American Journal of Physical Medicine & Rehabilitation:
From the Department of Neurology (MSC, FOW), Wake Forest University School of Medicine, Winston-Salem, North Carolina; Department of Physical Medicine and Rehabilitation (JSY, KHL), Medical Devices Clinical Trial Center at Guro, Korea University College of Medicine, Guro dong, Seoul, South Korea; and Department of Orthopedics (ND), Wake Forest University School of Medicine, Winston-Salem, North Carolina.
All correspondence and requests for reprints should be addressed to: Joon Shik Yoon MD, PhD, Physical Medicine and Rehabilitation, Korea University Hospital at Guro, 80 Guro Gu, Guro dong, Seoul, Republic of Korea.
Dr. Cartwright has a Clinical Research Training grant from the Muscular Dystrophy Association to study neuromuscular ultrasound. Financial disclosure statements have been obtained, and no conflicts of interest have been reported by the authors or by any individuals in control of the content of this article.
The radial nerve is the most commonly injured nerve in cases of long-bone fracture.1 Traditionally, radial neuropathy after trauma is evaluated through a combination of history, examination, electrodiagnostic studies, and, in some cases, surgical exploration.2 Recent studies suggest that high-resolution ultrasound may be valuable in the preoperative assessment of traumatic neuropathies.3-5 However, the benefit of dynamic ultrasound imaging (with movement of the arm in several positions) for traumatic radial nerve injury has not been described. We present a case in which dynamic high-resolution ultrasonography assisted in the diagnosis and treatment of decision making in an individual with a traumatic radial neuropathy.
A 36-yr-old man was shot in the right arm with a 0.45 caliber pistol, which shattered the humerus (Figs. 1A, B). Immediately, he had numbness over the dorsal forearm and hand and weakness in the forearm, wrist, and fingers. His wound was cleaned, no surgical exploration was performed, and he was discharged with a splint. Two months later, he continued to have neither wrist nor finger extension. Electrodiagnostic studies were consistent with severe axonal injury to the radial nerve in the mid-arm, and nerve transection could not be excluded.
A Philips iU22 high-resolution ultrasound instrument (Philips Medical Instruments, Bothell, WA) with a 12-MHz linear array transducer was used to examine the area of injury. The proximal portion of the radial nerve was followed distally because it wrapped around the humerus; however, at the site of the fracture, there was a 1 cm region over which the nerve was difficult to visualize. The radial nerve segments proximal and distal to the region that was difficult to visualize were aligned. The video of the nerve, both in cross-section and longitudinal view, is available online as supplemental digital material at www.AJPMR.com. The arm was repeatedly flexed and extended at the elbow, and ultrasound was used to visualize the proximal and distal nerve segments at the site of the fracture. These segments moved in unison and remained perfectly aligned during the full range of motion. These dynamic images provided strong evidence that the nerve was anatomically intact. In addition, the radial nerve was hypoechoic and enlarged at the proximal and distal sites around the fracture, with a maximal cross-sectional area of 27 mm2.
Because high-resolution ultrasound suggested that the radial nerve was anatomically intact, conservative management was pursued rather than surgical intervention. Three months after the ultrasound, he was seen in follow-up and had regained the ability to extend the fingers. He was still unable to extend the wrist, but given his improvement, conservative management was continued.
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