Keywords
Facial palsy - Facial reanimation - Free flap - Latissimus dorsi
INTRODUCTION
The first use of the latissimus dorsi (LD) as a myocutaneous flap was described by
Tansini in 1896 [[1]] and was subsequently used to cover a breast defect following a mastectomy by D'Este
[[2]] in 1912. Its use as a pedicled flap became widely popularised for chest wall and
head and neck reconstruction but it wasn't until 1979 that Watson et al. [[3]] described the first free microvascular transfer of the muscle. The LD is a popular
free flap to use due to its versatility; its muscle size makes it appropriate for
large defects to be filled, the ability to use a large skin island makes it suitable
for breast reconstruction and the ability to incorporate a osseous component makes
in useful in oral reconstruction. However, it is the possibility to use it for free
functional muscle transfer (FFMT) that makes it important when considering facial
reanimation.
Harii et al. [[4]] described the first use of gracillis for facial reanimation in 1976. Initially
its use for facial reanimation was limited
due to the bulkiness of the muscle yielding unfavourable aesthetic
outcomes. The two-stage procedure, utilizing a crossed
facial nerve graft (CFNG) at the first stage and then a FFMT at the second, became
popularised and either pectoralis minor or gracillis were most commonly used [[5],[6]].
The first description of raising the flap segmentally was in 1988 [[7]] and served to increase the potential use for facial reanimation. As anatomical
studies of the muscle were carried out, the ability to thin the flap became better
understood and allowed the bulkiness to be addressed [[8]]. The long neurovascular pedicle was also exploited and a novel concept of the one-stage
reanimation procedure was described [[9]], where the long pedicle allowed for a neurorrhaphy to be performed to a distal
buccal branch on the contra-lateral functioning side through a small separate naso-labial
incision. In our unit, the most common use of the flap in facial palsy is to treat
bilateral paralysis and also in one-stage reanimations.
Traditionally, the LD is harvested from the back in either the lateral decubitus or
prone position. The advantage of this positioning is the ability to raise the muscle
in its entirety and allow a skin paddle and/or osseous component to be raised. Whilst
this is important for large defect reconstructions, these are not commonly required
in facial reanimation; muscle bulk is not favourable and a skin paddle is seldom used.
The main disadvantage of this approach is the inability for two surgical teams to
work at the same time which when considering bilateral reanimations, can be costly
not only in ischaemic time but also in lengthening anaesthetic time on a potentially
difficult group of patients. In addition to this, brachial plexus, radial nerve and
other motor and sensory injuries [[10]] have been described as sequelae of this patient positioning. Endoscopic harvesting
of the flap has been described in detail [[11]]. Even with endoscopic methods, an initial 8 cm incision is required and the pedicle
is always dissected under direct vision and flap harvesting takes on average two hours.
The patient has to be placed in the lateral decubitus position that causes difficulties
for the second team to operate on the contra-lateral side of the face synchronously.
The favoured approach in facial reanimation is via a trans-axillary approach with
the patient in the supine position and although this has been frequently referred
to [[7],[9]], it is difficult to find a clear operative technique in a flap atlas or in the
literature.
The LD is a large fan-shape muscle which arises from the spinal processes of the lower
six thoracic vertebrae, the lumbar vertebrae, the sacral vertebrae and the iliac crest.
In inserts into the intertubercular groove of the humerus between pectoralis major
and teres major, forming the posterior axillary fold. The LD muscle is a type II muscle
according to the Mathes and Nahai classification. The dominant arterial supply is
via the thoracodorsal artery, which arises from the circumflex scapular artery and
predominantly supplies the proximal and lateral two thirds of the muscle. The perforating
branches of the intercostal arteries supply the distal and medial portions. Two large
branches arise from the thoracodorsal artery, a serratus branch and a branch to the
inferior angle of the scapular. The average extramuscular length of the vascular pedicle
is 9 cm (range, 6-16 cm) [[12]]. The intramuscular course of the arterial branching and of the nerve has been described
in great detail, and studies have shown that multiple secondary branches arise within
the muscle forming a dense network of anastomoses which allow for the flap to be extensively
thinned or be raised segmentally [[7],[13]].
IDEAS
Operative technique
Preoperative assessment
The anterior border of the LD should be marked preoperatively. This is made easiest
if the patient is standing and asked to press their hands against their hips. In the
obese patient this may be difficult and a line can be drawn between the dorsal axillary
fold and the midline of the iliac crest.
Operative draping
The patient is positioned in the supine position with the head supported by a head
ring. The endotracheal anaesthetic airway is orientated to pass directly caudially;
this is subsequently covered with a sterile endoscopic camera drape. Two teams prepare
the surgical fields on contra-lateral sides to allow for minimal crowding of either
operative field i.e. the left side of the face and the right axilla. Standard surgical
draping is carried out which permits access to the neck and the arm is free draped
([Fig. 1]). Whilst one surgical team works to raise the face and find appropriate neurovascular
recipients/donors, the other raises the LD flap via a trans-axillary approach.
Fig. 1 Free draping of the arm
This allows the arm to be moved intraoperatively to facilitate raising of the flap.
Raising the latissimus dorsi flap
A curvilinear incision is made 2 cm anterior to the lateral border of the LD and is
approximately 10 to 15 cm in length depending on the size of the patient ([Fig. 2]). The subcutaneous tissue is divided until the anterior border of the LD is identified.
The subcutaneous tissue is dissected off the posterior body of the muscle in the supra-fascial
plane and can extend all the way to the midline leaving thick skin flaps. At the lateral
border of the LD, a plane is developed between serratus along the entire lateral edge
of the LD. As this plane develops the first vascular branch to be identified is the
branch to serratus, which can be confused as being the thoracodorsal vessels and it
is important not to divide these at this stage. Once the branch to serratus has been
identified, it is safest to follow this cranially as it will lead to the thoracodorsal
pedicle. It is key to identify the lateral border of the LD tendon as this helps to
successfully develop the dissection plane postero-medially and is best-achieved using
sharp dissection. As the dissection progresses, it may become difficult to confidently
establish the plane between the muscle bulk of the LD and the subscapularis muscle.
A key component to achieving this successfully is with the use of the surgical assistant.
Since the arm is free draped, with careful internal and external rotation of the shoulder
the LD can be placed in extended and relaxed positions and greatly facilitates the
surgeon. Once this plane has been developed, the neurovascular pedicle can be raised
up to the origin from the circumflex scapular artery where the orientation of the
pedicle is such that the vein lies lateral to the artery and the nerve runs between
the two. In many circumstances it is desirable to achieve the maximal possible length
of the thoracodorsal nerve. The nerve can be separated from the vascular pedicle and
dissected up to its origin from the posterior cord of the brachial plexus; this is
particularly preferable in cases where a long pedicle is required to reach the contralateral
side as is in one-stage procedures where the nerve is co-apted to a functioning distal
buccal branch. Once the thoracodorsal pedicle has been confirmed, the branch to serratus
and other small branches should be ligated ([Fig. 3]). Two 2-0 silk sutures are placed in the muscle measured at 3 cm apart whilst the
arm is placed at 90° of adduction; this allows the muscle to be inset at the same
resting tension as the contralateral side in bilateral cases and helps to avoid over-tightening
the inset of the functional muscle transfer. To facilitate achieving the maximal pedicle
length, the tendon may be divided from its insertion to allow better exposure. Once
the vessels have been clearly identified and separated proximally, a 5-0 Prolene suture
is used to mark the artery and a 5-0 nylon suture is used to mark the vein; this is
a useful step as it avoids confusion when two independent teams are operating when
the time arises for the microsurgery. It is our practice at this stage to apply two
large Ligaclips (Ethicon LLC, Cincinnati OH, USA) to the artery first then the vein
and divide the neurovascular pedicle. The LD is divided transversely towards the midline
as far as required and then cranially, towards the tendonous portion. Although this
may add a little to the ischaemic time of the flap, it ensures that no traction is
placed on the pedicle whilst the muscle flap is being raised which may lead to catastrophic
results. Judicious haemostasis is required and particular attention must be paid to
the divided muscle edges to avoid the formation of a postoperative haematoma particularly
as the intercostal perforators supply these parts. A 10 g Redivac (B. Braun Medical
Ltd, Sheffield, UK) drain is inserted into the donor site and the wound is closed
in two layers.
Fig. 2 Incision marking
Preoperative marking of the incision used for the trans-axillary approach to the latissimus
dorsi.
Fig. 3 Intraoperative photograph of raising the flap
The loop passes around the neurovascular pedicle. At this stage the branch to serratus
has been divided.
Preparation of the flap
Once the flap has been raised it is frequently too bulky to transfer directly to the
face and requires thinning. Extensive studies have shown the robustness of the LD
with regard to the extensive network of intramuscular anastomoses. Excess muscle should
be trimmed and discarded and our practice is to shape the fan-like flap into three
separate strips at the tendonous portion to allow the flap to be inset in the face
at the alar base, the modiolus and the lower lip ([Fig. 4A]); the tension is set so that the two silk marking sutures are 3 cm apart. The flap
is then transferred to the face for insetting and microanastomosis ([Fig. 4B]). Once the anastomoses have been completed and the clamps released, meticulous attention
has to be paid to haemostasis particularly if the flap has been thinned.
Fig. 4 Flap preparation and inset
(A) Preparation of the flap prior to insetting. The muscle frequently needs to be
trimmed to ensure the appearance is not too bulky. The thoracodorsal nerve can be
separated from the vascular pedicle with enough length to reach the contra-lateral
side if required. (B) The insetting of the flap. The tendonous portion of the flap
has been divided into three slips to be inset at the alar base, the modiolus and the
lower lip.
DISCUSSION
Although the utilization of the LD free flap for functional muscle transfer has been
well established, the trans-axillary approach with the patient in the supine position
has not been clearly described. By raising the LD flap in this fashion for functional
muscle transfers, two surgical teams can work synchronously saving valuable operative
and anaesthetic time. By free draping the arm, the surgical assistant can make the
flap raising much easier by rotating the shoulder and has the advantage as it may
reduced the instance of brachial plexus injuries as a consequence of patient positioning
and additionally, the second team can dissect the opposite side of the face without
the difficulties associated with over-crowding.
The indications where the LD may be chosen as a suitable flap for facial reanimation
are clear. Our units experience has lead us to select the muscle on the merit of its
long neurovascular pedicle. Situations where this is advantageous include bilateral
cases, in revision cases and in one-stage procedures. In bilateral cases, frequently
the vasculature is variable and long pedicle avoids the necessitation of having to
use an artery or vein graft whilst also allowing the size of the muscle to be tailored
to the size of the face to improve symmetry. In cases where a previous FFMT has been
attempted, the facial vasculature may have been compromised, so the long vascular
pedicle is advantageous again. Finally, in one-stage procedures where a long nerve
is required to reach the contra-lateral side of the face to allow for a neurorrhaphy
to be performed to a distal functioning buccal branch, this flap is ideal. In total,
the senior author has used the LD for facial reanimation on 102 occasions. For the
majority of cases (n=64) it was used in congenital bilateral one-stage reanimations.
It was used on 32 occasions in patients who had had a previous failed attempt at reanimation
of which 10 were failed attempts by our unit and 22 were tertiary referrals from other
units. More recently as our practice has evolved, it has been used in 10 one-stage
reanimations.
Donor site morbidity is low with any approach to raising the LD flap [[14]] as long as primary closure of the skin can be achieved. In our experience of raising
the flap via this approach, one patient suffered a postoperative haematoma, one patient
developed a seroma and two patients required steroid injections for scar hypertrophy.
Although the scar is slightly longer in comparison to endoscopic approaches (10-15
cm compared to 8 cm) [[11],[15]] the operative time on average is 60 minutes, ranging from 35 to 75 minutes, in
comparison to 120 minutes endoscopic harvesting takes [[11],[15]]; this saves significantly on valuable ischaemic time. By raising the flap through
a trans-axillary approach the skin flaps can be raised to allow for maximal exposure
at the expense of only a small scar that does not breech the axillary fold and has
minimal impairment on shoulder movement. The dissection planes can be easily identified
and facilitated by movement of the limb and excellent exposure of the proximal aspect
of the pedicle can be achieved.
