Evaluation of brachial plexus injury by CT myelography

Objective: To evaluate the diagnostic value of CT myelography (CTM) in brachial plexus injury. Methods: Twenty-seven patients with brachial plexus injury were examined by using cervical CTM with spiral scan and bone reconstruction algorithm. CT images were reviewed by the senior radiologists, who determined if the nerve root avulsion was presented. The criteria of diagnosing nerve root avulsion were loss of normal nerve root appearance in the Isovist filled thecal sac in consecutive CTM slices plus companion signs. The sensitivity, specificity, and accuracy of CTM in diagnosing nerve root injuries were calculated with operation findings and follow-up results as gold standard. Results: Direct sign of nerve root avulsion was the loss of normal nerve root defect seen in the Isovist filled thecal sac in consecutive CTM slices. Indirect signs included: (1) Pseudomeningocele bulge: The leak of Isovist into nerve root sheath, and extended into foramina; (2) Arachnoid cyst: displacement of spinal cord; (3) Dissymmetry of subarachnoid cavity: deformity of thecal sac, partially lack of Isovist into arachnoid space; (4) Non-integrity of dural cap sule wall: one side of cap sule cavity was obstructed. Part of the surface of spinal cord was exposed. Brachial plexus injury could be diagnosed by direct sign with one of the indirect signs. Of the 27 patients (128 nerve roots), 91 nerve root avulsions were found on CTM, and 37 was found normal. Compared with operation findings, 84 were true positive, 7 false positive, 34 true negative, and 3 false negative. Based on these results, the sensitivity, specificity, and accuracy were 96.6%, 82.9%, and 92.2%, respectively. Conclusion: CTM is accurate in detecting nerve root avulsion of brachial plexus. (authors)