There are many possible causes of low back pain (LBP). But when the sciatic nerve is irritated, patients are classified in a subset group as having radicular LBP. Treatment for this problem remains under investigation. In this study, the early use of an intramuscular corticosteroid injection for this problem is studied.
Adults ages 21 to 50 with LBP and a positive straight leg raise (SLR) test were included. The researchers defined a positive response to this test as pain that went down either leg (past the knee) when the leg was lifted straight up between 30 and 70 degrees. Pain with this motion is a strong sign of a herniated disc.
All patients were first seen in the emergency department. Their back pain had started within the last week. Anyone with a previous history of back pain was not allowed to participate in this study.
Patients were divided into two groups. One group received a single injection of methylprednisolone acetate along with antiinflammatory and narcotic medications for pain relief. The second group received a placebo injection (no steroid) and the same medications for pain and inflammation.
Patients were contacted one month after discharge from the emergency department. The main outcome of the study was pain intensity at that time. Other measures used to assess results included use of pain relievers, function, and any adverse effects from the medications. The Roland-Morris-18 functional disability scale was used to measure the effect pain had on daily and work activities.
The main measure of difference between the two groups was not pain intensity. Both groups had equal amounts of pain relief. Use of pain relievers and the disability scale were better measures of the benefit of methylprednisolone. Improvements were seen at the end of one week and at the end of one month. The authors say this finding suggests that methylprednisolone may actually affect the underlying disc problem.
Previous studies led to the suggestion that corticosteroid drugs should not be used for radicular LBP. But this study has shown a benefit when using them early in the onset of symptoms. The patient population was specific to those who were probably having pain from an acute disc herniation. The use of a steroid injection for patients without a positive straight leg raise is not advised.
The results of this study show that young adults may benefit from the early administration of an intramuscular steroid injection. Further study is needed to find out the best drug to use, optimal dose, timing, and method of delivery (e.g., intramuscular versus intravenous).