Abnormal posturing

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Abnormal posturing is different from what is commonly called "bad posture" or "slouching." Instead, it is a tendency to hold a particular body position, or to move one or more parts of the body in a particular way.

This phenomenon is an important part of evaluating a person in a coma.

Certain abnormal posturing behaviors may be a sign of specific injuries to the central nervous system.

Pathologic posturing; Evaluating a person in a coma

Abnormal posturing present with little or only mild stimulation is a sign of serious central nervous system damage. Subtle abnormalities or damage of the nervous system may be brought out as posturing when performing certain tasks, such as walking on the sides of the feet, on the toes, or heels.

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Normally, when a muscle contracts, the muscles on the opposite side of the joint provide some resistance to contraction. Abnormal posturing occurs when damage to the central nervous system (brain or spinal cord) results in complete or partial lack of opposition to muscle contraction in various muscle groups.

See the following types of abnormal postures:

• Decerebrate posture -- rigid extension of the arms and legs, downward pointing of the toes, and backward arching of the head
• Decorticate posture -- rigidity, flexion of the arms, clenched fists, and extended legs
• Opisthotonos -- rigidity and severe arching of the back, with the head thrown backwards

An affected person may alternate between different postures as the condition fluctuates.

Injury or inflammation of a portion of the brain, spinal cord, or nervous system is the most common cause of abnormal posturing. The particular type of posturing can reflect the type and area of nervous system involvement.

• Cerebral edema
• Increased intracranial pressure due to any cause
• Reye syndrome
• Severe head injury
• Stroke
• Uncal herniation

Review Date: 03/26/2009
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and 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., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).