THE SPREAD OF SOLUTIONS INJECTED INTO THE EPIDURAL SPACE A Study using Epidurograms in Patients with the Lumbosdatic Syndrome

Radiological evidence of the distribution of solutions in the epidural space indicates that the volume used and the site of injection are the most relevant factors, while the height of the " patient is of little importance, and the rate of injection, posture, and age of the patient exert no influence. Even so, there are wide variations in spread with a given volume via the same route, and it is impossible to predict accurately the level which will be attained. Clinical improvement following epidural injection for the lumbosdatic syndrome does not appear to be correlated with a wide dissemination of the solution used, and large volumes seem to confer no advantage. The caudal route perhaps deserves re-evaluation, though the small number in this series prevents valid conclusions being drawn. One of the most effective methods of conservative treatment of the lumbosdatic syndrome is by the epidural injection of a local anaesthetic solution con-taining steroids. However, the volume of solution used, and the route and rate of injections vary widely in different centres. It was therefore considered desirable to study radiologically the distribution of solutions injected into the epidural space, to deter-mine what factors influence their spread, and to evaluate any correlation between the degree of spread and the clinical improvement produced. Most studies hitherto have investigated spread in terms of the resultant neurological blockade rather than the actual distribution of solutions in epidural space. METHOD The selection of patients, regime of treatment, and overall results of 500 cases have been reported pre-viously (Warr et al., 1972). For the radiological inves-tigation of this series of 56 patients, the procedure differed only in detail. Volume. The solutions injected were dther (a) 20 ml of 0.75 % lignocaine, containing hydrocortisone acetate 25 mg, methyl prednisolone 80 mg, and sodium iothalamate (Conray 420) 7 ml, or (b) 40 ml of 0.75 % lignocaine containing hydrocortisone ace