Steroids, drugs with potent antiinflammatory properties on the damaged nervous roots, have been especially used as adjuvants of
local anesthetics, by spinal route, in the treatments of
low-back pain. Spinal route was chosen to obtain a higher local concentration of
drug, with few systemic side effects and to improve
drug's action mechanism.
Steroids seem to interact with
GABA receptors and thus control neural excitability through a stabilising effect on membranes, modification of nervous conduction and membrane hyperpolarization, in supraspinal and spinal site. Epidural
steroids are especially used in the treatment of
low back pain due to irritation of nervous roots. They have been administered alone or in association with
local anesthetics and/or
saline solution. Slow release formulations have been generally used (
methylprednisolone acetate, and
triamcinolone diacetate). Other indications of epidural
steroids are: postoperative hemilaminectomy
pain, prevention of post herpetic
neuralgia, degenerative ostheoartrithis. Intra-thecal
steroids have been frequently used in the treatment of lumbar
radiculopathy due to discopathy, as an alternative treatment when epidural administration is ineffective. Positive results have been obtained with
methylprednisolone acetate, alone or in association with
local anesthetics. Complications related to intraspinal
steroids injections are due to execution of the block and
side effects of drugs. Complications associated with intrathecal
steroids are more frequent and severe than
epidural injections and include: adhesive
arachnoiditis,
aseptic meningitis,
cauda equina syndrome. Steroidal toxicity seems to be related to the polyethylenic glycole vehicle. Anyway, slow release formulations contain less concentrated polyethylenic glycole. The epidural administration, a correct dilution of
steroid with
local anesthetics solution and/or
saline solution, and a limited number of
injections (no more than three) allows a significant reduction of
steroid neurotoxicity.