Login to Access Video or Poster Abstract: MP26-12
Sources of Funding: This study was supported by NIH DK082644, Society of Urodynamics Female Pelvic Medicine and Urogenital Reconstruction, and the University of Houston.

Introduction

Motor unit number estimation (MUNE) techniques estimate the number of functioning motor units (MUs) in a muscle, and serve as a biomarker for neuromuscular and muscular atrophy. Application of current MUNE techniques to the pelvic floor is impractical because of the need for either multiple stimulations or invasive needle electrodes. The objective is to propose a novel MUNE technique applicable to pelvic floor muscles, by combining a high-density surface EMG (HD-sEMG) decomposition approach with pudendal nerve stimulation, negating the need for invasive needles or multiple stimulations.

Methods

All procedures were approved by UH IRB. The pudendal nerve was stimulated transrectally with a St. Mark&[prime]s electrode mounted on the operator&[prime]s glove. HD-sEMG recordings were acquired from the puborectalis muscle with a vaginal EMG probe (Figure 1b) during supramaximal stimulation and three maximal voluntary contractions of pelvic floor muscles. Firstly, single motor unit action potentials (SMUPs) were decomposed from EMG recordings during muscle contraction using our recently developed K-Means Clustering Convolution Kernel Compensation (KmCKC) Algorithm. All SMUPs were grouped into left or right side by visually checking their innervation zone locations following an established procedure. Next, mean SMUPs were derived for both sides by averaging all HD-sEMG profiles of grouped SMUPs. Last, MUNE was calculated as the weighted average of compound muscle action potential (CMAP) size to mean SMUP size ratios for both sides.

Results

Left and right branches of the pudendal nerve were simulated. Four SMUPs were decomposed from HD-sEMG signals (left: 3 and right: 1). MUNE for the left and right sides were 22.8 and 27.0, respectively.

Conclusions

This pilot study proves the feasibility of a novel MUNE technique for muscles in the pelvic floor region. The KmCKC algorithm enables a non-invasive collection of SMUPs, negating the need for repeated electrical stimulation or invasive needle electrodes. Results from more subjects will be available from our ongoing subject recruitment.

Funding

This study was supported by NIH DK082644, Society of Urodynamics Female Pelvic Medicine and Urogenital Reconstruction, and the University of Houston.