A prospective study of diagnostic epidural blockade in the assessment of chronic back and leg pain.

A consecutive series of 100 patients with back and leg pain were evaluated prospectively. All had a detailed clinical assessment together with radiculography and computed tomography (CT) of the lumbosacral spine. In addition, each patient underwent diagnostic epidural blockade that identified three kinds of response. Injection of local anaesthetic into the epidural space relieved the symptomatic pain--the positive result (51 patients). Local anaesthetic injection had no effect on the symptomatic pain--the negative result (30 patients). In 19 patients, saline injection into the epidural space relieved the symptomatic pain--the placebo result. The results of this investigation were assessed in the light of the number of inappropriate physical signs found on clinical examination, together with the result of the radiculogram and CT scan. No statistical correlation was found with any of these parameters.