Takagi M1,2, Yamada T2
1Kanagawa University of Human Services, Kanagawa, Japan, 2Tokyo Metropolitan University, Tokyo, Japan
Background: Electrical stimulation is one of the physical therapies for urinary incontinence. Although methods of inserting a probe into the vagina or anus are often used, interferential current (IFC) therapy with surface electrodes is also being performed and has been adopted in Japan. It has been reported that this method improved stress incontinence despite its inability to cause direct contraction of the pelvic floor muscles. Since peripheral stimulation has recently been reported to activate the cerebral cortex, we thought that stimulation may promote contraction of the pelvic floor muscle through the cerebral cortex.
Purpose: Therefore, we investigated whether the cerebral cortex is activated during IFC. Moreover, we compared pelvic floor muscle contraction (PFM) to IFC combined with PFM using functional near-infrared spectroscopy (fNIRS).
Methods: Fifteen female subjects aged 20-41 years participated in this study. The subjects had no history of incontinence and could perform voluntary PFM. We used a continuous-wave NIRS system for functional imaging. We used a 49-channel system with 30 optodes (15 light sources and 15 detectors). After the subjects' 10-20 system benchmarks and fNIRS probe locations were measured using a 3D position measuring system (FASTRAC, Polhemus, USA) and stochastic registration of the Montreal Neurological Institute brain coordinates was performed using NIRS-statistical parametric mapping (SPM), the brain locations corresponding to each channel were identified. During fNIRS data analysis, we used the oxyhemoglobin (oxyHb) levels as markers of cortical activity because oxyHb is the most sensitive indicator of changes in regional cerebral blood flow. Moreover, oxyHb signal changes served as measurements of cortical activation for neurofeedback. After collecting the fNIRS data, signal averaging of the three trials was performed for each condition. Measurement tasks were IFC, PFM, and IFC and PFM combined. Three trials were performed for each condition. For the IFC stimulus, the frequency was set at 50 Hz and the intensity was set up to 20 mA as the maximum. We performed a statistical analysis using a general linear model using NIRS-SPM. The level of significance was set at a p-value of 5%.
[Author1]Supplier information is typically not required in the abstract. Please consider deleting this information here and elsewhere in the document.
Results: In 7 of 15 subjects, a significant increase was observed in oxyHb levels for all conditions. When a group analysis was performed on the 7 subjects, oxyHb increased significantly only in the combination condition. For the combination condition, a significant increase in oxyHb levels was observed in the regions corresponding to BA4, BA5, and BA6.
Conclusion(s): We have shown IFC alone could not activate the cerebral cortex, but when combined with PFM, it activated supplementary motor cortex and motor cortex.
Implications: These results provide new insights into our understanding into the mechanism of motor cortical responses during IFC, PFM, and IFC with PFM.
Keywords: Interfential current, motor cotex, fNIRS
Funding acknowledgements: This study was rented an inertferential current therapy equipment by Medical-taskforce Co.
Purpose: Therefore, we investigated whether the cerebral cortex is activated during IFC. Moreover, we compared pelvic floor muscle contraction (PFM) to IFC combined with PFM using functional near-infrared spectroscopy (fNIRS).
Methods: Fifteen female subjects aged 20-41 years participated in this study. The subjects had no history of incontinence and could perform voluntary PFM. We used a continuous-wave NIRS system for functional imaging. We used a 49-channel system with 30 optodes (15 light sources and 15 detectors). After the subjects' 10-20 system benchmarks and fNIRS probe locations were measured using a 3D position measuring system (FASTRAC, Polhemus, USA) and stochastic registration of the Montreal Neurological Institute brain coordinates was performed using NIRS-statistical parametric mapping (SPM), the brain locations corresponding to each channel were identified. During fNIRS data analysis, we used the oxyhemoglobin (oxyHb) levels as markers of cortical activity because oxyHb is the most sensitive indicator of changes in regional cerebral blood flow. Moreover, oxyHb signal changes served as measurements of cortical activation for neurofeedback. After collecting the fNIRS data, signal averaging of the three trials was performed for each condition. Measurement tasks were IFC, PFM, and IFC and PFM combined. Three trials were performed for each condition. For the IFC stimulus, the frequency was set at 50 Hz and the intensity was set up to 20 mA as the maximum. We performed a statistical analysis using a general linear model using NIRS-SPM. The level of significance was set at a p-value of 5%.
[Author1]Supplier information is typically not required in the abstract. Please consider deleting this information here and elsewhere in the document.
Results: In 7 of 15 subjects, a significant increase was observed in oxyHb levels for all conditions. When a group analysis was performed on the 7 subjects, oxyHb increased significantly only in the combination condition. For the combination condition, a significant increase in oxyHb levels was observed in the regions corresponding to BA4, BA5, and BA6.
Conclusion(s): We have shown IFC alone could not activate the cerebral cortex, but when combined with PFM, it activated supplementary motor cortex and motor cortex.
Implications: These results provide new insights into our understanding into the mechanism of motor cortical responses during IFC, PFM, and IFC with PFM.
Keywords: Interfential current, motor cotex, fNIRS
Funding acknowledgements: This study was rented an inertferential current therapy equipment by Medical-taskforce Co.
Topic: Electrophysical & isothermal agents
Ethics approval required: Yes
Institution: Tokyo Metropolitan University
Ethics committee: Research Safety Ethics Review Committee
Ethics number: 18003
All authors, affiliations and abstracts have been published as submitted.
