KEY WORDS
Radial forearm flap - radial vessels - superficial vein
INTRODUCTION
The superficial veins of the upper limb are constantly neglected in anatomy literature[[1]] deeming them to be variable[[2]
[3]] in their position. Apart from the cephalic and basilic veins, they are never described
in detail. One often comes across a superficial vein just above the radial artery
and vena comitantes while dissecting the volar aspect of the forearm [[Figure 1]] while harvesting distally based radial forearm flaps.[[4]] This article aims at studying the vein in particular and notes its relation to
radial vessels, cephalic vein and explores their possible use as a teaching tool and
for use by plastic and reconstructive surgeons.
Figure 1: Photograph of the vein demonstrated while harvesting a reverse radial forearm flap
in a live Patient. The vein is marked with an arrow (white)
MATERIALS AND METHODS
The study was conducted on cadavers. About 26 upper limbs were dissected from 13 embalmed
human cadavers. Nine of 13 cadavers were males and the remaining 4 were that of females.
Their age varied from 40 to 70 years as from the records. The forearm was dissected
in the volar aspect using traditional H-shaped incisions.[[3]] The skin flaps were reflected, and the superficial fat was teased out as gently
as possible preventing damage to the superficial venous system. The vein [[Figure 2]] of interest was identified and traced from the distal wrist crease to cubital fossa.
The cephalic vein was also followed from the wrist crease. The relation of the vein
was considered with the radial vessels and the cephalic vein. Photographs were taken
to analyse, and the findings were recorded.
Figure 2: Cadaveric dissection tracing the vein from the wrist crease to the cubital fossa.
The pointer shows the surface vein communicating with cephalic vein recently and closely
related to the radial vessels medially.
RESULTS
All the 26 upper limbs showed the presence of this vein. The vein belonged to the
superficial venous system of the upper limb. It lies medial to the cephalic veins.
It is present just above the radial vessels and seems to surface mark[[5]] it [[Figure 3]]. It begins from the proximal palm region and then starts tracing the radial vessels
from the wrist crease. At the distal third or the mid-forearm level, it drains into
the cephalic vein. They communicate with vena comitantes of the radial vessels at
two places – one at their commencement at the level of the wrist crease [[Figure 4]] and the other – just before draining into the cephalic vein [[Figure 5]] after piercing the deep fascia in the form venous perforators.
Figure 3: Dissection showing the relation of the surface vein to the radial vessels. (a) Relationship
of surface vein (lateral white arrow) with the radial vessels (medial white arrow).
(b) magnified image of 3a. (c) surface vein (lateral white arrow) communicating with
cephalic vein (lateral most) and closet related to the radial vessels (medial white
arrow)
Figure 4: Venous perforator between the surface vein and the venacommitantes at the level of
the distal wrist crease. Perforator between the surface vein and the radial vessels
in the bed
Figure 5: venous perforator between the surface vein and the venacommitantes at the level of
its confluence with cephalic vein. Surface vein and radial artery and venacommitantes
are marked
Minor variations of the vein have been noted in four upper limbs belonging to two
female cadavers where the vein instead of a single entity begins as two smaller calibre
veins and then at the distal third again joins the cephalic vein. The perforators
were noted in them also again the distal crease region as well as just before joining
the cephalic vein.
Furthermore, in four upper limbs belonging to two male cadavers, the vein continues
as accessory cephalic vein even after the confluence with the cephalic vein.
However, ultimately all the limbs exhibited this venous communication between superficial
and deep venous systems at the distal forearm level as one form or the other.
DISCUSSION
The importance of superficial veins has been restricted to cephalic and basilica veins
owing to their large calibre and relative constant anatomy. Conventionally, the smaller
vein that has been the subject of interest in this study has been neglected even in
standard anatomy books.[[1]
[2]
[3]] Although the importance of these veins has not been realised earlier, it has been
the usual practice to include the cephalic vein when we harvest wider forearm radial
flaps.[[6]] In this manner, we not only harvest the cephalic vein but also might be well including
these communicating veins that are more essential for the survival of the dorsal component
of the flap. They might even have a role in very small islanded radial forearm flaps
(pedicled, reverse and free) that are planned around the axis of the radial vessels.
These veins can serve as important surface markers for the deeper vessels and can
form a teaching tool. Furthermore, by serving as mediators, they serve as important
communications between the cephalic veins and the deeper vena comitantes accompanying
the radial artery. The survivability of the dorsal part of the wider radial forearm
flap by including the cephalic vein may be explained because of this but might warrant
a functional study to prove this. The communications of these veins with deep vena
comitantes have been mentioned as perforators[[7]] in some studies in the past though they were not described pertaining to the vein
considered in our study.
Although the radial forearm flaps were described quite early both as pedicled and
their use in free tissue transfer, the debate regarding single versus dual vein anastomosis
as the best solution of venous drainage is ongoing. Series of meta-analysis review
still give varied consensus regarding the same. Studies by Bai et al, 2015.[[8]] suggested that the venous anastomosis of both the superficial and deep venous system
confers a better survival rate of these flaps. Ahmadi et al, 2014.[[9]] quoted a reduction in flap failure of 34% owing to venous failure when veins of
both the systems are used for anastomosis. In spite of such wide series of literature,
the exact mechanism of flap failure in single venous anastomosis has not been anatomically
analysed.
Valentino et al, 1996.[[10]] and Cha et al., 2017[[11]] have elaborated on a communicating vein in the cubital fossa that appears to function
as a conduit between the superficial and deep venous system. This communicating vein
has been isolated in 95% of patients by Cha et al. Cha et al.’s research on the use of radial forearm flap in penile reconstruction revealed flap
oedema and congestion when only superficial vein is used for anastomosis. Their study
uses this vein as the vein for venous anastomosis as it offers as a single conduit
to involve both the superficial and deep venous systems. The major disadvantage of
this is the lengthy dissection and the long conduit that has to be accommodated while
insetting of the flap. The study though makes one realise the existence of a communicating
system between the superficial and deep venous system in the proximal forearm but
fails to provide evidence of a similar system in the distal forearm.
Razzano et al., 2016[[12]] in 2013 have described the ‘vena comitantes clipping test’. Here, the authors dissect
the vena comitantes and the cephalic vein at the level of cubital fossa and then clips
the vena comitantes to test the venous drainage sufficiency in the skin paddle of
the radial forearm flap. If the flap does not show venous congestion, then they only
perform cephalic vein anastomosis. If venous compromise is observed, then they use
the vena comitantes with the larger calibre for venous anastomosis. Again, this study
does not provide any anatomic basis for the test but simply reinforces the plexus
communications between the superficial and deep venous systems. It has been conventionally
accepted by all the reconstructive and microsurgeons that the fascial plexus is the
chief mechanism of communication between the dorsal and the ventral system of veins
and the superficial and deep venous systems. Now that this vein has been isolated
in all the 26 forelimbs, it would be logical to ascertain the role of such veins in
the venous drainage of these flaps indeed instead of relying on the tiny calibre fascial
plexus vessels. It would be useful to look for this vein pre-operatively. The vein
if found in a larger study might also enable one to understand the reason for the
failure of some radial forearm flaps that have been used for microvascular reconstruction
using only a single vein anastomosis, especially cephalic vein.
Whether these veins play a role in the survivability of the dorsal component of radial
forearm flaps would need to be substantiated by a physiological study using fluorescent
dyes or dynamic infrared thermography[[13]] in living tissues. Further studies of the vein are planned on live individuals
using vein viewer or other techniques including venography.
CONCLUSION
This superficial vein of the radial vessel is an important communication between the
definitive superficial cephalic vein and the deep venous system of the radial aspect
of the forearm. This study result can be used while harvesting and planning flaps
in this part of the body. Furthermore, in future, further studies should be explored
to prove the existence of such vessels along the ulnar territory also. Whether they
have a role in thermoregulation[[14]] and in the survivability of venous flaps[[15]] are further topics of research. The vein if found in majority of the population,
a pre-operative workup to demonstrate the vein can be done before a single venous
anastomosis is contemplated. Hence, the vein can become important criteria for microsurgeons
and reconstructive surgeons while planning these flaps.
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Nil.
