Intradural connections between adjacent cervical spinal roots.

It is not always possible to localize the level of cervical pathology accurately on the basis of clinical signs and symptoms. Intradural intersegmental connections between sensory rootlets occur frequently in the cervical region and have been shown to be clinically and surgically significant. Similar connections between motor rootlets also have been noticed, but their incidence was not reported. Fifty-four human cervical spines were dissected to investigate the incidence of both types of connections. Fifty-three of the 54 specimens had posterior rootlet connections, and nine of the 54 had anterior connections. The preponderant pattern (85%) was for a peripheral dorsal or ventral rootlet to join the central portion of the next rostral or caudal root, and for the two to pass together into the spinal cord. Six distinct patterns were recognized, and a classification system is proposed. These connections may provide a pathway for overlap of sensory dermatomes and motor innervation of the neck and upper extremity. Our observations imply that when a cervical nerve root is injured, small segments of an adjacent root may be equally affected, and the process may be clinically localized one segment higher or lower than it actually is.