Evaluation of sympathetic response in cases with failed back surgery syndrome

The aim of this study was to investigate whether sympathetic skin response (SSR) was affected in cases with failed back surgery syndrome (FBSS).

Twenty-nine cases admitted to our department and diagnosed as FBSS were recruited for the study. All the cases had back, leg or back and leg pain in the months or in one year following spinal surgery. The control group consisted of 13 healthy hospital personnel. Electrophysiologic nerve conduction studies and SSR recordings were applied on the symptomatic side (29 legs) in study cases and both sides (26 legs) in the control group. SSRs of the study group were compared with those of the sex-, body mass index- and age-matched control group of 13 people. Patients having peripheral nerve entrapment syndromes, peripheral vascular disease, neurologic or psychiatric disease, alcoholism, or drug abuse were excluded from the study. Pain intensity was recorded by visual analog scale (VAS) and depression was recorded by Beck Depression Inventory (BDI).

Latency duration in SSR in the study group was significantly higher (p=0.006) when compared with the healthy controls. There was no SSR in 4 patients and there was a positive correlation between BDI and SSR (r=0.46).

It was concluded that the sympathetic nervous system is affected in FBSS patients with changes in SSR, and that the dysfunction of the sympathetic nervous system may contribute to the intensity and chronicity of pain states in this group of patients.