The neurological safety of epidural pamidronate in rats

Relationship between bone mineral density and the frequent administration of epidural steroid injections in postmenopausal women with low back pain

BACKGROUND

Epidural steroid injection (ESI) is one of the most common nonsurgical treatments for low back pain. In general, corticosteroid therapy often results in bone loss and osteoporosis. In previous studies, bone mineral density (BMD) was evaluated after epidural injections of relatively small numbers and relatively low total doses of corticosteroids. However, the relationship between BMD and multiple ESIs remains to be elucidated.

OBJECTIVE

To explore the relationship between BMD and multiple ESIs in postmenopausal women with low back pain.

METHODS

Medical records of postmenopausal women with low back pain treated with or without ESIs were reviewed. BMD was measured in the lumbar spine, femoral neck and total femur after the treatments. A total of 71 patients were divided into two groups: group 1 included patients who had received non-ESI medications; and group 2 included those who had received ESIs >10 times, with a cumulative administered triamcinolone dose >200 mg.

RESULTS

Patients in group 2 showed lower BMD in the femoral neck and total femur. However, no significant intergroup differences in the BMD of the lumbar spine were observed. The prevalences of osteoporosis and osteopenia in the lumbar spine and femoral neck were significantly higher in group 2; these patients also had lower femoral neck BMD Z-scores.

CONCLUSIONS

Multiple ESIs (approximately 14 injections with a cumulative triamcinolone dose of approximately 400 mg) can reduce BMD in postmenopausal women with low back pain.

The neurological safety of epidural parecoxib in rats

Epidural injection of cyclooxygenase-2 inhibitors has been suggested as a useful therapeutic modality in pain management in animal studies and clinical settings. Direct epidural administration of parecoxib, a highly selective cyclooxygenase-2 inhibitor, may have advantages over its parenteral administration regarding required dose, side effects, and efficacy. However, no animal studies have been performed to investigate the possible neurotoxicity of epidurally injected parecoxib. Therefore, the present study was performed to assess the neurotoxicity of epidurally injected parecoxib in rats. Rats (n=45) were randomly divided into three groups: normal saline group (group N, n=15), ethanol group (group E, n=15), and parecoxib group (group P, n=15). 0.3 mL of epidural parecoxib (6 mg) and the same volume of epidural ethanol or normal saline were injected into the epidural space. Neurologic assessment was performed 3, 7 and 21 days after the injection by pinch toe testing. Histologic changes were evaluated for vacuolation of the dorsal funiculus, chromatolytic changes of the motor neurons, neuritis, and meningeal inflammation. All rats in groups N and P showed normal response to pinch-toe testing and had a normal gait at each observation point. Histological examination showed no evidence suggestive of neuronal body or axonal lesions, gliosis, or myelin sheet damage in group N or P at any time. However, all rats in group E showed sensory-motor dysfunction, behavioral change, or histopathological abnormalities. No neurotoxicity on the spinal cord or abnormalities in sensorimotor function or behavior was noted in rats that received epidural parecoxib.