Content area
Full Text
The authors are from the Department of Orthopaedic Surgery and Traumatology, Medicana International Istanbul Hospital, Istanbul, Turkey.
The authors have no relevant financial relationships to disclose.
Ulnar neuropathy at the elbow, the second most frequent entrapment neuropathy, is typically idiopathic. However, several anatomic variations, including the anconeus epitrochlearis muscle, have been reported to cause ulnar nerve compression. 1-3 Cadaveric, 2 ultrasound, 4 and magnetic resonance imaging (MRI) 5 studies showed that the anconeus epitrochlearis muscle is a common variation, with a prevalence of up to 34%. 2 However, clinical diagnosis of ulnar neuropathy of the elbow as a result of this variation is rare, and the prevalence is unknown. 3 This article describes a case of ulnar nerve entrapment at the elbow in a 28-year-old woman secondary to compression by the anconeus epitrochlearis muscle, with MRI, surgical correlation, and clinical and neurophysiological differential diagnosis from idiopathic cubital tunnel syndrome.
Case Report
A 28-year-old right-hand-dominant woman presented with sudden onset of disturbing medial pain of the right elbow and tingling of the little finger of the right hand of 2 months' duration. She had no history of trauma and was otherwise healthy. On physical examination, the medial side of the right elbow was very painful on palpation, the little finger of the right hand was hypesthesic, and Tinel's sign over the cubital tunnel was significantly positive. The patient had no muscle atrophy or loss of fine motor skills, but grip strength was reduced compared with the contralateral hand. Wartenberg's and Froment's signs were absent. The patient had a score of 90 on the visual analog scale.
Neurophysiologic tests were performed, including nerve conduction studies and needle electromyography. Ulnar antidromic sensory and ulnar orthodromic motor stimulation at the wrist, and below and above the elbow, were performed and recorded from the abductor digiti minimi muscle. Nerve conduction studies showed conduction slowing of ulnar motor nerve fibers at the elbow (43 m/s on the right vs 56 m/s on the left side; normal, >50 m/s). Muscle compound amplitudes in the abductor digiti minimi were low (0.7 mV; normal, >10 mV), with temporal dispersion. Conduction block of the ulnar nerve was present. Findings of sensory nerve conduction studies were normal. Needle electromyography showed fibrillation activity, decreased motor unit recruitment,...