malities. However, isolated compression of the deep branch of the ulnar nerve is rare.

Introduction

Ulnar neuropathy at the wrist (UNW) is uncommon and Guyon’s canal is a region where the ulnar nerve is vulnerable to compression. Ulnar nerve compression within Guyon’s canal may produce various clinical

symptoms, including motor and (or) sensory abnor­

malities. However, isolated compression of the deep branch of the ulnar nerve is rare.

The etiology of the UNW includes tumors, fracture, or dislocations of the carpal bones, anatomical variations, or overuse injuries.

A ganglion has been known to a rare cause of UNW as well.

Ganglions are the most common soft tissue tumor of the hand and wrist, but their etiology and formation remain obscure.

Several studies have described intracarpal ligament lesions as the underlying cause of pain in wrist ganglions.

However, there is little known about the relationship between triangular

삼각섬유연골 복합체 병변과 연관된 결절종에 의한 손목부위 척골신경병증 - 증례 보고 -

이현일

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²

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1인제대학교 의과대학 일산백병원 정형외과학교실, ²울산대학교 의과대학 강릉아산병원 재활의학교실

Ulnar Nerve Deep Branch Compression at the Wrist by a Ganglion and an Associated Triangular Fibrocartilage Complex Lesion - Case Report-

Hyun Il Lee

, Jung Hoi Koo

, Sun Hong Song

1

Department of Orthopedic Surgery, Ilsan Paik Hospital, Inje University College of Medicine, Goyang,

2

Department of Rehabilitation Medicine, Gangneung Asan Hospital, University of Ulsan College of Medicine, Gangneung, Korea

Received February 9, 2017

Revised (1st) March 8, 2017, (2nd) April 20, 2017 Accepted April 21, 2017

Corresponding Author: Jung Hoi Koo

Department of Rehabilitation Medicine, Gangneung Asan Hospital, University of Ulsan College of Medicine, 38 Bangdong-gil, Gangneung 25440, Korea

Tel: 82-33-610-4951, Fax: 82-33-610-4960, E-mail: mdjhkoo@naver.com

Ulnar neuropathy at the wrist (UNW) is uncommon and it may result from various causes such as tumors, fracture, or overuse injuries. Also a ganglion has been reported as a rare cause of UNW. Ganglions are the most common soft tissue tumors of the hand and wrist, but their etiology remains controversial. Several studies have described associated abnormalities of the intracarpal ligaments. However, ganglions associated with triangular fibrocartilage complex (TFCC) lesions are rarely reported so far. We hereby report a case of UNW caused by a ganglion and an associated TFCC lesion.

Key Words: ulnar neuropathy, ganglions, triangular fibrocartilage complex

Copyright © by Korean Association of EMG Electrodiagnostic Medicine

This is an Open Ac cess article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

ISSN 1229-6066 https://doi.org/10.18214/jkaem.2017.19.1.5 J Korean Assoc EMG Electrodiagn Med 19(1):5-9, 2017

J Korean Assoc

Electrodiagn Med EMG

fibrocartilage complex (TFCC) lesions and ganglions.

Here we present a case of UNW caused by a ganglion and an associated TFCC lesion and review the literature.

Case Report

A 37­year­old man presented with right wrist pain and weakness in the fifth finger. Wrist pain was developed after falling down about 3 months ago, and finger weakness was shown 1 week ago after shoveling. On physical examination, there was tenderness on the distal radioulnar joint area. Intrinsic muscle atrophy was not shown. The power of little finger abduction was trace and sensory function was intact. Froment’s sign (When the patient is asked to adduct the thumb, patient will instead hyperflex the IP joint to compensate for loss of the adductor) was equivocal, but Wartenberg sign (A neurological sign consisting of involuntary abduction of the little finger, caused by unopposed action of the extensor digiti minimi) was positive.

He was referred from the department of orthopedic medicine for electrodiagnostic studies. 22 days later, eletrodiagnostic studies were done. Ulnar motor nerve

conduction studies (NCS) with abductor digiti minimi (ADM) recordings showed low amplitude on the right side, with normal responses on the left. Sensory NCS including dorsal ulnar cutaneous nerve were normal (Table 1). Needle electromyographic findings of the right ADM and first dorsal interossei muscles revealed profuse abnormal spontaneous activities and polyphasic motor unit potentials with reduced recruitment patterns (Table 2). Magnetic resonance image of the wrist showed a ganglion compressing ulnar nerve within Guyon’s canal (Fig. 1), and torn central disc of TFCC (Fig. 2). So he underwent arthroscopic surgery. A ganglion was removed and a torn TFCC was debrided (Fig. 3). After the surgery, the patient was significantly improved in terms of pain and disabilities in daily life.

Discussion

Ulnar neuropathy at the wrist (UNW) is uncommon compared with ulnar neuropathy at the elbow, and UNW may have more various presentations. UNW is classified into 3 types.

Type I syndrome occurs as a result of nerve compression proximal to or within

Table 1. Results of Nerve Conduction Study

Nerve Stimulation site Recording site Lat (ms) Amp* Dist (cm) CV (m/s)

Motor

Lt Median Wrist APB 2.45 21.4

Elbow APB 6.35 20.5 24 61.5

Rt Median Wrist APB 2.80 16.2

Elbow APB 6.60 15.7 24 63.2

Lt Ulnar Wrist ADM 2.05 14.2

BE ADM 5.45 13.3 22 64.7

AE ADM 6.85 13.3 11 78.6

Rt Ulnar Wrist ADM 2.20 3.5

BE ADM 5.60 3.3 22 64.7

AE ADM 6.95 3.3 11 81.5

Sensory

Lt median Wrist 3rd finger 2.65 53.4 14 52.8

Rt median Wrist 3rd finger 2.75 47.9 14 50.9

Lt ulnar Wrist 5th finger 2.45 40.3 14 57.1

Rt ulnar Wrist 5th finger 2.50 42.8 14 56.0

Lt DUCN Forearm 4th web 2.30 34.8 13 56.5

Rt DUCN Forearm 4th web 2.50 29.2 13 52.0

Lat: latency, Amp: amplitude, Dist: distance, CV: conduction velocity, Lt: left, Rt: right, APB: abductor pollicis brevis, ADM: abductor digiti minimi, BE: below elbow, AE: above elbow, DUCN: dorsal ulnar cutaneous nerve

*Amplitudes are measured in milivolt (mV, motor) and in microvolt (μV, sensory)

Guyon’s canal, before any nerve bifurcation, and manifests as motor weakness and sensory deficits.

Type II syndrome manifests exclusively as motor weakness of the hand and sensory branch is spared.

Type III syndrome occurs secondary to compression of the superficial sensory branch of the ulnar nerve and manifests as isolated sensory loss.

Numerous factors may cause the UNW, including space­occupying lesions, vascular lesions, and repeti­

tive trauma.

Shea and McClain reported that ganglion cysts and occupational neuritis were the 2 leading causes of UNW.

However, compression of the isolated motor branch of the ulnar nerve by a ganglion is very rare. Previous literature reported that a ganglion in the midpalmar or arising from the pisohamate joint can

Table 2. Results of Needle Electromyography

ASA MUAP

Recruitment

IA Fib PSW Amp Dur Poly

Rt BB N None None N N None Full

Rt Deltoid N None None N N None Full

Rt PT N None None N N None Full

Rt FCR N None None N N None Full

Rt FCU N None None N N None Full

Rt ADM N 2+ 2+ N N + Reduced

Rt FDI N 3+ 3+ N N + Reduced

Rt APB N None None N N None Full

Rt C7-T1 PVM N None None

ASA: abnormal spontaneous activity, MUAP: motor unit action potential, IA: insertional activity, Fib: fibrillation, PSW: positive sharp wave, Amp: amplitude, Dur: duration, Poly: polyphasic motor units, Rt: right, BB: biceps brachii, PT: pronator teres, FCR: flexor carpi radialis, FCU: flexor carpi ulnaris, ADM: abductor digiti minimi, FDI: first dorsal interossei, APB: abductor pollicis brevis, PVM: paravertebral muscle, N: normal

A B

Fig. 1. (A) T2-weighted axial magnetic resonance image of the wrist showed a ganglion (short arrow) compressing motor branch of ulnar nerve within Guyon’s canal (long arrow). (B) T2-weighted axial magnetic resonance image of the wrist showed a sensory branch (short arrow) and a motor branch of ulnar nerve (long arrow).

Fig. 2. T2-weighted coronal magnetic resonance image of the wrist

showed a torn central disc of TFCC (arrow).

lead to deep branch entrapment.

Ganglions are the most common soft tissue tumor of the hand and wrist, but their etiology remains controversial.

Several studies have described asso­

ciated abnormalities of the intracarpal ligaments.

The TFCC is the primary stabilizer of the distal radioulnar joint and composed of central disc, dorsal and palmar radioulnar ligament.

Although there are reports that its injury is related to ganglion formation, only a few studies suggested a possible relationship between TFCC lesions and ganglions.

In a prospective study of Lowden et al, only 2 of the 103 volunteers had a ganglion with an associated TFCC abnormality.

These results suggest that, in healthy subjects, an association between ganglions and TFCC lesions is rare. In our case, we found a ganglion compressing deep motor branch of the ulnar nerve and aTFCC lesion. However their causal relationship is not clear.

In a recent study in arthroscopically­treated patients with ganglions, Langner et al identified associated TFCC lesions (48%), but the question of whether TFCC lesions are the underlying cause of ganglions is difficult to answer in patients having simultaneous arthroscopic treatment of ganglion and TFCC lesion.

In our study, whether the TFCC abnormality is a cause of ganglion or an incidental finding is not clear as well. Although

we have not clarified the relationship between the two lesions in our case, if you see patients with a ganglion, you should keep in mind the possibility of TFCC associated with it.

In conclusion, we found a rare case of isolated ulnar deep motor branch by a ganglion which may be associated with TFCC lesion. If the clinician sees a patient with painful ganglion, thorough test such as arthroscopy will help identify TFCC lesions.

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