Spastic pelvic floor syndrome (dyssynergic defaecation)

Case Discussion

Spastic pelvic floor syndrome is one of the major causes of chronic constipation. It is a functional disorder characterised by involuntary and paradoxical contraction of the puborectalis muscle during defaecation. The puborectalis muscle fails to relax during defaecation, resulting in a decreased anorectal angle during defaecation and leading to prolonged and incomplete evacuation. Anterior rectocele is often associated with this condition.

Sometimes spastic pelvic floor syndrome or dyssynergic defaecation may be associated with psychological distress.

The diagnosis can be confirmed by a clinical history of constipation, manometric evaluation and abnormal colorectal test such as a defaecogram or balloon expansion test.

Reiner et al.(2011) observed that MR defaecogram is highly sensitive (100%) for diagnosing dyssynergic defaecation. However, the specificity is only 23%. Combined analysis of anorectal angle and paradoxical sphincter contraction were proved to be very effective for diagnosing dyssynergic defaecation or spastic pelvic floor syndrome.

In this case the patient had chronic constipation, the anorectal angle was significantly reduced and there was a lack of puborectalis sling relaxation. So, the clinical and radiological features suggest the diagnosis of spastic pelvic floor syndrome. However, it must be noted that due to the low specificity of MRI, and the fact that these findings can be easily mimicked by situational anxiety caused by the MRI environment, fluoroscopic proctography is the preferred technique to make this diagnosis.