Ultrasonography detects ulnar nerve dislocation despite normal electrophysiology and magnetic resonance imaging.

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Ultrasonography detects ulnar nerve dislocation despite normal electrophysiology and magnetic resonance imaging.

World Neurosurg. 2017 Jan 12;:

Authors: Pisapia JM, Ali ZS, Hudgins ED, Khoury V, Heuer GG, Zager EL

Abstract
BACKGROUND: Dislocation of the ulnar nerve (UN) occurs in a subset of patients with ulnar neuropathy. Electrodiagnostic and magnetic resonance imaging (MRI) studies are performed to support the clinical diagnosis. We report the case of a patient with ulnar neuropathy with normal electrodiagnostic and MRI studies but with ultrasound (US) showing UN dislocation, which prompted successful treatment by UN submuscular transposition.
CASE DESCRIPTION: A healthy 15 year-old female softball player presented with right medial elbow pain and paresthesias of the fourth and fifth digits. She had 4+/5 strength in the right hand intrinsic muscles and a Tinel's sign at the right elbow. A snap was palpated at the elbow upon flexion. MRI showed mild common flexor tendonitis, and electrodiagnostic studies showed normal motor responses and no conduction block at the elbow. High-resolution US showed dislocation of the UN over the medial epicondyle. UN dislocation was confirmed intra-operatively, and, following UN submuscular transposition, the patient reported complete resolution of her pre-operative symptoms at six week follow-up and continued resolution at one year.
CONCLUSIONS: Normal findings on electrodiagnostic or MRI studies should not immediately dissuade surgeons from operating on a symptomatic patient with a clinical exam supporting ulnar neuropathy and with ultrasound evidence of UN dislocation, as such a patient may experience post-operative symptom relief. Furthermore, the dynamic capability of US imaging complements data obtained from electrodiagnostic and MRI studies, especially when these tests are normal, and it should be considered by clinicians when evaluating patients with medial elbow pain or signs of ulnar neuropathy.

PMID: 28089807 [PubMed - as supplied by publisher]

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