A 55-year-old man comes to the clinic due to gradual, progressive weakness of the right upper extremity over the past 6 months. Over the last month, he has also noticed weakness in the left upper extremity. Vital signs are normal. Physical examination shows fasciculations and atrophy of the intrinsic muscles of the right hand and the muscles of the forearm. Reflexes are brisk in the upper extremities, and the plantar responses are extensor. Mild gait ataxia is present. Over the course of his illness, this patient will most likely develop which of the following?

Question

A 55-year-old man comes to the clinic due to gradual, progressive weakness of the right upper extremity over the past 6 months.  Over the last month, he has also noticed weakness in the left upper extremity.  Vital signs are normal.  Physical examination shows fasciculations and atrophy of the intrinsic muscles of the right hand and the muscles of the forearm.  Reflexes are brisk in the upper extremities, and the plantar responses are extensor.  Mild gait ataxia is present.  Over the course of his illness, this patient will most likely develop which of the following?

Quizplus · Accepted Answer

This patient has progressive weakness with signs of upper motor neuron (UMN) dysfunction (eg, brisk reflexes, extensor plantar reflex) and lower motor neuron (LMN) dysfunction (eg, fasciculations, muscle atrophy), which is characteristic of amyotrophic lateral sclerosis (ALS), a terminal neurodegenerative disease. Patients with ALS most often die of respiratory failure, which is caused by multiple factors: Inspiratory muscle (eg, diaphragm) atrophy and weakness, which leads to poor inspiratory strength. This is evident on pulmonary function testing as decreased vital capacity (the maximum volume displaced from the lung), which is followed as a marker of disease progression in patients with ALS. Expiratory muscle weakness, which leads to an ineffective cough and poor airway clearance. Bulbar muscle weakness, which leads to dysphagia and chronic aspiration. Treatment of ALS often focuses on improving respiratory function, which both prolongs survival and improves quality of life. (Choice A) Friedreich ataxia also presents with gait abnormalities and limb weakness. Death is typically due to cardiac dysfunction, due to either abnormalities of the cardiac conduction system or cardiac muscle defects (eg, decreased left ventricular compliance). However, Friedreich ataxia occurs in children age 5-15 years. (Choice C) Disseminated Lyme disease can present with radiculopathy; the classic triad of neurologic Lyme is meningitis, cranial neuropathy, and radiculoneuropathy (sensory or motor). Carditis can also occur, which can result in degeneration of the cardiac conduction system. However, this patient's combination of UMN and LMN signs is much more likely to be ALS. (Choice D) ALS is a disease that primarily affects motor neurons (both upper and lower). Although sensory disturbances can be present in some patients, widespread sensory defects do not occur. (Choice E) Tuberous sclerosis is an autosomal dominant disorder that results in tumors in multiple organ systems. Generalized tonic-clonic seizures often occur and become refractory as the disease progresses. This patient has no evidence of tumors or seizures nor a positive family history to suggest tuberous sclerosis. Educational objective: Patients with amyotrophic lateral sclerosis often develop respiratory failure due to inspiratory muscle weakness (causing decreased vital capacity), expiratory muscle weakness (causing a weak cough), and bulbar dysfunction (causing dysphagia and chronic aspiration). __________ References: Association between decline in slow vital capacity and respiratory insufficiency, use of assisted ventilation, tracheostomy, or death in patients with amyotrophic lateral sclerosis. (http://www.ncbi.nlm.nih.gov/pubmed/29181534)

A 55-Year-Old Man Comes to the Clinic Due to Gradual