The effect of mTOR inhibition on obstructive hydrocephalus in patients with tuberous sclerosis complex (TSC) related subependymal giant cell astrocytoma (SEGA)
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PURPOSE: Mammalian target of rapamycin inhibitors (mTORi) are known to effectively reduce the size of subependymal giant cell astrocytomas (SEGAs), which are benign brain lesions associated with Tuberous Sclerosis Complex (TSC) that commonly cause obstructive hydrocephalus (OH). This retrospective case series reviews an institutional experience of the effect of mTORi on OH in patients with TSC-related SEGA. METHODS: Thirteen of 16 identified patients with TSC-related SEGA treated with mTORi from October 2007 to December 2018 were included. Serial magnetic resonance imaging (MRI) and clinical charts were reviewed to correlate symptoms and signs of increased intracranial pressure (iICP) with ventriculomegaly on MRI. A proposed ventriculomegaly scale was used: none (< 7 mm), mild (7-10 mm), moderate (11-30 mm), and severe (> 30 mm). OH was defined as moderate or severe ventriculomegaly, based on the largest measurement. RESULTS: Patients' median age at start of mTORi was 13 (6-17) years and five (38%) patients were female. Eight patients had OH at the time of mTORi initiation, five of whom were asymptomatic. Six patients had improvement of hydrocephalus on serial MRI imaging with mTORi therapy, while seven patients had no change based on the ventriculomegaly scale used. All three patients who presented with symptoms of iICP and had OH also had papilledema. None had worsening of hydrocephalus or required shunt placement. Out of five patients with symptoms of iICP, four avoided surgery. CONCLUSION: Most patients had asymptomatic OH at the time of diagnosis, and ventricular enlargement was not correlated with iICP symptoms. mTORi was successful for treatment of OH from TSC-related SEGA, even in the setting of acute symptoms of iICP.