D. Van Rijckevorsel1, O. Boelens2, R. Roumen3,6, O. Wilder-Smith4,5, H. Van Goor1 1Radboud University Medical Center,Department Of Surgery,Nijmegen, , Netherlands 2Maasziekenhuis Pantein,Department Of Surgery,Boxmeer, , Netherlands 3Máxima Medical Center,Department Of Surgery,Veldhoven, , Netherlands 4Radboud University Medical Center,Department Of Anesthesiology, Pain And Palliative Medicine,Nijmegen, , Netherlands 5Aalborg University,Center For Sensory-Motor Interaction,Aalborg, , Denmark
Introduction:
Anterior Cutaneous Nerve Entrapment Syndrome (ACNES) is a common cause of chronic abdominal pain, refractory to local treatment in about 25% of cases for yet unknown reasons. We aimed to assess central pain processing after ACNES treatment and possible relationships between central pain processing and treatment outcomes by performing Quantitative Sensory Testing (QST).
Methods:
50 patients treated for ACNES with locally oriented treatment were tested. They were allocated to a responsive or refractory group based on response to treatment. Patients showing an improvement of the Visual Analogue Scale (VAS) pain score combined with an absolute VAS of < 40 were scored as responsive.
Thresholds to pressure and electric skin stimulation were determined in the ACNES dermatomes and four control areas. Conditioned pain modulation (CPM) response to a cold pressor task was determined. Patients filled in three pain-related psychological questionnaires.
Results:
Patients refractory to treatment showed significantly lower pressure pain thresholds in multiple dermatomes. No differences were found between groups for electric thresholds or CPM response. Duration of complaints before diagnosis and treatment was significantly longer in the refractory compared to the responsive group, and scores on pain-related questionnaires were higher.
Conclusion:
ACNES patients refractory to treatment have more signs of sensitized central pain processing and a longer duration of complaints before diagnosis and treatment. It appears that the presence of sensitized central pain processing is associated with less effective locally-orientated treatment.