What is the efficacy of lumbar interlaminar epidural steroid injections (ESIs)?

Updated: Aug 06, 2018
  • Author: Boqing Chen, MD, PhD; Chief Editor: Stephen Kishner, MD, MHA  more...
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Answer

Answer

A systematic review included 15 fluoroscopically guided randomized trials and 11 nonrandomized studies. The efficacy is good for radiculitis secondary to disk herniation with local anesthetics and steroids and fair with local anesthetic only, whereas it is fair for radiculitis secondary to spinal stenosis with local anesthetic and steroids and fair for axial pain without disk herniation with local anesthetic with or without steroids. [9]

A prospective study demonstrated that as compared with conventional lumbar interlaminar epidural injections, the lateral parasagittal interlaminar epidural approach has higher rate of contrast spread into the anterior epidural space. [10]

A recent prospective randomized study compared the efficacy of lumbar ESI using a parasagittal interlaminar (PIL) approach and midline interlaminar (MIL) approach. Thirty-seven patients were randomized to receive injection of 80 mg methylprednisolone either by the PIL (n = 19) or MIL (n = 18). A maximum of 3 injections were performed with 15-day intervals between injections, if necessary. Follow up was 6 months post injection. Patients were evaluated for effective pain relief (≥50% from baseline) by visual analog scale and improvement in disability by the modified Oswestry Disability Questionnaire at intervals of 15 days and 1, 2, 3, and 6 months. The results demonstrated that PIL approach has better ventral epidural spread in contrast (89.7% in the PIL vs 31.7% in the MIL group). At the end of 6 months, the PIL group had a significantly higher percentage of pain relief in the visual analogue scale (PIL 13 [68.4%] of 19) vs MIL 3 [16.7%] of 18)and improvement of disability using Oswestry disabilityquestionnaire score, as well as fewer total injections (29 in PIL vs 41 in MIL, P = .043). [11]

It is important to know that at least 3 cases of lumbar paraplegia have been reported, and each developed after interlaminar lumbar epidural steroid injections. [12] The suspected mechanism is similar to a paraplegia caused by a lumbar transforaminal ESI in which the epidural needle penetrates the radicular medullary artery, and the particulate corticosteroid being injected into this artery inside the spinal canal results in an embolism of spinal cord and subsequent paraplegia.

In fact, the anatomical studies have demonstrated that after the radicular medullary arteries enter the neuroforamen in the anterior aspect of exiting nerve root and dorsal root ganglion, they often travel a distance superiorly and laterally in the lateral epidural space to join the anterior spinal artery supplying the anterior two thirds of the spinal cord. Additionally, in about 63% of cases of cadaver studies, there is a posterior branch of the radicular medullary artery going to the dorsal aspect of the cauda equina. It is conceivable that the epidural needle in the interlaminar lumbar epidural steroid injection will very likely encounter the radicular medullar artery in the lateral aspect of the epidural space or midline posterior epidural space.

As the paraplegia after interlaminar lumbar ESIs is often underreported, the exact frequency of this event cannot be determinted. It is clear that in light of the anatomical positions of these radicular medullary arteries inside the spinal canal as described above, neither midline nor parasagittal interlaminar lumbar ESIs are completely risk free with respect to vascular injury and paraplegia. The alternative approach using the Kambin triangle may be the better choice (see below for description).


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