Keywords
Fournier's gangrene - gracilis muscle - dynamic sphincter - anal sphincter reconstruction
Introduction
Fourier's gangrene is an acute, rapidly progressive, and life-threatening infection
in the genitalia and perineum region. Prompt recognition, early initiation of broad-spectrum
antibiotics, and radical debridement of all infected tissue to obtain source control
is important in the initial setting to give the best survival chance.[1] Nonetheless, the morbidity and mortality in these group of patients remain high.
Most of these patients will require some form of coverage subsequently, whether it
is for skin coverage or obliteration of dead space, due to aggressive debridement
that is usually performed to control the infection. Anal incontinence that results
from anal sphincter involvement in Fournier's gangrene necessitates a colostomy. In
such circumstances, reconstruction and restoration of the anal sphincter function
is vital in order for the stoma to be reversed.
We present a case of Fournier's gangrene with anal sphincter involvement, who required
a diverting colostomy. Bilateral gracilis muscle flaps were used for obliteration
of dead space, and also to reconstruct the anal sphincter. Using a novel method of
inset, the double gracilis flap is able to imitate the function of the anal sphincter.
With biofeedback training alone, the patient is able to achieve continence, and was
able to reverse his stoma.
Idea
A 46-year-old male, with no significant past medical history, presented to our emergency
department with fever and perineal tenderness on August 31, 2020. On examination,
the patient appeared to be diaphoretic and lethargic, with a temperature of 38°C,
tachycardia of 120 beats per minute, hypotensive at 79/52 mm Hg, and oxygen saturation
was 100% on room air. There was a 5-cm indurated area over the perianal region at
11 o'clock position, associated with scrotal erythema and induration, with the epicenter
of the infection diagnosed to be at the perianal region, involving the scrotum up
to the penile base ([Fig. 1]). He was attended to promptly by the general surgery team and the urology team in
the emergency department. A diagnosis of septic shock secondary to Fournier's gangrene
was made, and the patient was then brought straight to the operating theater after
informed consent was taken.
Fig. 1 Initial presentation of the perineal region to the emergency department.
All the unhealthy tissue was debrided and the patient was admitted to the intensive
care unit as he required inotropic support. A relook debridement was performed the
next day, and there was a 25 cm-by-25 cm area of dusky perineal skin with crepitus,
and foul-smelling purulent discharge was noted from the 8 o'clock perineal region.
All the necrotic tissue was excised and the pus was drained. Fecal soilage of the
wound caused continued infection of the tissues surrounding the anus ([Fig. 2]). To achieve source control, the colorectal surgeon had to debride all perisphincteric
tissue, as this was the epicenter of infection. The patient was counseled for the
likelihood of permanent incontinence, and thus together with the need to divert feces
away from the perianal wound. The patient underwent a colostomy creation 2 weeks after
the initial admission. During the workup, he was also diagnosed to have type II diabetes
mellitus, and started on oral hypoglycemic agents. The tissue culture from the initial
operation showed a mixture of Streptococcus anginosus and Escherichia coli. Subsequent debridement and wound cultures showed an evolving pattern of infection—Klebsiella aerogenes, Pseudomonas aeruginosa, and Enterococcus faecium. Intravenous augmentin was started for the patient on admission and changed to culture-directed
antibiotics thereafter. After colostomy creation, fecal soilage of the wound was eliminated,
but the patient still required another 2 weeks of repeat debridement before the wound
was ready for definitive reconstruction. The resultant defect extended from the suprapubic
region to the base of the penis, involving the bilateral scrotum, and to the perianal
region involving the anus ([Fig. 3]). The most critical defect was the exposed anus with lack of sphincteric muscles,
Due to the necrotizing infection, all the sphincteric muscles had to be debrided by
the colorectal surgeon (senior author), and resulting in incontinence,
Fig. 2 Hand holding bilateral scrotum up. Persistent soilage of wound.
Fig. 3 Resultant wound defect prior to flap reconstruction.
About a month after the initial debridement (2 weeks after colostomy creation), definitive
reconstruction was planned when the wound was clean with sufficient granulation tissue
and tissue cultures were negative. The surgery was performed with the patient in a
lithotomy position. After debridement and thorough washing of the wound, bilateral
gracilis muscle flaps were harvested through medial inner thigh incisions, with preservation
of the obturator nerves. The muscle flaps were then tunneled subcutaneously into the
defect, so that they could abut the anus in a tension-free manner. The left gracilis
was used to wrap the upper half of the sphincter, while the right gracilis was used
to wrap the lower half of the sphincter. The distal tip of each gracilis flap was
then anchored to the opposite gracilis flap, forming an aperture that is similar to
that of a camera shutter ([Figs. 4] and [5]). Thus, the double-opposing gracilis flaps formed a camera shutter, with the anal
mucosa as its “aperture,” sprouted at the epicenter of the two muscle flaps ([Figs. 5] and [6]). When both the gracilis muscles were activated, they would shorten and narrow the
aperture of the anus, closing the anus and preventing leakage. The gracilis muscle
flaps were anchored with vicryl 2/0 and vicryl 3/0. Split-thickness skin grafts were
used to resurface the rest of the skin defect ([Fig. 7]). Wound inspection on postoperative day 12 showed that the flap and the skin graft
have contracted, forming a clear channel suitable for the passage of feces. During
the patient's inpatient stay, his glycemic control was also maintained within an acceptable
range.
Fig. 4 Harvest of bilateral gracilis flaps and inset of flaps.
Fig. 5 Final inset of flaps for the creation of neoanus.
Fig. 6 Illustration of technique.
Fig. 7 Skin grafts for resurfacing of raw surface.
After maturation of the double gracilis flaps and skin graft, a baseline anal sphincter
manometry was performed for the patient. The mean resting pressure was 26.1 mm Hg,
mean squeeze pressure was 29.1 mm Hg, and the maximum voluntary contraction was 32.4 mm
Hg. On proctometrography, the rectal volume at initial sensation was 30 mL, first
urge at 40 mL, and the maximal tolerable volume was 100 mL. The patient was then started
on biofeedback training with the aim of using the double gracilis muscle flaps for
dynamic restoration of the anal sphincter. To increase the closing tone of the neoanus,
he was instructed to adduct his thighs to activate the double gracilis flaps. A combination
of isometric and isotonic exercises of the thigh adductor muscle group were taught
to the patient.
After 1 year of biofeedback training, he demonstrated dramatic improvement on the
anal sphincter manometry. The final anal sphincter manometry performed for the patient
showed the improved values of a mean resting pressure of 43.7 mm Hg, mean squeeze
pressure of 101.6 mm Hg, and maximum voluntary contraction was 145.2 mm Hg. Rectosphincteric
inhibitory reflex was noted to be present at 30 mL. The rectal volume at initial sensation
was 48 mL, first urge at 99 mL, and the maximal tolerable volume at 160 mL. Although
the resting and squeeze pressure and the rectoanal inhibitory reflex typically reflect
sphincteric resting tone, it was unlikely to be due to the sphincters as they were
debrided away by the colorectal surgeon. This improvement was likely to be due to
the resting tone of the gracilis after 1 year of training with resultant neuroplasticity
with hypertrophy. In view of the good results from the manometry and proctometrography,
stoma reversal with anal continence was deemed feasible.
Fourteen months after the definitive reconstruction, the patient underwent reversal
of stoma and dilatation of anal opening. He was able to pass flatus on postoperative
day 1, and managed to pass motion on postoperative day 2. There was no evidence of
fecal incontinence, and rectosphincteric inhibitory reflex was completely functional.
The patient was followed up for a total of 12 months after stoma reversal, with maintenance
of continence throughout, without any accidental discharge. With just one session
of dilatation, the anal sphincteric function was well maintained without stenosis
([Fig. 8]).
Fig. 8 Twenty-four months postreconstruction of the anal sphincter—anal mucosa has contracted
and wounds have all healed.
Discussion
In cases of Fournier's gangrene with severe perineal involvement, the anal sphincters
may be directly involved by the infection, necessitating the debridement of the structure,
with the drastic morbidity of anal incontinence. Anal sphincter reconstruction is
thus required in such cases but difficult to achieve.[2] The estimated percentage of patients requiring end-colostomy after radical debridement
in Fournier's gangrene is approximately 15%.[3]
Achieving a functional sphincteric reconstruction is still a holy grail in perineal
reconstruction. Despite multiple attempts reported in the literature, a truly independent
functional autologous sphincter without the use of external devices has still not
been achieved. The use of unilateral or bilateral gracilis flap for anorectal reconstruction
following abdominoperineal reconstruction,[4] trauma, iatrogenic causes,[5] or even anorectal malformation,[6] have been described in the literature. Gracilis is a muscle that exhausts quickly
due to the fast-twitch fatigue-prone muscle fibers (type II muscle fibers). In the
past, electrostimulation is commonly used after the graciloplasty to transform the
gracilis muscle from type II to type I (slow-twitching fatigue-resistant fibers),
which allows the gracilis muscle to work as a new sphincter and maintain a sustained
contraction.[7] However, in most of these cases, they only achieved partial continence at best,
with continued fecal leakage requiring diapers still. The success of conventional
graciloplasty has been less than 50% mainly due to muscle fatigue and the inability
of patients to voluntarily contract the transposed muscle. Gohil et al described the
use of a single gracilis muscle wrapped around the anus in an “alpha,” “epsilon,”
and “gamma” configuration, and showed that satisfactory continence was achieved in
76.4% of the patients in adynamic gracilis reconstruction.[7] The disadvantage of wrapping around the anus completely, was that it would exert
a pulley effect, where the resultant force generated is centrifugal and could not
collapse the anus to enforce continence. Rouanet et al used a gamma configuration
for each gracilis muscle, and fixed both muscles to each other to create a double
gracilis wrap. With electrostimulation as the next stage after the double gracilis
wrap was performed, the study showed 5 out of 9 patients were continent for solids
(55.6%).[8] However, this technique relied on electrostimulation to work.
In our novel technique, we describe a geometric way of inset that makes use of the
orthograde contraction of the double gracilis flaps to narrow and collapse the neoanal
opening. This is akin to the way a camera shutter closes, by “sliding and shuttering”
the aperture close. The neurovascular pedicle of the gracilis muscle is carefully
preserved so that the gracilis is still a functioning muscle and thus can be trained.
Through biofeedback exercises, we instructed the patient to imagine adducting his
thighs, and due to the geometry nature of inset, the contraction of the double gracilis
muscles would be converted to a shuttering action on the anus, effectively closing
the anus. A committed and compliant patient is necessary for the success of this technique,
as our patient only achieved full continence after 1 year and 2 months of training.
Since our technique does not rely on electrostimulation, the patient could reliably
reverse his stoma without the need for long-term follow-up with electrical implants
or devices. This technique can be thought of as a mechanical solution to an electrodynamic
problem. There was also no need for microsurgery or neurotization procedures for this
sphincteric reconstruction. The only “neurotization” involved would be the utilization
of our cranial neuroplasticity during the biofeedback exercises.
With the inset of bilateral gracilis muscle flap in a double-opposing, camera shutter
fashion around the anus, reconstruction of anal sphincter can be successful without
the use of electrostimulation or complex microsurgery techniques. Intensive biofeedback
training is required after surgery to achieve an acceptable anal resting and squeeze
pressure before the reversal of stoma.
