Neurocutaneous island flaps in the hand: anatomical basis and preliminary results J. A. Bertelli and Z. Khoury Joana de Gusma”o Children’s Hospital, Ftoriandpolis, Brazil and the Laboratories of Anatomy and Neurobiology, UFR Biomhdicale des Saints-P&es, Paris, France SUMMARY. The neurocutaneous flap is an axial flap composed of one vein and one nerve, the arterial vascularisation of which is provided by the vascular plexus around and inside the nerve. The vascularisation of the radial and ulnar nerves on the dorsal aspect of the hand were studied in 20 fresh upper limbs. There is always a consistent arterial longitudinal plexus alongside the nerves, which links the cutaneous perforating arteries. On the basis of our anatomical findings, neurocutaneous island flaps with retrograde flow were raised on the hands of five patients and are reported on.
Several island flaps derived from the dorsal skin of the hand have been described (Levame and Otero, 1967; Earley and Milner, 1987; Kuhlmann, 1987; Earley, 1989a,b; Arria and Gilbert, 1990; Quaba and Davidson, 1990). The variations in the dorsal arterial system (Dubreuil-Chambardel, 1922; Coleman and Anson, 1961; Murakami et al., 1969; Braun, 1977; Mauppin. 1979) and the limited arc of rotation of some of these flaps may sometimes be a problem when covering the fingers. The fact that a cutaneous nerve is always accompanied by a cutaneous artery was stressed by Quenu and Lejars in 1892 and subsequently by Salmon (1936). The neural and venous networks of the dorsal side of the hand have been studied by several authors (Sayfi, 1967a,b; Falconer and Spinner. 1985; Kuhlmann, 1987; Brunet et al., 1988; Botte et al., 1990). However, we only found one study in the literature concerning the vascularisation of these sensory dorsal nerves of the hand (Szabo and Bolonyi, 1952). The aim of this work was to study the vascularisation of the radial and ulnar nerves on the dorsal aspect of the hand, with a view to planning cutaneous island flaps vascularised by the vessels around and inside the nerves.
microtome and mounted on slides, to study the intraneural vessels. On the basis of the anatomical findings, neurocutaneous island flaps, distally based, were raised from the hands of five patients; four of them had a cicatricial contracture of the interdigital web space and/or at the level of the metacarpophalangeal joint. The fifth patient had a benign tumour (juvenile fibromatosis) on the back of the fourth finger, with clinodactyly, camptodactyly and secondary joint stiffness. The neurocutaneous island flaps were based on sensitive branches of the radial nerve in two of these patients, and on the dorsal branch of the ulnar nerve in the other three. The skin flaps measured 2 x 1 to 3 x 1.5 cm and in all cases the flap was planned at the level of the carpometacarpal joint. We suggest that when raising the flap, it should be designed so that the proximal incision crosses the axis of the nerve and includes a dorsal vein. An incision from the distal limit of the flap up to its rotation point enables the skin to be dissected away from the subcutaneous tissue containing the vessels and the nerve. A strip of subcutaneous tissue 1.5 cm wide is necessary to ensure the continuity of the nerve, vein and paraneural vessels. The sides of the flap are incised and the flap is raised with the fascia included (Fig. 1).
Materials and methods
Twenty fresh upper limbs were injected with coloured latex via the brachial artery. The limbs were dissected 48 h later, using an operating microscope, at magnifications of x 6 to x 40. Structures dissected were the dorsal branches of the radial and ulnar nerves and their vessels, the palmar digital arteries, the dorsal interosseous arteries, the radial artery and the dorsal carpal branch of the ulnar artery. The styloid process of the ulna, and the radiocarpal, carpometacarpal and metacarpophalangeal joints were chosen as anatomical landmarks. Nerve segments were removed and serial longitudinal sections were cut using a freezing
Results Anatomical findings
The vascularisation of the radial nerve and the dorsal branch of the ulnar nerve was found to be very closely connected with the vascularisation of the skin of the dorsal side of the hand. Both the skin and nerves were vascularised by perforating neurocutaneous branches of the radial artery, the dorsal carpal branch of the ulnar artery, the dorsal interosseous arteries and the palmar digital arteries. Under magnification, we identi586
Neurocutaneous
587 -
Island Flaps in the Hand
intraneural and subcutaneous vessels were numerous. We observed that paraneural arteries were accompanied by two venae comitantes which drained into the main cutaneous vein.
Clinical experience The clinical results were satisfactory. All 5 flaps survived well, although hypertrophic scarring was noted in one patient. A representative clinical case is presented.
Case report A 3-year-old boy presented with a tumour on the back of the fourth finger, with clinodactyly. camptodactyly and secon-
dary distal and proximal interphalangeal (Fig. 8).
Fig.
1
The tumour was excised and repaired using a neurocutaneous island flap 3 x I .5 cm, distally based. The flap was based on the dorsal branch of the ulnar nerve and the skin was harvested at the level of the carpometacarpal joint of the fourth finger. The flap was dissected up to the interdigital web space and tunnelled at the dorsal aspect of the proximal phalanx in order to reach the defect over the middle phalanx (Fig. 9). The donor site was closed primarily. The postoperative course was uncomplicated (Figs IO. 1 I). The patient was reviewed 1 year after the operation, and he was using the hand very well. Proximal interphalangeal motion was normal but stiffness was still present in the distal mterphalangeal joint. No tumour recurrence was noted. The diagnosis of juvenile fibromatosis was contirmed by histological examination.
I
Opcrattvc procedure for thumb reconstruction using neurocutaneous island flap: DV-Dorsal vein. a sensitt\e SR-Thumb dorsal branch of the superficial radial nerve. PN---Thumb palmar digital nerve. (A) The flap design lies over the axis of the dorsal nerve and vein which will be included in the Rap dtssection. (B) From the distal margin of the flap up to its rotational point the subcutaneous tissue containing the vessels and the nerve is exposed extending from the extensor tendon border to the midlateral line of the digit. At the proximal margin of the flap the vein and the nerve are ligated. The nerve ligature ( P) should be placed more proximally in order to have adequate length for nerve anastomosis at the recipient site. (C) The flap tunnelled and transposed to cover the defect. Anastomosis of the SR, i.e. the flap nerve, with the PN ( /” ). (D) Direct closure of the donor site. Figure
articular stiffness
tied the collateral cutaneous branches of these perforating arteries over an area of 3 x I.5 cm. Most of these perforators were located at the level of the radiocarpal, carpometacarpal and metacarpophalangeal joints. but a few were visualised at the level of the middle third of the metacarpal bones. Small longitudinal vessels 0.2 to 0.4 mm in diameter (paraneural vessels) in close contact with the dorsal cutaneous nerves. which they supply. linked these perforating neurocutaneous arteries (Figs 2. 3, 4, 5). When the nerve divided the paraneural vessel divided too (Fig. 6). Some of the paraneural vessels entered the nerve. and others were located about 4 mm away from it. Besides these paraneural longitudinal vessels, the vascular pattern included intraneural longitudinal vessels (Fig. 7). Anastomoses between paraneural.
Discussion It is now a century since Quenu and Lejars (1892) provided detailed and accurate information about the anatomy of the blood supply to the peripheral nerves. They made three important observations: that the vascularisation of the skin is partly dependent on the vessels around the nerves, that these vessels constitute a major axis of circulation and collateral anastomosis in the skin and subcutaneous tissue, and that there is no cutaneous nerve without an arteria nervorum. In fact the nerves guide the growth of the vessels as soon as the embryonic limb stump is formed (Keith, 1949). In 1953. Szabo and Bolonyi proposed that the radial and ulnar nerve branches in the dorsum of the hand were subject to segmental vascularisation. They noted that the vessels stemmed from the dorsal interosseous arteries and ran over and inside the nerves. in agreement with our observations. The vascularisation of the cutaneous flap that we have proposed is ensured by the parancural and intraneural vascular network and the venous drainage by venac comitantes that drain into a major dor\-al vein. On the basis of the topography of the principal neurocutaneous perforating vessels we delineated five donor sites from which island flaps with retrograde flow can he harvested (Fig. 12) :
British Journal of Plastic Surgery
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Figure 2-Neurocutaneous perforating arteries. Figure &Longitudinal paraneural vessels of the dorsal branch of the ulnar nerve. Figure 4-Longitudinal paraneural vessels of the thumb branch of the radial nerve. Figure 5-Paraneural vessel. Microscopic view ( x 25). Figure &When the nerve divides the paraneural vessel does so too. ( x 40). Figure 7-Intraneural longitudinal vessels ( x 200). Note the rich vascular network inside the nerve.
(a) The lateral and medial aspects of the middle and distal thirds of the first metacarpal, based on the thumb dorsal branches of the radial nerve. (b) The lateral aspect of the base of the second metacarpal, for a flap based on the index finger branch of the radial nerve. (c) The carpometacarpal joint of the second metacarpal, with the flap based on the third digital branch of the radial nerve.
(d) At the level of the carpometacarpal joint of the fourth and fifth metacarpal, with the flap based on the dorsal branches of the ulnar nerve. In our clinical cases flaps were raised from sites b and c in one patient each, and from site d, for the other 3 patients. The flaps harvested from these sites are supplied in retrograde manner by serial anastomoses of the
Neurocutaneous
Island Flaps in the Hand
Fig. 9
Fig. 8
Fig. 10
Fig. I1
Figure (I--Juvenile fibromatosis. Large tumour on the back of the 4th finger. Figure 9-This cutaneous island flap. based on the dorsal branch of the ulnar nerve, was transposed to cover the dorsal surface of the second phalanx of the 4th finger. Dissection extended up to the web space. Figure IO 4 clays after surgery. Figure II-15 days after surgery.
Fig. 12 Figure 12-Prcfcrential
dorsal
donor aspect
Several island flaps derived from the dorsal skin of the hand have been described (Levame and Otero, 1967; Earley and Milner, 1987; Kuhlmann, 1987; Earley, 1989a,b; Arria and Gilbert, 1990; Quaba and Davidson, 1990). The variations in the dorsal arterial system (Dubreuil-Chambardel, 1922; Coleman and Anson, 1961; Murakami et al., 1969; Braun, 1977; Mauppin. 1979) and the limited arc of rotation of some of these flaps may sometimes be a problem when covering the fingers. The fact that a cutaneous nerve is always accompanied by a cutaneous artery was stressed by Quenu and Lejars in 1892 and subsequently by Salmon (1936). The neural and venous networks of the dorsal side of the hand have been studied by several authors (Sayfi, 1967a,b; Falconer and Spinner. 1985; Kuhlmann, 1987; Brunet et al., 1988; Botte et al., 1990). However, we only found one study in the literature concerning the vascularisation of these sensory dorsal nerves of the hand (Szabo and Bolonyi, 1952). The aim of this work was to study the vascularisation of the radial and ulnar nerves on the dorsal aspect of the hand, with a view to planning cutaneous island flaps vascularised by the vessels around and inside the nerves.
microtome and mounted on slides, to study the intraneural vessels. On the basis of the anatomical findings, neurocutaneous island flaps, distally based, were raised from the hands of five patients; four of them had a cicatricial contracture of the interdigital web space and/or at the level of the metacarpophalangeal joint. The fifth patient had a benign tumour (juvenile fibromatosis) on the back of the fourth finger, with clinodactyly, camptodactyly and secondary joint stiffness. The neurocutaneous island flaps were based on sensitive branches of the radial nerve in two of these patients, and on the dorsal branch of the ulnar nerve in the other three. The skin flaps measured 2 x 1 to 3 x 1.5 cm and in all cases the flap was planned at the level of the carpometacarpal joint. We suggest that when raising the flap, it should be designed so that the proximal incision crosses the axis of the nerve and includes a dorsal vein. An incision from the distal limit of the flap up to its rotation point enables the skin to be dissected away from the subcutaneous tissue containing the vessels and the nerve. A strip of subcutaneous tissue 1.5 cm wide is necessary to ensure the continuity of the nerve, vein and paraneural vessels. The sides of the flap are incised and the flap is raised with the fascia included (Fig. 1).
Materials and methods
Twenty fresh upper limbs were injected with coloured latex via the brachial artery. The limbs were dissected 48 h later, using an operating microscope, at magnifications of x 6 to x 40. Structures dissected were the dorsal branches of the radial and ulnar nerves and their vessels, the palmar digital arteries, the dorsal interosseous arteries, the radial artery and the dorsal carpal branch of the ulnar artery. The styloid process of the ulna, and the radiocarpal, carpometacarpal and metacarpophalangeal joints were chosen as anatomical landmarks. Nerve segments were removed and serial longitudinal sections were cut using a freezing
Results Anatomical findings
The vascularisation of the radial nerve and the dorsal branch of the ulnar nerve was found to be very closely connected with the vascularisation of the skin of the dorsal side of the hand. Both the skin and nerves were vascularised by perforating neurocutaneous branches of the radial artery, the dorsal carpal branch of the ulnar artery, the dorsal interosseous arteries and the palmar digital arteries. Under magnification, we identi586
Neurocutaneous
587 -
Island Flaps in the Hand
intraneural and subcutaneous vessels were numerous. We observed that paraneural arteries were accompanied by two venae comitantes which drained into the main cutaneous vein.
Clinical experience The clinical results were satisfactory. All 5 flaps survived well, although hypertrophic scarring was noted in one patient. A representative clinical case is presented.
Case report A 3-year-old boy presented with a tumour on the back of the fourth finger, with clinodactyly. camptodactyly and secon-
dary distal and proximal interphalangeal (Fig. 8).
Fig.
1
The tumour was excised and repaired using a neurocutaneous island flap 3 x I .5 cm, distally based. The flap was based on the dorsal branch of the ulnar nerve and the skin was harvested at the level of the carpometacarpal joint of the fourth finger. The flap was dissected up to the interdigital web space and tunnelled at the dorsal aspect of the proximal phalanx in order to reach the defect over the middle phalanx (Fig. 9). The donor site was closed primarily. The postoperative course was uncomplicated (Figs IO. 1 I). The patient was reviewed 1 year after the operation, and he was using the hand very well. Proximal interphalangeal motion was normal but stiffness was still present in the distal mterphalangeal joint. No tumour recurrence was noted. The diagnosis of juvenile fibromatosis was contirmed by histological examination.
I
Opcrattvc procedure for thumb reconstruction using neurocutaneous island flap: DV-Dorsal vein. a sensitt\e SR-Thumb dorsal branch of the superficial radial nerve. PN---Thumb palmar digital nerve. (A) The flap design lies over the axis of the dorsal nerve and vein which will be included in the Rap dtssection. (B) From the distal margin of the flap up to its rotational point the subcutaneous tissue containing the vessels and the nerve is exposed extending from the extensor tendon border to the midlateral line of the digit. At the proximal margin of the flap the vein and the nerve are ligated. The nerve ligature ( P) should be placed more proximally in order to have adequate length for nerve anastomosis at the recipient site. (C) The flap tunnelled and transposed to cover the defect. Anastomosis of the SR, i.e. the flap nerve, with the PN ( /” ). (D) Direct closure of the donor site. Figure
articular stiffness
tied the collateral cutaneous branches of these perforating arteries over an area of 3 x I.5 cm. Most of these perforators were located at the level of the radiocarpal, carpometacarpal and metacarpophalangeal joints. but a few were visualised at the level of the middle third of the metacarpal bones. Small longitudinal vessels 0.2 to 0.4 mm in diameter (paraneural vessels) in close contact with the dorsal cutaneous nerves. which they supply. linked these perforating neurocutaneous arteries (Figs 2. 3, 4, 5). When the nerve divided the paraneural vessel divided too (Fig. 6). Some of the paraneural vessels entered the nerve. and others were located about 4 mm away from it. Besides these paraneural longitudinal vessels, the vascular pattern included intraneural longitudinal vessels (Fig. 7). Anastomoses between paraneural.
Discussion It is now a century since Quenu and Lejars (1892) provided detailed and accurate information about the anatomy of the blood supply to the peripheral nerves. They made three important observations: that the vascularisation of the skin is partly dependent on the vessels around the nerves, that these vessels constitute a major axis of circulation and collateral anastomosis in the skin and subcutaneous tissue, and that there is no cutaneous nerve without an arteria nervorum. In fact the nerves guide the growth of the vessels as soon as the embryonic limb stump is formed (Keith, 1949). In 1953. Szabo and Bolonyi proposed that the radial and ulnar nerve branches in the dorsum of the hand were subject to segmental vascularisation. They noted that the vessels stemmed from the dorsal interosseous arteries and ran over and inside the nerves. in agreement with our observations. The vascularisation of the cutaneous flap that we have proposed is ensured by the parancural and intraneural vascular network and the venous drainage by venac comitantes that drain into a major dor\-al vein. On the basis of the topography of the principal neurocutaneous perforating vessels we delineated five donor sites from which island flaps with retrograde flow can he harvested (Fig. 12) :
British Journal of Plastic Surgery
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Figure 2-Neurocutaneous perforating arteries. Figure &Longitudinal paraneural vessels of the dorsal branch of the ulnar nerve. Figure 4-Longitudinal paraneural vessels of the thumb branch of the radial nerve. Figure 5-Paraneural vessel. Microscopic view ( x 25). Figure &When the nerve divides the paraneural vessel does so too. ( x 40). Figure 7-Intraneural longitudinal vessels ( x 200). Note the rich vascular network inside the nerve.
(a) The lateral and medial aspects of the middle and distal thirds of the first metacarpal, based on the thumb dorsal branches of the radial nerve. (b) The lateral aspect of the base of the second metacarpal, for a flap based on the index finger branch of the radial nerve. (c) The carpometacarpal joint of the second metacarpal, with the flap based on the third digital branch of the radial nerve.
(d) At the level of the carpometacarpal joint of the fourth and fifth metacarpal, with the flap based on the dorsal branches of the ulnar nerve. In our clinical cases flaps were raised from sites b and c in one patient each, and from site d, for the other 3 patients. The flaps harvested from these sites are supplied in retrograde manner by serial anastomoses of the
Neurocutaneous
Island Flaps in the Hand
Fig. 9
Fig. 8
Fig. 10
Fig. I1
Figure (I--Juvenile fibromatosis. Large tumour on the back of the 4th finger. Figure 9-This cutaneous island flap. based on the dorsal branch of the ulnar nerve, was transposed to cover the dorsal surface of the second phalanx of the 4th finger. Dissection extended up to the web space. Figure IO 4 clays after surgery. Figure II-15 days after surgery.
Fig. 12 Figure 12-Prcfcrential
dorsal
donor aspect
