Ocular Neuromyotonia

Ocular Neuromytonia is a characterised by by paroxysmal tonic contraction of the extraocular muscles supplied by the oculomotor nerve. It is has been reported after cranial radiation therapy, especially to the sellar-parasellar region and from compressive lesions such tumours or aneurysms. The pathophysiology is thought to be by ephaptic transmission (cross talking across damaged axons). This patient has history of midbrain glioma, VP shunt, radiotherapy 20 years prior. She came to me with chronic right third nerve palsy with ptosis. She shows tonic inward eye deviation and upper lid retraction triggered by sustained left gaze. The upper lid retraction and the left inward eye deviation lasts for about 1 minute before going back to normal. Interestingly this was noticed first time on the operating table as she did not have this abnormal eye movement in the clinic