QUANTITATIVE OPTICAL MEASUREMENT OF PELVIC FLOOR MUSCLE FUNCTION IN WOMEN WITH NEUROGENIC BLADDER USING NEAR INFRARED SPECTROSCOPY
G. DEEGAN1, L. STOTHERS 2, A. J. MACNAB 2, M. K. NIGRO 2, D. LAZARE 3;
1Experimental Medicine, University of British Columbia, Blusson Spinal Cord Ctr. - Intl. Collaboration on Repair Discoveries, Vancouver, Canada, 2Urologic Sciences, University of British Columbia, Blusson Spinal Cord Ctr. - Intl. Collaboration on Repair Discoveries, Vancouver, Canada, 3Univ. of British Columbia, Vancouver, Canada.
Introduction: Accurate assessment of pelvic floor muscle (PFM) function is crucial for implementing appropriate management of PFM dysfunction.1 Current devices used for assessment of PFM do not distinguish between right and left musculature. Asymmetrical contraction of PFM may be particularly problematic for patients with neurogenic bladder due to spinal cord injury, as right and left functionality is often affected differently. This study intends to use a near infrared spectroscopy (NIRS) vaginal speculum designed to quantify PFM function and distinguish asymmetry of right and left PFM during voluntary contraction. The NIRS speculum uses continuous wave light emitting diodes at 766nm, 861nm, 906nm and 971nm to detect changes of oxygen concentrations in hemoglobin chromophores in the PFM. Measuring changes in hemoglobin oxygenation provides interpretation of oxygen delivery and consumption occurring directly in the muscle.2 The NIRS speculum will be used to quantify right and left PFM function before and after exercise intervention in females with neurogenic bladder and in continent controls. It is hypothesized that the neurogenic bladder group will have asymmetry and poor PFM function compared to control group and that following the exercise intervention asymmetry and PFM function will improve.
Objective: The objectives of this study are to determine: (1)capability of NIRS to detect oxygen concentration changes of PFM in females with neurogenic bladder, (2)capability of NIRS to distinguish reliable differences between right and left PFM, (3)compare right and left PFM asymmetry between females with neurogenic bladder and controls, (4) capability of NIRS to detect quantifiable changes in PFM function after 8-weeks of home PFM exercise routine, (5) assess qualitative outcomes of PFM exercise in females with neurogenic bladder.
Methods: Ongoing comparative pilot study actively recruiting for total N=30 females, with N=15 in neurogenic bladder group and N=15 in control group. Information collected from subjects includes: urogynecological health history, incontinence symptoms, body mass index, life style index, post-void residual volumes and dipstick urinalysis. Subjects also completed the Questionnaire for Urinary Incontinence Diagnosis, Waterloo Footedness Questionnaire and bladder diaries. Subjects were positioned in the supine position, knees bent and hips flexed with external rotation. Examiner confirmed ability of subject to contract PFM with visual inspection of upward and inward lift of perineum.3 A perineometer was inserted and subject completed set of 3 maximal voluntary contractions (MVC), 1 sustained MVC and set of repeated contractions to fatigue. After 10-minute recovery the NIRS speculum was inserted and the same series of contractions were performed. After 10-minute recovery, perineometer measures were repeated to account for performance fatigue. Subjects were instructed on how to perform PFM exercise routine for completion at home over the course of 8-weeks before follow-up assessment.
Results: Preliminary results of 3 control subjects (32-71 years), yield 30 PFM contractions measured with NIRS and 30 PFM contractions measured with perineometry. The NIRS measurements displayed immediate graphical readings in response to PFM contraction. Statistical analysis performed in Excel using Paired T tests. There was no statistical difference (P>0.05) between the MVCs measured with the perineometer before and after NIRS across all 3 controls. The NIRS measurements showed statistically significant difference in the peak oxygen concentration changes during MVCs between the right and left PFM across all 3 controls: Control 1 (P<0.02), Control 2 (P<0.05) and Control 3 (P<0.01). No statistical difference (P>0.05) found when comparing resaturation rates of right and left PFM across subjects.
Conclusions: Asymmetry of the PFM during voluntary contractions is noted, even in healthy female control subjects. Difference in peak oxygen concentration from right and left PFM suggests a physiological difference in oxygen demand and consumption patterns of the musculature that may be pertinent for conservative and surgical management of pelvic floor dysfunction. Lack of difference found in resautration rates between right and left musculature suggests the muscles have similar oxygen delivery properties, allowing recovery from exercise at similar rates, despite having different oxygen demands during exercise. The immediate NIRS tracings produced in response to PFM function could be beneficial for biofeedback in conservative management for pelvic floor dysfunction and pelvic organ prolapse. These preliminary findings are limited by small sample size of only 3 controls, research is ongoing and requires further analysis.
References: 1 DOI: 10.1007/s00192-016-3123-4 2 DOI: 10.3233/BSI-140091 3 DOI: 10.1002/nau.20798