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This review, covering a timespan of almost a century, attempts to answer five pressing questions:
(1) Are intraspinal steroid therapies effective for back pain or radicular syndromes?
(2) Do epidural injections remain confined to the epidural space?
(3) Are presently prescribed steroid formulations neurotoxic?
(4) What are the risks of epidural steroid injection?
(5) What information should be given to patients in obtaining informed consent for these procedures?
Efficacy of intraspinal therapy
REMOTE HISTORY
Early cocaine and “pressure injections”
In 1901 there were reports of cocaine injection via the sacral hiatus for sciatica.1-3 De Pasquier and Leri2 used lumbar intrathecal injections containing 5 mg cocaine that produced “toxic cocaine accidents . . .to the bulbar and cerebral centers.” They attempted without success to prevent flow of cocaine intracranially “by the use of a band of rubber gently tightened around the neck.” Then they tried sacral epidural injections and claimed success. In 1925, Viner4also employed the sacral route, using procaine in normal saline, Ringer's solution, or “liquid petrolatum.” Evans5reported treating 40 patients with “idiopathic sciatica” by sacral hiatus injection of normal saline and procaine hydrochloride. In attempts to relieve “mechanical stretching” of nerve roots, he found that the volume of injectate (100 ml or more with and without local anaesthetic) was the most important factor. Sciatica was relieved completely in 24 patients and “considerable benefit” occurred in six In these uncontrolled trials, the nature of the pathological process and the duration of pain relief were not specified.4 5
Articular steroid injection—the harbinger of intraspinal therapy
Compound E (cortisone) was discovered in 1936.6 7 In 1950 Hench et al 8 9 reported that it produced transient improvement of “rheumatoid arthritis, rheumatic fever, and certain other conditions.” Then Hollander10 reported the intra-articular effects of a longer acting steroid, Compound F (hydrocortisone), warning that “ . . .it should be emphasised that its …