Repeatability of innervation zone identification in the external anal sphincter muscle
- Publication date
- Publisher
- 'Wiley'
Abstract
Knowledge of the distribution of the innervation zones (IZs) of the external anal sphincter (EAS) may be
useful for preventing anal sphincter incompetence during vaginal delivery. A method proposed for the automatic
estimation of the distribution of IZs of EAS from high-density surface electromyography (EMG) was evaluated for
repeatability in continent volunteers. Methods: In 13 healthy female subjects (age: 35 11 years) surface EMG
signals were acquired using an anal probe with three circumferential electrode arrays (of 16 contacts each) at
different depths within the anal canal (15mm distance between the centers of adjacent arrays), during four
independent experimental sessions. Three maximal voluntary contractions (MVCs) of 10 sec were performed for
each session for a total of 12 contractions per subject. Repeatability of the estimation of the distribution of IZ was
tested by evaluating the coefficient of multiple correlations (CMC) between the IZ distributions estimated from the
signals recorded from each subject. Results: A high repeatability (CMC > 0.8) was found comparing IZ distributions
estimated from signals recorded by each array within the same session. A slightly lower value was obtained
considering signals recorded during different sessions (CMC > 0.7), but a higher value (CMC > 0.8) was obtained
after aligning the estimated IZ distributions. The realignment compensates for the operator’s error in repositioning
the probe in the same position during different sessions. Conclusion: This result justifies clinical studies using
high-density surface EMG in routine examinations, providing information about IZs of EAS and assessing the
possibilities of preventing neuronal trauma during vaginal delivery