Faculty Bibliography

Summary: Tuberous sclerosis complex (TSC) is associated with medically refractory seizures and developmental delay in children. These epilepsies are often resistant to antiepileptic drugs (AEDs), may be quite severe, and usually have a negative impact on the child's neurological and cognitive development. It is believed that functional outcome is improved if seizures can be controlled at an early age. The surgical treatment of intractable epilepsy in children and adults with TSC has gained significant interest in recent years. Previously published studies have shown a potential benefit from resection of single tubers, with most of the results noted in relatively older children. All of these reports support the idea that if a single primary epileptogenic tuber/region can be identified, then a surgical approach is appropriate. However, most children with TSC have multiple potentially epileptogenic tubers, rendering localization challenging, and they are therefore rejected as possible surgical candidates. We have utilized a novel surgical approach using invasive intracranial monitoring, which is typically multistaged and bilateral. Here we present an illustrative case of a young boy with TSC and medically refractory epilepsy who underwent a staged surgical approach. This multistage surgical approach has been useful in identifying both primary and secondary epileptogenic zones in TSC patients with multiple tubers. Multiple or bilateral seizure foci are not necessarily a contraindication to surgery in selected TSC patients. Long-term follow-up will determine whether this approach has durable effects. We await better methods for identifying the epileptogenic zone, both noninvasive and invasive

PURPOSE: To assess the activity and tolerability of temozolomide in children with progressive low-grade gliomas (LGGs). PATIENTS AND METHODS: The authors reviewed the records of 13 children (6 months to 19 years old) with progressive LGGs and magnetic resonance imaging evidence of unresectable tumors who were treated with temozolomide at the authors' institution since 1999. RESULTS: Four patients received a 5-day regimen of temozolomide (150 mg/m2 per day) repeated every 28 days, and nine patients received a 42-day regimen (75 mg/m2 per day) repeated every 56 days. Three patients demonstrated partial responses to temozolomide, with a median time to maximal response of 5 months (range 4-12 months), and one had a minor response at 9 months. Four patients developed progression while on temozolomide, with a median time to progression of 7 months (range 1-12 months). Five patients had disease stabilization. Among the five patients with prior chemotherapy and/or radiation therapy, temozolomide was associated with disease stabilization in three and tumor response in one. In the three patients with neurofibromatosis type 1, two patients experienced tumor responses and one disease stabilization. Thrombocytopenia, nausea, emesis, and fatigue were the most common toxicities. Four patients discontinued therapy because of the side effects. CONCLUSIONS: Temozolomide is active in children with LGGs. It is effective in previously treated patients and in patients with neurofibromatosis type 1. The 42-day regimen appears less toxic than the 5-day regimen. Any impact on survival for these patients remains to be demonstrated

p34cdc2, collapsin response mediator protein 4 (CRMP4), doublecortin (DCX), HuD, and NeuN expression was assessed in tuber (n = 16) and subependymal giant cell astrocytoma (SEGA; n = 6) specimens in tuberous sclerosis complex to define the developmental phenotype and lineage of giant cells (CGs) in these lesions. Many GCs exhibited HuD and NeuN immunolabeling suggesting a differentiated neural phenotype. Giant cells in tubers, SEGAs and subependymal nodules in the Eker rat model of TSC expressed CRMP4 and DCX. Tubers and SEGAs exhibit a heterogeneous profile of differentiation and may share a common cellular lineage. Tubers may contain a subpopulation of newly generated cells

The Sonic hedgehog (Shh) signaling pathway plays a critical role in normal cerebellar development and has been implicated in medulloblastomas, common malignant childhood tumors of the cerebellum. To test whether Shh mis-expression is sufficient for medulloblastoma formation, we used ultrasound biomicroscopy-guided in utero injection of a Shh-expressing retrovirus into the cerebellum of 13.5-day mouse embryos to show that direct activation of the Shh pathway can lead to tumor formation. Significantly, medulloblastomas were observed in 76% of the mice infected with Shh-expressing retrovirus. Furthermore, contrary to recent suggestions that the Shh transcriptional target Gli1 plays a critical role in Shh-induced tumorigenesis, we found that medulloblastomas form in Gli1 null mutant mice. We have developed an efficient mouse model of medulloblastoma and shown that Gli1 is not required for tumorigenesis when Shh signaling is activated upstream in the pathway

OBJECT: In this study the authors evaluate the safety, efficacy, and indications for endoscopic third ventriculostomy (ETV) in patients with a history of subarachnoid hemorrhage or intraventricular hemorrhage (IVH) and/or cerebrospinal fluid (CSF) infection. METHODS: The charts of 101 patients from seven international medical centers were retrospectively reviewed; 46 patients had a history of hemorrhage, 42 had a history of CSF infection, and 13 had a history of both disorders. All patients experienced third ventricular hydrocephalus before endoscopy. The success rate for treatment in these three groups was 60.9, 64.3, and 23.1%, respectively. The follow-up period in successfully treated patients ranged from 0.6 to 10 years. Relatively minor complications were observed in 15 patients (14.9%), and there were no deaths. A higher rate of treatment failure was associated with three factors: classification in the combined infection/hemorrhage group, premature birth in the posthemorrhage group, and younger age in the postinfection group. A higher success rate was associated with a history of ventriculoperitoneal (VP) shunt placement before ETV in the posthemorrhage group, even among those who had been born prematurely, who were otherwise more prone to treatment failure. The 13 premature infants who had suffered an IVH and who had undergone VP shunt placement before ETV had a 100% success rate. The procedure was also successful in nine of 10 patients with primary aqueductal stenosis. CONCLUSIONS: Patients with obstructive hydrocephalus and a history of either hemorrhage or infection may be good candidates for ETV, with safety and success rates comparable with those in more general series of patients. Patients who have sustained both hemorrhage and infection are poor candidates for ETV, except in selected cases and as a treatment of last resort. In patients who have previously undergone shunt placement posthemorrhage, ETV is highly successful. It is also highly successful in patients with primary aqueductal stenosis, even in those with a history of hemorrhage or CSF infection

Refractory seizures are common in patients with tuberous sclerosis and can contribute to developmental delay and behavioral problems. Surgical intervention can reduce the seizure burden in selected patients with tuberous sclerosis and refractory epilepsy, thereby improving cognitive function, behavior, and quality of life. However, the risks of surgery are usually considered unacceptable when the epileptogenic focus lies over dominant hemisphere eloquent cortex or is multilobar. Multistage invasive monitoring can provide detailed data regarding the location and number of ictal foci and functional extraoperative mapping can precisely delineate the boundaries of eloquent areas of the brain. If independent ictal onsets are demonstrated, a staged surgical approach can allow a more aggressive yet safe procedure in selected patients. A combination of staged resection and multiple subpial transections may provide an opportunity to treat epileptogenic foci located over eloquent cortex. Bilateral staged resections can be used when independent bihemispheric foci are present in patients with tuberous sclerosis. This article presents two cases, one of which (case 2) was previously reported, on successful multistage surgical treatment of epileptogenic foci located over an eloquent cortex or in both hemispheres in children with tuberous sclerosis. This case is represented since there is additional follow-up available and the prior report was to a neurosurgical audience. This multistage approach permitted resection of epileptogenic foci that would traditionally have been considered inoperable