Gulf War Illness (GWI) is presented by a number of health symptoms, among them pain complaints and gastro-intestinal (GI) issues in returning veterans who have served in the Persian Gulf War.
Veteran groups compared
A study by Zhou et al. from 2018 utilizing Medoc’s TSA-II used QST and compared between veterans suffering from GWI with GI complaints (GWI+GI), veterans with GWI without GI complaints, and healthy veterans.
The experimental pain tests comprised of: Heat Pain Threshold, Cold Pressor Threshold, Ischemic Pain Threshold and Ischemic Pain Tolerance. Veterans with GWI+GI had significantly lower heat pain thresholds and cold pressor thresholds as compared to healthy veterans and veterans with GWI but no GI symptoms.
Correlation between experimental pain measures and clinical pain
There was no significant difference between healthy veterans and veterans with GWI, but no GI symptoms. For the ischemic pain threshold and tolerance test both GWI veterans groups reached their respective levels before the healthy veterans. Moreover, average daily abdominal pain in GWI+GI veterans was significantly correlated with the experimental pain measures.
Possible conversion between visceral and somatic pathways
These findings of increased pain sensitivity and their connection to GI symptoms in GWI veterans may point to convergence of visceral and somatic pain pathways, authors hypothesize.
Zhou, Q., Verne, M. L., Zhang, B., & Verne, G. N. (2018). Evidence for somatic hypersensitivity in veterans with Gulf War Illness and gastrointestinal symptoms. The Clinical journal of pain, 34(10), 944.