Examination of postoperative peripheral nerve lesions with high-resolutionsonography

OBJECTIVE, Peripheral nerve lesions after surgery are common and are relate d either to direct compromise of the nerve by the surgical procedure (iatro genic lesions) or to postoperative events such as scar formation. Despite a high sensitivity, electrodiagnosis may not reveal the exact location and c ause of a nerve lesion, We hypothesized that high-resolution sonography cou ld be helpful in diagnosing postoperative peripheral nerve lesions by direc t visualization of the nerve and surrounding tissues. SUBJECTS AND METHODS. Eighteen patients with postoperative peripheral nerve lesions that were confirmed with clinical examination and electrodiagnosis were examined on sonography. Eight patients had lesions caused by direct n erve surgery, and 10 patients had undergone a previous orthopedic operation or open biopsy. Sonographic diagnoses were correlated with neurologic exam inations and surgical findings. RESULTS. Reliable visualization of injured nerves on sonography was feasibl e in all patients. Axonal swelling of a nerve was diagnosed in three patien ts, direct compromise of a nerve by surrounding scar tissue or surgical imp lants was diagnosed in 10 patients, a neuroma was diagnosed in three, and i nsufficient surgical repair, in two. Sonographic findings were confirmed du ring surgery in all except one patient. CONCLUSION. In contrast to electrophysiologic tests, high-resolution sonogr aphy can show the exact location, extent, and type of a postoperative perip heral nerve lesion and the concurrent disease of surrounding tissues. Becau se the latter can often be thr causative agent for the development of a les ion or the lack of improvement with conservative treatment, sonography yiel ds important information that may not be obtained with other diagnostic mod alities.