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The median artery: Its potential implications for the radial forearm flap
Journal of Plastic, Reconstructive & Aesthetic Surgery (2008) 61, 693e695
CASE REPORT
The median artery: Its potential implications for the radial forearm flap Iain Varley*, Craig John Wales, Lachlan M. Carter Department of Oral and Maxillofacial Surgery, York Hospital, Wigginton Road, York YO31 8HE, UK Received 21 June 2006; accepted 29 November 2006
KEYWORDS Median artery; Anatomical variations; Ischaemia; Complications
Summary The median artery is an infrequent anomaly with a highly variable origin and course in the forearm. It is associated with other local anatomical variations, and may contribute significantly to the superficial palmar arch. We describe the incidental finding of a palmar median artery during harvesting of a radial forearm flap despite normal preoperative Allen’s test and colour Doppler ultrasonography. A review of the anatomy and embryology suggests that there is an association of a persistent palmar median artery and an incomplete palmar arch, and that the median artery may arise from the radial artery, leading to an increased risk of hand ischaemia if it is sacrificed during harvesting. In this case the origin of the median artery was not encountered, and the patient did not develop ischaemia. We suggest that in the event of finding such an artery, the surgeon must be vigilant in order to ensure its origin is not ligated during harvesting. ª 2007 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.
The chance finding of an unexpected anatomical variant should prompt the surgeon to ask him or herself ‘does this altered anatomy have a bearing on the operation performed?’ In a recent case we discovered a persistent palmar median artery whilst harvesting a radial forearm flap, with potential implications for both the viability of the donor arm and for the flap itself.
* Corresponding author. Tel.: þ44 1904 726568; fax: þ44 1904 726347. E-mail address: [email protected] (I. Varley).
Case history A 48-year-old gentleman presented to our department with a squamous cell carcinoma situated around the right palatoglossal fold and right pharynx. Reconstruction of the oropharynx following resection required a radial forearm flap with a distal fasciocutaneous paddle. A preoperative Allen test1 confirmed satisfactory perfusion to the hand from the ulnar artery, and did not suggest an anomaly. Colour Doppler ultrasonography showed normal arterial anatomy with no focal disease. During harvesting it became apparent that there was a pulsatile vessel accompanying the median nerve (Fig. 1).
1748-6815/$ - see front matter ª 2007 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.bjps.2006.11.025
694
Figure 1 Median artery (MA) visible radial to the median nerve between the tendons of palmaris longus (PL) and flexor carpi ulnaris (FCU).
The vessel was seen between the tendons of palmaris longus and flexor carpi ulnaris and continued deep into the flexor retinaculum into the palm. Its origin was not encountered during the dissection. The operation was completed successfully, and the patient was discharged home 13 days following surgery with both the flap and donor hand functioning well.
Discussion The median artery persists into adulthood in two reported forms.2,3 The first, an antebrachial type, commonly arises from the anterior interosseus artery to follow the median nerve. It does not reach the palm. This pattern is considered a normal variant rather than an abnormality due to its high incidence (76%). The second, a palmar type, as seen in our case, is rarer with a reported incidence of between 1.5 and 50%, with most authors suggesting an incidence of less than 12%. The wide range of reported incidence may be partially explained by different methods of calculation, such as using hands3 or people4 as the denominator. There is also a lack of consensus regarding nomenclature for anomalous arteries in the forearm.2 It has a variable origin, and may arise from any of the forearm arteries before following the median nerve. It terminates in the superficial palmar arch, forming a complete arch with the ulnar artery in 35% of cases. In those cases where it forms an incomplete arch, it may anastamose with the superficial radial artery, before providing some of the common digital arteries.3,5 It has previously been accepted that the median artery was formed as a branch of the embryological axial artery via sprouting angiogenesis. The axial artery extends to the wrist and represents the axillary, brachial and anterior interosseus arteries. The median artery is the first branch to develop, following which the anterior interosseus artery regresses. The ulnar artery then develops to unite with the median forming the superficial carpal arch. Lastly, the radial artery develops and then the median artery regresses to leave a small arteria comitans nervi mediani.2 This hypothesis has not been supported by clinical findings, with a large variability in the origin and course
I. Varley et al. of the median artery described. Previous descriptions include origins from the radial, ulnar, anterior interosseus or common interosseus arteries.3 A recent hypothesis proposed that the arterial supply of the upper limb develops from a plexus of capillaries which undergo progressive differentiation from proximal to distal. Persistence, enlargement and differentiation of the capillaries between stages 13 and 21 of development (days 28e52 of intrauterine life) result in the definitive arterial pattern, rather than sprouting angiogenesis of aberrant vessels.6 This complexity may give rise to numerous abnormalities, such as absence of the radial artery (which may occur with or without the finding of a median artery), unusual origins and courses of the major forearm arteries and absence of the ulnar artery.2 Structures related to the arteries may also be anomalous, and in one study 63% of those hands with a median artery had a variation in the anatomy of the median nerve.4 The potential clinical implications of the finding of a persistent median artery are related to its association with abnormalities in the superficial palmar arch. The incidence of an incomplete arch in the presence of a persistent median artery has been reported to be 65%,3 whereas incomplete arches occur in as few as 10e20% of those with normal radial and ulnar arteries.5 The superficial palmar arch exists in two distinct forms when contribution from a palmar median artery is present5 (Fig. 2). Symptoms of mild hand ischaemia (such as reduced exercise tolerance or claudication) following radial artery harvest also occur in approximately 10% of cases,7 suggesting that an incomplete arch is related to the development of ischaemia. Several methods of assessment of arterial supply to the hand exist, of which the most popular is the Allen test and its modifications.1 In theory this should demonstrate the presence of an incomplete arch, but can fail even to demonstrate the absence of an ulnar artery,7 and the median artery can be inadvertently occluded when performing the test.8 Reports of severe hand ischaemia following radial artery harvest exist even after a normal Allen test,7,9 and although colour Doppler ultrasonography is an accepted adjunct to the Allen test,10 in this case it failed to demonstrate the presence of an arterial anomaly.
Figure 2 Common contributions of the median artery to the superficial palmar arch. 5 (i) Ulnar-median type complete palmar arch. (ii) Radio-median type incomplete palmar arch.
Palmar median artery In the absence of a preoperative test that can eliminate the possibility of hand ischaemia, we suggest that the finding of a median artery at operation should alert the surgeon to the possibility of associated anomalies and the risk of ischaemia. Although the palmar pattern of persistent median artery is an infrequent abnormality, it may contribute significantly to the supply of the superficial palmar arch and may arise from any of the forearm arteries. Its association with a high incidence of incomplete palmar arches suggests that ligation of the artery should be avoided if ischaemic symptoms are to be prevented. We would suggest ligation of the radial artery distal to the origin of the median artery where possible, with primary reconstruction of the median artery where necessary.
References 1. Cable DG, Mullany CJ, Schaff HV. The Allen test. Ann Thorac Surg 1999;67:876e7. 2. Rodriguez-Niedenfuhr M, Vazquez T, Parkin IG, et al. Arterial patterns of the human upper limb: update of anatomical variations and embryological development. Eur J Anat 2003; 7(Suppl. 1):21e8.
695 3. Rodriguez-Niedenfuhr M, Sanudo JR, Vazquez T, et al. Median artery revisited. J Anat 1999;195:57e63. 4. Gassner EM, Schocke M, Peer S, et al. Persistent median artery in the carpal tunnel: color Doppler ultrasonographic findings. J Ultrasound Med 2002;21:455e61. 5. Bilge O, Pinar Y, Ozer MA, et al. A morphometric study on the superficial palmar arch of the hand. Surg Radiol Anat 2006. doi:10.1007/s00276-006-0109-9 [ePub ahead of print]. 6. Rodriguez-Niedenfuhr M, Burton GJ, Deu J, et al. Development of the arterial pattern in the upper limb of staged human embryos: normal development and anatomic variations. J Anat 2001;199:407e17. 7. Nunoo-Mensah J. An unexpected complication after harvesting of the radial artery for coronary artery bypass grafting. Ann Thorac Surg 1998;66:929e31. 8. Ruengsakulrach P, Buxton BF, Eizenberg N, et al. Anatomic assessment of hand circulation in harvesting the radial artery. J Thorac Cardiovasc Surg 2001;122:178e80. 9. Jones BM, O’Brien CJ. Acute ischaemia of the hand resulting from elevation of a radial forearm flap. Br J Plast Surg 1985; 38:396e7. 10. Abu-Omar Y, Mussa S, Anastasiadis K, et al. Duplex ultrasonography predicts safety of radial artery harvest in the presence of an abnormal Allen test. Ann Thorac Surg 2004;77:116e9.
CASE REPORT
The median artery: Its potential implications for the radial forearm flap Iain Varley*, Craig John Wales, Lachlan M. Carter Department of Oral and Maxillofacial Surgery, York Hospital, Wigginton Road, York YO31 8HE, UK Received 21 June 2006; accepted 29 November 2006
KEYWORDS Median artery; Anatomical variations; Ischaemia; Complications
Summary The median artery is an infrequent anomaly with a highly variable origin and course in the forearm. It is associated with other local anatomical variations, and may contribute significantly to the superficial palmar arch. We describe the incidental finding of a palmar median artery during harvesting of a radial forearm flap despite normal preoperative Allen’s test and colour Doppler ultrasonography. A review of the anatomy and embryology suggests that there is an association of a persistent palmar median artery and an incomplete palmar arch, and that the median artery may arise from the radial artery, leading to an increased risk of hand ischaemia if it is sacrificed during harvesting. In this case the origin of the median artery was not encountered, and the patient did not develop ischaemia. We suggest that in the event of finding such an artery, the surgeon must be vigilant in order to ensure its origin is not ligated during harvesting. ª 2007 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.
The chance finding of an unexpected anatomical variant should prompt the surgeon to ask him or herself ‘does this altered anatomy have a bearing on the operation performed?’ In a recent case we discovered a persistent palmar median artery whilst harvesting a radial forearm flap, with potential implications for both the viability of the donor arm and for the flap itself.
* Corresponding author. Tel.: þ44 1904 726568; fax: þ44 1904 726347. E-mail address: [email protected] (I. Varley).
Case history A 48-year-old gentleman presented to our department with a squamous cell carcinoma situated around the right palatoglossal fold and right pharynx. Reconstruction of the oropharynx following resection required a radial forearm flap with a distal fasciocutaneous paddle. A preoperative Allen test1 confirmed satisfactory perfusion to the hand from the ulnar artery, and did not suggest an anomaly. Colour Doppler ultrasonography showed normal arterial anatomy with no focal disease. During harvesting it became apparent that there was a pulsatile vessel accompanying the median nerve (Fig. 1).
1748-6815/$ - see front matter ª 2007 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.bjps.2006.11.025
694
Figure 1 Median artery (MA) visible radial to the median nerve between the tendons of palmaris longus (PL) and flexor carpi ulnaris (FCU).
The vessel was seen between the tendons of palmaris longus and flexor carpi ulnaris and continued deep into the flexor retinaculum into the palm. Its origin was not encountered during the dissection. The operation was completed successfully, and the patient was discharged home 13 days following surgery with both the flap and donor hand functioning well.
Discussion The median artery persists into adulthood in two reported forms.2,3 The first, an antebrachial type, commonly arises from the anterior interosseus artery to follow the median nerve. It does not reach the palm. This pattern is considered a normal variant rather than an abnormality due to its high incidence (76%). The second, a palmar type, as seen in our case, is rarer with a reported incidence of between 1.5 and 50%, with most authors suggesting an incidence of less than 12%. The wide range of reported incidence may be partially explained by different methods of calculation, such as using hands3 or people4 as the denominator. There is also a lack of consensus regarding nomenclature for anomalous arteries in the forearm.2 It has a variable origin, and may arise from any of the forearm arteries before following the median nerve. It terminates in the superficial palmar arch, forming a complete arch with the ulnar artery in 35% of cases. In those cases where it forms an incomplete arch, it may anastamose with the superficial radial artery, before providing some of the common digital arteries.3,5 It has previously been accepted that the median artery was formed as a branch of the embryological axial artery via sprouting angiogenesis. The axial artery extends to the wrist and represents the axillary, brachial and anterior interosseus arteries. The median artery is the first branch to develop, following which the anterior interosseus artery regresses. The ulnar artery then develops to unite with the median forming the superficial carpal arch. Lastly, the radial artery develops and then the median artery regresses to leave a small arteria comitans nervi mediani.2 This hypothesis has not been supported by clinical findings, with a large variability in the origin and course
I. Varley et al. of the median artery described. Previous descriptions include origins from the radial, ulnar, anterior interosseus or common interosseus arteries.3 A recent hypothesis proposed that the arterial supply of the upper limb develops from a plexus of capillaries which undergo progressive differentiation from proximal to distal. Persistence, enlargement and differentiation of the capillaries between stages 13 and 21 of development (days 28e52 of intrauterine life) result in the definitive arterial pattern, rather than sprouting angiogenesis of aberrant vessels.6 This complexity may give rise to numerous abnormalities, such as absence of the radial artery (which may occur with or without the finding of a median artery), unusual origins and courses of the major forearm arteries and absence of the ulnar artery.2 Structures related to the arteries may also be anomalous, and in one study 63% of those hands with a median artery had a variation in the anatomy of the median nerve.4 The potential clinical implications of the finding of a persistent median artery are related to its association with abnormalities in the superficial palmar arch. The incidence of an incomplete arch in the presence of a persistent median artery has been reported to be 65%,3 whereas incomplete arches occur in as few as 10e20% of those with normal radial and ulnar arteries.5 The superficial palmar arch exists in two distinct forms when contribution from a palmar median artery is present5 (Fig. 2). Symptoms of mild hand ischaemia (such as reduced exercise tolerance or claudication) following radial artery harvest also occur in approximately 10% of cases,7 suggesting that an incomplete arch is related to the development of ischaemia. Several methods of assessment of arterial supply to the hand exist, of which the most popular is the Allen test and its modifications.1 In theory this should demonstrate the presence of an incomplete arch, but can fail even to demonstrate the absence of an ulnar artery,7 and the median artery can be inadvertently occluded when performing the test.8 Reports of severe hand ischaemia following radial artery harvest exist even after a normal Allen test,7,9 and although colour Doppler ultrasonography is an accepted adjunct to the Allen test,10 in this case it failed to demonstrate the presence of an arterial anomaly.
Figure 2 Common contributions of the median artery to the superficial palmar arch. 5 (i) Ulnar-median type complete palmar arch. (ii) Radio-median type incomplete palmar arch.
Palmar median artery In the absence of a preoperative test that can eliminate the possibility of hand ischaemia, we suggest that the finding of a median artery at operation should alert the surgeon to the possibility of associated anomalies and the risk of ischaemia. Although the palmar pattern of persistent median artery is an infrequent abnormality, it may contribute significantly to the supply of the superficial palmar arch and may arise from any of the forearm arteries. Its association with a high incidence of incomplete palmar arches suggests that ligation of the artery should be avoided if ischaemic symptoms are to be prevented. We would suggest ligation of the radial artery distal to the origin of the median artery where possible, with primary reconstruction of the median artery where necessary.
References 1. Cable DG, Mullany CJ, Schaff HV. The Allen test. Ann Thorac Surg 1999;67:876e7. 2. Rodriguez-Niedenfuhr M, Vazquez T, Parkin IG, et al. Arterial patterns of the human upper limb: update of anatomical variations and embryological development. Eur J Anat 2003; 7(Suppl. 1):21e8.
695 3. Rodriguez-Niedenfuhr M, Sanudo JR, Vazquez T, et al. Median artery revisited. J Anat 1999;195:57e63. 4. Gassner EM, Schocke M, Peer S, et al. Persistent median artery in the carpal tunnel: color Doppler ultrasonographic findings. J Ultrasound Med 2002;21:455e61. 5. Bilge O, Pinar Y, Ozer MA, et al. A morphometric study on the superficial palmar arch of the hand. Surg Radiol Anat 2006. doi:10.1007/s00276-006-0109-9 [ePub ahead of print]. 6. Rodriguez-Niedenfuhr M, Burton GJ, Deu J, et al. Development of the arterial pattern in the upper limb of staged human embryos: normal development and anatomic variations. J Anat 2001;199:407e17. 7. Nunoo-Mensah J. An unexpected complication after harvesting of the radial artery for coronary artery bypass grafting. Ann Thorac Surg 1998;66:929e31. 8. Ruengsakulrach P, Buxton BF, Eizenberg N, et al. Anatomic assessment of hand circulation in harvesting the radial artery. J Thorac Cardiovasc Surg 2001;122:178e80. 9. Jones BM, O’Brien CJ. Acute ischaemia of the hand resulting from elevation of a radial forearm flap. Br J Plast Surg 1985; 38:396e7. 10. Abu-Omar Y, Mussa S, Anastasiadis K, et al. Duplex ultrasonography predicts safety of radial artery harvest in the presence of an abnormal Allen test. Ann Thorac Surg 2004;77:116e9.