Validated measures of reoxygenation recovery following voluntary muscle contraction are used in sports medicine to quantify function and evaluate effects of exercise training regimens. However, international guidelines for pelvic floor muscle (PFM) dysfunction currently lack oxygen kinetic measures. HYPOTHESIS: In women, with NLUTD due to partial spinal cord injury, residual neural function in the pelvic floor muscle can be identified using a rehabilitation regimen with pre and post quantification of half recovery time of reoxygenation following sustained maximal voluntary contraction (SMVC).  AIMS: develop a bidirectional vaginal interface & determine feasibility of using half-recovery time of hemoglobin difference  [HbDiff(½RT)] following SVMC to quantify PFM function in neurogenic lower urinary tract dysfunction (NLUTD).

N=20 women (7 cases UI & NLUTD; 13 asymptomatic controls) were evaluated at a tertiary care spinal cord injury (SCI) referral centre before and after 8 weeks of home-based PFM exercise therapy (PFMT). Clinical assessment included physical examination, perineometry, bladder diary & questionnaires (Qualiveen & UGDI-6); a vaginal speculum incorporating a near infrared emitter/detector interface monitored changes in oxygenated and deoxygenated hemoglobin concentration through SMVC. From these data the validated measure of post SMVC reoxygenation HbDiff(½RT) were calculated; data sets were compared within individuals and between clinical groups. 

Shown in figure 1: The right and left sides of a vaginal speculum housing the NIRS interface and a schematic of NIR photon transmission into the PFM.

HbDiff(½RT) data sets were obtained from all 7 symptomatic women; a post training treatment effect was deemed evident where HbDiff(½RT) shortened, indicating improved PFM reoxygenation (‘fitness’). Figure 2 shows data from a female subject with NLUTD secondary to an incomplete traumatic spinal cord injury, who had no detectable PFM contractile ability on initial clinical evaluation or her NIRS assessment of pelvic floor muscle voluntary contraction. However, in this subject following a 10 week home based PFMT regimen, taught be a health professional in a hospital setting initially, the NIRS measurement parameter employed enabled evidence of a unilateral left-sided improvement post-PMFT to be detected.

Figure  2 demonstrates composite graphs of NIRS data from the Right and Left PFM during SMVC and recovery at baseline and post-PFMT (the SMVC starts at 10 secs). The changes in chromophore concentration indicate unilateral improvement in the magnitude of contraction and reoxygenation kinetics in the Left side of the PFM after PFMT.

The changes in chromophore concentration in the graphs shown in figure 2 indicate unilateral improvement in the magnitude of contraction and reoxygenation kinetics in the Left side of the PFM after PFMT. This change from baseline assessment indicates that partial innovation was present in this subject and that a training effect from a 10 week PFMT regimen occurred with improvement in muscle strength and function.

A validated NIRS-derived reoxygenation parameter provides a quantifiable oxygen kinetic parameter of PFM ‘fitness’ applicable to measuring training effects from PFMT in NLUTD; PFM vaginal NIRS evaluation may aid application and evaluation of PMFT in this population to measure training effects from rehabilitation exercise, to improve management of symptomatic NLUTD.