Surgical Treatment of Intraneural Ganglion Cysts of the Ulnar Nerve at the Elbow: Long-Term Follow-up of 9 Cases.

Abstract

Intraneural ganglion (IG) cysts have been considered curiosities and their pathogenesis remains controversial. To clarify ulnar nerve at the elbow (UNE) pathogenesis and long-term surgical outcomes by presenting 9 rare cases of IG of the UNE. Surgical treatment of IG was performed. Clinical symptoms, physical examinations, and electromyogram were evaluated pre- and postoperatively. At least 4 yr of follow-up was performed. The Tinel's sign became negative and local elbow pain disappeared in all 9 patients after surgery, and the average visual analog scale/score dropped from 4.9 (3-8) to 0 (0-0) after 6.2 d (2-10) on average. Two patients retained positive Froment test, "claw hand" and paresthesias with the 2-point discrimination much different from the contralateral little finger. Postoperative the UK Medical Research Council muscle strength score (MRC) grades of the flexor carpi ulnaris and the flexor digitorum profundus muscle of the fourth and fifth digits recovered to M4-M5 from M0-M2 in all 9 patients. The postoperative MRC grades of the third to fourth lumbrical muscles, the interossei, and the hypothenar recovered to M3-M5 from M0-M2 in 7 patients. Cystic articular branch (CAB) was found in all 9 patients intraoperatively. No symptomatic recurrence of IG was seen. The mean motor nerve conduction velocity of ulnar nerve across the elbow recovered from 5.3 to 41.2 m/s. A unifying articular theory is responsible for the pathogenesis of IG of UNE and disconnection of the CAB would prevent recurrence. The long-term outcome is good after surgical treatment of IG of UNE.