Localization of the nerves innervating the pelvic floor muscles: An application to pelvic pain treatment.

The aim of this study was to achieve accurate localization of the body surface position and depth of the center of the intramuscular nerve dense region (CINDR) of the pelvic floor muscles and to establish a target site for treating pelvic floor muscle spasm or weakness. Thirty-six adult cadavers were studied in the prone position. To locate the CINDR of the levator ani and coccygeus muscles, horizontal (H) and longitudinal (L) reference lines were used. Sihler's staining revealed the intramuscular nerve dense region of the pelvic floor muscles. The CINDR was labeled with barium sulfate and spiral computed tomography scanning, and three-dimensional reconstructions were obtained. The anterior and posterior CINDR projection points (P and P'), the position of point P projected on to the H and L lines (P and P ), and the CINDR depth were determined using the Syngo system. The P of the CINDR of the levator ani and the coccygeus muscle were located at (24.73 ± 0.17)% and (15.93 ± 0.31)% of the H line, respectively. The P were located at (84.30 ± 2.47)% and (6.76 ± 0.93)% of the L line. The puncture depth of the levator ani muscle was located at (5.56 ± 0.53) cm, and the depth of the coccygeus muscle at (22.08 ± 2.11)% of the PP' line. The body surface position and depth of the CINDR of the pelvic floor muscles were conducive to locating the target more efficiently and enhancing the efficacy of botulinum toxin A injection for treating pelvic floor muscle spasm and weakness with electrical stimulation or biofeedback.