J Neurosurg 114:206–211, 2011 206 J Neurosurg / Volume 114 / January 2011 T he diagnosis and localization of peripheral nerve lesions relies primarily on the clinical history and physical examination. The diagnostic testing of pe- ripheral nerve lesions has previously been limited to use of NCSs and EMG. The development of ultrasonography and MR imaging has allowed visualization of nerve le- sions with varying degrees of clinical eficacy. 12,14–16,18 Magnetic resonance neurography provides high-res- olution imaging of peripheral nerves; T2-weighted MR imaging sequences combining fat and low suppression with 3D reconstruction yield good representations of peripheral nerve anatomy. Magnetic resonance imaging technology, however, is limited by dificulties of access, cost, and time. 14 Magnetic resonance neurography is not available at all centers, and considerable variability in imaging quality may be found. Ultrasonography is a rapid and widely available tech- nology that provides dynamic imaging. In carpal tunnel syndrome, ultrasonography has been shown to provide equal if not superior diagnostic capabilities compared with MR imaging. 2,6,12–14 The development of high-res- olution ultrasonography has allowed users to accurately identify a variety of neural pathologies including trauma, tumors, and entrapment neuropathies. 4,6,7 Ultrasonogra- phy has been used to guide surgical approaches, local- ize speciic lesions, and determine the extent of resec- tions in surgical procedures. The modality is used within the neurosurgical milieu in the removal of brain tumors, where it provides real-time intraoperative localization for precise cortical incision and ongoing guidance for extent of resection. 5 Intraoperative ultrasonography has demonstrated a sensitivity and speciicity of 97 and 84%, High-resolution ultrasonography in the diagnosis and intraoperative management of peripheral nerve lesions Clinical article Franklin C. lee, B.S., 1 Harminder SingH, m.d., 2 levon n. nazarian, m.d., 3 and JoHn k. ratliFF , m.d. 2 1 Jefferson Medical College, Thomas Jefferson University; and Departments of 2 Neurosurgery and 3 Radiology, Thomas Jefferson University Medical Center, Philadelphia, Pennsylvania Object. The diagnosis of peripheral nerve lesions relies on clinical history, physical examination, electrodiag- nostic studies, and radiography. Magnetic resonance neurography offers high-resolution visualization of structural peripheral nerve lesions. The availability of MR neurography may be limited, and the costs can be signiicant. By comparison, ultrasonography is a portable, dynamic, and economic technology. The authors explored the clinical applicability of high-resolution ultrasonography in the preoperative and intraoperative management of peripheral nerve lesions. Methods. The authors completed a retrospective analysis of 13 patients undergoing ultrasonographic evaluation and surgical treatment of nerve lesions at their institution (nerve entrapment [5], trauma [6], and tumor [2]). Ultra- sonography was used for diagnostic (12 of 13 cases) and intraoperative management (6 of 13 cases). The authors examine the initial impact of ultrasonography on clinical management. Results. Ultrasonography was an effective imaging modality that augmented electrophysiological and other neuroimaging studies. The modality provided immediate visualization of a sutured peroneal nerve after a basal cell excision, prompting urgent surgical exploration. Ultrasonography was used intraoperatively in 2 cases to identify postoperative neuromas after mastectomy, facilitating focused excision. Ultrasonography correctly diagnosed an in- lamed lymph node in a patient in whom MR imaging studies had detected a schwannoma, and the modality correctly diagnosed a tendinopathy in another patient referred for ulnar neuropathy. Ultrasonography was used in 6 patients to guide the surgical approach and to aid in intraoperative localization; it was invaluable in localizing the proximal seg- ment of a radial nerve sectioned by a humerus fracture. In all cases, ultrasonography demonstrated the correct lesion diagnosis and location (100%); in 7 (58%) of 12 cases, ultrasonography provided the correct diagnosis when other imaging and electrophysiological studies were inconclusive or inadequate. Conclusions. High-resolution ultrasonography may provide an economical and accurate imaging modality with utility in diagnosis and management of peripheral nerve lesions. Further research is required to assess the role of ultrasonography in evaluation of peripheral nerve pathology. (DOI: 10.3171/2010.2.JNS091324) key WordS • peripheral nerve • ultrasound • nerve entrapment • schwannoma Abbreviations used in this paper: EMG = electromyography; NCS = nerve conduction study.