Paroxysmal tonic eye deviation : an atypical presentation of hypothalamic hamartoma

Hypothalamic hamartoma is a rare developmental non-neoplastic malformation, often characterised by early onset gelastic seizures and later progressive cognitive and behavioural deterioration. In this case study, we have examined a child who presented with an atypical onset of benign paroxysmal gaze deviation between two to three months of age. The patient subsequently developed gelastic seizures at age 13. Based on the observation that hypothalamic hamartomas do not involve any functional region involved in eye motility, we speculate that both gaze deviation and gelastic seizures are a manifestation of the epileptogenic nature of the hypothalamic hamartoma. [Published with video sequences].