The MAPLe is a reliable instrument measuring the EMG signals of the different sides and levels nearest to the pelvic floor musculature and is capable to differentiate between men and women, nulliparous, parous, pre- and postmenopausal. The findings of this study have implications for the diagnosis and treatment of pelvic floor dysfunction in the future.
EMG BAPFMT is effective in the OAB syndrome in women. It significantly reduces symptoms and complaints of OAB and increases QoL for patients. It shows that EMG changes in individual PFM, measured with the MAPLe, are relevant and related to symptom reduction.
Purpose
Sacral neuromodulation (SNM) is an established minimally invasive therapy for functional disorders of the pelvic organs in which electrodes are stimulated in proximity of the sacral spinal nerves. Reprogramming of the electrodes is regularly required and is based on the sensory response. This study assesses the repeatability of a pelvic chart and grading system to enable a more objective assessment of the sensory response upon electrode stimulation.
Material and Methods
In 26 SNM patients, with OAB or NOUR, assessment of the sensory response was done using the sensory threshold (ST) and a pelvic chart with 1 cm2 coordinates, each coordinate corresponding with a dermatome and location of sensation (LoS). A grading system was developed based upon the ST and LoS. Repeatability of ST was assessed using a two‐way mixed effects, absolute agreement, single rater/measurement intraclass correlation coefficient (ICC), and displayed using a correlation and Bland Altman plot. Repeatability of dermatomes, LoS, and grading system was assessed using kappa correlation coefficient.
Results
On average, 1.55 ± 0.85 coordinates were used to point out the area where the stimulation was perceived. The mean amount of coordinates between the area pointed at during the first and second measurement was 0.47 ± 0.74. ST showed excellent repeatability (ICC 0.93, 95%CI 0.90‐0.94, P < 0.001). Dermatomes, LoS and grading system showed a substantial to almost perfect agreement (κ = 0.740‐0.833, P < 0.001).
Conclusions
The pelvic chart and grading system, using the sensory response upon electrode stimulation, are repeatable tools and can be used to assist in follow up and troubleshooting of SNM patients.
Background
In sacral neuromodulation (SNM) patients, it is thought the bellows response elicited upon sacral spinal nerve stimulation is reflex‐mediated. Therefore the mechanism of action of SNM is considered to be at the spinal or supraspinal level. These ideas need to be challenged.
Objective
To identify the neural pathway of the bellows response upon sacral spinal nerve stimulation.
Design, Setting, and Participants
Single tertiary center, prospective study (December 2017‐June 2019) including 29 patients with overactive bladder refractory to first‐line treatment.
Intervention
Recording of the pelvic floor muscle response (PFMR) using a camcorder and electromyography (EMG) (intravaginal probe and concentric needles) upon increasing stimulation during lead or implantable pulse generator placement.
Outcome Measurements and Statistical Analysis
The lowest stimulation intensity needed to elicit a visual PFMR and electrical PFMR was determined. Electrical PFMRs were subdivided according to their latency.
Outcome: the association between visual and electrical PFMRs. Statistical analyses were performed using the weighted kappa coefficient.
Results
Three different electrical PFMRs could be identified by surface and needle EMG, corresponding with a direct efferent motor response (R1), oligosynaptic (R2), and polysynaptic (R3) afferent reflex response.
Only the R1 electrical PFMR was perfectly associated with the visual PFMR (κ = 0.900).
Conclusions
The visual PFMRs upon sacral spinal nerve stimulation are direct efferent motor responses. A reopening of the discussion on the mechanism of action of SNM is possibly justified.
Purpose
To assess the activation of the different parts of the pelvic floor muscles (PFM) upon electrical stimulation of the sacral spinal nerves while comparing the different lead electrode configurations.
Material and Methods
PFM electromyography (EMG) was recorded using an intravaginal multiple array probe with 12 electrodes pairs, which allows to make a distinction between the different sides and depths of the pelvic floor. In addition concentric needle EMG of the external anal sphincter was performed to exclude far‐field recording. A medtronic InterStim tined lead (model 3889) was used as stimulation source. Standard SNM parameters (monophasic pulsed square wave, 210 microseconds, 14 Hz) were used to stimulate five different bipolar electrode configurations (3+0−/3+2−/3+1−/0+3−/1+3−) up to and around the sensory threshold. Of each EMG signal the stimulation intensity needed to evoke the EMG signals as well as its amplitude and latency were determined. Linear mixed models was used to analyse the data.
Results
Twenty female patients and 100 lead electrode configurations were stimulated around the sensory response threshold resulting in 722 stimulations and 12 times as many (8664) EMG recordings. A significant increase in EMG amplitude was seen upon increasing stimulation intensity (P < .0001). Large differences were noted between the EMG amplitude recorded at the different sides (ipsilateral>posterior>anterior>contralateral) and depths (deep>center>superficial) of the pelvic floor. These differences were noted for all lead electrodes configurations stimulated (P < .0001). Larger EMG amplitudes were measured when the active electrode was located near the entry point of the sacral spinal nerves through the sacral foramen (electrode #3). No differences in EMG latency could be withheld, most likely due to the sacral neuroanatomy (P > .05).
Conclusions
A distinct activation pattern of the PFM could be identified for all stimulated lead electrode configurations. Electrical stimulation with the most proximal electrode (electrode #3) as the active one elicited the largest PFM contractions.
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