Nervous Tissue Damage Markers in Cerebrospinal Fluid after Cervical Spine Injuries and Whiplash Trauma

Clinical examination is the only tool available to assess the extent of the nerve tissue damage after a spinal cord injury, and it is well known that the reliability of classification based on clinical examination is not satisfactory, especially in cases with incomplete motor injuries. There is a need to evaluate new methods in order to improve the possibilities of classifying and prognosticating spinal cord injuries. Methods for assessing central nervous system (CNS) damage using markers in cerebrospinal fluid (CSF) have recently been developed. Previous studies have reported glial fibrillary acidic protein (GFAp) and neurofilament protein (NFL) levels in non-traumatic diseases in the central nervous system. The present study is the first report of GFAp and NFL levels in CSF after trauma to the cervical spine. Six cases with cord damage and pronounced neurological deficit showed significantly increased concentrations of both GFAp and NFL in the CSF. Patients with tetrapareses showed higher values than those with incomplete injuries. Three of the 17 whiplash cases had increased levels of NFL, but normal GFAp. Assessment of nervous tissue markers in CSF will probably improve possibilities to classify and prognosticate spinal cord injuries and also to evaluate pharmacological intervention. The increased levels of NFL in three whiplash cases indicate neural damage in a proportion of the cases with neurological deficit. Neurological examinations are presently the only tools for grading and prognostication of spinal cord injuries. Assessment of nervous tissue markers in CSF makes it possible to quantify the degree of nerve cell damage after different types of cervical spine injury ranging from spinal cord lesions to whiplash injuries.

In Vivo Pressure Responses of the Cervical Cerebrospinal Fluid in a Porcine Model of Extension and Flexion Whiplash Exposures

PURPOSE

The mechanisms of whiplash injury remain poorly understood. One theory suggests that the characteristic inertial loading of the head and neck in motor vehicle collisions can produce injurious cerebrospinal fluid (CSF) pressure transients in the cervical spine. However, these in vivo CSF pressure responses have not yet been adequately characterized.

METHODS

This study used a pig model to characterize the cervical CSF pressure responses to head kinematic inputs in extension (simulating low-speed rear-end collisions with no head restraint) and flexion (simulating low-speed frontal collisions). We also compared the pressure and pressure impulses at three spinal levels to determine if the pressure transient responses differ spatially. Four anesthetized pigs were instrumented with intrathecal pressure transducers placed at the C2, C5, and C7 levels. A servomotor system was programmed to actuate the head through specific trajectories to model two extension, and two flexion, whiplash exposures.

RESULTS

During the extension tests, mean peak pressure transients ranged from - 31.2 to 148.7 mmHg, whereas during the flexion tests, mean peak pressure transients ranged from - 50.8 to 126.9 mmHg. Peak individual responses ranged from - 71.1 to 244.8 mmHg across all tests. Pressure impulses reached a maximum of 6.77 mmHg·s. Peak pressure and pressure impulses were largest at the C5 and C7 levels during extension exposures and at the C2 level in flexion exposures.

CONCLUSION

The reported pressure and pressure impulse responses could be used to determine neural tissue tolerances relevant to whiplash injury and contribute to the development and validation of computational models of whiplash.