-five patients (69 male and 56 female patients) were included. Average age at shunt placement was 2.3 ± 2.58 months. Sixty-one patients (48.8 percent) developed craniosynostosis at a median of 26 months after shunt placement. Of these, 28 patients fused one suture; the majority involved the sagittal suture (n = 25). Thirty-three patients fused multiple sutures; the most common were the coronal (n = 32) and the sagittal (n = 30) sutures. Multivariable logistic regression identified older age at shunt placement and more shunt revisions as independent predictors of craniosynostosis. Shunt valve type was not significant.

CONCLUSIONS

Craniosynostosis developed in nearly half of infants who underwent ventriculoperitoneal shunt placement for hydrocephalus. The sagittal suture was most commonly involved. The effect of suture fusion on subsequent cranial growth, shunt failure, or the development of intracranial pressure is unclear.

CLINICAL QUESITON/LEVEL OF EVIDENCE

Risk, III.

The Science Behind the Springs: Using Biomechanics and Finite Element Modeling to Predict Outcomes in Spring-Assisted Sagittal Synostosis Surgery

Spring-assisted surgery for the correction of scaphocephaly has gained popularity over the past 2 decades. Our unit utilizes standardized torsional springs with a central helix for spring-assisted surgery. This design allows a high degree of accuracy and reproducibility of the force vectors and force distance curves. In this manuscript, we expand on the biomechanical testing and properties of these springs. Standardization of design has enabled us to study the springs on bench and in vivo and a comprehensive repository of calvarial remodeling and spring dynamics has been acquired and analyzed.Finite element modeling is a technique utilized to predict the outcomes of spring-assisted surgery. We have found this to be a useful tool, in planning our surgical strategy and improving outcomes. This technique has also contributed significantly to the process of informed consent preoperatively. In this article, we expand on our spring design and dynamics as well as the finite element modeling used to predict and improve outcomes.In our unit, this practice has led to a significant improvement in patient outcomes and parental satisfaction and we hope to make our techniques available to a wider audience.

In vitro performance of six combinations of adjustable differential pressure valves and fixed anti-siphon devices with and without vertical motion

OBJECTIVE

Adjustable differential pressure (DP) valves in combination with fixed anti-siphon devices are currently a popular combination in counteracting the effects of cerebrospinal fluid overdrainage following implantation of a ventriculoperitoneal shunt system. The study examined the flow performance of three DP valves in successive combination with an anti-siphon device in an in vitro shunt laboratory with and without vertical motion.

METHODS

We analyzed three DP valves (Codman Hakim Medos programmable valve [HM], Codman CertasPlus [CP], and Miethke proGAV [PG], in combination with either Codman SiphonGuard [SG] or Miethke ShuntAssistant [SA]), resulting in the evaluation of six different valve combinations. Defined DP conditions between 4 and 40 cm H₂O within a simulated shunt system were generated and the specific flow characteristics were measured. In addition, combinations with SA, which is a gravity-dependent valve, were measured in defined spatial positions (90°, 60°). All device combinations were tested during vertical motion with movement frequencies of 2, 3, and 4 Hz.

RESULTS

All valve combinations effectively counteracted the siphon effect in relation to the chosen DP. Angulation-related flow changes were similar in the three combinations of DP valve and SA in the 60° and 90° position. In CP-SA and PG-SA, repeated vertical movement at 2, 3, and 4 Hz led to significant increase in flow, whereas in HM-SA, constant increase was seen at 4 Hz only (flow change at 4Hz, DP 40 cm H₂O: PG (opening pressure 4 cm H₂O) 90°: 0.95 ml/min, 60°: 0.71 ml/min; HM (opening pressure 4 cm H₂O) 90°: 0.66 ml/min, 60°: 0.41 ml/min; CP (PL 2) 90°: 0.94 ml/min, 60°: 0.79 ml/min; p < 0.01); however, HM-SA showed relevant motion-induced flow already at low DPs (0.85 ml/min, DP 4 cm H₂O). In combinations of DP valve with SG, increase of flow was far less pronounced and even led to significant reduction of flow in certain constellations. Maximum overall flow increase was 0.46 ± 0.04 ml/min with a HM (opening pressure 12 cm H₂O) at 2 Hz and a DP of 10 cm H₂O, whereas maximum flow decrease was 1.12 ± 0.08 with a PG (opening pressure 4 cm H₂O) at 3 Hz and a DP of 10 cmH₂O.

CONCLUSION

In an experimental setup, all valve combinations effectively counteracted the siphon effect in the vertical position according to their added resistance. Motion-induced increased flow was consistently demonstrated in combinations of DP valve and SA. The combination of HM and SA especially showed relevant motion-induced flow already at low DPs. In combinations of DP and SG, the pattern of the motion induced flow was more inconsistent and motion even led to significant flow reduction, predominantly at DPs of 10 and 20 cmH₂O.

Spring-Assisted Distraction Osteogenesis for the Treatment of Shunt-Induced Craniosynostosis

Shunt-induced craniosynostosis is a rare complication of ventricular shunting for hydrocephalus in pediatric patients. Although the exact pathophysiology of this form of secondary craniosynostosis is not well understood, the current understanding is that persistent drainage of the ventricular shunt causes decreased dural tension, resulting in decreased expansile force on the cranium and premature sutural fusion. Due to the low incidence of this complication, there is no consensus on the ideal treatment for shunt-induced craniosynostosis. In recent years, distraction osteogenesis has been employed with greater frequency, as it is felt to counter the fundamental problem of decreased expansile force on the cranium. However, in a patient with a ventricular shunt, placement of external hardware in close proximity to the shunt could cause significant morbidity due to the increased risk of shunt infection. We present the management of a patient with shunt-induced craniosynostosis who continued to be shunt-dependent. We chose to use fully buried springs to create an expansile force on the cranium as an alternative to external distractors so as to mitigate the risk of infection. We demonstrate that spring-assisted distraction osteogenesis can be an effective treatment modality for patients with shunt-induced craniosynostosis. This method should be considered in patients with contraindications to external distraction devices, such as ongoing shunt dependency.

The Incidence of Chiari Malformations in Patients with Isolated Sagittal Synostosis

Background:

We report the incidence of Chiari malformation I (CMI) in a cohort of 377 patients with isolated sagittal synostosis (ISS), which is to the best of our knowledge the largest such series reported to date.

Methods:

A retrospective review of patients seen at a single institution from 2007 to 2017 was completed. ISS, Chiari malformations (CMI and CMII) and hydrocephalus were diagnosed by a senior neuroradiologist (G.Z.). Patients who met the inclusion criteria were divided into early (group A) and late (group B) presenting groups, as well as operated (group I) and unoperated (group II) groups. The patients were further subdivided into group AI (early operated), group AII (early unoperated), group BI (late operated), and group BII (late unoperated). Once identified, patient notes were examined for the following data sets: date of birth, age of presentation, age at last follow-up, other systemic conditions as well as molecular testing results. Surgical interventions, ophthalmological, and other relevant data were recorded. Statistical analysis was run in the form of a chi-square test to identify a significant difference between each subgroup. A literature review of the incidence of Chiari malformations in patients with ISS was conducted.

Results:

Three hundred seventy-seven patients constitute the study’s total cohort (272 were males and 105 females). This cohort was divided into patients who underwent surgical repair of ISS (group 1: n = 200), and patients who did not (group 2: n = 177). The entire cohort was also divided into early (group A: n = 161) and late (group B: n = 216) presenting craniosynostosis. In the total cohort, 22/377 (5.8%) patients with CMI were identified. CMI was found in 14/200 (7.0%) patients in group I, and 8/177 (4.5%) patients in group II. CMI was found in 2/161 (1%) patients in group A, and 20/216 (9.2%) patients in group B. The incidence of CMI in group AI (early operated) was 2/151 (1.3%), in group AII (early unoperated) was 0/10, in group BI (late operated) was 11/49 (21%), and in group BII (late unoperated) was 9/167 (5.4%). Chi-square analysis revealed a significant difference between the incidence of CMI in the early-presenting (group A) and late-presenting (group B) groups (P = 0.001) and between the late-presenting operated (BI) and late-presenting unoperated (BII) groups (P = 0.001). The incidence of hydrocephalus was 1.6% (6/377) in the total cohort. However, all patients diagnosed with hydrocephalus came from group II (no surgical ISS correction). The incidence of hydrocephalus in group II was 3.3% (6/177). The incidence of hydrocephalus in group BII (late unoperated ISS) was 3.0% (5/167). The incidence of hydrocephalus in group AII (early unoperated ISS) was 9.0% (1/11).

Conclusions:

We noted the highest incidence of CMI—21%—in group BI (late-presenting operated). We noted hydrocephalus in group II (nonoperated), with the highest incidence of hydrocephalus found in the group BII (late-presenting unoperated) subgroup. We therefore recommend patients with ISS receive funduscopic examination to screen for raised intracranial pressure (ICP) associated with CMI and hydrocephalus, especially patients with late-presenting ISS.

Continuous Intracranial Pressure Monitoring in 24 Microcephalic Children with Developmental Delay: A Significant Portion of Microcephalic Children with Developmental Delay Have High Intracranial Pressure

OBJECTIVE

The new direct gradual cranial expansion surgical technique has been used to treat children with postshunt microcephaly and slit ventricle syndrome. To evaluate the feasibility of this new surgical treatment, we studied intracranial pressure (ICP) in microcephalic children with developmental delay.

METHODS

Mean ICP, age, sex, head size, and developmental assessments were compared in 24 microcephalic children with developmental delay who had had continuous ICP monitoring.

RESULTS

Children studied included 9 boys and 15 girls with a mean age of 4.9 ± 2.0 years. Mean ICP was 18.7 ± 8.6 mm Hg. Children with high ICP had significantly lower age and higher B wave ratios than children with low ICP. There were no statistically significant differences in developmental scores and head sizes between children with high ICP and children with low ICP. In multiple linear regression analysis, we observed significantly increased risk of mean ICP elevation by B wave ratio and developmental score and decreased risk of mean ICP elevation by age, but not significantly increased risk of mean ICP elevation by head circumferences (z score).

CONCLUSIONS

Our findings suggest that a portion of microcephalic children with developmental delay have high ICP that cannot be expected from head sizes, and high ICP has decreasing tendency with age.

Isolated Post-Shunt Metopic Synostosis and Neural Tube Defects

BACKGROUND

Craniosynostosis is an uncommon complication after shunting procedures for congenital hydrocephalus. We report a case of a child with myelomeningocele and normocephaly at the time of birth. She underwent ventricular shunting for Chiari malformation and hydrocephalus at 3 days of age. An immediate postoperative CT scan confirmed all sutures were open. Serial CT scans document an open metopic suture at 2 months, closed metopic suture at 5 months, and trigonocephaly at 11 months with concomitant slit ventricle syndrome, and collapsed lateral and third ventricles.

METHODS

An Ovid MEDLINE search within the dates of 1948 through 2017, using the keywords "synostosis AND shunt" was carried out. A tabulation of all patients and their respective synostosis patterns were recorded.

RESULTS

We identified 8 case series and 2 case reports during 43 years (1966-2017). Seventy-eight patients with 79 suture synostosis patterns were identified (one patient underwent a second cranial reconstruction for identification of a separate, newly formed synostosis). Eighteen (30.5%) cases were associated with a neural tube defect (NTD). Patients with NTD and secondary craniosynostosis had on average earlier age of shunt placement (P = 0.001), craniosynostosis presentation (P = 0.146), and cranioplasty (P = 0.325) than secondary craniosynostosis patients without NTD.

CONCLUSIONS

Ventricular shunt drainage in treating hydrocephalus rarely may lead to early synostosis and cranial deformity, especially in patients with NTDs. Early shunt placement poses significant risk in patients with NTD. Close follow-up may be necessary to evaluate overdrainage and cranial deformity after shunting procedures.

Surgical management of craniosynostosis in the setting of a ventricular shunt: a case series and treatment algorithm

PURPOSE

Cerebrospinal fluid diversion via ventricular shunt is a common treatment for hydrocephalus. Change in cranial morphology associated with a sutural fusion has been termed shunt-related or induced craniosynostosis (SRC) or craniocerebral disproportion (CCD). We present a series of patients with SRC who underwent cranial vault remodeling (CVR) and our treatment algorithm.

METHODS

Thirteen patients were retrospectively reviewed who had SRC and CVR; 92% of patients had a ventriculoperitoneal (VP) shunt placed for largely intraventricular hemorrhage of prematurity (69% of patients) at a mean age of 2.2 months. The shunt revision rate was 38.4%, and 54% of patients had a programmable shunt placed initially.

RESULTS

The mean age at time of CVR was 3.6 years old. The most commonly affected sutures (CT confirmed) were the sagittal and coronal sutures, with three patients exhibiting pancraniosynostosis. The mean time from placement of the shunt to CT evidence of sutural fusion was 2.0 years. Abnormal head shape was noted in all 13 patients; 11 of these also had either chronic headaches, papilledema, seizures, or behavioral changes in the setting of functional shunt. Mean follow-up after the initial CVR was 3.3 years. No shunt infections were attributed to the CVR. The families of all patients were contacted and reported improvement in head shape with 60% of families reporting improvement in behavior, 75% reported improvement in headaches, and 40% reported decrease in seizure frequency or intensity. Shunt setting or type was not routinely changed after CVR.

CONCLUSIONS

Our threshold for CVR in SRC is met when shunt malfunction has been ruled out and there are (1) radiographic evidence of craniosynostosis, (2) signs of increased ICP clinically or radiographically, and (3) cranial dysmorphism, i.e., dolichocephaly. The majority of cases of SRC result in improved cranial morphology in addition to some abatement of the symptoms of increased intracranial pressure. Early involvement of an experienced craniofacial/neurosurgical team could allow for early diagnosis and intervention which may prevent progression to more severe deformities. SRC is a complex entity, with multiple etiologies, and a future study is needed.

In vitro performance of the fixed and adjustable gravity-assisted unit with and without motion-evidence of motion-induced flow

BACKGROUND

Anti-siphon devices and gravitational-assisted valves have been introduced to counteract the effects of overdrainage after implantation of a shunt system. The study examined the flow performance of two gravitational-assisted valves (shunt assistant - SA and programmable shunt assistant - proSA, Miethke & Co. KG, Potsdam, Germany) in an in vitro shunt laboratory with and without motion.

METHODS

An in vitro laboratory setup was used to model the cerebrospinal fluid (CSF) drainage conditions similar to a ventriculo-peritoneal shunt and to test the SA (resistance of +20 cmH2O in 90°) and proSA (adjustable resistance of 0 to +40 cmH2O in 90°). The differential pressure (DP) through the simulated shunt and tested valve was adjusted between 0 and 60 cmH2O by combinations of different inflow pressures (40, 30, 20, 10, and 0 cmH2O) and the hydrostatic negative outflow pressure (0, -20, and -40 cmH2O) in several differing device positions (0°, 30°, 60°, and 90°). In addition, the two devices were tested under vertical motion with movement frequencies of 2, 3, and 4 Hz.

RESULTS

Both gravity-assisted units effectively counteract the hydrostatic effect in relation to the chosen differential pressure. The setting the proSA resulted in flow reductions in the 90° position according to the chosen resistance of the device. Angulation-related flow changes were similar in the two devices in 30-90° position, however, in the 0-30° position, a higher flow is seen in the proSA. Repeated vertical movement significantly increased flow through both devices. While with the proSA a 2-Hz motion was not able to induce additional flow (0.006 ± 0.05 ml/min), 3- and 4-Hz motion significantly induced higher flow values (3 Hz: +0.56 ± 0.12 ml/min, 4 Hz: +0.54 ± 0.04 ml/min). The flow through the SA was not induced by vertical movements at a low DP of 10 cmH2O at all frequencies, but at DPs of 30 cmH2O and higher, all frequencies significantly induced higher flow values (2 Hz: +0.36 ± 0.14 ml/min, 3 Hz: +0.32 ± 0.08 ml/min, 4 Hz: +0.28 ± 0.09 ml/min).

CONCLUSIONS

In a static setup, both tested valves effectively counteracted the hydrostatic effect according to their adjusted or predefined resistance in vertical position. Motion-induced increased flow was demonstrated for both devices with different patterns of flow depending on applied DP and setting of the respective valve. The documented increased drainage should be considered when selecting appropriate valves and settings in very active patients.

Safety of Open Cranial Vault Surgery for Single-Suture Craniosynostosis: A Case for the Multidisciplinary Team

INTRODUCTION

Single Suture Craniosynostosis (SSC) occurs in 1 in 2,500 live births and is the most common type of craniosynostosis treated in most centers. Surgical treatment has evolved over the past century and open techniques are tailored to the specific suture type. Additionally, the concept of multi-disciplinary team care has proliferated and is becoming the standard of care for SSC. The combination of these evolutions, we believe, has improved the safety of cranial vault surgery for SSC.

METHODS

A retrospective review of patients participating in the Infant Learning Project at Seattle Children's Hospital who underwent cranial vault surgery for treatment of SSC between 2002 and 2006 was performed. Pre-operative assessment, surgical techniques, anesthetic and intraoperative events and both intra-operative and post-operative adverse events were analyzed.

RESULTS

Eighty eight patients fulfilled the inclusion criteria (42 sagittal, 23 metopic, 19 unicoronal, 4 lambdoid). Length of procedure varied (FOA 5.2 hrs, modified pi 2.5 hrs, total vault 4.9 hrs and switch cranioplasty 4.6 hrs), as did transfusion amount (FOA 385 mL, modified pi 216 mL, total vault 600 mL, switch cranioplasty 207 mL) although 99% of patients received a transfusion of some sort. There were no deaths and no major intraoperative complications. Minor events include; ET tube malposition (1), desaturation (1), acidosis (1), hypothermia (9), coagulopathy (2), Hct < 25 (55). Average hospital stay was 3.4 days with no major post-operative complications. One patient was readmitted to the ICU and 1 had a scalp hematoma, but no patients returned to the operating room within 6 months after surgery.

DISCUSSION

The surgical treatment of SSC has evolved from lengthy, risky procedures to become almost routine at most craniofacial centers. Additionally, the care for patients with SSC has evolved from a single provider to a multidisciplinary team concept based around protocols for workup, delivery of anesthesia, streamlined surgical procedures and post-operative care and assessment. This evolution has given open cranial vault surgery for SSC an acceptable safety profile.

Comparison Between Two Different Isolated Craniosynostosis Techniques: Does It Affect Cranial Bone Growth?

INTRODUCTION

Craniosynostosis is a premature closure of a cranial suture. Cranioplasty is indicated to correct skull deformity, relieve increased intracranial pressure, and promote homogenous cranial growth. Different techniques have been adopted to achieve optimal outcomes. Although surgical benefits are widely accepted, this intervention might also affect cranial skeletal growth.

METHODS

The authors conducted a retrospective case-control study including patients operated for isolated metopic or sagittal synostosis. These patients had undergone a computed tomography (CT) scan before surgery and/or at 3 years of age postoperatively. These were operated between 2002 and 2012. Intracranial volume was measured using a MATLAB application. The control group was age and sex-matched individuals who had CT scans for trauma or neurological indications. All results with P value <0.05 were considered statistically significant.

RESULTS

A total of 185 patients were included in the study with a preoperative CT scan (143 sagittal synostosis and 42 metopic synostosis). Postoperatively 160 patients were identified including 103 sagittal synostosis and 57 metopic synostosis. These patients were compared to 414 controls. There was a statistically significant reduction in intracranial volume (ICV) in patients operated for metopic synostosis with both techniques. It also demonstrated a statistically significant difference in ICV in patients with sagittal synostosis operated with Pi-plasty and a nonsignificant difference in ICV in patients operated with strip craniotomy and springs.

CONCLUSION

In conclusion, these measurements of ICV have revealed that extensive cranioplasties for premature craniosynostosis can lead to minor but significant growth restriction and reduced ICV at long-term follow-up.

Slit ventricle syndrome and early-onset secondary craniosynostosis in an infant

Patient: Female, 14 months

Final Diagnosis: Slit ventricle syndrome

Symptoms: Hydrocephalus • lethargy and seizure • vomiting

Medication: —

Clinical Procedure: —

Specialty: Pediatrics and Neonatology

Craniosynostosis following hemispherectomy in a 2.5-month-old boy with intractable epilepsy

The authors report on the case of a 6-week-old boy who presented with infantile spasms. At 2.5 months of age, the patient underwent a right hemispherectomy. Approximately 3 months postoperatively, the patient presented with left coronal craniosynostosis. Subsequent cranial vault remodeling resulted in satisfactory cosmesis. Four years after surgery, the patient remains seizure free without the need for anticonvulsant medications. The authors believe this to be the first reported case of iatrogenic craniosynostosis due to hemispherectomy, and they describe 2 potential mechanisms for its development. This case suggests that, in the surgical treatment of infants with intractable epilepsy, minimization of brain volume loss through disconnection techniques should be considered, among other factors, when determining the best course of action.

Adaptation of the cranium to spring cranioplasty forces

BACKGROUND

During spring-assisted cranioplasty, the spring transmits forces through adjacent cranium. We have previously demonstrated that the ectocranial-endocranial thickness of cranial sutures increases significantly over time in the presence of continuous spring forces. We wished to investigate if cranial bone showed similar adaptational responses.

METHODS

New Zealand white rabbits were randomized into a treatment group [a spring was placed across a posterior frontal suture (PFS) suturectomy and a control group (PFS suturectomy)]. Animals (n = 6) were euthanized from each group at 4, 7, and 10 weeks, respectively. A sham group (n = 6) was euthanized at 10 weeks. Frontal bone thickness was recorded at five reproducible anatomical points on the frontal bone. Histological analysis of the bone architecture was performed.

RESULTS

Frontal bone thickness was significantly greater than controls at all five sites at weeks 7 and 10. There were multiple significant differences between the 4-, 7-, and 10-week groups with each site progressively thickening over time. Histological analysis revealed a uniform increase in thickness of the endocranial and ectocranial cortical bone in the treatment groups.

CONCLUSIONS

Cranial bone adapts to the presence of continuous spring cranioplasty forces by progressively thickening over time. This property is beneficial in craniosynostosis cases with very thin and poor quality bone and may partly explain the observed lack of spring erosion through bone.

Management of cranial deformity following ventricular shunting

PURPOSE

Ventricular shunt-induced craniosynostosis is a widely recognised cause of secondary craniosynostosis. We reviewed the management and long-term outcome of the cases of cranial deformity post cerebrospinal fluid shunting in our unit and compared these with previously published series.

METHODS

The Australian Craniofacial Unit and Department of Neurosurgery database was searched to identify cases of ventricular shunt-induced cranial deformity and a case note review was undertaken.

RESULTS

Eight cases were identified, and all were shunted within 6 months of birth. Our patients required shunting with a low pressure valve for hydrocephalus secondary to either aqueduct stenosis or intraventricular haemorrhage. The diagnosis was made following computed tomography (CT) three-dimensional surface reconstruction of the skull. Two cases of confirmed suture fusion were treated with cranial vault remodelling and programmable shunt insertion. In six cases, the sutures were not completely fused on the CT images despite a scaphocephalic head shape. These patients were managed conservatively with close monitoring.

CONCLUSION

Cranial vault remodelling together with insertion of programmable shunt valve is indicated in CT confirmed cases of secondary craniosynostosis.

Correction of nonsynostotic scaphocephaly without cranial osteotomy: spring expansion of the sagittal suture

BACKGROUND

Scaphocephaly is usually due to sagittal synostosis. Scaphocephaly may also be seen in the presence of a nonsynostosed sagittal suture. In this situation traditional surgery is controversial due to the altered risk-benefit profile. This paper reports the first known series of patients with nonsynostotic scaphocephaly treated using spring assisted expansion of the sagittal suture.

METHODS

All patients referred to our craniofacial program over the period February 2005-February 2008 were retrospectively reviewed. Eleven patients were seen with nonsynostotic scaphocephaly. Seven patients underwent spring expansion of the sagittal suture without osteotomy.

RESULTS

Four female and three male patients had spring expansion of a patent sagittal suture. Four patients were born prematurely. Two patients had Beckwith-Weidemann syndrome. The ages ranged from 6 to 26 months (mean 12 months). The average preoperative cranial index was 66 (range 63-67). This improved to 76 at the time of spring removal (range 73-78). Springs were kept in situ for an average of 7.25 months. The mean blood loss was 7 ml and the mean operative time 36 min.

CONCLUSION

Spring cranioplasty for sagittal synostosis is ideally performed before 6 months of age however in nonsynostotic scaphocephaly older children can be considered due to the absence of frontal bossing. Significant aesthetic improvement was achieved in all cases and normalization of the cranial index was achieved in 86% of cases with minimal morbidity and no significant complications. This technique is an alternative for nonsynostotic cases that were previously either untreated or undergone major remodelling surgery.