Medical Encyclopedia


Medical Encyclopedia

Other encyclopedia topics:  A-Ag  Ah-Ap  Aq-Az  B-Bk  Bl-Bz  C-Cg  Ch-Co  Cp-Cz  D-Di  Dj-Dz  E-Ep  Eq-Ez  F  G  H-Hf  Hg-Hz  I-In  Io-Iz  J  K  L-Ln  Lo-Lz  M-Mf  Mg-Mz  N  O  P-Pl  Pm-Pz  Q  R  S-Sh  Si-Sp  Sq-Sz  T-Tn  To-Tz  U  V  W  X  Y  Z  0-9 

Autonomic hyperreflexia

Contents of this page:


Central nervous system
Central nervous system

Definition    Return to top

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    Return to top

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:

Symptoms    Return to top

Symptoms can include any or all of the following:

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

Exams and Tests    Return to top

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:

Treatment    Return to top

This condition is life-threatening, so it is important to quickly identify and treat the problem.

Proper treatment depends on the cause. If medications or drugs are causing the symptoms, those drugs must be stopped. Any underlying illness that is causing the symptoms needs to be treated. If a slowing of the heart rate is causing the symptoms, drugs called anticholinergics (such as atropine) may be used.

Very high blood pressure needs to be treated quickly but carefully because a sudden and severe drop in blood pressure is possible, and can also cause problems. Commonly used emergency drugs for high blood pressure include: nifedipine (Procardia), nitroglycerin, phenoxybenzamine hydrochloride (Dibenzyline), mecamylamine (Inversine), and diazoxide (Hyperstat).

A pacemaker may be required for certain unstable heart-related situations.

Outlook (Prognosis)    Return to top

The outlook depends on the underlying cause. People with autonomic hyperreflexia due to medications usually recover when the medications that are causing the symptoms are stopped. When the condition is caused by other factors, recovery depends on the success of treating the underlying disease.

Possible Complications    Return to top

Complications may occur as a result of side effects of medications. If the pulse rate drops severely, it can cause cardiac arrest.

Prolonged, severe high blood pressure may cause seizures, bleeding in the eyes, stroke, or death.

When to Contact a Medical Professional    Return to top

Call your health care provider if you have symptoms of autonomic hyperreflexia.

Prevention    Return to top

Prevention of autonomic hyperreflexia includes avoiding medications that cause this condition or make it worse. In people with spinal cord injury, the following may also help prevent this complication:

References    Return to top

Khastgir J, Drake MJ, Abrams P. Recognition and effective management of autonomic dysreflexia in spinal cord injuries. Expert Opin Pharmacother. 2007;8:945-956.

Kirshblum SC, Priebe MM, Ho CH, Scelza WM, Chiodo AE, Wuermser LA. Spinal cord injury medicine: 3. Rehabilitation phase after acute spinal cord injury. Arch Phys Med Rehabil. 2007;88:S62-S70.

Update Date: 5/29/2008

Updated by: Daniel B. Hoch, PhD, MD, Assistant Professor of Neurology, Harvard Medical School, Department of Neurology, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M. Logo

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 1997-2009, A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.