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290 Chapter 14 injections, these procedures usually have a permanent effect. The major risk of these two procedures is that the basal pressure of the anal sphincter can be weakened to the point of causing fecal incontinence. Therefore, in cases of intractable FC with high sphincter pressure or a non-relaxing sphincter, after ruling out Hirschsprung's disease, it seems sensible to opt for internal anal sphincter botulinum injections. Subsequent symptomatic improvement would confirm that the anal sphincter dysfunction is contributing to the problem. There have been reports of symptom improvement after botulinum toxin injections lasting longer than 6 months, 28,31 which suggests that the pathophysiology of the non-relaxing anal sphincter is complex and that breaking the vicious cycle of painful defecation and withholding behavior could be an important additional benefit of this treatment. Colonic manometry and surgery The responses to our case-based questions highlight the complexity of therapeutic decision-making and the broad variance in interpretation of colonic manometry results with regards to the surgical management of intractable FC. Colonic manometry is used to differentiate between myopathic and neuropathic motility disorders and to identify dysmotile colonic segments amenable for surgery. 27,34,35 Dysmotility of the colon is usually defined by the absence of high amplitude propagating contractions (HAPCs) and in severe cases this abnormality can be used to justify a total or partial colonic resection and/or diversion of the dysmotile colonic segment by means of an ostomy. 11,36–38 However, it has also been shown that findings of dysmotility are potentially reversible and that motility as measured by colonic manometry can improve after decompression of the colon. 36–38 An improvement in colonic motility has also been demonstrated to occur in patients after using ACE. 39 This suggests that colonic dysmotility may not only contribute to the severity of the constipation but may also be a consequence of long-standing constipation, possibly because of fecal stasis and colonic distension which in turn may lead to suboptimal motor function. Although total or partial colonic resection may lead to symptom improvement 40 , it has never been investigated whether this is necessary or if temporary decompression through diversion alone might be equally effective. Furthermore, with the development of high-resolution colonic manometry, there is an increasing body of evidence suggesting that colonic dysmotility is more complex than just an evaluation of the presence and morphology of HAPCs and that there are other motor abnormalities that may be of clinical importance. 27,41 Future studies are needed to further evaluate the utility of high-resolution colonic manometry in surgical decision-making in the management of children with intractable FC.