Myasthenia gravis and amyotrophic lateral sclerosis overlap syndrome in a patient with bulbar palsy

Myasthenia gravis (MG) and amyotrophic lateral sclerosis (ALS) overlap syndrome is rare and presents substantial diagnostic challenges because both disorders may share bulbar manifestations and electrophysiological evidence of neuromuscular junction (NMJ) dysfunction. We report a 68-year-old man presenting with progressive dysphagia, dysarthria, and respiratory distress over 11 months. Neurological examination demonstrated severe bulbar palsy, upper motor neuron signs, split-hand phenomenon, and generalized muscle atrophy. Brain MRI excluded structural brainstem lesions, and chest imaging showed no thymoma. Low-frequency repetitive nerve stimulation (3 Hz) of the left trapezius revealed a 25.7% decremental response, and treatment with pyridostigmine and methylprednisolone produced objective improvement reflected by a reduction in the myasthenia gravis composite (MGC) score from 20 to 12 and successful oxygen weaning to room air. Needle electromyography demonstrated widespread active and chronic denervation fulfilling the revised Awaji electrodiagnostic criteria for definite ALS. In the absence of anti-AChR, anti-MuSK, and anti-LRP4 antibody testing, the diagnosis is presented as probable MG–ALS overlap syndrome. Recognition of this rare association is essential to guide accurate diagnosis, timely respiratory monitoring, and appropriate multidisciplinary management.