[Bilateral 3rd cranial nerve palsy disclosing oligodendroglioma].

The patient was a 30 year-old man. He had no previous history. For several months he experienced a slowly progressive horizontal diplopia which was the expression of a bilateral third cranial nerve palsy with an intact intrinsic component. Muscular or neuro-muscular pathology as myasthenia was initially suspected but not confirmed. CT scan and MRI revealed an atypical left temporo-insular lesion which led us to discuss a chronic inflammatory pathology as sarcoidosis or a tumoral process. Finally cerebral biopsy showed a high grade oligodendroglioma. Symptomatology was attributed to infiltration of the peduncles from this tumor. Such a case has never been seen before. Early neuroradiological explorations would be useful in case of clinical suspicion of cranial nerve palsy.