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Open Segmental Lateral Internal Sphincterotomy Improves Functional Outcome of
Surgical Treatment of Chronic Anal Fissure: A Comparative Study versus Conventional
Lateral Internal Sphincterotomy
Ashraf M. Abdel kader MD
General Surgery Department, Faculty of Medicine, Benha University
Abstract
Objectives: To compare surgical and functional outcome of segmental lateral internal sphincterotomy (SLIS) versus
conventional lateral internal sphincterotomy (CLIS) for treatment of chronic anal fissure (CAF).
Patients & Methods: The study included 120 patients with CAF divided randomly into two equal groups: Group C
included patients assigned for CLIS and group S included patients assigned for SLIS. All patients underwent clinical
examination and evaluation of pain severity during defecation and rest using 10-points pain visual analogue scale
(VAS). Operative technique for SLIS included LIS for about 50% of internal sphincter midway between 4 and 5
O'clock and another incision for about 50% of internal sphincter at 3 O'clock; both incisions are about 1cm apart.
For group C, LIS was done from anoderme up to dentate line or fissure apex. Wounds were left open to heal with
secondary intention and sentinel pile was removed. Operative data included operative time, intraoperative bleeding
or complications, surgical wound pain, time till oral intake and hospital discharge. Impact of LIS on continence was
evaluated using the modified Wexner score at postoperative (PO) 1-week, 1-month and 3-months.
Results: All patients passed uneventful intraoperative course with non-significant difference between both groups
concerning operative and immediate PO data. Pain VAS scores determined at 1-m and 3-m PO were significantly
lower in both groups at both rest and defecation compared to preoperative pain scores with significantly lower
scores at 3-m compared to at 1-m PO in both groups. Pain scores at 1-m and 3-m PO were significantly lower in
SLIS compared to CLIS. No patient had solid stool incontinence, 13 had liquid and 26 had flatus incontinence with
significantly higher frequency of incontinent patients in group C compared to group S. For each of questionnaire
items, incontinent CLIS patients were more frequent among usually and sometimes strata, while SLIS patients were
more frequent among rarely and sometimes strata. Patients of both groups showed time-steep improvement of their
continence with the difference in favor of SLIS. The impact of incontinence on patients' quality of life showed
progressive improvement with time and was in favor of SLIS.
Conclusion: Open segmental LIS for 100% (50% + 50%) of internal sphincter at two levels about 1 cm apart is
appropriate therapeutic modality for CAF with acceptable surgical outcome and improved functional outcome
manifested as perfect continence, regular pain-free bowel habit and improved quality of life.
Keywords: Lateral internal sphincterotomy, Pain, Continence, Quality of life
Introduction
Anal fissure is a painful linear wound in the squamous epithelium of the anal canal distal
to the dentate line. The incidence of anal fissures is around 1 in 350 adults. They occur equally in
men and women and most often occur in young adults aged 15 to 40. It is usually located in the
posterior midline but occurs anteriorly in a fifth or more or patients. It typically causes pain
during defecation which may last for 1–2 hour afterwards. The finding on physical examination
is spasm of the anal canal due to hypertonia of the internal anal sphincter (IAS). It has been
postulated that this may either be due to or be the result of ischaemia (1).
The optimal algorithm of therapy for chronic anal fissure (CAF) is still debated. The
management of CAF aims to reduce anal tone and the initial approach is non-operative.
Chemical sphincterotomy with nitrates, calcium blockers or botulinum toxin is safe, with rapid
relief of pain, mild side-effects and no risk of surgery or anesthesia, but is a statistically less
effective therapy for CAF than surgery. Lateral internal sphincterotomy (LIS) is a surgical
treatment and is considered as the 'gold standard' therapy for CAF. It relieves CAF symptoms
with a high rate of healing, but although the technique is simple and effective, a drawback of this
surgical procedure is its potential to cause minor but sometimes permanent alteration in rectal
continence (2, 3).
Furthermore, there is still debate about the ideal technique for surgical management of
CAF whereas Magdy et al. (4) compared conventional LIS, V-Y advancement flap, and
combined tailored LIS with V-Y advancement flap in treating CAF and concluded that although
all the three procedures are simple and easy to perform, tailored LIS with V-Y flap appears to
produce the greatest healing rate, with the fewest complications and less rate of recurrence.
Abramowitz et al. (5) documented that given its high rate of healing and low rate of de-novo anal
incontinence, fissurectomy with anoplasty is a valuable sphincter-sparing surgical treatment for
CAF. Gupta et al. (6) found closed LIS technique is the treatment of choice for CAF as it is
effective, safe, less expensive, and associated with a lower rate of complications than the open
LIS technique.
Moreover, how much of the internal sphincter may be divided during LIS and where to
localize the incision in the sphincter is a matter of controversy; Lasheen et al. (7) found
segmental LIS is a safe, easy, and effective procedure and not associated with risk of
incontinence for the treatment of CAF. The current prospective comparative study aimed to
compare surgical and functional outcome of segmental lateral internal sphincterotomy (SLIS)
versus conventional lateral internal sphincterotomy (CLIS) for treatment of chronic anal fissure.
Patients & Methods
The study was conducted at General Surgery Department, Benha University Hospital and
King Abdul-Aziz hospital in Makah since Dec 2011 till Sep 2013 including 3 months follow-up
for the last case operated upon. After approval of the study protocol by the Local Ethical
Committee and obtaining written fully informed patients' consent; all patients presented with
chronic anal fissure fulfilling the inclusion criteria were enrolled in the study.
A chronic anal fissure was defined by duration of symptoms longer than 6 weeks,
presence of induration at fissure edges, sentinel pile, hypertrophied anal papillae, and circular
muscle fibers at the base of the cutaneous defect (8). Patients had previous anal surgery for
similar pathology or having hemorrhoids, bleeding diathesis, chronic liver, renal or cardiac
impairment, and pregnant and newly delivered women were excluded from the study.
All patients underwent determination of demographic data, duration of diseases, and
history of previous attacks of constipation and if it is still present and previous history of medical
or surgical management. Pain was evaluated using 10-points pain visual analogue scale (VAS)
with 1: no pain and 10: intractable pain (9). Pain was evaluated at both time of defecation and rest.
Clinical examination included general and abdominal examination and local anal examination.
All patients underwent evaluation of resting anorectal pressure and sphincter tonic pressure using
anal manometrey.
Patients were randomly allocated into two equal groups according to the assigned
operative procedure using sealed envelops: Group C included patients assigned for CLIS and
group S included patients assigned for SLIS.
Operative procedures
All surgeries were conducted under general inhalational or spinal anesthesia. Patients
were positioned in lithotomy position skin preparation and toweling was done. For group S, skin
incision (0.5 cm) was made at a point midway between 4 and 5 O'clock, the internal sphincter
was dissected and elevated (Fig. 1a) and sphincterotomy incision was made using diathermy
knife for about 50% of the lower half of the internal sphincter (Fig. 1b). Then another skin incision
(0.5 cm) was made at 3 O'clock, the internal sphincter was dissected and elevated (Fig. 1c) where
about 50% of the upper half of internal sphincter was divided under direct vision and with >1 cm
apart from the first incision (Fig. 1d). For group C, open CLIS was done (Fig. 1f). Good
hemostasis is achieved by using diathermy and then sentinel pile (Fig. 1e) was excised. The
wounds were left open to heal with secondary intention. Prophylactic intravenous broad
spectrum antibiotic was used and to be continued for 3 days after surgery in oral form.
Fig. (1a): showing the IAS dissected through an
incision at point between 4 and 5 O'clock and was
freed from its attachments
Fig. (1b): showing an incision in IAS (lower half) was
made using diathermy knife
Fig. (1c): showing the IAS dissected through an
incision at 3 O'clock and was freed from its
attachments
Fig. (1d): showing the second incision of the IAS in its
upper half.
Fig. (1e): showing the two skin incisions at the
Fig. (1f): showing the open CLIS
lateral side of the anal verge and sentinel pile
prepared for excision
Operative data included operative time, amount of intraoperative bleeding or
complications. Immediate postoperative data included severity of wound pain sensation judged
by pain VAS scoring, time till oral intake, postoperative hospital stay. The impact of surgery on
continence was evaluated using the modified Wexner score composed of four categories
included type of incontinence (solid, liquid, gas), and alteration in lifestyle; each item was scores
as 0: Never, 1: Rarely (<1/month), 2: Sometime (<1/week, ≥1/month), 3: Usually (<1/day,
≥1/week), 4: Always (≥1/day) (10). Additionally, another three categories were scored separately
and include the need to wear a pad or plug (0=no, 2=yes), taking anti-diarrheal medications
(0=no, 2=yes) and lack of ability to defer defecation (0=no, 4=yes). The maximum score in the
modified Wexner scale was 24 implying complete incontinence and 0 indicate perfect continence
(12)
. Continence scoring was determined at 1-week, 1-month and 3-months after surgery.
Statistical analysis
Obtained data were presented as mean±SD, ranges, numbers and ratios. Results were
analyzed using Wilcoxon; ranked test for unrelated data (Z-test) and Chi-square test (X2 test).
Statistical analysis was conducted using the SPSS (Version 15, 2006) for Windows statistical
package. P value <0.05 was considered statistically significant.
Results
The study included 120 patients; 78 males and 42 females with mean age of 42.2±9.5;
range: 21-57 years. Enrolled patients were mostly overweight with a mean body mass index of
27.7±4.2; range: 17.9-34.9 kg/m2. All patients had chronic anal fissure since a mean duration of
5.75±1.2; range: 4-9 months. There was non-significant difference between studied groups
concerning these data as shown in table 1.
Table (1): Patients' enrolment data
Data
Age (years)
Gender
Males
Females
Weight (kg)
Height (cm)
BMI (kg/m2)
Duration of disease (months)
Group C
43±9.3 (24-56)
37 (61.7%)
23 (38.3%)
79.2±12 (50-109)
169.6±3.7 (163-178)
27.5±3.9 (17.9-34.5)
5.9±1.2 (4-9)
Group S
41.4±9.6 (21-57)
41 (68.3%)
19 (31.7%)
80.9±13.7 (52-107)
170.4±3.4 (166-178)
27.9±4.5 (17.9-34.9)
5.6±1.2 (4-8)
P value
=0.582
=0.175
=0.361
=0.353
=0.686
=0.142
Data are presented as mean±SD & numbers; ranges and percentages are in parenthesis; BMI: Body mass index
All patients passed uneventful intraoperative events within a mean operative time of
19.2±4.9; range: 14-30 minutes. Patients were cared after full recovery in surgical ward and
allowed to take oral fluids within a mean duration of 2.7±0.6; range: 2-4 hours and all were
discharged from the hospital within a mean duration of total PO hospital stay of 4.1±1.1; range:
3-6 hours. Mean PO pain VAS score was 4.5±0.9; range: 3-6 and all received PO analgesia for a
mean times of 1.55±0.6; range: 1-3 times throughout their hospital stay. Forty-six patients
requested for PO analgesia once, 70 patients requested it twice and only 4 patients requested it
for three times. There was non-significant difference between studied groups concerning
operative and immediate PO data as shown in table 2.
Table (2): Operative and immediate postoperative data
Operative time (min)
Amount of intraoperative bleeding (ml)
PO pain data
Times of request of Once
analgesia
Twice
Trice
Pain VAS score
Time till 1st oral intake (hours)
Total PO hospital stay (hours)
Group C
18.2±4 (14-25)
31.5±10.5 (15-46)
25 (41.7%)
34 (56.7%)
1 (1.6%)
4.3±0.8 (3-6)
2.7±0.6 (2-4)
4.3±1.1 (3-6)
Group S
20.1±5.4 (15-30)
34.4±8.8 (20-45)
21 (35%)
36 (60%)
3 (5%)
4.6±0.9 (3-6)
2.6±0.6 (2-4)
4±1 (3-6)
P value
=0.063
=0.127
=0.239
=0.055
=0.424
=0.078
Data are presented as mean±SD & numbers; ranges and percentages are in parenthesis; PO: postoperative
Preoperative pain VAS scores were non-significantly different between both groups at
both defecation and at rest. Pain VAS scores determined at 1-m and 3-m PO were significantly
lower in both groups at both rest and defecation compared to preoperative pain VAS scores. Pain
scores determined at 3-m PO were significantly lower scores compared to at 1-m PO in both
groups. At 1-m PO, pain VAS scores at both defecation and rest were significantly lower in
group S compared to group C. At 3-m PO, pain VAS scores at defecation were significantly
lower in group S compared to group C, while pain scores at rest were non-significantly lower in
group S compared to group C, (Table 3, Fig. 2).
Table (3): Pain VAS scores of studied groups determined at 1-m and 3-m PO compared to Preoperative
scores
Preoperative
1-m PO
3-m PO
At defecation
At rest
At defecation
P2
At rest
P2
At defecation
P2
P3
At rest
P2
P3
Group C
6±1
2.8±0.7
2.3±0.5
=0.0001
1.7±0.8
0.0004
1.9±0.6
=0.0001
=0.0008
1.1±0.3
=0.0003
=0.001
Group S
5.8±1
2.65±0.8
1.8±0.8
=0.0001
1.2±0.4
=0.0003
1.4±0.6
=0.0001
=0.0008
1.03±0.2
=0.0001
=0.0009
P1
>0.05
>0.05
=0.0008
=0.0005
=0.001
>0.05
Data are presented as mean±SD; P1: significance of difference between groups C and S; P2: significance of difference of pain
scores at 1-m and 3-m versus preoperative scores; P2: significance of difference between 1-m and 3-m pain scores
7
Group C
Group S
6
Pain VAS score
5
4
3
2
1
Pain at def
3-m PO
1-m PO
Preoperative
3-m PO
1-m PO
Preoperative
0
Pain at rest
Fig. (2): Pain VAS scores determined at time of defecation and
at rest at 3-m and 6-m PO compared to preoperative scores
At 1-week PO, 39 patients complained of incontinence; 13 complained of liquid
incontinence and 26 of flatus incontinence. In group C, 28 complained of incontinence; 9
complained of liquid and 19 of flatus incontinence, while in group S, 4 complained of liquid and
7 of flatus incontinence with significant (X2=5.123, p=0.013) reduction of the frequency of
incontinence in group S compared to group C.
At 1-month PO, patients of both groups showed improved continence and 21 patients
were still complaining of incontinence; 7 of liquid and 14 of flatus incontinence. In group C, 16
were still complaining of incontinence; 5 of liquid and 11 of flatus incontinence, while in group
S, 5 were still complaining of incontinence; 2 of liquid and 3 of flatus incontinence with
significant (X2=5.339, p=0.013) reduction of the frequency of incontinence in group S compared
to group C. At 3-month PO, only 9 patients of group C were still complaining of incontinence; 2
of liquid and 7 of flatus incontinence, while in group S, all patients regained their control and
non had incontinence with significant (X2=3.279, p=0.036) reduction of the frequency of
incontinence in group S compared to group C, (Table 4, Fig. 3).
As regards severity of incontinence, at 1-m PO both patients of group S had fluid
incontinence and two of those had flatus incontinence scored it by one (occurred rarely) and only
one patient scored his flatus incontinence by 2 (occurred sometimes). In group C, 5 patients
scored their incontinence (3 fluid and 2 flatus) by one (occurred rarely), another 5 patients scored
their incontinence (2 fluid and 3 flatus) by two (occurred sometimes), 4 patients scored their
flatus incontinence by 3 (usually occurring) and 2 patients scored their fluid incontinence by 4
(always occurring). The frequency of patients had incontinence at 1-m PO was significantly
(X2=25.254, p=0.0004) lower in group S compared to group C. At 3-m PO, all patients of group
S were continent, while in group C, 2 patients still had liquid incontinence; one scored it as
rarely occurring and the other as occurred sometimes; 7 patients had flatus incontinence; 2
scored it as rarely occurring, 3 as sometimes and 2 as usually occurring, (Table 4).
Table (4): Wexner scoring of liquid and flatus incontinence determined in both groups at 1-w, 1-m and
3-m PO
Group
1-w PO
Liquid
Flatus
1-m PO
Liquid
Flatus
3-m PO
Liquid
Flatus
Group C
Group S
Group C
Group S
Group C
Group S
Group C
Group S
Group C
Group S
Group C
Group S
Continent
Never
51
56
41
53
55
58
49
57
58
60
53
60
Rare
2
3
0
2
3
2
2
2
1
0
2
0
Incontinent
Sometimes Usually
5
2
1
0
2
10
4
1
2
0
0
0
3
4
1
0
1
0
0
0
3
2
0
0
Always
0
0
7
0
0
0
2
0
0
0
0
0
Total
9
4
19
7
5
2
11
3
2
0
7
0
Data are presented as
1-w
1-m
3-m
20
18
16
Patients
14
12
10
8
6
4
2
0
Group C
Group S
Liquid
Group C
Group S
Flatus
Fig. (3): Frequency of patients developed liquid stool and
flatus incontinence throughout follow-up period
Incontinence imposed bad QOL on patients affected that was manifest with significantly
higher score in group C compared to group S throughout follow-up period. Impact of
incontinence on QOL showed steady improvement in both groups and all patients of group S
denied bad QOL at 3-m visit, while 7 patients in group C were still had varied impact on their
QOL, (Table 5, Fig. 4).
Table (5): Wexner scoring of impact of incontinence on quality of life (QOL) of studied patients in both
groups at 1-w, 1-m and 3-m PO
At 1-w
At 1-m
At 3-m
Group
C
S
C
S
C
S
Never
41
53
49
57
53
60
Rare
3
4
3
2
5
0
Sometimes
6
2
4
1
1
0
Usually
7
1
3
0
1
0
Always
3
0
1
0
0
0
Total
19
7
11
3
7
0
Score
0.8±1.3
0.18±0.57
0.4±0.9
0.07±0.57
0.17±0.53
0
P
=0.001
=0.010
=0.014
Data are presented as mean±SD; P: significance of difference between groups C and S
0.9
0.8
0.7
QOL scoring
0.6
0.5
0.4
0.3
0.2
0.1
0
1-w
1-m
Fig. (4): QOL scoring at 1-week and at 1 and 3 months in both
groups
3-m
Group C
Group S
Discussion
The current study proved the efficacy of surgical treatment of chronic anal fissure (CAF)
with high success rate and satisfaction rate secondary to perfect pain control and minimal
affection of continence. In support of the surgical option for treatment of CAF, multiple recent
trials compared surgical versus chemical sphincterotomy as line of treatment of CAF and
documented surgery as the best choice where de Rosa et al. (12) found lateral internal
sphincterotomy (LIS) is an effective, less painful, fast recovery treatment for CAF and concluded
that incontinence rate is overestimated and often the fear of a continence disturbance, albeit with
a low incidence following surgery, may obscure the need to relieve symptoms which may be so
severe as to make the patient's life intolerable. Also, Chen et al. (13) conducted a meta-analysis
showed that LIS was superior to botulinum toxin injection in terms of healing rate and lower
recurrence rate.
Concerning surgical outcome; segmental LIS (SLIS) was feasible and easy to perform
within a mean operative time of about 20 minutes and with minimal blood loss. Also, the
procedure is safe without intraoperative complications and postoperatively all patients were
allowed to take oral fluid within about 2 hours postoperative (PO) and to go home within about 4
hours PO. These results go in hand with and confirm that previously reported by Lasheen et al.
(7)
; the parent work for the procedure of SLIS.
The current study overcame the limitation of the parent work which was non-comparative
study wherein the current study reported non-significant difference between SLIS and
conventional LIS (CLIS) as regards operative and immediate PO data, despite being in favor of
CLIS. This could be attributed to the duplication of the procedure for performing two
sphincterotomies which logically consumes more operative time and induces more pain, but the
difference being non-significant could be considered in favor of SLIS not CLIS.
Another limitation of the parent work was the collective evaluation of functional outcome
and absence of comparison. However, the current study evaluated the progress of functional
outcome throughout 3-m PO follow-up; at 1 week, 1-month and 3-months PO using the modified
Wexner scale for evaluation of PO continence and its impact on quality of life (QOL). No patient
had solid stool incontinence, while 39 patients complained of incontinence; 13 had liquid and 26
flatus incontinence with significantly higher frequency of incontinent patients in group C
compared to group S. Moreover, for each of questionnaire items, incontinent CLIS patients were
more frequent among usually and sometimes strata, while SLIS patients were more frequent
among rarely and sometimes strata.
Fortunately, patients of both groups showed time-steep improvement of their continence,
but the difference was still in favor of SLIS. The impact of incontinence on patients' quality of
life also showed progressive improvement with time and was in favor of SLIS
The reported improvement of continence with time indicated that the gutter formation
with CLIS that was accused by Lasheen et al. (7) as the cause of development of incontinence
was not the sole underlying pathogenic mechanism. In the current study, the occurrence of
incontinence in both groups and its improvement with time could be attributed to irritation of the
mucosa and/or to neuroplasticity occurring secondary to long lasting constipation (14, 15, 16) due to
painful defecation concomitant with CAF. Both mucosal irritation and neuroplasticity could be
improved with time and patients' training to distinguish between the new and old situation so as
to control their bowel habit by themselves not by their rectal behavior.
In support of such assumption, the significantly decreased pain VAS scores with time
progress in both groups could explain the habituation on regular bowel evacuation without pain
thus minimizing fecal matter retention with subsequent less fermentation responsible for flatus
formation so decreasing their frequencies and involuntary passage. Also, getting regular bowel
motion allowed stoppage of dependence on laxatives which induce more liquid stool that may
escape around hard fecal matter inducing liquid incontinence.
The reported significantly improved scoring on modified Wexner scale with the
concomitant improved pain VAS scores in group S compared to group C manifested the better
functional outcome with SLIS compared to CLIS and supported the provided attribution for
continence.
In support of the efficacy of the applied technique of segmental sphincterotomy for about
half of the internal sphincter at two levels about 1cm apart Murad-Regadas et al. (17) used 3dimensional anal ultrasonography to determine the proportion of the IAS that may be divided
during LIS without predisposing them to a high risk of fecal incontinence and found that the safe
extent of division is mostly less than 1 cm. Also, Aslam et al. (18) demonstrated that open partial
lateral internal sphincterotomy is superior to topical 0.2% nitroglycerin application in the
treatment of CAF, with good symptomatic relief, high rate of healing, fewer side effects, and a
very low rate of early continence disturbances.
It could be concluded that open segmental LIS for about half of the internal sphincter at
two levels about 1 cm apart is appropriate therapeutic modality for CAF with acceptable surgical
outcome and improved functional outcome manifested as perfect continence, regular pain-free
bowel habit and improved quality of life.
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