Dale M. Swift

Posterior fossa syndrome: Identifiable risk factors and irreversible complications

Cerebellar mutism was first described by Rekate et al. in 1985 as a transient condition which occurs after posterior fossa operations in children. Posterior fossa syndrome (PFS) and cerebellar mutism are often used interchangeably in the literature. In our experience, we found cerebellar mutism to be a reversible component of a persistent neurologic syndrome. The cause and identifiable risk factors have not been clearly elucidated in the literature. To further characterize PFS, we reviewed 253 children with posterior fossa tumors who underwent surgical resection. We documented 20 cases of PFS (8%), 12 males and 8 females. Age ranged from 1.5 to 13 years (mean = 6.5). Of the 20, 16 were medulloblastoma, 3 ependymoma and 1 astrocytoma. There was a 21% incidence (16/76) of PFS in medulloblastoma of the posterior fossa. The incidence for ependymoma was 13% (3/24) and 1% (1/102) for astrocytoma. All 20 cases (100%) had brainstem involvement by the tumor. The most frequent postoperative findings included mutism, ataxia, 6th and 7th nerve palsies and hemiparesis. Mutism had a latency range of 1–7 days (mean = 1.7) and a duration of 6–365 days (mean = 69.2, median = 35). Although mutism resolved in all cases, the remaining neurologic complications which characterized our findings of PFS were rarely reversible. We describe potential risk factors for developing PFS after surgery with hopes of making neurosurgeons more aware of potential problems following the removal of lesions in this area. Early recognition of PFS would further promote patient and family understanding and coping with this syndrome.

Robotically guided radiosurgery for children

A robotically guided linear accelerator has recently been developed which provides frameless radiosurgery with high precision. Potential advantages for the pediatric population include the avoidance of the cognitive decline associated with whole brain radiotherapy, the ability to treat young children with thin skulls unsuitable for frame‐based methods, and the possible avoidance of general anesthesia. We report our experience with this system (the “Cyberknife”) in the treatment of 21 children.

GMFM 1 year after continuous intrathecal baclofen infusion

The purpose of this study was to assess whether there is an improvement in motor function in persons with cerebral palsy (CP) who have had a reduction of muscle tone by continuous intrathecal baclofen infusion. This was a prospective, open label, non-blinded case series without a control group, conducted at multiple centres. There were 31 subjects, aged 4–29 years. All had a pre-treatment mean lower extremity Ashworth scores of  ≥ 3 and a significant reduction in tone after a bolus injection of intrathecal baclofen (ITB) and received an implanted pump for continuous delivery of ITB. Motor function was assessed by the Gross Motor Function Measure (GMFM) prior to and 1 year following pump implantation. Significant improvement (p < 0.05) in mean GMFM scores was seen in subjects < 8 years (mean change 4.1) and in those from 8–18 years (mean change 3.7) and in subjects with CP Classes 2 and 5 (mean changes 6.2 and 2.9). There was a statistically significant decrease (p < 0.05) in Ashworth scores in CP classes 2–5. Subjects or their caregivers that completed a survey about perceived changes stated that motor control, positioning and endurance improved.

A new approach to closure of large lumbosacral myelomeningoceles: the superior gluteal artery perforator flap.

The most common form of neural tube defect is the myelomeningocele, developing during the fourth week of gestation. The era of early closure of myelomeningoceles began in the sixties with the demonstration that these patients had a lower rate of mortality.1 The goals of early surgical closure are to (1) prevent infection, (2) eliminate cerebrospinal fluid leaks, (3) preserve neural function, and (4) diminish negative late sequelae such as pain over the closure site and possibly even tethered cord.2 After closure of the neural tube and dura, the majority of these patients have enough local skin to allow for simple closure of the skin over the dural closure. When the skin defect is large or the surrounding skin quality is poor, more elaborate methods of obtaining stable skin closure over the dural closure must be devised.3 Multiple methods of soft-tissue closure for larger lumbosacral myelomeningocele defects have been described, including skin grafting,4 random flaps,5 skin undermining with relaxing incisions,6 and musculocutaneous flaps.7,8 None of these approaches are ideal, however, particularly when the skin defect is large and/or the quality of the surrounding skin is poor. We have developed a new approach to closure of large lumbosacral defects with superior gluteal artery perforator flaps.

Subarachnoid hemorrhage fails to produce vasculopathy or chronic blood flow changes in rats

Cerebral blood flow was measured by a [14C]butanol indicator fractionation technique in rats subjected to subarachnoid hemorrhage, in control rats, and in rats given injections of buffered saline into the subarachnoid space (sham hemorrhage). Cerebral blood flow was significantly decreased in both the subarachnoid hemorrhage and sham hemorrhage rats 3 hours after injection. However, blood flow returned to control levels by 24 hours, and measurement for 14 days after subarachnoid hemorrhage failed to show any delayed decrease in cerebral blood flow. Electron microscopic studies of basilar arteries from rats subjected to subarachnoid hemorrhage 72 hours before killing failed to show any of the morphologic changes that have been associated with vasospasm in humans or in higher animal models. Our studies indicate that the rat model of subarachnoid hemorrhage has limited applicability to the study of subarachnoid hemorrhage following ruptured cerebral aneurysms in humans. However, although rats are not a perfect model of this clinical condition, some pathophysiologic changes similar to those observed in human subarachnoid hemorrhage have been demonstrated in this model and deserve further investigation.

Complications of ventricular shunts

Abstract:Ventricular shunting is the most widely accepted form of treatment of hydrocephalus. The placement of cerebrospinal fluid shunts has become one of the most common procedures in modern neurologic surgery. Despite significant improvements in shunt procedures, shunt complications remain common

Predictors of tumor progression among children with gangliogliomas. Clinical article.

OBJECT Few reports describe the outcome and prognostic factors for children with gangliogliomas. The objective of this report was to describe the progression-free survival (PFS) for children with low-grade gangliogliomas and identify risk factors for tumor progression. METHODS A retrospective study was performed in children with low-grade gangliogliomas who were evaluated and treated in the neuro-oncology department between 1986 and 2006 to determine risk factors for subsequent tumor progression. RESULTS A total of 38 children with newly diagnosed gangliogliomas were included in this report. Thirty-four children were treated with surgery alone, 3 with subtotal resection and radiation therapy, and 1 with subtotal resection and chemotherapy. The follow-up ranged from 4 months to 15.8 years (mean 5.7+/-4.2 years [+/-SD]). Seven children have experienced tumor progression, and 1 child died after his tumor subsequently underwent malignant transformation. The 5-year PFS was calculated to be 81.2% using Kaplan-Meier survival analysis. Initial presentation with seizures (p=0.004), tumor location in the cerebral hemisphere (p=0.020), and complete tumor resection (p=0.035) were associated with prolonged PFS. Further analysis of the above significant variables by a Cox regression model identified initial presentation with seizures as being associated with prolonged PFS (p=0.028). CONCLUSIONS The PFS and overall survival of children with gangliogliomas are good. Tumors located in the cerebral hemispheres, the achievement of total resection, and seizures at presentation were associated with prolonged PFS. Cox regression analysis identified presenting symptoms including seizures as significant predictive factors of PFS. Prospective studies with larger numbers of children are needed to define the significant factors of tumor progression.

Multiple Epidural Hematomas following Ventriculoperitoneal Shunt

Although extra-axial hematomas are a well-known complication of ventricular shunting, epidural hematomas are uncommon in this setting. We report an unusual case of multiple epidural hematomas in a patient with hydrocephalus treated by ventriculoperitoneal shunt. The patient became symptomatic 5 days after shunting and required craniotomy for evacuation of one of the hematomas. The literature is reviewed and treatment discussed.

Elevation of brain norepinephrine concentration after experimental subarachnoid hemorrhage

Regional brain tissue catecholamine concentrations were measured in 5 control rats and in 10 rats 72 hours after experimental subarachnoid hemorrhage (SAH). Catecholamine levels were determined in the cerebral hemispheres, brain stem, and cerebellum of each animal using a radioenzymatic assay. Three days after SAH, the tissue concentration of norepinephrine (NE) in the cerebral hemispheres was 64% greater than that in control rats (P less than 0.001). NE levels did not change significantly in either the brain stem or the cerebellum. Most if not all of the NE in the brain tissue rostral to the brain stem is derived from neurons that originate in the locus coeruleus (LC). These data may therefore indicate that the LC is activated after SAH. The possible pathophysiological consequences of activation of the LC in relation to delayed cerebral ischemia after SAH will be discussed.

Suboccipital decompression during posterior cranial vault remodeling for selected cases of Chiari malformations associated with craniosynostosis.

OBJECT The optimal management of Chiari malformations in the setting of craniosynostosis is not well established. In this report the authors describe their outcomes with the combined technique of simultaneous suboccipital decompression (SOD) during posterior cranial vault remodeling (PCVR). METHODS A retrospective review was performed of all patients undergoing PCVR and simultaneous SOD. Demographic data, diagnosis, imaging studies, operative intervention, and clinical follow-up were evaluated. RESULTS Thirty-four patients were identified as having undergone a simultaneous PCVR/SOD for Chiari malformation associated with craniosynostosis. Eighty-eight percent of these patients had syndromic, multisutural craniosynostosis, and the remaining patients had unilateral lambdoid craniosynostosis. There were no postoperative complications as a direct result from this combined procedure. Two patients required a subsequent direct approach for decompression of the Chiari malformation. The interval between these subsequent surgeries was 3 years and 19 months. CONCLUSIONS Chiari malformations are commonly associated with syndromic, complex craniosynostosis and isolated lambdoid craniosynostosis. In appropriately selected patients, a combined posterior cranial vault enlargement and SOD of the foramen magnum is associated with a low complication rate and appears to be an effective procedure.