Opioid-refractory rectal tenesmus treated with burst ketamine.

A man with severe rectal tenesmus caused by rectal carcinoma, whose pain was difficult to manage due to adverse effects from several medications, experienced reduced pain after a seven-day continuous subcutaneous infusion of ketamine combined with midazolam and dexamethasone. His self-reported pain scores improved, and his opioid requirements decreased. This is the first reported use of ketamine for rectal tenesmus.

Study at a glance

Abstract

Rectal tenesmus is the painful sensation of incomplete evacuation of the bowels, which is distressing and difficult to manage. Tenesmus is often caused by rectal carcinoma. It is thought there is a significant neuropathic component to tenesmus pain. Ketamine is an antagonist to the N-methyl D-aspartate receptor and has been used for neuropathic pain. We describe the case of a man with difficult-to-manage rectal tenesmus who experienced adverse effects to several medications, limiting titration. A trial of 'burst' ketamine over seven days via a continuous subcutaneous infusion, combined with midazolam and dexamethasone, resulted in a decrease in his pain, as shown by his improved self-reported pain scores and reduced PRN and background opioid requirements. To the authors' knowledge, this is the first report of using ketamine for rectal tenesmus.