Recognition and Treatment of Concurrent Amyotrophic Lateral Sclerosis and Multiple Sclerosis.

Amyotrophic lateral sclerosis (ALS) and multiple sclerosis (MS) are neurological disorders with different underlying pathophysiology but can share similar clinical features. Co-occurrence of both diseases is extremely rare with only 46 documented cases in literature to our knowledge. This case report relays the diagnosis of ALS in a patient with a decades'-long history of MS, and illustrates the importance of expanding the differential diagnosis and pursuing additional workup in a patient with overlapping progressive symptoms that can be caused by an alternate neurological etiology.