Pre-operative pain and sensory function in groin hernia.
BACKGROUND
Although persistent postherniotomy occurs in 5-10% of patients, pathogenic mechanisms remain debatable. Since pre-operative pain has been demonstrated to be a risk factor for persistent postherniotomy pain, pre-operative alterations in nociceptive function may be a potential pathogenic mechanism.


OBJECTIVE
To investigate the correlation between pre-operative pain intensity and sensory functions in the groin hernia area.


METHODS
Patients with unilateral groin hernia were examined preoperatively by quantitative sensory testing (thermal, mechanical, and pressure [detection and pain thresholds]) and assessments were correlated to patients' reports of intensity and frequency of spontaneous pain in the groin area.


RESULTS
Forty-two patients were examined, whereof one was excluded since no hernia was found intraoperatively. Mechanical pain threshold was inversely correlated with spontaneous pain intensity (rho=-0.413, p=0.049), indicating a paradoxical association between level of mechanical pain threshold and magnitude of spontaneous pain. No other sensory modality was significantly correlated to pain intensity. New/increased pain during repetitive pinprick stimulation (wind-up) was seen in 3 patients (7%), all whom experienced no pain or pain less than weekly. Only cool detection thresholds were significantly lower between the hernia vs. contralateral side (p<0.04), but with numerically very small differences (Delta=0.4 degrees C, range 0.1-0.7 degrees C).


CONCLUSIONS
Pre-operative groin hernia pain is not related to findings of hyperalgesia or other changes in sensory function that may support pain-induced pre-operative neuroplasticity as a pathogenic mechanism for the development of persistent postherniotomy pain.
Aasvang
Eske K
EK
Section of Surgical Pathophysiology, 4074 Rigshospitalet, Blegdamsvej 9, Copenhagen University, 2100 Copenhagen Ø, Denmark. eskeaasvang@yahoo.dk
Hansen
Jeanette B
JB
Kehlet
Henrik
H
D000293:Adolescent; D000328:Adult; D002138:Calibration; D006119:Groin / Q000601:surgery; D059685:Herniorrhaphy; D006358:Hot Temperature; D006801:Humans; D006930:Hyperalgesia / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000209:etiology* / Q000503:physiopathology; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology; D010812:Physical Stimulation; D057234:Preoperative Period; D012307:Risk Factors; D012677:Sensation / Q000502:physiology; D055815:Young Adult