Voluntary anal continence after surgery for anorectal malformations

Voluntary Anal Continence After Surgery for Anorectal Malformations By Naomi Iwai, Jun Yanagihara, Kazuaki Tokiwa, Eiichi Deguchi, and Toshio Takahashi Kyoto, Japan 9 Electromyography (EMG) and measurement of voluntary contraction pressure of the external sphincter muscle were performed in 28 patients, aged 5 to 14 years, to assess the function of the external sphincter after surgical correction of anorectal malformations. Ten normal children, aged 5 to 15 years, served as controls. External sphincter function in patients with high-type anomalies was disturbed in the areas of tonic activity, inflation reflex, and activity during further rectal filling. In patients with low-type or intermediate-type anomalies, function was preserved and was equal to that in normal controls. Phasic activity was observed in patients with all types of anomalies and in normal subjects. Among those with high-type anomalies, the three patients with Kelly's score of < 2 had voluntary contractions of 20 cmH20 or less. However, the mean voluntary contraction pressures w e r e not significantly different among the three types of anomalies. Therefore, patients with high-type anomalies may acquire compensatory voluntary continence through bowel train-ing. 9 1988 by Grune & Stratton. Inc. INDEX WORDS: Anal continence; anorectal malformation; imperforate anus.

HE IMPORTANCE of the puborectalis muscle in patients with high-type anorectal malformations has been stressed by many investigators. On the other hand, it seems that the function of the external sphincter muscle has not been emphasized sufficiently. The external sphincter muscle provides fine control, especially at the time of a "sense of urgency." The purpose of this study is to assess by electromyography (EMG) and anorectal manometry the function of the external sphincter in patients with anorectal malformations. The possibility of acquiring further voluntary anal continence is discussed.

T

MATERIALS AND METHODS From 1960 to 1986, 140 patients with anorectal malformations were treated in the Division of Surgery, Children's Research Hospital, Kyoto Prefectural University of Medicine. There were 66 patients (53 males and 13 females) with high-type, 23 patients (15 males and 8 females) with intermediate-type, and 51 patients (34 males and 17 females) with low-type anomalies. The usual operative procedure in this department has been a colostomy for the high and intermediate types in the neonatal period, followed by abdominoperineal rectolasty. At the time of the pull-through operation, the puborectalis sling is clearly observed with the aid of an electric stimulator, and this electric stimulator is also used to make a Y-shaped perineal skin incision within the external sphincter. Lowtype anomalies have been treated by neonatal perineoplasty. Of these 140 patients, 28 (13 with high-type anomalies, 6 with intermediate-type, and 9 with low-type) were tested with EMG of the external sphincter muscle and measurement of voluntary anal contraction pressure. The 13 patients with high-type anomalies were

Journal of Pediatric Surgery, Vol 23, No 5 (May), 1988: pp 393-397

aged 5 to 11 years, the six with intermediate-type, 5 to 9, and the nine with low type, 5 to 14. Ten normal controls, aged 5 to 15 years, were tested in the same way.

Electromyographic Assessment Electromyography was recorded from the external anal sphincter by two surface electrodes placed just outside the anal orifice. The patient was grounded with a similar electrode. Electromyography was recorded on a Sanei (Tokyo) thermal pen recorder (Sanei-360, 8 channel polygraph), and the EMG electrodes were connected to a Sanei bioelectric amplifier. The time constant was 0.03 second. The patients were examined awake without sedation and in a supine position. An enema was given two hours before the examination. The external sphincter electrogram at rest was first recorded. The electrical activity at rest was classified into three grades: ( + ) , an amplitude of 40 #V or higher; (_+), between 20 and 40 ~V; ( - ) , lower than 20 #V. When the rectum was transiently distended by a balloon containing 10 to 20 mL of air, contraction of the external sphincter was observed. This response was defined as the presence of an inflation reflex (Fig 1), as reported by Ihre. l The rectal balloon was further inflated to a maximum tolerable level, and the electrical activity was observed during rectal filling (Fig 2). In cooperative patients, the presence or absence of phasic activity during voluntary anal contraction was studied (Fig 3).

Manometric and Clinical Assessments The manometric study was done only in cooperative patients. The probe was made with a Foley catheter, as we 2 previously reported. The probe was perfused at a constant speed of 10 m L / h . This apparatus was connected to a transducer (P231D: Gould Inc.), and the pressure was recorded on the Sanei thermal pen recorder. Voluntary anal contraction pressures were measured twice at 2 cm and at 1 cm from the anal verge. The mean pressure was expressed as the voluntary contraction pressure. Clinical assessment of functional results followed the Kelly score system 3 based on three criteria: (1) control of feces and bowel habits, (2) fecal staining, and (3) sling action of the puborectalis muscle.

RESULTS

Normal Subjects

All ten normal subjects examined showed tonic activity at rest, and eight of the ten had a positive

From the Division of Surgery, Children's Research Hospital, Kyoto Prefectural University of Medicine, and the First Department of Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan. Presented at the 20th Annual Meeting of the Pacific Association of Pediatric Surgeons, Seattle and Rosario, WA, April 26 to May 1, 1987. Address reprint requests to Naomi lwai, MD, Division of Surgery, Children's Research Hospital, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto, 602, Japan. 9 1988 by Grune & Stratton, lnc. 0022-3468/88/2305-0002503.00/0 393

394

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inflation reflex. E l e c t r i c a l activity d u r i n g further rectal filling was increased in all ten. V o l u n t a r y contraction pressures 2 c m and 1 c m from the a n a l verge were 52.0 _+ 7.0 c m H 2 0 and 63.6 _+ 9.1 c m H 2 0 , respectively.

V o l u n t a r y c o n t r a c t i o n pressure could be m e a s u r e d in these t h r e e patients. T h e m e a n values of contraction pressures 2 c m and 1 c m from the a n a l verge were 27.0 c m H 2 0 a n d 30.0 c m H 2 0 , respectively.

Patients With Intermediate-Type Anomalies

Patients With Low-Type Anomalies

A s shown in T a b l e 2, tonic activity at rest was observed in all six patients. T h e inflation reflex was present in two of the six patients. E l e c t r i c a l activity during f u r t h e r rectal filling was i n c r e a s e d in four patients with scores of m o r e t h a n 4. A l l six patients showed phasic activity d u r i n g v o l u n t a r y contractions. T h e m e a n values of v o l u n t a r y c o n t r a c t i o n pressure 2 cm and 1 c m from the a n a l verge were 42.8 _+ 7.0 c m H 2 0 and 39.2 _+ 6.0 c m H 2 0 , respectively. T h e

Tonic activity at rest was found in eight of the nine patients, and in one p a t i e n t it was j u d g e d to be ( + ) ( T a b l e 1). A n inflation reflex was observed in eight of the nine; the p a t i e n t with a score of 4 did not have an inflation reflex. Electrical activity d u r i n g f u r t h e r rectal filling was increased in all nine patients. P h a s i c activity was present in all t h r e e patients who were cooperative in this e x a m i n a t i o n . Voluntary

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contraction pressure 1 cm from the anal verge was significantly (P < .05) lower than that of the normal controls. Patients With High-Type

Anomalies

Tonic activity at rest was present in five of the 13 patients, and six patients had an electrical amplitude of 20 to 40 uV (_+) (Table 3). The remaining two patients had an electrical amplitude lower than 20/~V ( - ) . Two of the 13 patients showed the inflation reflex, and the remaining 11 had no inflation reflex. Electrical activity during further rectal filling was increased in three of the 12 patients, who had Kelly scores of more than 4 points. On the other hand, electrical activity was stationary in the remaining nine patients in spite of further rectal filling. Phasic activity was present in all of the eight patients who were cooperative in this examination. The mean values of contraction pressure 2 cm and 1

cm from the anal verge were 33.5 _+ 6.7 cmH20 and 28.9 _+ 5.1 cmH20, respectively. The contraction pressure 1 cm from the anal verge was significantly (P < .01) lower than that of the normal controls, and there was no significant difference in voluntary contraction pressures between the high-type and intermediate-type anomaly groups. DISCUSSION

Stephens and Smith 4 stressed the importance of the puborectalis muscle in providing fecal continence. However, they seemed to discount the importance of the external sphincter muscle. In the present study, adequate electrical activity of the external sphincter at rest was observed in patients with low-type and intermediate-type anomalies. On the other hand, tonic activity was observed less often in patients with high-type anomalies. These results suggest that patients with high-type anomalies have a

Table 1. Electromyography Recordings and Contraction Pressures of the External Sphincter in Nine Patients With Low-Type Anomalies (Mean _+ SE) E M G Recording

Case

1 2 3 4 5 6

A g e at Follow-up

5 5 14 8 5 9 (Trisomy 18) 7 5 8 6 9 5

Activity During Further Rectal Filling

V o l u n t a r y Contraction Pressure (crnH20) Phasic A c t i v i t y During V o l u n t a r y Contraction

2 cm from the Anal Verge

Kelly Score

Tonic Activity

Inflation Reflex

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1 cm from the Anal Verge

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396

IWAI ET AL

Table 2. Eleetromyography Recordings and Contraction Pressures of the External Sphincter in Six Patients W i t h Intermediate-Type Anomalies (Mean _+ SE) Voluntary Contraction Pressure(emiliO)

EMG Recording

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Follow-up

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activity during further rectal filling; this result is in agreement with Ihre's report. In most of the patients with high-type anomalies, electrical activity of the external sphincter was stationary in spite of further rectal filling. Therefore, electrical activity during further rectal filling is an index of external sphincter function in patients with high-type anomaly, as is tonic activity or the inflation reflex. Ihre showed that in normal subjects, electrical activity of the external sphincter reached a higher amplitude, corresponding to voluntary contraction of the anal canal, and this response has been called phasic activity. In the present study, phasic activity was observed in patients with high-type anomalies as well as in patients with other types of anomalies and in normal subjects. This result indicates that although patients with high-type anomalies may have congenitally rudimentary external sphincter muscles, they still may be able to improve external sphincter function. Arhan et al 7 previously reported that pressure in the upper anal canal during contraction is significantly lower in incontinent subjects, although this deficiency

congenital function problem with the external sphincter muscle. Gaston 5 reported that rectal distension normally elicited a brief contraction of the striated anal sphincter muscle; this response has been called the inflation reflex. Molander et al6 showed that the presence of an inflation reflex correlated well with the development of voluntary anal continence. In the present study, all of the normal subjects and the patients with low-type anomalies did not necessarily have a positive inflation reflex. However, the inflation reflex was much more common in normal subjects and patients with low-type anomalies. This finding indicates that from the point of view of the inflation reflex, the function of the external sphincter is more frequently disturbed in patients with high-type anomalies. In addition, it is noteworthy that patients with an inflation reflex had good Kelly scores regardless of the type of anorectal malformation. Electrical activity of the external sphincter was recorded when the balloon in the rectum was inflated further. All of the normal subjects showed increased

Table 3. Electromyography Recordings and Contraction Pressures of the External Sphincter in 13 Patients W i t h High-Type Anomalies (Mean • SE) EMG Recording Age at

Kelly

Inflation Reflex

Activity During Further Rectal Filling

Voluntary Contraction Pressure (cmH20)

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Follow-up

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VOLUNTARY ANAL CONTINENCE

397

is less frequent t h a n the r e c t o a n a l inhibitory reflex or a lower a n a l pressure at rest. In the present study, the three patients with K e l l y ' s score of < 2 h a d v o l u n t a r y contraction pressure of 20 c m H 2 0 or less. However, there was no significant difference in v o l u n t a r y contraction pressures a m o n g the three types of a n o m a l y .

T h e results of phasic activity a n d v o l u n t a r y a n a l contraction pressure testing indicate t h a t patients with h i g h - t y p e a n o m a l i e s m a y achieve c o m p e n s a t o r y volunt a r y continence of defecation if the e x t e r n a l sphincter muscle is developed by v o l u n t a r y bowel training.

REFERENCES

1. lhre T: Studies on anal function in continent and incontinent patients. Scand J Gastroenterol Suppl 25, 1974 2. lwai N, Ogita S, Kida M, et al: A clinical and manometric correlation for assessment of postoperative continence in imperforate anus. J Pediatr Surg 14:538-543, 1979 3. Kelly JH: Cineradiography in anorectal malformations. J Pediatr Surg 4:538-546, 1969 4. Stephens FD, Smith ED: Anorectal Malformations in Children. Chicago, Year Book Medical, 1971

5. Gaston EA: The physiology of fecal continence. Surg Gynecol Obstet 87:280-290, 1948 6. Molander ML, Frenckner B: Electrical activity of the external anal sphincter at different ages in childhood. Gut 24:218-221, 1983 7. Arhan P, Faverdin C, Devroede G, et al: Manometric assessment of continence after surgery for imperforate anus. J Pediatr Surg 11:157-166, 1976