How is nerve root injury differentiated from spinal cord injury (SCI)?

Updated: Nov 01, 2018
  • Author: Lawrence S Chin, MD, FACS; Chief Editor: Brian H Kopell, MD  more...
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Answer

A careful neurologic assessment, including motor function, sensory evaluation, deep tendon reflexes, and perineal evaluation, is critical and required to establish the presence or absence of spinal cord injury and to classify the lesion according to a specific cord syndrome.

The presence or absence of sacral sparing is a key prognostic indicator. Sacral-sparing is evidence of the physiologic continuity of spinal cord long tract fibers (with the sacral fibers located more at the periphery of the cord). Indication of the presence of sacral fibers is of significance in defining the completeness of the injury and the potential for some motor recovery. This finding tends to be repeated and better defined after the period of spinal shock.

Determine the level of injury and try to differentiate nerve root injury from spinal cord injury, but recognize that both may be present. Differentiating a nerve root injury from spinal cord injury can be difficult. The presence of neurologic deficits that indicate multilevel involvement suggests spinal cord injury rather than a nerve root injury. In the absence of spinal shock, motor weakness with intact reflexes indicates spinal cord injury, whereas motor weakness with absent reflexes indicates a nerve root lesion.

ASIA has established pertinent definitions (see the following image). The neurologic level of injury is the lowest (most caudal) level with normal sensory and motor function. For example, a patient with C5 quadriplegia has, by definition, abnormal motor and sensory function from C6 down.

American Spinal Injury Association (ASIA) method f American Spinal Injury Association (ASIA) method for classifying spinal cord injury (SCI) by neurologic level.

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