A 40-year-old woman comes to the physician because of a 3-month history of weakness in her left hand and right leg. She has occasional twitching of all four extremities. Examination shows weakness and atrophy of both hands and feet, and frequent twitching of the shoulder girdle muscles. Deep tendon reflexes are increased in all extremities. Babinski sign is present on the left. Jaw reflex is brisk. Sensory examination shows no abnormalities. Serum creatinine kinase is elevated. Electromyography shows denervation of several muscles in the upper and lower extremities. Which of the following is the most likely diagnosis?
Amyotrophic lateral sclerosis
Guillain-Barre
Multiple sclerosis
Polymyalgia rheumatica
Polymyositis
