As per CT evaluations, the presence of common anatomical impediments to epidural injection, particularly at the L5–S1 level, may promote the failure of epidural injections in patients with low back pain. These study results reveal that low-dose intrathecal injections of isobaric bupivacaine are safe, tolerable, and effective in reducing pain and disability in patients with low back and lower extremity pain. 

To examine the safety and efficacy of intrathecal injection as a substitute to the epidural injection for analgesia.

Total 70 consecutive outpatients with chronic low back and lower extremity pain received a lumbar intrathecal injection of low-dose isobaric bupivacaine via a 25-gauge pencil-point needle. The patients received 0.5, 1.0, and 1.5 mg of bupivacaine at 1-week intervals to determine the optimal dose. After that, they received two more weekly injections with an optimal dose. The safety and efficacy of the treatment were examined over 1 year.

There were no serious adverse events. The optimal dose of bupivacaine (1.0 mg in 60% of patients) relieved pain and disability (both, p<0.0001) and provided anaesthesia below L1 (L5–T6). Motor block was negligible, and balance impairment improved relative to baseline (p<0.0001). 

The intrathecal injection of low-dose bupivacaine found to be safe and effective for the treatment of chronic low back and lower extremity pain.