[Weak respiratory muscles as a first sign of ALS: symptoms may put the physician on the wrong track]

Patients with decreased exercise tolerance and orthopnoea are often referred to an internist, a cardiologist or a pulmonologist. These symptoms can also be caused by weakness of the respiratory muscles, as an indication of a neuromuscular disease. If these symptoms are not recognized as such, this may result in a delay in timely diagnosis.

An 82-year-old man had suffered from decreased exercise tolerance for 18 months. For the last months he had been sleeping upright and had lost 20 kg in weight. Analyses by the cardiologist and the internist had not led to a definitive diagnosis. He was finally brought to the emergency department with loss of consciousness and hypercapnic respiratory insufficiency. Neurological examination was suggestive of motor neuron disease such as progressive spinal muscular atrophy or amyotrophic lateral sclerosis. The patient died within 24 hours of admission.

Patients with symptoms resulting from respiratory muscle weakness are commonly referred to non-neurological specialists, leading to a delay in diagnosis and treatment of an underlying neuromuscular disease.