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Characterizing pelvic floor muscles activities using magnetomyography
Author(s) -
EscalonaVargas Diana,
Oliphant Sallie,
Siegel Eric R.,
Eswaran Hari
Publication year - 2019
Publication title -
neurourology and urodynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 90
eISSN - 1520-6777
pISSN - 0733-2467
DOI - 10.1002/nau.23870
Subject(s) - pelvic floor , amplitude , electromyography , root mean square , receiver operating characteristic , medicine , spectral density , anatomy , contraction (grammar) , physics , nuclear magnetic resonance , physical medicine and rehabilitation , mathematics , statistics , optics , quantum mechanics
Aims To characterize levator ani muscle (LAM) activity in nulligravidas using magnetomyography (MMG) and define MMG characteristics associated with LAM activity with and without accessory muscle contributions. Methods MMG data were collected from eight nulligravidas during rest and voluntary LAM contractions (Kegels) of varying intensity. We utilized simultaneous vaginal manometry and surface electromyography (sEMG) to evaluate for accessory muscle recruitment. Moderate Kegel (MK) MMG trials were sub‐selected based on the presence or absence of accessory muscle interaction. Amplitude and spectral‐related indicators were calculated across MK epochs: root‐mean square (RMS) amplitude, percentage amplitude relative to rest, and relative power spectrum density (rPSD) in three frequency bands (low, middle, high). Ternary diagram characterized rPSD from selected Kegels and ROC analysis was performed to identify cut‐points to differentiate MKs from interacting MKs. Results Nineteen MMG recordings were obtained. Amplitude and spectral parameters were significantly different between isolated and interacting MK epochs. Mean RMS and power values of the isolated MK were, respectively, 120.66 ± 43.8 fT and 1.72 ± 1.44 (T 2 /Hz)*10 −28 . Amplitudes of MK were 64% and 117 higher than baseline activities for the isolated and interacting epochs, respectively. ROC curves reveled cut‐off points on low and middle frequency bands that achieved perfect separation (ROC‐AUC = 1.0) between isolated and interacting MK. Conclusions Our study demonstrates that MMG, a novel biomagnetic technique, allows precise detection and characterization of normal female pelvic floor function. Results show that isolated moderate voluntary contraction of the LAMs produces distinct MMG amplitude and spectral characteristics compared with Kegels involving co‐activation of other muscle groups.