Epidural steroid effects on nerves and meninges.

There have been encouraging reports of symptomatic improvement in patients with low back pain following injection of a mixture of a local anesthetic and a corticosteroid into the lumbar epidural space. However, there is a lack of animal or human studies which examined possible long-term effects of this combination on the exposed neural tissues. This study evaluated by both light and electron microscopy the effect of triamcinolone diacetate in vehicle and of the vehicle itself (both in 2% lidocaine) in 48 cats after percutaneous epidural injections were done at the lumbosacral space. When the animals were killed at 30 or 120 days, specimens of the spinal root, the root exit zone, and the meninges at the level of injection and level above and below were obtained. Because all of the histologic findings were found to be mild, it is concluded that local anesthetic-steroid combinations do not cause significant damage to neural tissues.