The role of pharmacological tests in patients with failed back surgery syndrome

Background. Chronic pain syndromes constitute a great therapeutic problem. One of the steps leading to precise diagnosis and to choosing an appropriate therapeutic strategy are the pharmacological tests (PT). They allow an indirect identification of the mechanism of pain and lead to a more efficient treatment. Material and methods. The study population consists of 19 consecutive patients suffering from failed back surgery syndrome. Patients were administered analgetic drugs with a known mechanism of action intravenously (lidocaine, ketoprofen, tramadol, fentanyl, metamizole) and placebo. Before and after each drug administration patients rated their pain severity based on the VAS scale and reported adverse events. Results. A very good result (≥ 50% reduction of pain intensity) was achieved only in 4 patients (21.1%). Additionally the satisfactory result (≥ 30% reduction of pain intensity) was achieved in 8 patients (42.1%). Fentanyl turned out to be the most effective drug, however its efficacy was low. Fentanyl elicited a 30% reduction of pain severity in 31.3% of patients and 50% reduction of pain severity only in 18.8% of patients. Conclusions. Pharmacotherapy is effective only in a small number of patients. Use of target pharmacotherapy (an effective drug based on pharmacological tests) in combination with other therapeutic methods (central and peripheral blocks, psychotherapy, neuromodulation, rehabilitation) appears to be the best approach.