Perilesional gliosis and seizure outcome: a study based on magnetization transfer magnetic resonance imaging in patients with neurocysticercosis.

We studied the effect of perilesional gliosis on seizure recurrence after stopping antiepileptic drug (AED) therapy in 108 patients with a solitary cysticercal brain cyst. All patients received albendazole therapy in the beginning, and magnetic resonance imaging (MRI) done after 2 seizure-free years showed complete disappearance of the lesion in 67, partial degeneration in 12, and healing by calcification in 29. The gliosis, which was not visible on initial MRI, was observed near the lesion in 22 (20%) patients on T1-weighted magnetization transfer spin-echo (MTSE) MRI. Initial seizure control was difficult with single AED therapy in 16 of 22 patients with gliosis but only in 8 of 86 patients without gliosis. On stopping AED therapy, patients with perilesional gliosis had a higher incidence of seizure recurrence (19 of 22 patients) compared with those who did not demonstrate gliosis (9 of 86 patients). The presumption that gliosis visible on MTSE MRI correlates with seizure recurrence had a high specificity (96%) but only moderate sensitivity (68%). Our findings suggest that there is a group of patients with neurocysticercosis in whom the risk of seizure recurrence is actually high. Several such patients have perilesional gliosis that can be identified on T1-weighted MTSE MRI. These patients probably need long-term AED administration.