Ocular myasthenia gravis

Abstract

Ocular myasthenia gravis (OMG) is a relatively common subtype of myasthenia gravis (MG) in which the weakness is limited to ocular and bulbar muscles, which may lead to significant visual disability. Patients usually present with fluctuating ptosis, diplopia, and weakness of lid closure. Those patients with purely ocular weakness are at risk of developing generalized MG, especially early in the disease. This autoimmune disorder occurs due to the production of autoantibodies against nicotinic acetylcholine receptors (AChRs) at the neuromuscular junction of skeletal muscles. Examination findings may range from isolated muscle palsy to complete ophthalmoplegia. Some specific findings that support the clinical diagnosis of OMG are Cogan’s lid twitch, peek sign, and saccadic fatigue. Tests to confirm the diagnosis are edrophonium challenge test, repetitive nerve stimulation, single-fiber electromyography of the frontalis, and assays for antibody directed against the AChR. There are a variety of treatment options for OMG such as pyridostigmine, immunosuppression, intravenous immunoglobulin, plasmapheresis, thymectomy, ptosis surgery, and extraocular muscle surgery. MG is known to be great masquerade due to its varied clinical presentations. It mimics isolated cranial nerve palsies, internuclear ophthalmoplegia, gaze palsies, and sometimes blepharospasm or even may be even stroke. The aim of the review is to feature the diagnosis, investigations, and treatment of OMG.