Nerve-stimulator-guided pudendal nerve block by pararectal approach.

Aim: Various techniques have been described for performing a pudendal nerve block (PNB) and have associated problems such as multiple needle injections, the need for special equipment and consumption of time. This study aimed to describe a nerve-stimulator-guided PNB using a pararectal approach and to evaluate the safety and the efficacy of that procedure.

Method: We conducted a prospective study of 53 patients who underwent a PNB from December 2009 to July 2010. With the index finger of the left hand inserted into anus, we guided the nerve stimulator needle along the second finger tip on the ischial spine to the site where the maximal contraction of the external anal sphincter could be felt. Once the position of the needle tip had been confirmed, the desired drug was injected. Of the 53 patients, a cohort of eight underwent manometry before and after the pudendal block.

Results: A total of 53 patients underwent the nerve-stimulator-guided procedure: 13 patients for pudendal neuralgia and the other 40 patients for anorectal disease. The mean maximal resting and squeezing pressures before the block were 55 and 161 mmHg, respectively, compared with 35 and 67 mmHg after the block. The PNB took just minutes to perform, was well tolerated by the patients, and resulted in neither severe complications nor repeated attempts.

Conclusion: Nerve-stimulator-guided PNB using a pararectal approach proved to be easy and safe, with acceptable patient tolerance. In addition, it can be used for a variety of anorectal procedures where relaxation of anal tone is required.