The goal of treatment for anorectal malformations (ARM) is to achieve anal continence, and various attempts have been made to obtain objective assess- ments for it. These objective measures give us accu- rate information about postoperative sphincter func- tion or sphincter distribution, and provide us with further strategies for postoperative treatments.
We have two main objective assessments: physi- ological examinations and imaging studies. In this chapter we describe our experience with postopera- tive electromanometric, electromyographic, and anal endosonographic evaluations, in addition to the use of biofeedback therapy.
26.1 Electromanometric Evaluation
For the complete evaluation of postoperative conti- nence, anorectal manometric studies have been per- formed on patients with ARM [1,2]. We also investi- gated whether there was a correlation between clinical assessment and manometric assessment [3].
26.1.1 Manometry Study
Manometry was done without anesthesia, except in restless children, who required mild sedation at the time of examination. The probe was filled with water
before the examination, but was not perfused during the test. The anorectal pressure profile was first re- corded in centimeters by withdrawing the probe that was introduced 8 cm above the mucocutaneous line into the rectum. The presence or absence of an ano- rectal reflex was determined by distending the bal- loon in the rectum.
26.1.2 Results of Anorectal Manometry Patients with a good clinical result after staged ab- dominoperineal rectoplasty or perineoplasty exhib- ited the same anorectal pressure profile as normal subjects, with a high-pressure zone in the anal canal (Fig. 26.1). They also had an adequate anorectal pres- sure difference that was not significantly different from that of normal subjects. On the other hand, pa- tients with a poor clinical result showed a slight radial change in the anorectal pressure profile and did not have such a high-pressure zone as was found in nor- mal subjects (Fig. 26.2). The anorectal pressure differ- ence was as low as 3 cmH2O. Most of the patients with a good clinical result, regardless of the type anomaly, exhibited an anorectal reflex. In high anomalies, how- ever, some patients with a good clinical result did not necessarily show the reflex.
Manometric investigations showed that good clini- cal results after surgery were associated with a normal function of the anorectum. The anorectal pressure profile, observed in all patients with adequate conti- nence, characteristically had a marked high-pressure zone, as did normal subjects. Thus, the presence of normal anal pressure at rest as well as an adequate anorectal pressure difference was found to correlate well with continence after surgery for ARM. How- ever, the anorectal reflex in high anomalies did not necessarily correlate well with continence. Accord- ingly, it seems that the reflex is not essential to achieve continence, at least in patients with high anomalies.
This might be explained as follows. In a high anomaly, only a mechanical resistance remains without sensi-
Contents
26.1 Electromanometric Evaluation . . . 345 26.1.1 Manometry Study . . . 345
26.1.2 Results of Anorectal Manometry . . . 345 26.2 Electromyography . . . 347
26.2.1 EMG study . . . 347
26.2.2 Results of the EMG Study . . . 347 26.2.3 Anal Endosonography . . . 347
26.2.4 Results of Anal Endosonography . . . 348 References . . . 349
26 Postoperative Electromanometric, Myographic, and Anal Endosonographic Evaluations
Naomi Iwai, Eiichi Deguchi, Takashi Shimotake, and Osamu Kimura
Fig. 26.2 Anorectal pressure pro- file in a patient with a poor result after staged abdominoperineal rectoplasty. A slight radial pres- sure change in the anal canal was found without a high-pressure zone
Fig. 26.1 Anorectal pressure pro- file in patients with good results.
A Staged abdominoperineal recto- plasty. B Perineoplasty. The same anorectal pressure profile with a high-pressure zone was observed
Fig. 26.3 Electromyographic re- cording of the external sphincter (EAS) during rectal distension.
In response to each rectal disten- sion, relaxation of the anal canal pressure and contraction of the external sphincter were observed (arrows)
Fig. 26.4 Electromyographic re- cording of the EAS during further rectal filling. The further rectal filling elicited renewed contrac- tion of the external sphincter
tive receptors in the mucosa, which is concerned with initiating the anorectal reflex. Therefore, normal anal resting pressure and an adequate anorectal pressure difference in a high anomaly are apparently more important factors relating to continence after recon- structive surgery for ARM.
26.2 Electromyography
In the treatment of ARM it seems that the function of the external sphincter has not been emphasized sufficiently. The external sphincter muscle provides fine control, especially at the time of a “sense of ur- gency”. The external sphincter function was assessed by electromyography (EMG) and voluntary contrac- tion pressure.
26.2.1 EMG study
The EMG was recorded by two surface electrodes placed just outside the anal orifice, as reported pre- viously [4]. The patient was grounded with a similar electrode. The time constant was 0.03 s. The patients were examined awake, without sedation, and in a supine position. The external sphincter electrogram at rest was recorded first. When the rectum was transiently distended by a balloon, contraction of the external sphincter was observed. This response was defined as the presence of an inflation reflex (Fig. 26.3). The rectal balloon was further inflated to a maximum tolerable level, and the electrical activity was observed during rectal filling (Fig. 26.4). In coop- erative patients, the presence or absence of phasic activity during voluntary anal contraction pressures were measured at 2 cm and at 1 cm from the anal verge.
26.2.2 Results of the EMG Study
In patients with low anomalies, the inflation reflex was observed, and electrical activity during further rectal filling was increased. Phasic activity was pres- ent in all of them. On the other hand, in patients with intermediate or high anomalies, most did not show an inflation reflex, and electrical activity was station- ary in spite of further rectal filling. Phasic activity was present in all.
Adequate electrical activity of the external sphinc- ter at rest was observed in patients with low and in-
termediate anomalies. On the other hand, tonic ac- tivity was observed less often in patients with high anomalies. These results suggest that patients with high anomalies have a congenital functional prob- lem of the external sphincter muscle. Molander and Frenckner [5] showed that the presence of an infla- tion reflex correlated well with the development of voluntary anal continence. In our study the inflation reflex was much more common in normal subjects and in patients with low anomalies. From the point of view of the inflation reflex, the function of the exter- nal sphincter is more frequently disturbed in patients with high anomalies. Electrical activity during further rectal filling is an index of external sphincter function in patients with high anomalies, as is tonic activity or the inflation reflex. The results of phasic activity indicate that although patients with high anomalies may have congenitally rudimentary external sphinc- ter muscles, they may still be able to improve their external sphincter function. Therefore, patients with high anomalies may achieve compensatory volun- tary continence of defecation if the external sphincter muscle is developed by voluntary bowel training such as biofeedback training (Fig. 26.5). These results have led us to devise a new computer-assisted biofeedback therapy in patients who have fecal incontinence after surgery for ARM [6,7].
26.2.3 Anal Endosonography
Information on sphincter morphology cannot be ob- tained by physiological examination. Accordingly, anal endosonography has come into use for the mor- phological evaluation of the external anal sphincter (EAS) and the internal anal sphincter (IAS) [8,9], and we have applied this method to assess ultrasonically the structures around the anal canal in ten patients with high-type anomalies and five patients with inter- mediate anomalies [10].
An ultrasonographic scanner (ASU-61; Aloka, To-
kyo, Japan) was used with a 7.5-MHz rotating endo-
probe. The endoprobe is protected by a hard sonolu-
cent plastic cone with a diameter of less than 2 cm,
designed to fit within the anal canal. The presence or
absence of a well-defined uniform hypoechoic band
that corresponds to the IAS was examined. Whether
the hypoechoic band was well or moderately defined
from the surrounding tissues and whether continuity
of the band was interrupted were also examined. In
addition, the appearance of the layer and its continu-
ity were checked.
26.2.4 Results of Anal Endosonography An image of the EAS was obtained in all ten patients with high anomalies; however, the distribution of the image was inadequate. The hyperechoic layer corre- sponding to the EAS was not completely defined from the surrounding tissues, although it was moderately defined in all ten patients (Fig. 26.6). The continuity of the hyperechoic layer was partially interrupted in
two patients, and was complete in eight. The IAS was seen in five of the ten patients with high anomalies.
Four out of the five patients showed a well-defined layer corresponding to the IAS with circular continu- ity, but the other showed complete interruption of the hypoechoic band.
The EAS was seen in all five patients with inter- mediate anomalies (Fig. 26.7). In addition, a well-de- fined layer corresponding to the EAS and uninter-
Fig. 26.5 Voluntary contraction pressures and phasic activities of the external sphincter before (A) and after (B) biofeedback ther- apy. Voluntary contraction pressures and electrical activities of the phasic activities are increased after therapy
Fig. 26.6 An endosonographic image showing the hyperechoic band and hypoechoic band (high anomaly). The hyperechoic band layer is moderately defined from the surrounding tissues, and the continuity is uninterrupted. The hypoechoic band layer is well defined and the continuity is uninterrupted
Fig. 26.7 An endosonographic image showing the hypere- choic band corresponding to the EAS (intermediate type). The lower portion of the hyperechoic band is well defined from the surrounding tissues, and the continuity is not interrupted. Ant Anterior, Post posterior
rupted continuity of the EAS image were noted in two. A moderately defined layer was observed in the other three patients. The IAS was seen in one patient with an intermediate anomaly, and was not seen in the remaining four patients.
Anal endosonography has demonstrated that pa- tients with high anomalies have less adequate distri- bution of the EAS compared with those with interme- diate anomalies, especially for the hyperechoic layer.
These results indicate that patients with high anoma- lies have a congenitally rudimentary EAS.
The IAS has been regarded as being congenitally absent in patients with high or intermediate anoma- lies. However, Rintala reported the presence of the IAS even in patients with high anomalies, and stressed the importance of preserving the IAS at the time of surgery [11]. In the present study, five of the ten pa- tients with high-type anomalies and one of the five patients with intermediate-type anomalies showed the hypoechoic band that corresponds to the IAS.
Therefore, if the IAS is present in patients with high or intermediate anomalies, its preservation might contribute to the improvement of postoperative ano- rectal function.
References
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