Venous Architecture of the Glabellar to the Forehead Region

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1 Clinical Anatomy 00: (2012) ORIGINAL COMMUNICATION Venous Architecture of the Glabellar to the Forehead Region YUSUKE SHIMIZU, 1 * NOBUAKI IMANISHI, 2 TATSUO NAKAJIMA, 1 HIDEO NAKAJIMA, 1 SADAKAZU AISO, 2 AND KAZUO KISHI 1 1 Department of Plastic and Reconstructive Surgery, Keio University School of Medicine, Tokyo, Japan 2 Department of Anatomy, Keio University School of Medicine, Tokyo, Japan The precise venous anatomy of the glabellar to the forehead region remains unknown. This study aimed to detail the venous architecture of the glabellar region to the forehead in conjunction with that of the supratrochlear artery to reduce the risk of venous congestion of flaps in this area. Fifteen fresh human cadavers were examined here. In five specimens, contrast medium was injected only into the venous system; in 10 specimens, two different types of contrast media were injected into the arterial and venous systems, respectively. A total of 30 hemifacial specimens were radiographed stereoscopically and observed microscopically. In all the cadavers, a distinct vein (termed as the transverse nasal root vein ) connected the bilateral angular veins. One or two large ascending veins branched from the transverse nasal root or angular vein, coursing toward the forehead skin. Numerous small veins branched out from the large ascending vein(s), forming a subdermal polygonal venous network. Small ascending veins arose from this network and coursed toward the dermis, draining venous flow from the dermis. Three different-sized valves prevented the reflux of blood in the venous pathway. The large ascending vein(s) and supratrochlear artery ran parallel only in the medial canthal area. Tiny venous vasa vasorum surrounded the adventitia of the supratrochlear artery and anastomosed with the polygonal venous network, while a few small veins from the vasa vasorum ascended toward the dermis. Understanding the venous architecture of this region is expected to facilitate the safe elevation of various flaps in the area. Clin. Anat. 00: , VC 2012 Wiley Periodicals, Inc. Key words: vein; transverse nasal root vein; supratrochlear artery; valve; vasa vasorum INTRODUCTION The arterial anatomy of the glabellar to the forehead region is well described in the literature (Shumrick and Smith, 1992; Whetzel and Mathes, 1992; Blandini et al., 1996; Wild and Hybarger, 2001; Kelly et al., 2008); however, only a few reports have discussed the venous anatomy of this region (Taylor et al., 1990; Houseman et al., 2000; Kleintjes, 2007). The region between the glabella and the forehead is a clinically important site as it is used for raising several types of glabellar and forehead flaps, which are commonly used in mid-facial reconstruction. In these surgeries, if kinking of the skin paddle can be avoided by using an appropriate flap design, almost no arterial complications develop because of the abundant blood supply from the facial subdermal *Correspondence to: Yusuke Shimizu, Department of Plastic and Reconstructive Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo , Japan. yyssprs@gmail.com Received 17 April 2012; Revised 29 June 2012; Accepted 5 July 2012 Published online in Wiley Online Library (wileyonlinelibrary.com). DOI /ca VC 2012 Wiley Periodicals, Inc.

2 2 Shimizu et al. Fig. 1. Arteriovenogram of the face (left) and its schema (right). The hemi-loop-like vein comprises the superior transverse orbital, angular, and facial veins. It anastomoses with the zygomatic temporal vein in the upper lateral area and the ophthalmic vein in the medial canthal area. In the glabellar region, the transverse nasal root vein (asterisk) connects the bilateral angular veins. Most of the veins in the forehead runs in a cephalocaudal direction and proximally anastomose with the transverse nasal root or angular veins. plexus. However, occasionally, venous congestion occurs, resulting in partial flap necrosis (Batchelor et al., 1984). Partial flap necrosis of the forehead flap has been reported by several authors, with the incidence varying from 1.4 to 14% (Zilinsky et al., 1999; Boyd et al., 2000; Rohrich et al., 2004). Based on a 10-year experience, Menick (2002) reported that flap necrosis and contour irregularities are especially common in smokers and in major nasal reconstructions. To reduce the risk of these surgical complications, the venous anatomy needs to be considered along with the arterial anatomy when Fig. 2. Cross-sectional schema of the course of the transverse nasal root vein in the glabella. The vein branches from the angular vein under the procerus muscle and anastomoses with its contralateral counterpart to form a large communicating vein under the skin of the nasal root.

3 Venous Anatomy of Glabella to Forehead 3 Fig. 3. Branching patterns of the large ascending veins from the medial canthal area. (Left) Branching from the transverse nasal root vein, (center) branching directly from the angular vein, and (right) branching from both the transverse nasal root and the angular veins. planning the flap design. This study primarily aimed to detail the venous architecture of the glabellar to forehead region with the supratrochlear artery, which typically comprises the main pedicle in most glabellar and forehead flaps. MATERIALS AND METHODS In this study, a total of 15 fresh human cadavers were used, comprising eight male and seven female Asians, whose age ranged from 67 to 88 years. None of the cadavers showed any evidence of venous disease or had any facial scars. The cadavers were examined between 24 h and 10 days postmortem. Five cadavers were used to investigate only venous geometry by injecting a barium gelatin mixture into the venous system. The facial skin was incised along the coronal suture up to the lower mandibular margin via the posterior border of the auricle. The skin and subcutaneous tissue including the mimetic muscles (facial flap) were elevated en masse from the facial bones. Using a 24G indwelling needle, we locally injected the barium sulfate gelatin mixture into the facial, superficial temporal, and zygomaticofacial veins as well as into the stumps of the other cutaneous veins. Numerous veins that leaked the contrast medium over the cross-section or under the specimens were ligated. Then, each specimen was radiographed stereoscopically and observed microscopically at high magnification (34 8 power, Carl Zeiss OPMI 6 SH). Ten cadavers were used to clarify the relationship between the venous architecture and the surpratrochlear artery. Prior to facial flap elevation, they were arterially injected with L of lead oxide gelatin mixture via the carotid or femoral arteries, according to the Rees and Taylor method (Rees and Taylor, Fig. 4. Drainage patterns of the bilateral large ascending veins. (Left) The bilateral veins anastomose with each other at the level of the lower third of the forehead and form a single large ascending vein; (center) the bilateral veins run independently; and (right) the bilateral veins arising from the transverse nasal root vein anastomose with each other at the level of the lower third of the forehead and run in the right paramedian area whereas the vein from the left periorbital vein runs in the left paramedian area. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]

4 4 Shimizu et al. 1986). Then, each facial flap specimen was elevated from the facial bones, and the barium sulfate gelatin mixture was injected into the venous system as mentioned earlier. To clarify the relationship between the arteries (stained orange with the lead oxide gelatin mixture) and the veins (stained white with the barium sulfate gelatin mixture), the subcutaneous fat was carefully removed from the undersurface of the specimens and observed microscopically at high magnification. The specimens were also radiographed stereoscopically. RESULTS General Venous Geometry Observation of the 30 hemifaces from the 15 cadavers revealed a hemi-loop-like vein surrounding the orbit (Fig. 1). This vein was determined to be the superior transverse orbital, angular, or facial vein, depending on its location. These veins were connected to the zygomatic temporal vein, arising from the middle temporal vein in the upper lateral region to the facial vein, arising from the external jugular vein in the lower lateral region. In the medial canthal area, two major veins arose from the angular vein: one branched deep and connected to the ophthalmic vein, whereas the other branched superficially and ran transversely. The latter branch pierced the procerus muscle and anastomosed with its contralateral counterpart to form a large communicating vein under the skin of the nasal root (Fig. 2). We termed this communicating vein the transverse nasal root vein ; this appeared to be convex toward the nasal tip. Further, one or two large veins branched bilaterally from the angular or the transverse nasal root vein and ran toward the forehead skin; this vein was termed the large ascending vein. Venous Origin We observed 23 large ascending veins branching from the transverse nasal root vein in the 30 hemifaces (77%; Fig. 3 left). In six hemifaces, two large ascending veins branched from the angular vein (20%; Fig. 3 center). In one cadaver, two large ascending veins branched from the transverse nasal root and angular veins only unilaterally (3.3% Fig. 3 right). These large ascending veins pierced the procerus muscle near their branching site, ran cranially, and gradually passed just beneath the dermis of the forehead. Venous Course In eight cadavers (53%), the bilateral large ascending veins anastomosed at the level of the lower third of the forehead and formed a single large ascending vein, which coursed cranially in the median forehead area (Fig. 4 left). In six cadavers (40%), the bilateral large ascending veins ran independently in the paramedian forehead region (Fig. 4 center). In one cadaver (6.7%), the bilateral large ascending veins arising from the transverse nasal root vein anastomosed at the level of the lower third Fig. 5. Magnification of a venogram of the forehead skin (left) and its schema (right). Numerous veins branch from the large ascending veins (arrow in schema) and anastomose with each other to form the polygonal venous network. The inner area of the network was not completely radiographed (green area in schema); only a few areas are radiographically visible (yellow area in schema). The red squares in both facial figures correspond to the area of the venogram and schema. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.] of the forehead and ran cranially in the right paramedian area, whereas the large ascending vein arising from the left angular vein ran cranially in the left paramedian area (Fig. 4 right). Stereoscopic Venous Architecture In the glabellar to forehead region, we observed the superior transverse orbital vein, angular vein, facial vein, and the root of the transverse nasal root vein to be located beneath the orbicularis oculi muscle; these acted as the deep venous drainage system. Above the muscle layer, the main venous drainage route comprised the large ascending vein(s), which acted as the superficial venous drainage system. Numerous small veins branched from this vein and ascended toward the skin, draining venous flow from the dermis. These small veins anastomosed with each other in the superficial layer, creating a subdermal venous network of differently sized and shaped polygons. We therefore termed this network the polygonal venous network. The inner areas of the network were not completely radiographed in most of the regions (Fig. 5). By focusing on the radiographed parts inside the network, we noted veins arising from the network and ascending toward the epidermis. We termed these branches the small ascending veins (Fig. 6 top).

5 Venous Anatomy of Glabella to Forehead 5 Fig. 6. Magnification of the dotted red squares in the venogram of Figure 5. (Top right and left) Stereographic venograms of the radiographed inner area of the polygonal venous network. Cross your eyes to superimpose the images of the left and right white circles and then elevate your gaze to the central venogram to see the images three-dimensionally. Small ascending veins (red arrow) arise in a superficial direction. (Lower right and left) Poorly radiographed inner area of the polygonal venous network, in which several small diverticulum-like projections are visible (red arrow). [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.] Venous Valves We noted numerous small diverticulum-like projections around the polygonal venous network (Fig. 6 lower). Based on previous studies, these small diverticulum-like projections were recognized to be venous valves (Taylor et al., 1990; Imanishi et al., 2000, 2001). In our study, we determined them to be venous valves by administering an additional bolus of the contrast medium into the polygonal venous network, following which some of the small diverticulum-like projections disappeared and small ascending veins arising from the site of the projections could be radiographed (Fig. 7). This phenomenon suggested the presence of venous valves at the sites of the small diverticulum-like projections. A close-up photograph of the branching sites of the small ascending veins is shown in Figure 8. Venous valves were similarly observed at the junction between the polygonal venous network and the branches from the large ascending vein. Further,

6 6 Shimizu et al. Fig. 7. Magnification of venograms of the glabellar skin. (Left) A small amount of barium sulfate mixture was injected into the polygonal venous network; small diverticulum-like projections (red arrow) are visible. (Right) After an additional bolus of barium was injected into the polygonal venous network, some of the small ascending veins (red arrow) arising from the site of the small diverticulum-like projections became visible. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.] the transverse nasal root and angular vein at the medical canthal area had a few diverticulum-like projections. These valves could be categorized based on the location as follows (Fig. 9): type 1, valves located at the junction between the small ascending veins and the polygonal venous network; type 2, valves located at the junction between the polygonal venous network and the large ascending veins; and type 3, valves located at the junction between the veins arising from the forehead region including the large ascending veins and the transverse nasal root or angular vein in the medial canthal area. Relationship Between the Supratrochlear Artery and the Veins The skin of the glabellar to forehead region is mainly supplied by branches from the bilateral supratrochlear arteries. The supratrochlear artery branches from the ophthalmic artery in the orbit and emerges by piercing the orbital septum above the medial canthal tendon. It runs in the vicinity of the procerus and corrugator muscles in the nasal root and the glabellar area and subcutaneously in the forehead toward the top of the head. The artery has several branches during its course and anastomoses with the supraorbital artery and the supratrochlear artery from the contralateral side. In the Fig. 8. Macroscopic specimen of glabellar skin. Orange indicates arteries and white indicates veins. There are valves at the branching site of small ascending veins from the polygonal venous network. Scale bar ¼ 1 mm. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]

7 Venous Anatomy of Glabella to Forehead 7 Fig. 9. Top: Venogram of the glabellar to forehead skin. The diverticulum-like projections indicate the presence of venous valves. There are three types of venous valves. Type 1: very small valves located at the junction between the small ascending veins and the polygonal venous network. Type 2: small valves located at the junction between the polygonal venous network and the large ascending veins. Type 3: large valves located at the junction between the cutaneous veins including the large ascending veins and the transverse nasal root or angular vein. The blue, green, and red arrows indicate the sites of type 1, type 2, and type 3 valves, respectively. Bottom: Cross-sectional schema of the venous drainage route and locations of the venous valves in the forehead to the glabellar region. The blue, green, and red arrows correspond to the valves shown in Figure 9 (top). [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]

8 8 Shimizu et al. Fig. 11. Magnification of the macroscopic specimen of the forehead skin. Orange indicates arteries and white indicates veins. A venous vasa vasorum (asterisk) surrounds the supratrochlear artery and has several connections with the polygonal venous network (long arrow). Scale bar ¼ 1 mm. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.] Fig. 10. Macroscopic specimen of the glabellar to forehead skin. Orange indicates arteries and white indicates veins. The supratrochlear artery (arrow) branches from the ophthalmic artery (asterisk). The large ascending veins (long arrow) accompany the supratrochlear artery only near their origin (black dotted circle). Scale bar ¼ 10 mm. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.] cadavers, the large ascending veins accompanied the supratrochlear artery only in the medial canthal area (Fig. 10 top), which was unlike the parallel course of arteries and veins typically observed in the other parts of the human body. Microscopically, we observed a minute reticular venous network surrounding the adventitia of the supratrochlear artery; we decided to call this structure vasa vasorum. The vasa vasorum was hardly identifiable radiographically. It showed connections with the polygonal venous network (Fig. 11 lower), and a few small ascending veins from the vasa vasorum directly drained the dermis (Fig. 12). DISCUSSION Many reports indicate that flaps taken from the glabella or forehead are designed on the basis of the course of the supratrochlear artery, while the corresponding venous anatomy is not considered in depth. If the veins in this area did follow the arteries, it would not be necessary to investigate the venous anatomy, because clarifying the arterial anatomy Fig. 12. Magnification of the macroscopic specimen of the forehead skin. Orange indicates arteries and white indicates veins. There are several direct connections between the vasa vasorum of the supratrochlear artery and the dermis through the small ascending veins (long arrows). Scale bar ¼ 1 mm. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]

9 Venous Anatomy of Glabella to Forehead 9 Fig. 13. Schema of the venous drainage of the forehead to the glabellar region. a: Main venous drainage pathway. First, blood perfusing the dermis flows into the polygonal venous network through the small ascending veins. After pooling in the network, the blood flows into the angular veins through the large ascending cutaneous veins. b: Supplementary venous drainage pathway. Blood perfusing the dermis flows directly into the vasa vasorum around the supratrochlear artery through the small ascending veins. The blood in the vasa vasorum can flow either alongside the artery or into the polygonal venous network through several connecting branches, finally draining into the periorbital veins. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.] would automatically also clarify the venous anatomy. However, Houseman et al. (2000) found that the veins of the forehead are often located at some distance from the major arteries; they postulated that island flaps suffer engorgement because of good inflow but poor outflow, considering that these flaps are isolated on a narrow arterial pedicle that excludes venous outflow. Converse and Wood-Smith (1963) reported that a common problem with island flap surgery is venous obstruction with marginal or subtotal flap loss. Most plastic surgeons consider flaps from the glabellar to forehead region to be relatively safe; however, at times, such flaps carry the risk of partial flap necrosis due to venous congestion. Clarifying the venous anatomy in this clinically important region would reduce this risk and help in efficacious flap elevation. However, only a few reports have discussed the precise venous anatomy of the glabellar to forehead region. Taylor (1990) investigated the entire human body and defined the venous territories as venosomes. Although his work proposed an excellent

10 10 Shimizu et al. Fig. 14. Arteriovenogram of the glabellar skin and its macroscopic specimen. The large ascending cutaneous vein (blue line) should be included in the flap and the anastomosis between the large ascending vein and the transverse nasal root vein (red circle) should be preserved during surgery. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.] concept of the comprehensive venous system, the glabellar to forehead region was not focused upon in detail. Houseman (2000) detailed the precise arterial anatomy to define the angiosomes of the head and neck. However, for the corresponding venous anatomy, he only reviewed the side-view venogram of this region, and the specific veins around the glabella were not mentioned. Further, Kleintjes (2007) examined 30 cadavers using latex solution and summarized the relationship between the supratrochlear artery and the adjacent veins. However, the drawback of this study was that it did not demonstrate the microscopic relationships between the arteries and the veins in this region. In this study, we first investigated the two-dimensional venous architecture of the region. We found that the distinct transverse nasal root vein was consistently present in all the cadavers. Although the vein had also been radiographed in Taylor s venosome (1990), it has not been particularly focused on nor named previously. The preservation of this vein might improve the venous circulation in any flaps designed in the glabellar and forehead region. In our study, 77% of the large ascending veins arose from the transverse nasal root vein. Blood from the large ascending veins can flow in either direction of the transverse nasal root vein, which bridges the bilateral angular veins. We consider that blood from the right large ascending vein flows into the right angular vein, while that from the left large ascending vein flows into the left angular vein. Finally, blood in the angular veins flows into the deeper veins via three routes: the zygomatic temporal vein, arising from the middle temporal vein in the upper lateral area; the facial vein, arising from the external jugular vein in the lower area; and the ophthalmic vein, arising from the internal jugular vein in the medial canthal area. We previously termed the veins that mainly collect blood from the skin as the cutaneous veins (Imanishi et al., 2000, 2001a, b, 2002, 2003). These veins branch from the small ascending veins, arising from the polygonal venous network, and anastomose with the veins branching from the veins accompanying the arteries in various layers. The venous drainage in the glabellar to forehead region comprises mostly cutaneous veins; therefore, the large ascending veins should be called the large ascending cutaneous veins. Our observations indicated that the large ascending cutaneous veins provided the main route for venous drainage of the forehead to the glabellar region. Then, we radiographically investigated the stereoscopic venous architecture. We found the venous drainage in the glabellar to forehead region to be similar to that in the forearm, scapular region, and abdomen (Imanishi et al., 2000, 2001a, b, 2002, 2003). First, the venous blood from the dermal capillaries in the skin flows into the small ascending veins that arise from the polygonal venous network. Then, the blood flows into the polygonal venous network and accumulates therein. We could not determine the exact direction of blood flow in the polygonal venous network; however, we presume that the blood flows into the branches of the large ascending cutaneous veins.

11 Venous Anatomy of Glabella to Forehead 11 Fig. 15. Simulated designs of the flap in the right forehead to the glabellar region. (a) The left flap margin should be placed more than 1 cm lateral to the midline. (b) If there are two large ascending cutaneous veins and the left flap margin is far from the midline, left marginal flap necrosis might occur (purple). (c) The inferior flap margin should be placed 1 cm below the nasal root to include the anastomosis between the large ascending cutaneous vein and the transverse nasal root vein. (d) To elongate the right flap margin inferiorly, the margin should be placed laterally. (e) Even if the flap margin cuts the angular vein both superiorly and inferiorly, the flap will survive. The large ascending cutaneous veins are located proximally and in the deep tissue to the polygonal venous network, with valves being present at the anastomoses of the polygonal venous network and the branches of the large cutaneous ascending veins (Fig. 8 lower). We categorized the valves in the glabellar to forehead region into three types according to their location and size as follows: type 1, very small valves located at the junction between the small ascending veins and the polygonal venous network; type 2, small valves located at the junction between the polygonal venous network and the large ascending veins; and type 3, large valves located at the junction between the veins arising from the forehead region, including the large ascending veins and the transverse nasal root or angular veins. These valves help to prevent venous reflux from the deep layer to the superficial layer. Our results are consistent with the description of the meticulous venous valve architecture provided by Taylor et al. (1990), who stated that venous valves exist in different tiers and that sentinel osteal valves guard venous entry into the superficial tier. To clarify the relationship between the veins in this region and the supratrochlear artery, we first attempted to identify a vein accompanying the supratrochlear artery. However, in contrast to our previous studies, we could not find any distinct longitudinal vein around the supratrochlear artery over most of its course in any of the cadavers, although we performed a microscopic examination and carefully applied the bolus barium sulfate gelatin mixture into the venous system. Instead, we found a minute reticular venous network surrounding the adventitia of this artery; we decided to call this structure vasa vasorum. Vasa vasorum is generally discussed in the cardiovascular field (Barger et al., 1984; Lescalie et al., 1986; Crotty, 1989; Stefanadis et al., 1995; Kwon et al., 1998; Dashwood et al., 2004) and not in relation

12 12 Shimizu et al. to the facial region. The vasa vasorum gives rise to the capillary network within the outer layer of blood vessels (Wheater et al., 1987), and it is normally present in the adventitial layer, presumably to provide oxygen and nutrients to the outer layer of the arterial walls (Wolinsky and Glagov, 1967). In peripheral arteries, little is known about the precise architecture of the venous vasa vasorum or its role. The minute venous vasa vasorum of the artery may be termed an accompanying vein because it runs longitudinally parallel to the artery. However, this structure is rather small and appears to be composed of a retiform network rather than a single large longitudinal vein; therefore, we decided to called this network vasa vasorum rather than terming it an accompanying vein. Despite its size, the vasa vasorum may act as an accompanying vein of the artery even in the absence of a distinct independent accompanying vein. Our findings showed several direct connections between the vasa vasorum and the dermis through the small ascending veins. It is reasonable to suppose that a direct venous drainage route exists between the skin and the vasa vasorum of a main arterial trunk. These results imply that the vasa vasorum may function as an accompanying vein. The blood in the vasa vasorum can either directly return proximally alongside the arterial vessels or flow into the polygonal venous network. When we compare the size and volume of the vasa vasorum of the supratrochlear artery, and the large cutaneous ascending veins, the latter is much larger and more plentiful in number. Hence, the venous pathway used by the large ascending cutaneous veins should be classified as the main venous drainage pathway, whereas the pathway through the vasa vasorum of the supratrochlear artery should be classified as an alternative supplementary venous drainage pathway (Fig. 13). We hypothesize that the main cause of flap failure in the region is venous congestion resulting from inappropriate flap design despite the intricate extensive branching venous network observed here. Thus, if a large flap is designed, the main venous drainage route (i.e., the large ascending cutaneous vein) should be included in the flap in order to reduce the risk of venous congestion. In addition, the anastomosis between the large ascending cutaneous vein and the transverse nasal root or angular veins in the medial canthal area should be preserved to secure the main venous drainage route (Fig. 14). If the flap is designed only on the island base of the supratrochlear artery without securing the main venous drainage route, the increased amount of venous blood may not be able to return through the supplementary, minute vasa vasorum of the artery. Considering the large ascending cutaneous vein to be the main venous drainage system, we propose a forehead to glabellar flap design on the basis of the right cutaneous veins. The left margin of the flap should be placed more than 1 cm lateral to the midline because the bilateral large ascending cutaneous veins often form a single vein in the midline forehead area (Fig. 15a). If there are two independent large ascending cutaneous veins and the left flap margin is placed far from the midline, left marginal flap necrosis might occur because of interrupted venous drainage through the left large ascending cutaneous vein. Further, the left marginal area is distant to the right large ascending vein, via which venous blood drainage is difficult (Fig. 15b). When the left flap margin is elongated inferiorly, the margin should be placed 1 cm below the nasal root to include the anastomosis between the large ascending cutaneous veins and the transverse nasal root vein (Fig. 15c). When the right flap margin is elongated inferiorly, the margin should not be placed too medially in order to preserve the anastomosis between the large ascending cutaneous vein and the angular vein (Fig. 15d). Even if the flap margin cuts the angular vein both superiorly and inferiorly, the flap will survive because the anastomosis with the ophthalmic veins is preserved and the venous drainage is secured (Fig. 15e). In contrast, if a very small forehead flap is designed with a narrow base on the basis of the supratrochlear artery alone, the venous return might theoretically be secured because the venous vasa vasorum of the supratrochlear artery might function as an accompanying vein and drain the venous blood into the deeper vein. However, from the present results, we could not determine the exact area (i.e., how small the flap should be) with only supplementary venous drainage (i.e., the vasa vasorum of the artery) that could survive without venous congestion. The vasa vasorum of the peripheral artery in the facial region should be examined in greater detail using microscopy to determine the exact venous drainage system and thereby reduce the flap congestion in the area. REFERENCES Barger AC, Beeuwkes R 3rd, Lainey LL, Silverman KJ Hypothesis: vasa vasorum and neovascularization of human coronary arteries. A possible role in the pathophysiology of atherosclerosis. N Engl J Med 310: Batchelor AG, Davison P, Sully L The salvage of congested skin flaps by the application of leeches. Br J Plast Surg 34: Blandini D, Tremolada C, Beretta M, Mascetti M Use of a versatile axial dorsonasal musculocutaneous flap in repair of the nasal lobule. Plast Reconstr Surg 98: Boyd CM, Baker SR, Fader DJ, Wang TS, Johnson TM The forehead flap for nasal reconstruction. Arch Dermatol 136: Converse JM, Wood-Smith D Experiences with the forehead island flap with a subcutaneous pedicle. Plast Reconstr Surg 31: Crotty TP The role of vasa vasorum in atherosclerosis. 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