Haas, S8; Brock, C3; Krogh, K9; Gram, M3; Nissen, T D5; Lundby, L9; Laurberg, S10; Drewes, A M1
1 Center for Sensory-Motor Interaction, The Faculty of Medicine, Aalborg University, VBN2 Department of Health Science and Technology, The Faculty of Medicine, Aalborg University, VBN3 Klinik Medicin, The Faculty of Medicine, Aalborg University, VBN4 Medicinske Mave- og Tarmsygdomme (Gastroenterologi og Hepatologi), The Faculty of Medicine, Aalborg University, VBN5 Aalborg University Hospital, The Faculty of Medicine, Aalborg University, VBN6 The Faculty of Medicine, Aalborg University, VBN7 Mech-Sense, The Faculty of Medicine, Aalborg University, VBN8 Department of Surgery, Aarhus University Hospital, Denmark.9 unknown10 Department of Architecture & Design, The Faculty of Engineering and Science, Aalborg University, VBN
BACKGROUND: Neurophysiological evaluation of anorectal sensory function is hampered by a paucity of methods. Rapid balloon distension (RBD) has been introduced to describe the cerebral response to rectal distension, but it has not successfully been applied to the anal canal. METHODS: Nineteen healthy women received 30 RBDs in the rectum and the anal canal at intensities corresponding to sensory and unpleasantness thresholds, and response was recorded as cortical evoked potentials (CEPs) in 64-channels. The anal canal stimulations at unpleasantness level were repeated after 4 min to test the within-day reproducibility. CEPs were averaged, and to overcome latency variation related to jitter the spectral content of single sweeps was also computed. KEY RESULTS: Repeated stimulation of the anal canal generated CEPs with similar latencies but smaller amplitudes compared to those from the rectum. Due to latency jitter, reproducibility of averaged CEPs was lower than what was found in the rectum. The most reproducible feature was N2P2 peak-to-peak amplitude with intra-class correlation coefficient (ICC) of 0.7 and coefficient of variation (CV) of 18%. Spectral content of the single sweeps showed reproducibility with ICCs for all bands >0.8 and corresponding CVs <7%. CONCLUSIONS & INFERENCES: Cortical potentials evoked from the anal canal are challenged by latency jitter likely related to variability in muscle tone due to the distensions. Using single-sweep analysis, anal CEPs proved to be reproducible and should be used in future evaluation of the anal function.
Neurogastroenterology and Motility, 2014, Vol 26, Issue 6, p. 862-873