Constipation and faecal incontinence (FI) are common gastrointestinal disorders, affecting 8-18% of the Western population. These disorders severely impact patients’ quality of life and are associated with a substantial financial burden on health systems. The diagnosis of both of these conditions relies on careful history taking, physical examination, including digital rectal examination, and anorectal physiological testing. When conservative management fails, anorectal biofeedback (BF) treatment is usually the treatment of choice. The aims of this work were to (1) improve the diagnostic algorithms currently used to diagnose and classify patients with chronic constipation and/or FI, and (2) refine and expand the treatment options, mainly BF, for these patients.
Following a comprehensive literature review, data from anorectal physiology testing, namely anorectal manometry and balloon expulsion testing, are examined in both patients and in healthy subjects. The novel findings in this Section inform and guide the optimum methods and metrics for these tests, which are then used to suggest a novel diagnostic phenotype. In the following Section, the long-term efficacy of BF, and the predictors for successful BF treatment - key to improving patient selection and improving access to this effective yet limited resource - are explored. The effect of BF is found to be durable, and factors predicting successful long term treatment outcomes are determined. Next, the role of BF in 'difficult-to-treat' patients, such as patients with spinal cord injury are addressed, and the benefits of treatment in these patient groups, are quantified. Lastly, novel modifications to the BF treatment protocol by either abbreviating or augmenting it with peripheral neuromodulation are shown to be possible alternatives to standard BF treatment.
In summary, the experimental studies undertaken and described in this thesis provide novel insights into the diagnostic and therapeutic aspects of constipation and FI. This work makes a significant contribution to improving patient care and quality of life in these patients whose lives are often severely impacted by these disorders. These studies also provide a firm basis for further research in these areas.