Motor neurone disease

Motor neurone disease, also known as amyotrophic lateral sclerosis (ALS) and Lou Gehrig’s disease, is a condition that affects the nerves that control movement. It is a chronic and progressive disease, which means that it gets worse over time and eventually leads to death. There is no known cure.

Motor neurone disease
Classification and external resources
spinal diagram
ICD-10	G12.2
ICD-9	335.2
DiseasesDB	8358
MeSH	D016472

There is a slow but steady death of the nerve cells in the central nervous system making them stop sending messages to the muscles. The disorder causes muscle weakness and muscle shrinking (atrophy) throughout the body. Unable to function, the muscles gradually weaken and waste away. Eventually, the ability of the brain to start and control voluntary movement is lost. However, even patients in later stages of the disease may still have the same intelligence, memory, and personality they had before it started.

Amyotrophic lateral sclerosis (ALS) is the most common of the five types of motor neurone disease. About 5 to 10% of cases are inherited from a person's parents.

Symptoms

Motor neurone disease does not show many symptoms, making it very hard to diagnose. It usually affects people ages 40-60. The earliest symptoms may include twitching, cramping, or stiffness of muscles; muscle weakness affecting an arm or a leg; slurred and strange-sounding nasal speech; or having a difficult time chewing or swallowing. These general symptoms then develop into clear weakness or atrophy that may cause a physician to believe that a person has ALS.

The parts of the body affected by early symptoms of ALS depend on which muscles in the body are affected first. About 75% of people have limb onset ALS. In some of these cases, symptoms first affect one of the legs, and patients have awkwardness when walking or running or they notice that they are tripping or stumbling more often. Other limb onset patients first see the effects of the disease on a hand or arm as they have a difficult time with simple tasks requiring hand dexterity, or ability to move small things, such as buttoning a shirt, writing, or turning a key in a lock.

About 25% of cases are bulbar onset ALS. These patients first have difficulty speaking clearly. Speech becomes hard to understand and slurred. Speaking through the nose and softer talking are often the first symptoms. Difficulty swallowing, and loss of tongue movement follow. Eventually total loss of speech and ability to keep the airway clear when swallowing are experienced.

Treatment

There is no cure for ALS. However, the Food and Drug Administration (FDA) has approved the first drug treatment for the disease: riluzole. Riluzole is believed to reduce damage to motor neurons. Clinical trials with ALS patients showed that riluzole gives a better chance of survival by several months, mainly in those with a hard time swallowing. The drug also allows more time before a patient needs breathing help by a ventilator or tracheotomy. Riluzole does not heal the damage already done to motor neurons.

Other treatments for ALS are designed to make symptoms less painful and improve the quality of life for patients.

Motor Neurone Disease Media

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  Classic ALS involves neurons in the brain and spinal cord (upper motor neurons, highlighted red), as well as the lower motor neurons, which go from the spinal cord to the muscles, highlighted teal.

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  Illustration showing the range of upper and lower motor neuron involvement in the two most common types of ALS (top row) and three of the most common rare subtypes of ALS (bottom row)

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  This figure shows ten proposed disease mechanisms for ALS and the genes associated with them.

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  An MRI of the brain (axial FLAIR) looking at a person as if from above that shows increased T2 signal as a small white region within the posterior part of the internal capsule around the center of the image, consistent with the diagnosis of ALS

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  An MRI of the brain looking at a person from side-on that shows increased T2 signal as a white region in the posterior part of the internal capsule that can be tracked to the motor cortex, consistent with the diagnosis of ALS

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  A person with late-stage ALS with a range of assistive technologies to support movement (power wheelchair), breathing (invasive ventilation), and communication (eye tracker and computer)

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  Chemical structure of riluzole, a medication that prolongs survival by 2–3 months

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  Non-invasive ventilation supports breathing with a face or nasal mask connected to a ventilator.

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  A man with ALS communicates by pointing to letters and words using a head-mounted laser pointer.

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  A gastrostomy tube is placed through the wall of the abdomen into the stomach.