Question

True about decorticate rigidity?

• A. Removal of cerebral cortex and basal ganglia
• B. Flexion of lower limbs & extension of upper limbs
• C. Rigidity is less pronounced than decerebrate rigidity
• D. None of the above

Answer 1

The Correct Option is C

Decorticate rigidity, also known as decorticate posturing, is a condition observed in patients with severe brain injury, typically associated with damage above the midbrain level, involving the cerebral cortex. It is characterized by:

• Flexion of the upper limbs, with arms bent at the elbows and held close to the body, wrists and fingers flexed.
• Extension of the lower limbs, with legs held straight and inwardly rotated.

The condition reflects an interruption of cortical input to the brainstem and spinal cord, resulting in unopposed activity of the red nucleus, which facilitates flexion of the upper extremities while the lower extremities remain extended due to unchecked vestibular and reticulospinal tract influences.

Among the options given for decorticate rigidity:

1. Removal of cerebral cortex and basal ganglia: This does relate to the cause but is not a characteristic feature.
2. Flexion of lower limbs & extension of upper limbs: This is incorrect as it describes decerebrate posturing.
3. Rigidity is less pronounced than decerebrate rigidity: Correct, as decorticate rigidity is typically less severe than decerebrate rigidity, which involves brain damage affecting the brainstem and is marked by extension in both upper and lower limbs.
4. None of the above: Incorrect, as option 3 provides an accurate description.

Thus, the true statement about decorticate rigidity is that its "Rigidity is less pronounced than decerebrate rigidity."