Faculty Bibliography

Cranial defect repair in the pediatric population requires a variety of special considerations. The pediatric skull has a dynamic nature that prohibits the use of rigid fixation, which is commonly applied in the adult population. A technique using a combination of polylactic acid plates and carbonated apatite bone cement has been devised by our group. Skull defects of varying sizes were repaired in 34 pediatric patients. Patients were examined on postoperative day 3 and at 3 months via three-dimensional computed tomography scans. Patients have been followed up to 60 months after surgery without complications or failures to date. This method benefits the pediatric patients undergoing cranioplasty by minimizing the insertion of long-term foreign bodies and allows the possibility for transformation of this construct into viable tissue

STUDY DESIGN: A case study with review of surgical technique in craniovertebral stabilization for young children with mucopolysaccharidosis. OBJECTIVES: To describe an interesting patient with a rare metabolic disorder and review surgical technique for craniovertebral instability in this rare patient population. SUMMARY OF BACKGROUND DATA: Craniovertebral instability has been reported in patients with mucopolysaccharidosis and poses a problem for spinal surgery because of the inherent metabolic disorder and age at presentation. We present the first case of craniovertebral instability and spinal cord compression occurring in Sly syndrome (mucopolysaccharidosis type VII) who is the youngest patient afflicted with this metabolic disorder to undergo craniovertebral stabilization. METHODS: A 17-month-old boy presented with inability to support his head, decreasing muscle strength in all extremities, distended abdomen, and shortness of breath. The patient was found to have a dilated cardiomyopathy, hepatosplenomegaly, abnormal hepatobiliary function, corneal clouding, and a questionable tracheal anomaly. Genetic testing provided a diagnosis of Sly syndrome, mucopolysaccharidosis type VII. Magnetic resonance imaging revealed focal stenosis with significant spinal cord compression at the craniovertebral junction. Neurologic examination revealed normal muscle volume with strength 3/5 in all extremities and significant weakness in the neck muscles with instability at the craniovertebral junction. RESULTS: On a concerted preoperative medical clearance by pediatric intensive care, pediatric neuroanesthesia, pediatric cardiology, pediatric gastroenterology, and pediatric neurosurgery, the patient underwent occipital to C3 decompression and fusion with autogenous rib grafts. The patient was placed in a prefitted halo-vest after surgery and was neurologically intact. CONCLUSIONS: This case demonstrates the heterogeneity of cervical spine deformities among the mucopolysaccharidosis syndromes and confirms the propensity for deposition of glycosaminoglycans at the craniovertebral junction. Further studies should investigate the etiology for this propensity of glycosaminoglycan deposition at the craniovertebral junction. We think that this case demonstrates that, with appropriate preoperative planning, these patients can undergo successful posterior cervical arthrodesis despite their age or metabolic defects

CASE REPORT. An 8-year-old developmentally normal boy (status: post third ventriculostomy and resection of posterior fossa low-grade glioma 4 years earlier and with known history of ventriculomegaly/arrested hydrocephalus) presented to the emergency room with vomiting and lethargy after a minor head trauma. Computed tomography scan of the head revealed no acute changes since previous studies. However, the patient's neurological status rapidly declined in the emergency room, where an emergency ventriculostomy demonstrated increased intracranial pressure. The patient's clinical condition improved over 24 h: he underwent placement of a ventriculoperitoneal shunt without complications and was discharged intact. DISCUSSION. The pathogenesis of rapid neurological decline associated with minor head trauma in chronic hydrocephalus is reviewed

Intrathecal pump catheter complications are the most common cause of failure in drug delivery. A previous report has documented that intra-abdominal positioning of the intrathecal pump may predispose the pump-catheter neck to premature catheter breakdown and leakage. Based on this report, we reviewed over 100 intrathecal pump cases to determine the frequency of malpositioning and its role in the pathogenesis of catheter failure. We found three specific cases where a 'fulcrum effect' occurred due to intra-abdominal positioning of the pump predisposing the catheter to breakdown. This study demonstrates that intra-abdominal placement of the pump can predispose the catheter to failure/breakdown and that surgeons should attempt to place the pump catheter neck in a superiomedial position, distant from any bony prominences, to prevent the 'fulcrum effect' on the pump-catheter neck junction and reducing the likelihood of either internal or external compressive forces

To date, there are no broad-based studies defining the standard of care for pediatric neurosurgeons in the area of cranial fixation. Thus, the techniques for cranial fixation remain largely surgeon dependent. Over the past few years, there have been several new cranial fixation devices approved for use in the United States. To gain insights into techniques currently in use by pediatric neurosurgeons, we polled all pediatric neurosurgeons listed in either the American Society of Pediatric Neurosurgeons or the International Society of Pediatric Neurosurgeons regarding their techniques for cranial fixation in a variety of age groups. These survey findings may provide a basis for establishing recommendations and lead to a standard of care for cranial fixation techniques among pediatric neurosurgeons

Intrathecal baclofen pump catheter complications are the most common cause for failure in drug delivery. A 4-year-old boy presented with repeated signs of baclofen tolerance despite progressive increases in dosing. External computerized interrogation of the pump and radiograph evaluation of the pump-catheter-intrathecal sac system were normal. Subsequently, he was taken to the emergency room for baclofen overdosage and brought to the operating room for exploration of the implant. Intraoperative assessment of the pump catheter found a cut on the catheter neck that was visible only when the catheter neck was flexed. The catheter was replaced without complications. Two months later, the patient returned with similar symptoms. Repeat computerized and radiographic assessment of the pump were normal. Intraoperative assessment showed a cut within the same portion of the catheter as previously discovered. The catheter cut was in the least flexible portion, the pump-catheter neck, which was found to be overlying the iliac crest in both surgeries. The authors hypothesize that the repetitive compressive forces of the catheter overlying the iliac crest led to catheter breakdown. Surgical placement of the pump-catheter neck should be superio-medial to reduce the likelihood of either internal or external compressive forces

A newborn presented with a cerebral ganglioglioma. This is a rare diagnosis in a neonate. The imaging appearance (hyperdense on CT, hyperintense on T1-weighted and hypointense on T2-weighted MRI) is very unusual for this type of tumor

The long-term outcome of 75 children who underwent methyl methacrylate cranioplasty over a 15-year period is presented. Forty-two patients underwent cranioplasty for posttraumatic skull defects and 33 for nontraumatic causes. Within 8 years following initial cranioplasty procedure, a total of 17 (23%) complications occurred. Several factors correlated with the development of complications, including postoperative radiotherapy, the size of the defect, involvement of the frontal sinus, and the presence of prior infection. The authors currently recommend avoiding methyl methacrylate cranioplasty in selected patients who have received postoperative radiation therapy, in patients with large cranial defects, involvement of the frontal sinus, or any history of prior infection

OBJECTIVE AND IMPORTANCE: Intracranial shunts are commonly placed in children and frequently require replacement during the child's growing years. Severe signs of increased intracranial pressure often are the first indication of shunt displacement and malfunction. Subtle neuro-ophthalmic signs in children are usually overlooked. CLINICAL PRESENTATION: Two cases are described in which homonymous hemianopsia resulted from unsuspected movement of the shunt catheter in growing children. In one male patient, the catheter tip impaled the optic tract, and in the other male patient the shunt became embedded in the midbrain tegmentum and shunt failure led to compression of the posterior cerebral artery. INTERVENTION: In the presence of optic atrophy, papilledema may go unnoticed without serial examinations. This stresses the importance of detecting other early warning signs of shunt displacement and increased intracranial pressure, including visual field changes and subtle abnormalities of motility. CONCLUSION: Because early diagnosis and shunt revision may allow visual recovery, children with shunts should be followed with visual fields and serial disc photographs