Amyotrophic lateral sclerosis

What is amyotrophic lateral sclerosis?

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.

What are the causes?

Amyotrophic lateral sclerosis is characterised by progressive loss of motor nerves in the spinal cord and the 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.

What are the symptoms?

Symptoms usually do not develop until after the age of 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. The symptoms include:

• muscle weakness, decrease in muscle strength and
• coordination
  
• gradual onset
  
• progressively worsens
  
• commonly involves one limb initially (such as the hand)
  
• 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

What is the diagnosis?

The patient requires a detailed neuromuscular examination, which shows 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.

The following investigations are usually done:

• 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.
  
• A breathing test may be given to see if respiratory muscles are affected.
  
• Blood tests can exclude other conditions that may cause similar symptoms.

What is the treatment?

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 limited 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.

What are the complications?