Abstract
To The Editor:
Case Report
The case presented here was a 12-year-old boy referred to our clinic with complaints of fecal incontinence almost every day throughout his life, and excessive cleanliness for the previous 6 months. He had had a colon operation when he was 10 months of age because of Hirschsprung's disease. According to his mother, he had not been constipated after the operation. In 2008 and 2012, the patient had undergone colonoscopies to investigate the origin of his encopretic symptoms, but no cause could be found to explain them. There were no pathological findings on physical examination. The patient was diagnosed as having primary encopresis, non-retentive type, and obsessive-compulsive disorder (OCD) according to the American Psychiatric Association, Diagnostic and Statistical Manual of Mental Disorders, 4th ed., Text Revision DSM-IV-TR criteria (American Psychiatric Association 2000). Imipramine 25 mg/day was initiated. Behavioral therapy, including psychoeducation, toilet sitting, and scheduling was begun concomitantly for encopresis, biweekly. Because the patient's encopretic and OCD symptoms did not improve, sertraline 25 mg/day was added 2 months later. During the follow-up at 1 year, the patient's OCD symptoms had decreased, but the encopresis symptoms had not changed. After 1 year of treatment, sertraline and imipramine treatment was terminated. Although the patient did not meet DSM-IV-TR criteria for ADHD (met one of nine attention-deficit criteria and none of nine hyperactivity/impulsivity criteria) (American Psychiatric Association 2000), the extended release form of methylphenidate 27 mg/day was started, based on the findings of our recent study, which showed that the effectiveness of methylphenidate on coexisting encopresis is unrelated to improvement in core ADHD symptoms in children with ADHD (Yılmaz, 2013). After administering the drug, the encopretic symptoms disappeared rapidly and never recurred over 2 months of follow-up.
Discussion
Treatment of encopresis with imipramine and sertraline has been reported previously. However, these drugs did not affect the encopresis symptoms in our case. This may be related to the low dose of these drugs that was administered. Methylphenidate brought about improvement in non-retentive encopretic symptoms in our case. Some authors suggest that the antiencopretic effects of methylphenidate, imipramine, or atomoxetine may be related to the direct impact they have on executive functioning, self-organizing skills, and impulse control, which enable children to recognize and respond to internal cues to defecate (Golubchik and Weizman 2009); on the other hand, the positive effects of ADHD drugs may be secondary to the resolution of child–parent relationship conflicts and poor social and school functioning (Bilgiç 2011). However, in our case, there were no attention, cognitive, or behavioral problems. Moreover, in a recent study, we evaluated patients treated with methylphenidate retrospectively and found no association between improvement in attention, hyperactivity, or behavioral problems and improvement in encopretic symptoms (Yılmaz, 2013). This study and our case indicate that the effect of methylphenidate on encopresis is different from the effect on ADHD symptoms such as attention deficits or behavioral problems. In a recent study, it was reported that amphetamine, which has similar effects to methylphenidate, reduced the gastric emptying and intestinal motility via D1 and D2 receptors in rats (Huang 2012). Dopamine is known to be effective in gastrointestinal system (GIS) motility, and the GIS contains D1 and D2 receptors (Li 2006). Furthermore, encopresis is generally related to intestinal dysfunctions (Mikkelsen 2002).
Conclusion
The antiencopretic effects of methylphenidate may be related to its impact on cognitive functions. On the other hand, methylphenidate may act by altering GIS motility because of its peripheral effects. Future studies investigating the peripheral effects of methylphenidate on the GIS will improve our knowledge of this topic.