title: Ultrasonography Detects Ulnar Nerve Dislocation Despite Normal Electrophysiology and Magnetic Resonance Imaging.
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 ultrasonography (US) showing UN dislocation, which prompted successful treatment by UN submuscular transposition.
  
  
  METHODS
  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 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 intraoperatively, and, after UN submuscular transposition, the patient reported complete resolution of her preoperative symptoms at 6-week follow-up and continued resolution at 1 year.
  
  
  CONCLUSIONS
  Normal findings on electrodiagnostic or MRI studies should not immediately dissuade surgeons from operating on a symptomatic patient with a clinical examination supporting ulnar neuropathy and with US evidence of UN dislocation, because such a patient may experience postoperative 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.
authors.affiliation: Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA. Electronic address: Jared.Pisapia@uphs.upenn.edu.
authors.forename: Jared M
authors.initials: JM
authors.lastname: Pisapia
authors.affiliation: Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Zarina S
authors.initials: ZS
authors.lastname: Ali
authors.affiliation: Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Eric D
authors.initials: ED
authors.lastname: Hudgins
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Viviane
authors.initials: V
authors.lastname: Khoury
authors.affiliation: Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA; Division of Neurosurgery, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.
authors.forename: Gregory G
authors.initials: GG
authors.lastname: Heuer
authors.affiliation: Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Eric L
authors.initials: EL
authors.lastname: Zager
mesh_terms: D000293:Adolescent; D004550:Elbow / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D009431:Neural Conduction; D014459:Ulnar Nerve / Q000000981:diagnostic imaging*; D020424:Ulnar Neuropathies / Q000000981:diagnostic imaging*; D014463:Ultrasonography
keywords: Dislocation; Subluxation; Ulnar nerve; Ulnar neuropathy; Ultrasonography