A 55-year-old man comes to the office due to progressive difficulty walking and frequent falls over the past year. Initially the patient had difficulty with balance when walking up and down the stairs. Now he has to brace himself against a wall even when walking on flat surfaces. He has had no urinary incontinence, slurred speech, or headaches. The patient was diagnosed with type 2 diabetes mellitus and hypertension several years ago but is not compliant with medications. He also has a history of long-term, heavy alcohol and tobacco use. Blood pressure is 170/96 mm Hg and pulse is 84/min. The patient is alert and oriented. Bilateral pupils are equal and reactive. Extraocular movements are normal. Muscle bulk, tone, and strength are normal. Proprioception and vibration sensation are normal in the lower extremities. The patient exhibits a wide-based gait and is unable to perform tandem walking. Heel-knee-shin testing is abnormal but finger-nose testing is normal. Which of the following is the most likely cause of his ambulatory dysfunction?

Question

A 55-year-old man comes to the office due to progressive difficulty walking and frequent falls over the past year.  Initially the patient had difficulty with balance when walking up and down the stairs.  Now he has to brace himself against a wall even when walking on flat surfaces.  He has had no urinary incontinence, slurred speech, or headaches.  The patient was diagnosed with type 2 diabetes mellitus and hypertension several years ago but is not compliant with medications.  He also has a history of long-term, heavy alcohol and tobacco use.  Blood pressure is 170/96 mm Hg and pulse is 84/min.  The patient is alert and oriented.  Bilateral pupils are equal and reactive.  Extraocular movements are normal.  Muscle bulk, tone, and strength are normal.  Proprioception and vibration sensation are normal in the lower extremities.  The patient exhibits a wide-based gait and is unable to perform tandem walking.  Heel-knee-shin testing is abnormal but finger-nose testing is normal.  Which of the following is the most likely cause of his ambulatory dysfunction?

Quizplus · Accepted Answer

11ec25c8_d554_47fa_bc81_8fd59c03fae4_MD0003_00 This patient with a long history of heavy alcohol use has slowly progressive postural gait dysfunction, suggestive of cerebellar degeneration due to alcohol neurotoxicity. Cerebellar degeneration typically occurs after >10 years of heavy alcohol use and is due to the degeneration of Purkinje cells in the cerebellar vermis. As these neurons are largely responsible for truncal coordination, patients with cerebellar degeneration usually develop slowly progressive wide-based gait and postural instability. Physical examination typically shows evidence of postural incoordination (eg, inability to tandem walk, abnormal heel-knee-shin testing) with relatively preserved limb coordination (normal finger-nose testing). Cognitive function is usually preserved. Although alcohol cessation and nutritional supplementation prevent disease progression, ambulatory difficulties do not typically improve. Patients therefore usually benefit from ambulatory assist devices such as canes or walkers. (Choice B) Impaired absorption of cerebrospinal fluid is seen with normal-pressure hydrocephalus. Manifestations include progressive imbalance, cognitive decline, and urinary incontinence. This patient has normal cognition and no urinary incontinence. (Choice C) Spondylotic myelopathy is associated with osteophyte-mediated spinal cord compression. Manifestations include gait dysfunction, extremity weakness, vibratory/proprioception abnormalities, and both lower and upper motor neuron findings. This patient has no lower motor neuron findings (eg, muscle atrophy, weakness) and no loss of vibration/proprioception. (Choice D) Diabetes mellitus may cause small vessel injury with resultant peripheral nerve ischemia. Patients typically manifest a distal symmetric polyneuropathy of both small fibers (pain/temperature) and large fibers (vibration/proprioception). Gait is usually preserved. (Choice E) Wernicke encephalopathy is characterized by thiamine deficiency-induced thalamic neuronal loss and usually causes gait ataxia, oculomotor dysfunction (eg, horizontal nystagmus), and encephalopathy. This patient's cognition and oculomotor function is unaffected. (Choice F) Vascular dementia is caused by multiple small infarctions. Manifestations typically develop in a stepwise fashion over years and include cognitive changes; a short, shuffling gait; and postural instability. (Choice G) Vitamin B₁₂ deficiency may cause spinal cord degeneration. Early manifestations include ataxia, symmetric paresthesia, and a loss of vibration and proprioception sensation. This patient's vibration and proprioception are normal. Educational objective: Alcoholic cerebellar degeneration is caused by damage to the Purkinje cells of the cerebellar vermis. Manifestations typically include the slowly progressive onset of ambulation difficulties, including wide-based gait and postural instability. Truncal coordination (eg, tandem gait) is impaired, but limb coordination (eg, finger-nose test) is relatively intact. References: Population-based study of alcoholic cerebellar degeneration: the Atahualpa Project. (http://www.ncbi.nlm.nih.gov/pubmed/27423619) Early-stage alcoholic cerebellar degeneration: diagnostic imaging clues. (http://www.ncbi.nlm.nih.gov/pubmed/26848494) Effects of ethanol on the cerebellum: advances and prospects. (http://www.ncbi.nlm.nih.gov/pubmed/25933648)

A 55-Year-Old Man Comes to the Office Due to Progressive