LEVATOR ANI MUSCLE IN WOMEN WITH GENITOURINARY PROLAPSE - INDIRECT ASSESSMENT BY MUSCLE HISTOPATHOLOGY

The objective of this study was to assess the state of innervation in levator ani muscle sites using muscle histopathology. Asymptomatic wom en and patients with genitourinary prolapse were included. Histopathol ogic analysis allows indirect assessment of a muscle's innervation. Th erefore, levator ani muscle was collected in a standardized fashion du ring abdominal surgery and frozen in the operating room using isopenta ne slush cooled by liquid nitrogen. Serial sections of levator ani mus cle in cross-section were studied with standard histochemical and immu nohistochemical techniques. The staining patterns from these histochem ical techniques allowed quantitative determination of the ratios of fi ber types I, IIA, and IIB and their fiber diameters. Objective assessm ent of fiber type grouping was performed. The distribution of both fib er type percentage and diameter were non-parametric. Therefore, the Ma nn-Whitney U-test was used to analyze the data for statistical differe nces between the means for these variables. There was no statistical d ifference in levator ani muscle fiber type percentage and diameter in patients with prolapse and/or urinary incontinence when compared to as ymptomatic women. Levator ani muscles have a higher proportion of slow fibers (66%) than found in other human female muscle (48%). There was no evidence for denervation/reinnervation in any of the biopsy specim ens. In this study, levator ani muscle biopsies from incontinent and/o r prolapse patients were neither denervated nor reinnervated. (C) 1995 Wiley-Liss, Inc.