A 51-year-old woman comes to the physician for a 4-month history of generalized muscle cramping. Examination shows a left foot-drop, fasciculations, and muscle atrophy. Reflexes are brisk. Sensory examination shows no abnormalities. Which of the following is the most likely diagnosis?
Amyotrophic lateral sclerosis
Charcot-Marie-Tooth disease
Myotonic dystrophy
Neuromyelitis optica
Subacute combined degeneration
