Guyon's Canal Syndrome Due to Tortuous Ulnar Artery:A Case Report

Tortuyoz Ulnar Artere Bagh Guyon Kanah Sendromu: Vaka Takdimi

ERHAN EMEL, FEYZA KARAGOZ GDZEY, iBRAHiM ALATA$

Department of Neurosurgery, SSK Vakif Gureba Teaching Hospital, Istanbul, Turkey(EE, FKG, iA)

Running Title: Guyon's canal syndrome

Received: 28.06.2002 C> Accepted: 01.11.2002

Abstract: Aims: To report of a case with Guyon's canalsyndrome due to tortuous distal ulnar artery. Althoughulnar nerve entrapment has been quite frequentlyreported due to posttraumatic false aneurysms,thrombosis, or true aneurysms of the distal ulnar arteryin Guyon's canal, only one case has been reported due totortuous distal ulnar artery in literature by now.Methods: A 62 year-old woman with intermittent pain,intermittent burning sensation and continuousnumbness on the ulnar side of her left hand was

admitted. Electromyographic examination showed anulnar neuropathy in the Guyon's canal and an ipsilateralcarpal tunnel syndrome.Results: Exploration of the ulnar nerve in the Guyon'scanal at the wrist showed that an S shaped tortuousulnar artery compressed the ulnar nerve. Ulnar nervedecompression by ulnar artery transposition wasperformed and carpal ligament was partially excised.After the operation, pain and burning sensation wereimproved completely in a few hours, but numbness wascontinued.Conclusion: Tortuous peripheral arteries are too rarecauses of peripheral nerve entrapment syndromes.Resolution of intermittent pain and burning sensation byulnar artery transposition in the presented case wassuggested that the symptoms might be due to pulsatilepressure like in vascular compression of cranial nerves.

Key Words: peripheral nerve compression, ulnar nerve,Guyon's canal

Ozet: Ama{:lar: Klvnmh ulnar arter tarafmdan baslyabagh Guyon kanah sendromu olan bir olgununsunulmasl. Ulnar arterde travma sonraSl yalanClanevrizma, tromboz ya da gen;ek anevrizma tarafmdanbas!ya bagh ulnar sinir tuzaklanmas! olduk~a s!kbildirilmi~ olmasma ragmen, k!vnmh ulnar artertarafmdan bas!ya bagh Guyon kanah sendromuliteratUrde sadece bir olguda yay!mlanm!~hr.Yontemler: Sol elinde arahkl! agn, arahkh yanma hissi veuyu~ma yakinmalan olan 62 ya~mda bir kadm hastasunuldu. Elektromiyografi incelemesinde Guyonkanahnda ulnar nbropati ve ayru tarafta karpal tUnelsendromu ile uyumlu bulgular saptandl.Bulgular: Ameliyatta ulnar sinirin Guyon kanah i~inde S~eklindeki k!vnmh ulnar arter tarafmdan bas!ld!g!izlendi. Arterin yeri degi~tirilerek sinire olan bas!kaldmld! ve karpal bag kesildi. Giri~im somas! eldekiagn ve yanma hissi birka~ sa at i~de tamamen diizeldi,ancak uyu~ma yakinmas! devam etti.SOnllF KIvnmh periferik arterler nadiren periferik sinirtuzaklanmas! sendromlanna neden olur. Sunulan olgudaarahkl! agn ve yanma hissinin ulnar arterin yerinindegi~tirilmesi ile diizelmesi, bu belirtilerin, kafa9ftlerinin damarsal bas!larma benzer ~ekilde, pulsatilbas!ya bagh olabilecegini dii~iindiirdii.

Anahtar Kelimeler: Periferik sinir basIs!, ulnar sinir,Guyon kanah

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Turkish Neurosurgery 13: 107-110, 2003 Giizey: GUYOIl'S Cmml Sy"d1'Ol1Ie Due to Tortuous Ulllar Artery: A Case Report

INTRODUCTION

The distal ulnar tunnel (Guyon's canal) is afibroosseous tunnel along the anteromedial portionof the wrist that contains the ulnar nerve, ulnar

artery and veins. As with the adjacent carpaltunnel, its main clinical significance is that it maycause nerve compression. A variety of causes ofulnar nerve compression in the Guyon's canal havebeen determined, including trauma, lipoma,ganglion cysts, and normal anatomic variants suchas presence of abductor digiti minimi musclescoursing through the canal, or existence of afibrous arch overlying the deep motor branch ofthe ulnar nerve (3,4,5,6,8,9,11). Ulnar entrapmentmay be due to arterial compression also. Althoughsegmental ulnar neuropathy has been quitefrequently reported as a result of ulnar nervecompression due to posttraumatic false aneurysms,thrombosis, or true aneurysms of the distal ulnarartery (1,4,5,7,12), only one case has been reporteddue to tortuous distal ulnar artery in Guyon's canalby now (10).

The authors present a 62-year-old case ofsegmental ulnar neuropathy in the wrist due totortuous ulnar artery.

CASE REPORT

A 62-year-old woman was admitted with a 6months history of intermittent pain, intermittentburning sensation and continuous numbness alongthe hypothenar eminence and the fourth and fifthdigits of her left hand. The intermittent pain andburning sensation were lasting about ten to fifteenminutes. On examination, there was a slightdiminution of the hypothenar eminence musclemass, with mild weakness of the fourth and fifth

digits abduction. Sensation to touch and pinprickwas diminished in the ulnar distribution of thehand.

Left ulnar nerve conduction velocity did notdemonstrate ulnar nerve segmental delay acrossthe elbow. Left ulnar nerve united muscle action

potential revealed a significantly decreasedamplitude of 1,3 mV (normal 15 to 50 m V) and a

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prolonged distal latency of 4,2 ms (normal 1,5-3,1).Electromyography (EMG) showed that there weresparse (only one MUP), prolonged and polyphasicmotor unite potentials and abundant denervationpotentials in the intrinsic hand muscles innervatedby the ulnar nerve. In addition to these ulnar nervefindings, there was also a minimal ipsilateral carpaltunnel syndrome findings.

Exploration of the ulnar nerve in the Guyon'scanal at the wrist showed an S shaped tortuousulnar artery compressing the ulnar nerve (Figure1). Ulnar nerve decompression by ulnar arterytransposition was performed. To providetransposi tion, ulnar artery was dissected fromunderlying nerve, and was pulled to radial side ofthe nerve. Then, the artery was fixed to soft tissueby a nonabsorbable suture wrapping around butnot compressing the artery. Then the carpalligament was incised.

Figure 1: Operative photograph of the case. Note thevascular loop on the radial side of the ulnar nerve.

After the operation, intermittent pain andburning sensation were improved completely in afew hours, but numbness and weakness were

continued. On 6-month follow-up, numbness waspresent, and hypoesthesia on ulnar side of lefthand and weakness of the fourth and fifth digitsabduction were continued on neurologicalexamination. On EMG examination after 6 months,

a minimal improvement was observed in the lesioncausing excessive axonal loss on the left ulnarnerve.

Turkish Neurosurgery 13: 107-110, 2003 Gii:ey: Guyon's Callal Syndrome Due to Tortuous Ulnar Artery: A Case Report

DISCUSSION

The clinical importance of the distal ulnartunnel is that it may become the site of ulnar nervecompression. Although most commonlyidiopathic, ulnar entrapment can result fromcompression of the nerve by osteoarthriticprocesses, soft tissue tumours, synovial cysts,bursal enlargement, anomalous muscles,ganglions, calcinosis, and atypical fibrous band(3,4,5,6,8,9,11). It may also be due to arterialpathologies. Unlike cranial nerves, which havebeen reported to be compressed by aneurysmal orelongated, tortuous, and dilated arteries,peripheral nerve compression syndromes may berarely due to arterial pathologies. Only aneurysmalor thrombosed ulnar arteries have been identified

as impinging on ulnar nerve among peripheralnerves (2). A good number of reports describecompression of the ulnar nerve due toposttraumatic false aneurysms of the ulnar arteryat the wrist and hand (1,5). This pathology has alsobeen reported with thrombosis of the ulnar arteryas it emerges from the Guyon's canal, usually dueto repetitive trauma (4), or anomalous arterialanatomy (7). Infrequently, compression by trueulnar artery aneurysms has been described (12).However, the only case with ulnar nervecompression caused by tortuous ulnar artery hasbeen reported by Segal et al. in literature (10). Inour case, it was also determined ulnar nerve

compression by a tortuous ulnar artery in theGuyon's canal as that case.

Segal et al. (10) have reported in their casethat, paresthesia, tingling and burning had beenthe prominent symptoms, and they have statedwith immediate resolution of these symptoms bysimply moving aside the pulsatile pressure thatmight have triggered ectopic activation of sensorynerve fibers as the cases with pulsatile vascularcompression of cranial nerves. In our case, theprominent symptoms were an intermittent burningpain as the one of Segal et al. (10) and numbness inaddition. Burning pain was completely resolved ina few hours after the operation. Therefore, it wasstated that this symptom may be due to pulsatilecompression by the tortuous ulnar artery. On theother hand, numbness and hypoesthesia on ulnarside of the hand and mild weakness of the fourth

and fifth digits were not improved. On 6-monthfollow-up, EMG findings were improved onlyminimally. So, it was stated that, pulsatilecompression of the peripheral nerves may be dueto permanent deficits.

The specific internal topography of the ulnarnerve in relation to the structures comprising thedistal ulnar tunnel into three zones (5). Each zonesconsists of both a specific portion of the ulnar nerveand the structures surrounding it. Zone I is thatportion of the tunnel proximal to the bifurcation ofthe nerve. In Zone I, the nerve has both motor and

sensory fibers. Cross sections of the nerve in thiszone showed two distinct group of fascicules. Thepalmar-radial fibers became the superficial branch,while the dorsal-ulnar fibers became the deepmotor branch. Zone II encompasses the deep motorbranch of the nerve, and Zone III surrounds thesuperficial branch.

Gross and Gelberman (5) have reported in areview that, most of the ulnar nerve entrapmentcases in Zone I had combined motor and sensorydeficits. Ulnar artery is located lateral side of thenerve through the Zone I of the canal (5). Therefore,it is expected that nerve compression due toarterial pathology must cause principally sensorialsymptoms and signs as in the case of Segal et al (5).However, unlike that case, there were both

sensorial and motor deficits, and also permanentdeficits in our case whose compression was in Zone1. Therefore, it may be stated that pulsatilecompression of the nerve due to arterial loop inZone I may affect both lateral-sensorial andmedial-motor fascicules, and may also cause topermanent sensorial and motor deficits, if it islong-lasting sufficiently.

CONCLUSIONS

Tortuous peripheral arteries are too rarecauses of peripheral nerve entrapment syndromes.Resolution of pain and burning sensation by ulnarartery transposition in the case presented heresuggests that the symptoms may be due topulsatile pressure like in vascular compression ofcranial nerves. But some of the symptoms andsigns may be permanent after decompression as inour case if compression is long-lasting sufficiently.

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Turkish Neurosurgery 13: 107-110, 2003 Giizey: Guyon's Canal Syndrome Due to Tortuous Ulnar Artery: A Case Report

Corresponding: Feyza Karagoz Gtizey, M.D.Address: Fatma Sultan Mah.

Kahal Bagl Sok. 31/6, Fatih, 34270,istanbul-TurkeyPhone: 90-212-5346900Fax: 90-212-6217580

E-mail: fkarag@yahoo.com

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