Midbrain neurocysticercosis presenting as isolated pupil sparing third cranial nerve palsy

Brainstem alone is involved very infrequently in patients with neurocysticercosis; usually, it occurs in association with disseminated form of the disease. Isolated involvement of the third nerve is commonly due to vascular causes. We are reporting a case due to cysticercus lesion presenting as isolated third-nerve involvement with sparing of the pupil. The diagnosis of neurocysticercosis was established by the presence of characteristic granulomatous lesions in the midbrain along with positive ELISA for cysticercal antigen in the cerebrospinal fluid. The patient responded well to corticosteroids with almost complete recovery. A follow-up MRI scan showed a significant decrease in the size of the lesion.