S Haas1,2, P M Faaborg3,4, M Gram5, L Lundby6,4, C Brock5, A M Drewes5,4, S Laurberg6,4, K Krogh7,4, P Christensen6,4. 1. Department of Surgery, Aarhus University Hospital, Palle Juul-Jensens Blvd 99, 8200, Århus N, Denmark. susahaas@rm.dk. 2. Danish Cancer Society Centre for Research and Late Adverse Effects After Cancer in the Pelvic Organs, Aarhus and Aalborg University Hospitals, Aalborg, Denmark. susahaas@rm.dk. 3. Department of Surgery, Vejle Hospital, Vejle, Denmark. 4. Danish Cancer Society Centre for Research and Late Adverse Effects After Cancer in the Pelvic Organs, Aarhus and Aalborg University Hospitals, Aalborg, Denmark. 5. Mech-Sense, Department of Gastroenterology and Hepatology, Clinical Institute, Aalborg University Hospital, Aalborg, Denmark. 6. Department of Surgery, Aarhus University Hospital, Palle Juul-Jensens Blvd 99, 8200, Århus N, Denmark. 7. Neurogastroenterology Unit, Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aalborg, Denmark.
Abstract
BACKGROUND: Bowel dysfunction is common after surgery for rectal cancer, especially when neoadjuvant radiotherapy is used. The role of sensory function in the pathogenesis remains obscure, and the aim of the present study was to characterize the sensory pathways of the brain-gut axis in rectal cancer patients treated with resection ± radiotherapy compared with healthy volunteers. METHODS: Sensory evaluation by (neo)rectal distensions was performed and sensory evoked potentials (SEPs) were recorded during rapid balloon distensions of the (neo)rectum and anal canal in resected patients with (n = 8) or without (n = 12) radiotherapy. Twenty healthy volunteers were included for comparison. (Neo)rectal latencies and amplitudes of SEPs were compared and spectral band analysis from (neo)rectal and anal distensions was used as a proxy of neuronal processing. RESULTS: Neorectal sensation thresholds were significantly increased in both patient categories (all p < 0.008). There were no differences in (neo)rectal SEP latencies and amplitudes between groups. However, spectral analysis of (neo)rectal SEPs showed significant differences between all groups in all bands (all p < 0.01). On the other hand, anal SEP analyses only showed significant differences between the delta (0-4 Hz), theta (4-8 Hz) and, gamma 32-50 Hz) bands (all p < 0.02) between the subgroup of patients that also received radiotherapy and healthy volunteers. CONCLUSIONS: Surgery for rectal cancer leads to abnormal cortical processing of neorectal sensation. Additional radiotherapy leads to a different pattern of central sensory processing of neorectal and anal sensations. This may play a role in the functional outcome of these patients.
BACKGROUND:Bowel dysfunction is common after surgery for rectal cancer, especially when neoadjuvant radiotherapy is used. The role of sensory function in the pathogenesis remains obscure, and the aim of the present study was to characterize the sensory pathways of the brain-gut axis in rectal cancerpatients treated with resection ± radiotherapy compared with healthy volunteers. METHODS: Sensory evaluation by (neo)rectal distensions was performed and sensory evoked potentials (SEPs) were recorded during rapid balloon distensions of the (neo)rectum and anal canal in resected patients with (n = 8) or without (n = 12) radiotherapy. Twenty healthy volunteers were included for comparison. (Neo)rectal latencies and amplitudes of SEPs were compared and spectral band analysis from (neo)rectal and anal distensions was used as a proxy of neuronal processing. RESULTS:Neorectal sensation thresholds were significantly increased in both patient categories (all p < 0.008). There were no differences in (neo)rectal SEP latencies and amplitudes between groups. However, spectral analysis of (neo)rectal SEPs showed significant differences between all groups in all bands (all p < 0.01). On the other hand, anal SEP analyses only showed significant differences between the delta (0-4 Hz), theta (4-8 Hz) and, gamma 32-50 Hz) bands (all p < 0.02) between the subgroup of patients that also received radiotherapy and healthy volunteers. CONCLUSIONS: Surgery for rectal cancer leads to abnormal cortical processing of neorectal sensation. Additional radiotherapy leads to a different pattern of central sensory processing of neorectal and anal sensations. This may play a role in the functional outcome of these patients.