Velocity drop in anconeus epitrochlearis-associated cubital tunnel syndrome.
The anconeus epitrochlearis (AE) muscle is a common anatomical variation in the cubital tunnel retinaculum of the elbow with an incidence of up to 28%; it is one cause of compressive ulnar neuropathy. In this study, we report the significance of preoperative recognition of AE-associated cubital tunnel syndrome, based on the grade of velocity drop of the compressed ulnar nerve in electrophysiological studies. Twenty-two cases with idiopathic cubital tunnel compression (CTC) were retrospectively analyzed; AE was present in 6 cases. Velocity drop of the ulnar nerve was calculated by dividing the difference in velocity (m/s) by distance (cm); the results were classified into the following grades: + (0-2.99 m/s per cm) and ++ (< 3.00 m/s per cm). Categorical data were compared using Fisher's exact test; the Mann-Whitney U test was used to determine statistical significance of ordinal data. In patients with AE-associated CTC, 3 of the 6 (50%) cases had grade ++ velocity drop. In comparison, only 1 patient of the 16 non-AE cases (6%) had grade ++ velocity drop (P = .046). Preoperative nerve velocity conduction studies that show grade ++ velocity drop (< 3.00 m/s per cm) in ulnar nerve are highly suggestive of the presence of AE.
Thomas
T
Cheriyan
Valentin
V
Neuhaus
Orthopaedic Hand Service, Yawkey Center, Massachusetts General Hospital, Boston, MA. cmudgal@partners.org.
Chaitanya S
CS
Mudgal
D000328:Adult; D000368:Aged; D020430:Cubital Tunnel Syndrome / Q000209:etiology*; D004568:Electrodiagnosis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000503:physiopathology*; D012189:Retrospective Studies; D014459:Ulnar Nerve / Q000503:physiopathology*; D017769:Ulnar Nerve Compression Syndromes / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery; D055815:Young Adult