Amyotrophic Lateral Sclerosis Regional Variants (Brachial Amyotrophic Diplegia, Leg Amyotrophic Diplegia, and Isolated Bulbar Amyotrophic Lateral Sclerosis).

Amyotrophic lateral sclerosis (ALS), a rapidly progressive, invariably fatal disease, involves mixed upper and lower motor neurons in different spinal cord regions. Patients with bulbar onset progress more rapidly than patients with limb onset or with a lower motor neuron presentation. Recent descriptions of regional variants suggest some patients have ALS isolated to a single spinal region for many years, including brachial amyotrophic diplegia, leg amyotrophic diplegia, and isolated bulbar palsy. Clearer definitions of regional variants will have implications for prognosis, understanding the pathophysiology of ALS, identifying genetic factors related to slower disease progression, and future planning of clinical trials.