What is the primary difference between decorticate and decerebrate posture?

The distinction between decorticate and decerebrate postures is primarily based on the positioning of the limbs in response to various stimuli and reflects different levels of neurological impairment.

Decorticate posture involves an abnormal flexion response. In this condition, both arms are flexed at the elbows with the hands brought close to the body, while the legs are extended. This posture is indicative of damage to the areas of the brain above the midbrain, particularly the corticospinal pathways. It typically suggests some degree of preserved function in the brain's upper regions, particularly relating to arm movement.

In contrast, decerebrate posture is characterized by an extension response. In this posture, the arms are extended at the sides and the legs are extended as well, usually with the feet plantar-flexed. This pattern arises from severe brain damage, particularly involving the brainstem where the pathways that control muscle tone are severely disrupted. This posture indicates more significant injury than decorticate posture and suggests loss of brain function at a deeper level.

Understanding these postures is crucial in clinical settings, as the type of posture can provide insights into the severity and location of neurological damage in patients.