Myasthenia gravis is an autoimmune disorder of the neuromuscular junction characterized by fluctuating weakness of certain voluntary muscles rarely involving the respiratory muscles. Presenting a case of a lady who presented with features of respiratory distress which on evaluation was found to be due myasthenia of respiratory group of muscles. A 45yr old lady presented with progressive dyspnoea for 3 months and had orthopnoea on presentation. Preliminary evaluation including echocardiography, PFT, CTPA were normal. Electromyography studies on routine group of muscles were normal. As the symptoms persisted, EMG was done on specific respiratory group of muscle which were suggestive of myasthenia. Patient improved with steroids and Anticholinesterases thus supporting the diagnosis of isolated myasthenia of respiratory muscles. Myasthenia gravis is a muscular weakness which in rare and mostly advanced cases include the respiratory group of muscles and even the external sphincters of bladder and bowel. Confirmation of diagnosis especially in doubtful presentations are done by electrophysiological testing, pharmacological tests and measurement of specific antibodies. Anti Ach-R and anti MUSK are sensitive and specific marker of this condition. This particular case implies the need to consider a possibility of myasthenia of isolated respiratory group of muscles in patients presenting with respiratory distress. ENMG of the respiratory group of muscles though rarely indicated can clinch the diagnosis.
