Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis, or Lou Gehrig's disease, is a progressive degeneration of selected upper and lower motor neurons, of unknown etiology. Patients present with dysfunction of the voluntary muscles, most often having problems with ambulation as well as difficulties with tongue movements, causing dysphagia and dysarthria. This dysfunction inevitably progresses to respiratory difficulties as the disease worsens, but cognitive, sensory, and autonomic nerve functions are spared. Eye movements are usually not involved with this disorder. Diagnosis is made by demonstrating upper motor neuron disease on exam (spasticity with exaggerated reflexes), fasciculations, and EMG findings. Although the hypoglossal nerve is by far the most common cranial nerve affected in the disorder (66%), the facial nerve can also be affected (23%) (95).

The mechanism of injury is unknown, but pathologic examination has demonstrated symmetric demyelination of the pyramidal column with loss of anterior horn cells and motor nuclei. Diagnosis is based on history and clinical examination as well as EMG. Treatment is supportive and often involves physical therapy as well as respiratory support. Tracheostomy and gastrostomy tubes are often required. Chronic aspiration can complicate the course and may require additional procedures such as epiglottic oversew or laryngectomy in refractory cases. Only 50% of patients survive for three years after diagnosis, with only 20% of patients surviving for greater than five years after the diagnosis (95).

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