Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, is a degenerative nerve disorder that results in damage to and the death of nerve cells in the brain and spinal cord. Patients with ALS have irreversible, progressive muscle weakness and atrophy (loss of muscle mass) that leads to accelerated physical decline. Typically, death occurs two to five years after the onset of ALS symptoms. The symptoms of ALS were first described by Charles Bell (of Bell’s palsy fame) in 1824, and in 1874 French physician Jean-Martin Charcot coined the name ALS. Disease prevalence is slightly higher in men, and ALS is usually seen in middle-aged and older adults, although it has been seen in younger people, Lou Gehrig and Stephen Hawking being two notable young examples. Each year ALS affects two to three people per 100,000 worldwide.
The disease may present in two forms – the initial symptoms may be either peripheral or central. About 70% of patients initially show peripheral symptoms – arm and/or leg weakness, about 25% have central nervous system symptoms – difficulty speaking, chewing, or swallowing, and less than 5% of patients initially have respiratory muscle weakness. As ALS progresses, common symptoms include increasing weakness in the arms and legs, muscle twitching, limb cramping or stiffness, speech that is slow, halting, or slurred, difficulty chewing or swallowing, a weak cough, or shortness of breath. Up to 15% of ALS patients develop dementia and may undergo personality changes or difficulty controlling their thoughts, emotions, and behavior.
While the cause of ALS is unknown, it has been linked to both hereditary and environmental factors. Environmental factors include (a weak link to) prior military service, cigarette smoking, heavy alcohol use, and exposure to certain chemicals and pesticides. About 10% of cases are linked to a specific genetic variant. These people have a family history of the disease. In all cases, the hallmark of the disease is the death of both upper motor neurons (located in the brain) and lower, or spinal, motor neurons. The cause(s) of the deaths of these nerve cells remains a mystery. The diagnosis of ALS is made by a neurologist and is based on the patient’s symptoms, physical examination, and tests that evaluate muscle and nerve including electromyography and nerve conduction studies. Brain and spinal MRIs are usually performed as well and can help differentiate ALS from other neurodegenerative diseases. Lumbar puncture, specialized blood testing, and muscle biopsy may be required as well. Genetic testing is done for those with a family history.
Until recently, treatments to slow or halt disease progression were non-existent. The only available treatments attempted to keep the patient alive and comfortable for as long as possible, using ventilators, feeding tubes, aggressive nursing to prevent skin breakdowns, and physical therapy. Oral riluzole and intravenous edaravone have shown modest success at prolonging survival, and last September the FDA approved a combination therapy of taurursodiol and sodium phenylbutyrate which is still undergoing trials. Unfortunately, most patients with ALS will eventually need palliative care and end-of-life planning.
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By Peter Galvin, MD