Conus Medullaris Infarction After a Right L4 Transforaminal Epidural Steroid Injection Using Dexamethasone.

BACKGROUND For decades, epidural steroid injections have been an effective tool in the management of many pain related conditions, including lumbar radiculopathy. Transforaminal epidural steroid injections in particular have been reported to potentially result in central nervous system infarctions which have not been reported with interlaminar epidural steroid injections, while providing comparable efficacy. This rare, catastrophic complication has been attributed by some authors to be due to vascular injury secondary to vasospasm, thrombus formation, dissection, as well as concerns with placing the needle at the so-called "safe triangle." Others, however, have proposed it to be secondary to embolization of the vessel by particulate steroids. This has led to the recommendation of the use of soluble steroids such as dexamethasone when performing TFESI's, despite concerns over its efficacy and potential for neurotoxicity in the literature. Furthermore, there have also been multiple studies which have revealed that IV dexamethasone is analgesic and that peri-neural dexamethasone is no more effective than IV dexamethasone. CASE HISTORY The present case involves a 60-year-old patient with right back and radicular leg pain for 3 years. Two right L4 TFESI's had been performed with betamethasone several years prior with satisfactory results, until the patient presented to the physician with a pain recurrence of 6 weeks of duration. The patient again underwent a right L4 TFESI with dexamethasone, which provided good relief after 2 weeks. The patient underwent a repeat right L4 TFESI with dexamethasone which was followed by a prompt onset of lower extremity numbness, weakness, and incontinence that was discovered to be related to a conus infarction. While this is the first publicly reported case of a conus medullaris infarction following a lumbar transforaminal injection utilizing dexamethasone, the incidence of these reports may rise as the prevalence of dexamethasone use increases in clinical practice. CONCLUSION The spinal cord infarction with TFESI's may occur related to various mechanisms, regardless of the type of particulate or non-particulate steroid used during these procedures.