A 50-year-old man presented for evaluation of progressive clumsiness and unsteady gait. His first symptoms began around age 39 years when he noted progressive difficulty performing calisthenics such as jumping jacks during intramural sports practice. Approximately 8 years later, he reported difficulty using handheld carpentry tools at work and trouble maintaining balance while carrying drywall from room to room. Because of intermittent neck pain, he was referred to a spine surgeon, who noted hyperreflexia with cervical stenosis on imaging. Anterior cervical discectomy and fusion was performed, with no benefit. The patient reported continued difficulty with balance, and around age 48 years, he could no longer participate in sports practice. He denied focal weakness, numbness, or tingling. He began falling, particularly on uneven ground, and at the time of presentation required a walking stick. He had no other medical history and no pertinent family history. His only medication was baclofen, 10 mg, three times a day. He denied alcohol, tobacco, or drug use, and he was disabled owing to his condition. Owing to his progressive gait disorder, he was referred to our neuromuscular clinic for evaluation.On general medical examination, he was a well-appearing man weighing 78.8 kg with a height of 1.8 m. Results of a general medical examination were normal. On neurologic examination, there was significant ptosis, more prominent on the left than the right. He was observed to have slow and limited eye movements while giving his history, and he frequently turned his head to compensate for impaired extraocular movements. This observation prompted additional questions from the examiner, and he denied diplopia, symptomatic ptosis, or ophthalmoplegia. Eye movements were approximately 75% of normal in both horizontal and vertical directions, and the remaining limitation of eye movements could not be overcome by vestibulo-ocular reflex testing. There was gazeevoked nystagmus in the midright and midleft gazes. Saccades were slowed and there was no dysarthria. On detailed motor examination, there was spastic tone in the lower extremities (2 on the Ashworth scale), but power was 5/5 (by Medical Research Council) in all 4 extremities. Quantitative vibratory sense was diminished at the toes, ankles, and knees, but normal in the fingers. There was no sen-sory level to pinprick examination. Romberg examination showed an inability to stand with his feet together, even with eyes open. Reflexes were 2+ at the biceps, 3+ at the knees, and 2+ at the ankles. Mild appendicular ataxia was noted during finger-nose-finger and rapid alternating movements tests. His gait was wide-based, tremulous, and ataxic.