Movements after the clinical diagnosis of brain death: supraspinal motor responses or spinal reflexes

In a recent issue of Critical Care, Wu and Orizaola Balaguer [1] hypothesized that nociceptive head turning after brain death (BD) is a spinal reflex. We argue that it can be a supraspinal response, which would invalidate a diagnosis of BD. The sternocleidomastoid and trapezius are innervated by the spinal nucleus of the accessory nerve extending from the lower medulla to the ventral horn of the spinal cord (C1-C4) [2]. Lower motor neurons from the lower medulla to C2 project to the sternocleidomastoid [2], contributing to the reported motor responses. The spinal nerve roots of the accessory nerve ascend through the foramen magnum and descend through the jugular foramen. Compression of the vertebral-basilar arteries (causing intracranial circulatory arrest) and the spinal nerve roots by cerebellar tonsillar herniation at the foramen magnum would abolish the spinal accessory nerve reflex as well as cause cervicomedullary infarction.