Section 6. Brain, Spinal Cord, and Nerve Disorders

Chapter 91. Movement Disorders

Topics: Introduction | Myoclonus | Tremor | Parkinson's Disease | Progressive Supranuclear Palsy | Shy-Drager Syndrome | Tics | Chorea and Athetosis | Huntington's Disease | Dystonia | Coordination Disorders

Shy-Drager Syndrome

Shy-Drager syndrome (idiopathic orthostatic hypotension) results in tremor when muscles are at rest (resting tremor) and in malfunction of the autonomic nervous system, including pronounced instability of blood pressure.

Shy-Drager syndrome usually develops between the ages of 37 and 75. It is 2 or 3 times more common among men than among women. It results from degeneration of the parts of the brain that control the autonomic nervous system (see Section 6, Chapter 76), including the motor nerve cells of the cerebellum, basal ganglia, and spinal cord. The cause of the degeneration is unknown. Shy-Drager syndrome is thought to be a form of multiple systems atrophy--a group of overlapping disorders that cause many symptoms and simultaneously affect several body systems.

Symptoms and Diagnosis

Shy-Drager syndrome is a progressive disorder. It is similar to Parkinson's disease, causing tremor, muscle rigidity, and problems with movements (such as difficulty walking and speaking). However, Shy-Drager syndrome also causes malfunction of the autonomic nervous system, which regulates internal body processes. This disorder therefore interferes with the regulation of blood pressure, heart rate, secretion of hormones, bladder and bowel function, body temperature, and focusing of the eyes. Blood pressure drops dramatically when a person stands up, causing dizziness, light-headedness, or fainting--a condition called orthostatic hypotension. Blood pressure may increase when a person lies down. The production of sweat, tears, and saliva decreases. Vision becomes poor. A person may have difficulty urinating or become constipated, and urinary or fecal incontinence may develop. In men, erectile dysfunction (impotence) may develop. Walking may become unsteady, and incoordination may develop. The disorder results in death 7 to 10 years after symptoms begin.

The diagnosis is based on symptoms.

Treatment

Generally, drugs used to treat Parkinson's disease are not effective in treating Shy-Drager syndrome, but response to them varies from person to person. Measures are taken to stabilize the sudden changes in blood pressure. The drug fludrocortisone can help increase blood pressure because it causes the body to retain salt and water. Adding salt to the diet and drinking a lot of water may increase the volume of blood and thus may also help increase blood pressure. Midodrine, which is used to treat orthostatic hypotension, may help prevent blood pressure from decreasing too much when a person stands, as may wearing fitted elastic stockings up to the waist. Raising the head of the bed can help prevent blood pressure from increasing too much when the person lies down. If blood pressure does increase, an antihypertensive drug may be given at night.

Avoiding extreme heat, abstaining from alcoholic beverages, eating small meals, getting up slowly, and not straining during a bowel movement may also help.

People with Shy-Drager syndrome should establish advance directives, indicating what kind of medical care they want at the end of life (see Section 1, Chapter 9).