Brain death and the cervical spinal cord: a confounding factor for the clinical examination

This study is a systematic review.

Brain death (BD) is a clinical diagnosis, made by documenting absent brainstem functions, including unresponsive coma and apnea. Cervical spinal cord dysfunction would confound clinical diagnosis of BD. Our objective was to determine whether cervical spinal cord dysfunction is common in BD.

A case of BD showing cervical cord compression on magnetic resonance imaging prompted a literature review from 1965 to 2008 for any reports of cervical spinal cord injury associated with brain herniation or BD.

A total of 12 cases of brain herniation in meningitis occurred shortly after a lumbar puncture with acute respiratory arrest and quadriplegia. In total, nine cases of acute brain herniation from various non-meningitis causes resulted in acute quadriplegia. The cases suggest that direct compression of the cervical spinal cord, or the anterior spinal arteries during cerebellar tonsillar herniation cause ischemic injury to the cord. No case series of brain herniation specifically mentioned spinal cord injury, but many survivors had severe disability including spastic limbs. Only two pathological series of BD examined the spinal cord; 56-100% of cases had upper cervical spinal cord damage, suggesting infarction from direct compression of the cord or its arterial blood supply.

Upper cervical spinal cord injury may be common after brain herniation. Cervical spinal cord injury must either be ruled out before clinical testing for BD, or an ancillary test to document lack of brainstem blood flow is required in all cases of suspected BD. BD may not be a purely clinical diagnosis.