A clinical conundrum: unilateral decerebrate rigidity.

A case is described in which, following a motorcycle accident resulting in a closed head injury, a young woman was rendered unconscious. On examination she was found to have unilateral decerebrate rigidity. Further clinical and radiological examination revealed that there was no damage to the limbs, vertebral column, or spinal cord. Readers are expected to be able to make an anatomical diagnosis on the basis of the facts presented.