June 25, 2013
9:23:24am
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Hand Surgery, Vol. 18, No. 2 (2013) 251 253 © World Scientific Publishing Company DOI: 10.1142/S0218810413720143
ISOLATED ABDUCTOR DIGITI MINIMI PALSY — AN UNUSUAL CASE OF GUYON’S CANAL COMPRESSION Kannan Kumar and Sunil Thirkannad
Hand Surg. 2013.18:251-253. Downloaded from www.worldscientific.com by UNIVERSITY OF NEW ENGLAND LIBRARIES on 01/24/15. For personal use only.
Christine Kleinert Institute for Hand and Microsurgery Louisville, KY 40202, USA Received 24 September 2012; Revised 1 December 2012; Accepted 3 December 2012 ABSTRACT We present a case of isolated Abductor Digiti Minimi (ADM) palsy caused by an anomalous branch from the ulnar artery. Electrophysiology suggested selective involvement of the motor branch to the ADM in the Guyon’s canal. Surgical exploration revealed an anomalous branch of the ulnar artery causing a pincer effect on the nerve to the ADM. Division and ligation of this branch effectively decompressed the nerve and the patient recovered satisfactorily. This report highlights the need to consider vascular aberrations as a differential diagnosis for ulnar neuropathy in Guyon’s canal. Keywords: Ulnar Neuropathy; Guyon’s Canal Syndrome; Anomalous Branch; Ulnar Artery.
INTRODUCTION
distribution of the ulnar nerve. However, we were able to elicit a positive Tinel’s sign over the ulnar nerve at the level of Guyon’s canal. A clinical diagnosis of Guyon’s canal syndrome with selective motor involvement of the ADM was made. Electrophysiological tests were then performed and showed ulnar neuropathy at the level of the wrist, selectively involving the motor branch to the ADM. Owing to the unusual nature of the problem, an MRI was ordered to rule out the presence of any space occupying lesion within the Guyon’s canal and was found to be normal. At this point, a decision was made to surgically explore the Guyon’s canal and its contents. Intra-operatively, we noticed an anomalous arterial branch arising from the ulnar artery which passed superficial to the ulnar nerve, immediately looped around the motor branch to the Abductor Digiti Minimi muscle
Ulnar neuropathy at the level of the wrist is not an uncommon condition and is usually associated with intrinsic weakness and sensory loss to the volar aspects of the ring and small finger.1 Isolated involvement of the motor branch to Abductor Digiti Minimi (ADM) has not been reported so far in the English literature. We report such a case.
CASE REPORT A 58-year-old lady presented with complaints of profound hypothenar wasting and weak abduction of the small finger (Fig. 1). No weakness was demonstrable in any of the other intrinsic muscles. The patient reported no sensory disturbances and two point discrimination was found to be normal in the
Correspondence to: Dr. Sunil Thirkannad, Christine Kleinert Institute for Hand and Microsurgery, 225 Abraham Flexner Way, Suite 800, Louisville, KY 40202, USA. E-mail: [email protected] Disclaimer: No benefits, financial or otherwise have been or will be received for part or whole of this study. 251
June 25, 2013
9:23:24am
Hand Surg. 2013.18:251-253. Downloaded from www.worldscientific.com by UNIVERSITY OF NEW ENGLAND LIBRARIES on 01/24/15. For personal use only.
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Fig. 1 Preoperative picture showing severe wasting of the Abductor Digiti Minimi muscle.
Fig. 3
Schematic representation of the same image as in Fig. 2.
and then passed distally into the muscles (Figs. 2 and 3). It was evident that this anomalous artery was causing a pincer-like effect exclusively on the motor branch to the ADM. At this point, a decision was made to ligate and divide the anomalous artery to relieve pressure on the motor branch to the ADM. However, to ensure that ligating the anomalous artery would not compromise distal circulation, a vascular clamp was first placed across the vessel and the tourniquet was let down. Once it was confirmed that distal vascularity was not compromised, the anomalous vessel was ligated and divided.
Fig. 4 Postoperative picture showing restored muscle bulk of the Abductor Digiti Minimi muscle.
Subsequent follow-up in the clinic demonstrated recovery of power and muscle bulk in the abductor digiti minimi muscle (Fig. 4).
DISCUSSION
Fig. 2 Intra-operative picture showing the anomalous artery lying superficial to the ulnar nerve and looping around the nerve to ADM. A zoomed-out picture of the hand is shown as an inset for purposes of orientation.
Guyon’s canal syndrome is a well-known entity and many causes have been reported.2,3 There are a few reports ascribing Guyon’s canal syndrome to pathology in the ulnar artery. These include arterial leiomyoma, pseudoaneurysms, tortuous ulnar artery, and the more common hypothenar hammer syndrome.4 8
June 25, 2013
9:23:45am
WSPC/135-HS
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1372014
Hand Surg. 2013.18:251-253. Downloaded from www.worldscientific.com by UNIVERSITY OF NEW ENGLAND LIBRARIES on 01/24/15. For personal use only.
Isolated Abductor Digiti Minimi Palsy
Gross and Gelberman described the ulnar nerve’s passage in the wrist and divided it into three zones.9 Zone-I lies just proximal to the Guyon’s canal. Zone-II is within the canal but proximal to the division of the Ulnar nerve into superficial and deep branches. Zone-III encompasses the main divisions of the ulnar nerve. The branch to Abductor Digiti Minimi usually arises in Zone II just proximal to the ulnar nerve’s entrance into the fascia overlying the hypothenar muscles.9 The ulnar artery has been described to give off four main branches at the level of the wrist: the palmar carpal branch, palmar radiocarpal branch, palmar intercarpal branch, and the dorsal carpal branch.10 Another smaller branch has been reported by Konig et al., in their series of 31 cadaver dissections. They demonstrated a branch arising in the Guyon’s canal from the ulnar aspect of the artery and supplying the hypothenar muscles.11 In a more detailed study, Lindsey and Watamull classified this hypothenar artery into two types.12 Type-I demonstrated a vascular branch passing from the ulnar artery to the hypothenar muscles palmar to the main ulnar nerve while in Type-II the branch passed palmar to the motor branch and dorsal to the sensory branch. The location and direction of the artery found in our case lead us to believe that it was an anomalous Type-I hypothenar artery affecting the ulnar nerve in Zone-II of the Guyon’s canal. As can be seen in Figs. 2 and 3, the artery was passing palmar to the main ulnar nerve. However, it appeared to take an anomalous loop around the motor branch to the Abductor Digiti Minimi, thereby causing a pincer-like effect. This lead to the profound wasting and weakness that was clinically evident. Surgical ligation and division of the anomalous artery relieved pressure on the nerve and led to a satisfactory recovery of motor power and muscle bulk (Fig. 4). This report highlights the need to consider vascular anomalies as a differential diagnosis for ulnar neuropathy in Guyon’s canal.
253
References 1. Nicolle FV, Woolhouse FM, Nerve compression syndromes of the upper limb, J Trauma 5:313 318, 1965. 2. Botte MJ, Gelberman RH, Ulnar nerve compression at the wrist, in Szabo RM (ed.), Nerve Compression Syndromes: Diagnosis and Treatment, Slack, Thorofare, NJ, pp. 121 136, 1989. 3. Murata K, Shih JT, Tsai TM, Causes of ulnar tunnel syndrome: a retrospective study of 31 subjects, J Hand Surg 28:647 651, 2003. 4. Miyamoto W, Yamamoto S, Kii R, Uchio Y, Vascular leiomyoma resulting in ulnar neuropathy: case report, J Hand Surg 33:1868 1870, 2008. 5. Plant MA, Scilley CG, Ulnar artery pseudoaneurysm in a patient with factor ix deficiency (hemophilia b), J Can Chir Plast 15:223 225, 2007. 6. Zeeshan M, Ahmed F, Kanwal D, Khalid QS, Ahmed MN, Guyon’s canal syndrome due to tortuous ulnar artery with dequervain stenosing tenosynovitis, ligamentous injuries and dorsal intercalated segmental instability syndrome, a rare presentation: a case report, Cases J 2:9390, 2009. 7. Jose J, Dreizin D, Hypothenar hammer syndrome, Am J Orthop 41:380 382, 2012. 8. Monacelli G, Rizzo MI, Spagnoli AM, Monarca C, Scuderi N, Ulnar artery thrombosis and nerve entrapment at guyon’s canal: our diagnostic and therapeutic algorithm, In vivo 24:779 782, 2010. 9. Gross MS, Gelberman RH, The anatomy of the distal ulnar tunnel, Clin Orthop Rel Res 196:238 247, 1985. 10. Doyle JR, Botte MJ, Surgical Anatomy of the Hand and Upper Extremity, 1st ed., Lippincott, Philadelphia, USA, 2003. 11. Konig PS, Hage JJ, Bloem JJ, Prose LP, Variations of the ulnar nerve and ulnar artery in guyon’s canal: a cadaveric study, J Hand Surg 19:617 622, 1994. 12. Lindsey JT, Watumull D, Anatomic study of the ulnar nerve and related vascular anatomy at guyon’s canal: a practical classification system, J Hand Surg 21:626 633, 1996.
9:23:24am
WSPC/135-HS
FA1
1372014
Hand Surgery, Vol. 18, No. 2 (2013) 251 253 © World Scientific Publishing Company DOI: 10.1142/S0218810413720143
ISOLATED ABDUCTOR DIGITI MINIMI PALSY — AN UNUSUAL CASE OF GUYON’S CANAL COMPRESSION Kannan Kumar and Sunil Thirkannad
Hand Surg. 2013.18:251-253. Downloaded from www.worldscientific.com by UNIVERSITY OF NEW ENGLAND LIBRARIES on 01/24/15. For personal use only.
Christine Kleinert Institute for Hand and Microsurgery Louisville, KY 40202, USA Received 24 September 2012; Revised 1 December 2012; Accepted 3 December 2012 ABSTRACT We present a case of isolated Abductor Digiti Minimi (ADM) palsy caused by an anomalous branch from the ulnar artery. Electrophysiology suggested selective involvement of the motor branch to the ADM in the Guyon’s canal. Surgical exploration revealed an anomalous branch of the ulnar artery causing a pincer effect on the nerve to the ADM. Division and ligation of this branch effectively decompressed the nerve and the patient recovered satisfactorily. This report highlights the need to consider vascular aberrations as a differential diagnosis for ulnar neuropathy in Guyon’s canal. Keywords: Ulnar Neuropathy; Guyon’s Canal Syndrome; Anomalous Branch; Ulnar Artery.
INTRODUCTION
distribution of the ulnar nerve. However, we were able to elicit a positive Tinel’s sign over the ulnar nerve at the level of Guyon’s canal. A clinical diagnosis of Guyon’s canal syndrome with selective motor involvement of the ADM was made. Electrophysiological tests were then performed and showed ulnar neuropathy at the level of the wrist, selectively involving the motor branch to the ADM. Owing to the unusual nature of the problem, an MRI was ordered to rule out the presence of any space occupying lesion within the Guyon’s canal and was found to be normal. At this point, a decision was made to surgically explore the Guyon’s canal and its contents. Intra-operatively, we noticed an anomalous arterial branch arising from the ulnar artery which passed superficial to the ulnar nerve, immediately looped around the motor branch to the Abductor Digiti Minimi muscle
Ulnar neuropathy at the level of the wrist is not an uncommon condition and is usually associated with intrinsic weakness and sensory loss to the volar aspects of the ring and small finger.1 Isolated involvement of the motor branch to Abductor Digiti Minimi (ADM) has not been reported so far in the English literature. We report such a case.
CASE REPORT A 58-year-old lady presented with complaints of profound hypothenar wasting and weak abduction of the small finger (Fig. 1). No weakness was demonstrable in any of the other intrinsic muscles. The patient reported no sensory disturbances and two point discrimination was found to be normal in the
Correspondence to: Dr. Sunil Thirkannad, Christine Kleinert Institute for Hand and Microsurgery, 225 Abraham Flexner Way, Suite 800, Louisville, KY 40202, USA. E-mail: [email protected] Disclaimer: No benefits, financial or otherwise have been or will be received for part or whole of this study. 251
June 25, 2013
9:23:24am
Hand Surg. 2013.18:251-253. Downloaded from www.worldscientific.com by UNIVERSITY OF NEW ENGLAND LIBRARIES on 01/24/15. For personal use only.
252
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FA1
1372014
K. Kumar & S. Thirkannad
Fig. 1 Preoperative picture showing severe wasting of the Abductor Digiti Minimi muscle.
Fig. 3
Schematic representation of the same image as in Fig. 2.
and then passed distally into the muscles (Figs. 2 and 3). It was evident that this anomalous artery was causing a pincer-like effect exclusively on the motor branch to the ADM. At this point, a decision was made to ligate and divide the anomalous artery to relieve pressure on the motor branch to the ADM. However, to ensure that ligating the anomalous artery would not compromise distal circulation, a vascular clamp was first placed across the vessel and the tourniquet was let down. Once it was confirmed that distal vascularity was not compromised, the anomalous vessel was ligated and divided.
Fig. 4 Postoperative picture showing restored muscle bulk of the Abductor Digiti Minimi muscle.
Subsequent follow-up in the clinic demonstrated recovery of power and muscle bulk in the abductor digiti minimi muscle (Fig. 4).
DISCUSSION
Fig. 2 Intra-operative picture showing the anomalous artery lying superficial to the ulnar nerve and looping around the nerve to ADM. A zoomed-out picture of the hand is shown as an inset for purposes of orientation.
Guyon’s canal syndrome is a well-known entity and many causes have been reported.2,3 There are a few reports ascribing Guyon’s canal syndrome to pathology in the ulnar artery. These include arterial leiomyoma, pseudoaneurysms, tortuous ulnar artery, and the more common hypothenar hammer syndrome.4 8
June 25, 2013
9:23:45am
WSPC/135-HS
FA1
1372014
Hand Surg. 2013.18:251-253. Downloaded from www.worldscientific.com by UNIVERSITY OF NEW ENGLAND LIBRARIES on 01/24/15. For personal use only.
Isolated Abductor Digiti Minimi Palsy
Gross and Gelberman described the ulnar nerve’s passage in the wrist and divided it into three zones.9 Zone-I lies just proximal to the Guyon’s canal. Zone-II is within the canal but proximal to the division of the Ulnar nerve into superficial and deep branches. Zone-III encompasses the main divisions of the ulnar nerve. The branch to Abductor Digiti Minimi usually arises in Zone II just proximal to the ulnar nerve’s entrance into the fascia overlying the hypothenar muscles.9 The ulnar artery has been described to give off four main branches at the level of the wrist: the palmar carpal branch, palmar radiocarpal branch, palmar intercarpal branch, and the dorsal carpal branch.10 Another smaller branch has been reported by Konig et al., in their series of 31 cadaver dissections. They demonstrated a branch arising in the Guyon’s canal from the ulnar aspect of the artery and supplying the hypothenar muscles.11 In a more detailed study, Lindsey and Watamull classified this hypothenar artery into two types.12 Type-I demonstrated a vascular branch passing from the ulnar artery to the hypothenar muscles palmar to the main ulnar nerve while in Type-II the branch passed palmar to the motor branch and dorsal to the sensory branch. The location and direction of the artery found in our case lead us to believe that it was an anomalous Type-I hypothenar artery affecting the ulnar nerve in Zone-II of the Guyon’s canal. As can be seen in Figs. 2 and 3, the artery was passing palmar to the main ulnar nerve. However, it appeared to take an anomalous loop around the motor branch to the Abductor Digiti Minimi, thereby causing a pincer-like effect. This lead to the profound wasting and weakness that was clinically evident. Surgical ligation and division of the anomalous artery relieved pressure on the nerve and led to a satisfactory recovery of motor power and muscle bulk (Fig. 4). This report highlights the need to consider vascular anomalies as a differential diagnosis for ulnar neuropathy in Guyon’s canal.
253
References 1. Nicolle FV, Woolhouse FM, Nerve compression syndromes of the upper limb, J Trauma 5:313 318, 1965. 2. Botte MJ, Gelberman RH, Ulnar nerve compression at the wrist, in Szabo RM (ed.), Nerve Compression Syndromes: Diagnosis and Treatment, Slack, Thorofare, NJ, pp. 121 136, 1989. 3. Murata K, Shih JT, Tsai TM, Causes of ulnar tunnel syndrome: a retrospective study of 31 subjects, J Hand Surg 28:647 651, 2003. 4. Miyamoto W, Yamamoto S, Kii R, Uchio Y, Vascular leiomyoma resulting in ulnar neuropathy: case report, J Hand Surg 33:1868 1870, 2008. 5. Plant MA, Scilley CG, Ulnar artery pseudoaneurysm in a patient with factor ix deficiency (hemophilia b), J Can Chir Plast 15:223 225, 2007. 6. Zeeshan M, Ahmed F, Kanwal D, Khalid QS, Ahmed MN, Guyon’s canal syndrome due to tortuous ulnar artery with dequervain stenosing tenosynovitis, ligamentous injuries and dorsal intercalated segmental instability syndrome, a rare presentation: a case report, Cases J 2:9390, 2009. 7. Jose J, Dreizin D, Hypothenar hammer syndrome, Am J Orthop 41:380 382, 2012. 8. Monacelli G, Rizzo MI, Spagnoli AM, Monarca C, Scuderi N, Ulnar artery thrombosis and nerve entrapment at guyon’s canal: our diagnostic and therapeutic algorithm, In vivo 24:779 782, 2010. 9. Gross MS, Gelberman RH, The anatomy of the distal ulnar tunnel, Clin Orthop Rel Res 196:238 247, 1985. 10. Doyle JR, Botte MJ, Surgical Anatomy of the Hand and Upper Extremity, 1st ed., Lippincott, Philadelphia, USA, 2003. 11. Konig PS, Hage JJ, Bloem JJ, Prose LP, Variations of the ulnar nerve and ulnar artery in guyon’s canal: a cadaveric study, J Hand Surg 19:617 622, 1994. 12. Lindsey JT, Watumull D, Anatomic study of the ulnar nerve and related vascular anatomy at guyon’s canal: a practical classification system, J Hand Surg 21:626 633, 1996.
