A 33-yr-old female patient was seen for hypoesthesia of the fourth and fifth fingers in her left hand 3 mos after an open surgery for ipsilateral carpal tunnel syndrome. The medical history was otherwise noncontributory. The findings from the physical examination revealed weakness in the abduction and the adduction of the second, third, fourth, and fifth digits and weakness in the adduction of the first digit. The findings from nerve conduction studies of the ulnar and median nerves were normal bilaterally. The result of the needle electromyography of the first dorsal interosseosus muscle was consistent with partial axonal injury and regeneration of the left ulnar nerve (a few fibrillations, increased polyphasia, and decreased recruitment were observed). Thereafter, ultrasound imaging of the median and ulnar nerves was performed. The operated median nerve was still edematous and accompanied by a persistent median artery (Figs. 1A–B, 2A–B). Further, the left ulnar nerve also seemed to be injured (Figs. 3A–B). The patient was diagnosed with a mild iatrogenic ulnar neuropathy and a healing median nerve after carpal tunnel surgery.
Median neuropathy at the wrist is the most common entrapment neuropathy, and decompression surgery can be performed for its treatment. However, there may be certain early postoperative complications such as injury to the median nerve (and its branches), the ulnar nerve/Guyon canal, the superficial palmar arch, and the ulnar artery and incomplete release of the transverse carpal ligament.1 Complications associated with the ulnar nerve are relatively rare, and the relevant literature comprises only anectodal cases.2 Moreover, the diagnosis is generally based on clinical and electromyographic findings. The authors know of only one case report whereby ultrasound was used for such a diagnosis.2
The diagnostic value of ultrasound in peripheral nerve lesions is well established.3 Particularly in entrapment syndromes, it can confirm the diagnosis morphologically and it may be used to guide an onward intervention/surgery or assist with close follow-up thereafter.3 In the described subject, the ultrasound detected the postoperative edema in the ulnar nerve and, additionally, it depicted the persistent median artery as the likely cause of the carpal tunnel syndrome.This interesting case underscores the role of ultrasound in the diagnosis, treatment, and long-term follow-up of peripheral nerve entrapment syndromes.
1. Seiler JG III, Barnes K, Gelberman RH, et al. Endoscopic carpal tunnel release: An anatomic study of the two-incision method in human cadavers. J Hand Surg [Am]
1992; 17: 996–1002
2. Kim NH, Kim DH: Ulnar neuropathy at the wrist in a patient with carpal tunnel syndrome after open carpal tunnel release. Ann Rehabil Med
2012; 36: 291–6
3. Kara M, Özçakar L, De Muynck M, et al. Musculoskeletal ultrasound for peripheral nerve lesions. Eur J Phys Rehabil Med
2012; 48: 665–74