Autonomic hyperreflexia Health Article

Definition

Autonomic hyperreflexia is a reaction of the autonomic (involuntary) nervous system to overstimulation. This reaction may include high blood pressure, change in heart rate, skin color changes (paleness, redness, blue-grey skin color), and excessive sweating.

Causes, incidence, and risk factors

The most common cause of autonomic hyperreflexia is spinal cord injury. In this condition, types of stimulation that are tolerated by healthy people create an excessive response from the person's nervous system.

Other causes include medication side effects, use of illegal stimulants such as cocaine and amphetamines, Guillain-Barre syndrome (a severe form of paralysis that can lead to respiratory failure), subarachnoid hemorrhage (a form of brain bleeding), severe head trauma, and other brain injuries.

The following conditions share many similar symptoms with autonomic hyperreflexia, but have a different cause:

• Carcinoid syndrome -- a disease caused by abnormalities of hormone-producing cells in the lungs and the gut
• Neuroleptic malignant syndrome -- a condition characterized by muscle stiffness, high fever, and drowsiness, which can be caused by some antipsychotic and anesthesia medications
• Serotonin syndrome -- an abnormal release of serotonin, a brain chemical
• Thyroid storm -- a condition caused by too much production of thyroid hormone

Symptoms

Symptoms can include any or all of the following:

• Anxiety or apprehension (fear)
• Bladder or bowel dysfunction
• Blurry vision
• Fever
• Flushing (skin turning red)
• Goose bumps
• Heavy sweating
• Lightheadedness or dizziness
• Muscle spasm
• Nasal congestion
• Throbbing headache

Sometimes, despite a dangerous rise in blood pressure, there are no symptoms at all.

Signs and tests

• Dilated pupils
• Flushed (red) skin above the level of the spinal cord injury
• High blood pressure
• Slow pulse or fast pulse

The doctor will do a complete neurological and medical examination. Patients must tell their doctor all medications they are currently taking and all medications they've taken in the past, to help determine which tests are necessary.

Tests may include:

• Blood and urine tests
• Brain pictures including head CT or MRI
• EKG (measurement of the heart's electrical activity)
• Lumbar puncture
• Spine pictures, particularly MRI
• Tilt-table testing (testing of blood pressure regulation as body position changes)
• Toxicology screening (tests for any drugs, including medications, in the patient's bloodstream)
• X-rays