Dorsal root ganglia atrophy and serum biomarkers supporting the diagnosis of chronic postsurgical inguinal pain

Background: Chronic postsurgical inguinal pain (CPIP) is the most common complication of groin hernia surgery. The characteristics of patients, their medical care, and choice of the best diagnostic tools remain to be defined to optimize preventive and therapeutic interventions. Methods: Claims data from 2018 and a 1-year follow-up were analysed and deep phenotyping including sensory testing, blood and skin biopsies, MRI imaging of the dorsal root ganglion (DRG), and patient-reported outcomes were used to define normative values, as well as incidence, medical care, and pathophysiological factors. Results: 11,221 patients with hernia surgery in 2018 were identified; 8.5% had pain before which was relieved by surgery, but a similar percentage had novel groin pain. Deep phenotyping of 141 healthy controls provided a map of the inguinal sensory system. CPIP patients suffered from moderate pain with neuropathic features, individual sensory abnormalities, and unilateral L1 DRG atrophy. In the blood, C-C-motif chemokine ligand (CCL2) and brain-derived neurotrophic factor (BDNF) were upregulated while apolipoprotein A1 (ApoA1) was reduced. A cluster of DRG atrophy, BDNF, ApoA1 and anxiety correlated best with the diagnosis. CPIP patients with novel pain had significantly more DRG atrophy (-22% ipsi vs. contra). Conclusion: CPIP is relevant and often newly acquired after surgery. A combination of DRG imaging, serum markers, and anxiety screening can support the diagnosis. Using this core set of markers could guide surgeons towards more personalized therapies and possible preventive intraoperative techniques. Trial registration: German Trial Registry DRKS00024588 and DRKS00016790