Abstract
OBJECTIVE: Tectal gliomas are a rare subset of brainstem gliomas accounting for less than 5% of brainstem tumours in children and 8% in adults. Historically, it has been reported that tectal gliomas are more likely to follow a benign, indolent course than brainstem gliomas. We investigated the clinical history, radiological surveillance and operative management of tectal plate glioma in a large adult series. METHODS: All neuroradiology reports available at our institution from January 2007 to March 2015 were searched using ‘tectal plate’, ‘tectal lesion’ and ‘tectal glioma’ as keywords. Clinical details including presenting history, age, clinical course, neuropathology and any operative interventions were identified from case notes. RESULTS: The keyword search identified 344 reports which were subsequently narrowed to 69 patients with tectal plate tumours. We identified 39 suspected low grade tectal plate gliomas of which 12 had confirmed neuropathology. 7 tectal plate lipomas and 3 non glial tumours involving the tectal plate were identified. Of the 12 patients with proven histology the average age at diagnosis was 24 years with all but 3 presenting with hydrocephalus, which was successfully managed with endoscopic third ventriculostomy (n=8) or VP shunt (n=1). Neuropathology confirmed 9 grade II astrocytoma and 3 pilocytic astrocytomas. 3 patients subsequently received radiotherapy and 2 received chemoradiotherapy for radiological progression since diagnosis. All patients remain alive with a median follow up of 9.5 years. 27 patients had a radiological diagnosis of presumed tectal plate glioma. Average age at diagnosis was 32 years with 80% (21/27) presenting with hydrocephalus. 2 patients underwent stereotactic needle biopsy but the tissue obtained was inconclusive, one of these patients received interstitial radiotherapy at the time of biopsy. During a median follow up of 8 years one patient died of unrelated causes while all other patients remain well. Of the 39 suspected tectal plate gliomas in our series 9 (23%) showed some radiological progression over a median 9 year follow up. Surgery was undertaken in 2 patients, chemotherapy in 1 and radiotherapy in 1 at time of progression, the other 5 patients remain under radiological surveillance CONCLUSION: Tectal plate glioma is a rare tumour in adults that usually presents with hydrocephalus requiring CSF diversion. The majority of these tumours are grade II astrocytoma or grade I pilocytic astrocytoma. Approximately one quarter of patients progressed on radiological follow up. The natural history and course of tectal plate glioma is therefore not entirely benign and patients should remain under close annual MRI surveillance with consideration of biopsy if radiological progression is observed.