Abstracts

Rationale: Patients with low grade brain tumors frequently experience seizures that can significantly affect their quality of life. However there are no guiding principles for their management or identification of prognostic variables that affect the seizure outcome. Our objective was to identify factors that could prognosticate the outcome of low grade tumor associated seizures. Methods: This was a retrospective review of patients with low grade intraparenchymal brain tumors evaluated and followed in the neuro-oncology clinic since 2002 with at least one year of follow up. Patient characteristics, tumor histology, treatment modalities, tumor prognosis and outcome of seizures were tabulated. Outcome was classified by Engel classification at last follow up. Results: Of 98 patients seen for low grade intraparenchymal brain tumor, only the 73 patients with supratentorial tumors were included for assessment of seizure outcome. Histologic diagnosis was glial tumors in 56 (77%) and neuronal tumors in 17(23%). Mean age at diagnosis was 39.8 years (range 8.0-79.8 years) and mean follow up was 54.3 months. Fifty-four patients experienced a seizure. 46 had seizures prior to surgery, 5 had perioperative seizures and 3 developed seizures after resection. In 2 of the latter 3 patients the onset of seizures was associated with tumor recurrence. Three of the 54 patients with seizures had perioperative seizures only. Of the 46 patients who presented with presurgical seizures, 11 (23%) ceased to have seizures after initial surgical intervention. Twenty (43%) had a class I outcome at their last follow up visit. Pathology, loss of 1p19q, undergoing chemotherapy or radiotherapy, tumor recurrence, initial partial or total resection of the tumor, presence or absence of generalized tonic clonic seizures were not associated with persistent seizures after initial surgical intervention or seizure outcome at last follow up (p>0.05). All patients with a seizure received AEDs,that were discontinued in 21 patients based on best clinical judgment. Three (14%) had recurrent seizures after AED discontinuation. Five patients with continued seizures had subsequent epilepsy surgery, four of which had significant improvement of their seizure outcome. Two patients had a VNS implanted with a significant reduction in their seizure frequency. Conclusions: Despite best medical management the likelihood of continued seizures after low grade tumor resection is high if seizures occur at presentation. Tumor histology, prognosis and treatment does not necessarily influence seizure outcome. Patients with low grade tumors could potentially benefit from integrating epilepsy surgery into the initial surgical approach.