Psychoneuroimmunological correlates of persisting sciatic pain in patients who underwent discectomy

Patients suffering from persisting sciatic pain 8 weeks following discectomy were compared with patients displaying low complaints and healthy, pain-free volunteers regarding their interleukin-6 (IL-6) levels, morning cortisol levels and degree of psychological distress. Whereas serum concentrations of IL-6 were measured by collecting blood samples between 0945 and 2400 h in intervals of 45 min, morning cortisol levels were obtained by sampling saliva on five ensuing measurements, beginning immediately after awakening. In addition, questionnaires aimed at measuring depressive mood, somatic symptoms, coping and chronic stress were filled out by the subjects. The patients with ongoing pain displayed significantly elevated IL-6 levels and an attenuated elevation of cortisol secretion after awakening compared to the two other groups. Patients with persisting pain were also suffering more frequently from depressive mood and ongoing work-related strains. In addition, maladaptive coping strategies were favoured by these patients. The presented data support the hypothesis that the persistence of pain in many of the concerned patients may significantly be related to dysfunctional reciprocal relations between neural, endocrine and immune function.