Utility of Intramuscular Corticosteroids for Radicular Low Back Pain

This is a randomized, double-blind placebo-controlled clinical trial evaluating intramuscular methylprednisolone acetate as adjunctive therapy for radicular low back pain. This trial randomizes subjects after they had been evaluated and treated in the ED and are ready for discharge. All subjects are followed by telephone call one week and one month after ED discharge. In addition to the steroid injection, all subjects are given a complimentary one week supply of naproxen 500 mg tablets and oxycodone 5mg/ acetaminophen 325 tablets and a detailed low back pain instruction sheet. This study was approved by the Montefiore Medical Center institutional review board.

Patients are included if their low back pain lasted less than one week, if they are 50 years old or younger, and if they had not experienced any direct trauma to the back during the previous week. Low back pain is described as pain originating below the tips of the scapulae and above the buttocks.Patients are only included if their straight leg raise test, as described below, is positive. Patients are excluded if the emergency physician felt that there is a high likelihood that the patient has a secondary cause of low back pain, e.g., metastatic bone disease or infection. Patients are also excluded for temperature greater than 100.3 degrees, pregnancy, lactation, allergy to or intolerance of a study medication. Patients can only enroll once. Patients can not have had another episode of back pain within four weeks prior to the current back pain attack. Patients are excluded for systemic steroid use within four weeks, a history of back surgery, a neoplasia known to metastasize, a chronic pain syndrome, an inflammatory arthritis, suspected vascular, urologic or gynecologic pathology, or direct blunt trauma to the back within the previous week.

Rationale for the straight leg raise test: Although the true test characteristics of the straight leg raise test are unknown, a positive ipsilateral straight leg raise is felt to be a sensitive marker for a herniated intervertebral disc. Therefore, if this test is negative, it can help rule-out the disease. To maintain a homogenous cohort, subjects were stratified based on results of the straight leg raise test. Many definitions of the straight leg raise test exist. In order to identify distinct populations, the research assistants were given a strictly-defined, conservative definition of this test: namely, the test was considered positive if a subject had ipsilateral pain shooting below the knee when either leg was raised between 30 and 70 degrees, as measured with a protractor. Contralateral pain below the knee, considered more specific for a herniated disc, was also considered a positive straight leg raising test.

All patients with low back pain are treated at the discretion of the attending physician. When the patient's pain had been controlled to a level sufficient for the patient to be discharged, the patient is asked for consent to participate as a research subject. After consent is obtained, subjects receive an intramuscular injection of methylprednisolone acetate or placebo. All subjects are discharged with a "back pack" containing 14 tablets of naproxen 500mg, 12 tablets of oxycodone 5mg/ acetaminophen 325 tablets, and a standardized discharge instruction sheet.

Subjects are followed-up by telephone at one week and one month after discharge. At each of these telephone interviews, research assistants read standardized questions about pain and activity limitations from the data collection instrument.