Amyotrophic lateral sclerosis

Alternative names
Lou Gehrig’s disease; ALS

Amyotrophic lateral sclerosis, or ALS, is a disease of the motor nerve cells in the brain and spinal cord. It causes progressive loss of motor control.

Causes, incidence, and risk factors

Amyotrophic Lateral Sclerosis is characterized by progressive loss of motor nerves in the spinal cord and brain. In about 10% of cases, ALS is caused by a genetic defect. In other cases, the cause of the nerve deterioration is unknown.

ALS affects approximately 1 out of every 100,000 people.

Except for having a family member affected with the hereditary form of the disease, there are no known risk factors.


Symptoms usually do not develop until after age 50. Progressive loss of muscle strength and coordination eventually interfere with the ability to perform routine activities, such as going up steps, getting out of a chair, or swallowing. Occasionally, breathing or swallowing muscles may be the first to be affected.

As the disease progresses, more muscle groups are affected and patients become progressively incapacitated. There is no effect on the ability to think or reason.

Symptoms include:

  • muscle weakness, decrease in muscle strength and coordination       o gradual onset       o progressively worsens       o commonly involves one limb initially (such as the hand)       o progresses to difficulty lifting, climbing stairs, and walking  
  • paralysis  
  • muscle cramps  
  • voice changes, hoarseness  
  • speech impairment, slow or abnormal speech pattern  
  • difficulty swallowing, gags or chokes easily  
  • difficulty breathing (increasing effort required to breathe)  
  • head drop due to weak spinal and neck muscles

Additional symptoms that may be associated with this disease:

  • muscle contractions  
  • muscle spasms  
  • muscle atrophy  
  • ankle, feet and leg swelling  
  • weight loss  
  • drooling

Signs and tests

A neuromuscular examination indicates weakness, often beginning in one limb or area (such as shoulders or hips). There may be muscle tremors, spasms, twitching, or muscle atrophy (loss of tissue). Atrophy and twitching of the tongue are common.

The gait may be stiff or clumsy. Reflexes may be abnormal, including loss of the gag reflex. Some patients have “emotional incontinence” in which it is hard to control crying or laughing.

  • An EMG indicates that the motor nerves are not functioning, yet the sensory nerves are normal.  
  • A head CT or MRI of head may be done to rule out other conditions.  
  • If there is a family history, a genetic test may be performed.  
  • A breathing test may be given to see if respiratory muscles are affected.  
  • Blood tests can exclude other conditions that may cause similar symptoms.


There is no known cure for ALS. Riluzole may prolong life, but does not reverse or stop disease progression.

Treatment is aimed at controlling the symptoms. Baclofen or diazepam may be used to control spasticity that interferes with activities of daily living. Trihexyphenidyl or amitriptyline may be prescribed for people with impaired ability to swallow saliva.

Physical therapy, rehabilitation, use of appliances (such as braces or a wheelchair) or orthopedic intervention may be required to maximize muscle function and general health.

Choking is common and there may be an early need for placement of a tube into the stomach for feeding (gastrostomy). A referral to an otolaryngologist may be advised. A nutritionist is helpful to prevent weight loss, especially for patients with limitied ability to swallow.

The use of devices to assist in breathing includes machines that are only used at night as well as mechanical ventilation. Patients should discuss their wishes regarding artificial ventilation with their doctors.

Support Groups

Emotional support is vital in coping with the disorder, because mental functioning is not affected. Groups such as the ALS Association may be available to assist in coping with the disorder. See ALS - support group.

Expectations (prognosis)

There is progressive loss of ability to function or care for oneself. Death often occurs within 3 to 5 years of diagnosis, although there are some rare cases of patients living decades.


  • Loss of ability to care for self  
  • Inhaling food or fluid  
  • Pneumonia  
  • Respiratory failure (see adult respiratory distress syndrome)  
  • Skin breakdown (pressure sores)  
  • Weight loss

Calling your health care provider
Call your health care provider if symptoms suggest ALS, particularly if there is a family history of the disorder.

Call your health care provider if ALS has been diagnosed and symptoms worsen or new symptoms develop. Increased difficulty swallowing, difficulty breathing, and episodes of apnea are symptoms that require immediate attention.

Genetic counseling may be advised if there is a family history of ALS.

Johns Hopkins patient information

Last revised: December 4, 2012
by Harutyun Medina, M.D.

Medical Encyclopedia

  A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | 0-9

All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.