Respiratory failure as the presenting manifestation of amyotrophic lateral sclerosis

Although amyotrophic lateral sclerosis (ALS) does not directly affect the lung parenchyma, it can jeopardize the mechanical function of the respiratory system. About one-quarter of ALS patients have had at least one prior misdiagnosis. Therefore, a high clinical suspicion, and careful correlation of physical examination and electromyography (EMG) are needed to reach the correct diagnosis. We report a 65-year-old man who presented with a progressive exertional dyspnea. He was subsequently found to have a diaphragmatic paralysis that was felt to be secondary to spinal cord stenosis. However, his subsequent EMG showed evidence of muscle fasciculation and he was ultimately diagnosed with ALS.