Abstract
Fatigue, anorexia, and weight loss are common symptoms of patients presenting at general internal
medicine departments. Their commonality requires physicians to consider a wide range of differential diagnoses. Amyotrophic lateral sclerosis (ALS) is a progressive, fatal, paralytic disorder characterized by upper and lower motor neuron deficits. We present a case of ALS who developed unexpected CO2 narcosis during a colonoscopy done without sedation. Patients not yet diagnosed with ALS may present to a physician with nonspecific symptoms such as fatigue, loss of appetite, and weight loss. Furthermore, in some cases of ALS, acute respiratory failure develops due to respiratory muscle palsy, even though there is still muscle activity in their limbs. ALS should be included in the differential diagnosis of patients who complain of fatigue or weight loss, and it should be noted that they could develop hypoventilation and acute respiratory failure.
