__NOTOC__ Abnormal posturing, which indicates severe brain injury, refers to an involuntary flexion or extension of the extremities. It occurs when one set of muscles becomes incapacitated and the other set is not, and an external stimulus such as pain causes the working set of muscles to contract (AllRefer.com, 2003). Since posturing is an important indicator of the amount of damage that has occurred to the brain, it is used by medical professionals to measure the severity of a coma with the Glasgow Coma Scale (for adults) and the Pediatric Glasgow Coma Scale (for infants). Two types of abnormal posturing are decorticate and decerebrate posturing, also called decorticate and decerebrate responses, respectively. Opisthotonos, in which the head and back are arched backward, is another form of abnormal posturing. The presence of posturing indicates a severe medical emergency requiring immediate medical attention.

Causes

Posturing can be caused by conditions that lead to an increase in intracranial pressure and brain herniation. Such conditions include traumatic brain injury, stroke, intracranial hemorrhage, brain tumors, and encephalopathy (ADAM, 2005).

Decorticate Posturing

Patients with decorticate, or flexor, posturing present with the arms flexed, or bent inward on the chest, the hands are clenched into fists, and the legs extended. Decorticate posturing indicates damage to the mesencephalic region, or the corticospinal tract, along which impulses travel from the brain to the spinal cord (AllRefer.com, 2003). While an ominous sign of severe brain damage, decorticate posturing is not as serious as decerebrate posturing.

Decerebrate Posturing

In decerebrate, or extensor, posturing, the arms are extended by the sides, the head is arched back, and the legs are extended (ADAM, 2005). Decerebrate posturing indicates brain stem damage. A patient with decorticate posturing may begin to show decerebrate posturing, or may go from one form of posturing to the other (AllRefer.com). Posturing may occur on one or the other side of the body, or it may occur on both sides (AllRefer.com).

References

1. ADAM. 2005. "Decerebrate Posture".
2. AllRefer.com. 2003 “Decorticate Posture”. Available via the World Wide Web.
3. World Health Organization. 2005. Management of Severe Malaria: A Practical Handbook.
4. Yamamoto, Loren G. 1996. “Intracranial Hypertension and Brain Herniation Syndromes: Radiology Cases in Pediatric Emergency Medicine". Volume 5, Case 6. Kapiolani Medical Center for Women and Children; University of Hawaii; John A. Burns School of Medicine.

Neurotrauma | Medical signs