P160 – 2423: Idiopathic ocular neuromyotonia in a child: Case report

Abstract

Objective To describe clinical features and course of a child with ocular neuromyotonia (ONM), a rare ocular syndrome that causes ocular paroxysms because of an abnormal delay in extra ocular muscle relaxation. Methods A case report is presented to demonstrate clinical characteristics and treatment of ONM. Results A 4.5 year-old old girl was admitted with transient painless, unilateral spontaneous abnormal ocular deviation which started one week ago. The episodic spell duration was 30 to 40 seconds and occurred nearly 10 to15 times a day. She had preserved awareness during the paroxysms. She did not have headache, fever or any systemic or neurological symptoms. Her neurological examination, in between the ocular paroxysms, was normal. The MRI and MR angiography of brain and cervical cord was normal. Since the ictal video EEG was normal, epileptic seizure was excluded. Her spells characterized by spontaneous inward shift of left eye together with ptosis during 30 to 40 seconds without any nystagmoid movement, pupillary defect and change in consciousness. She was diagnosed as ONM. Her blood investigations, including haematological, biochemical, endocrine function tests and paraneoplastic as well as detailed vasculitic workup, were normal. Cerebrospinal fluid analysis for immunological markers, immunoglobulin (Ig) G index and oligoclonal band was all negative. The voltage-gated potassium channel (VGKC) antibody could not be detected in serum. Therefore we could not find an underlying abnormality to account for ONM. Treatment with carbamazepine 10 mg/kg twice a day was started and the attacks were completely resolved. Conclusion After conducting a search of the medical literature using the terms “ONM” and “child” we identify only 5 previously published reports of ONM in children. To the best of our knowledge this patient is the youngest patient reported with a diagnosis of ONM.