Parasagittal Lumbar Steroid Injection Safest, Most Effective

Kate Johnson

February 07, 2012

February 7, 2012 (Miami Beach, Florida) — A modified interlaminar lumbar epidural steroid injection, referred to as the parasagittal approach, can achieve better pain relief than a midline approach in patients with unilateral lumbosacral radicular back pain.

This approach provides pain relief equal to that of the potentially risky transforaminal technique, said Kenneth Candido, MD, here at the 6th World Congress of the World Institute of Pain.

"I just have to get people to accept and to embrace this concept because there are a lot of people who are still advocating and pushing for the transforaminal approach," said Dr. Candido, who is chair and professor in the Department of Anesthesiology at Advocate Illinois Masonic Medical Center in Chicago, Illinois, during an interview with Medscape Medical News.

"If we can demonstrate the utility of the parasagittal approach, it is my expectation — not my hope, but my expectation — that people will start to move away from transforaminal injections and back toward a modified interlaminar, which I think has similar efficacy but greater safety for the patient."

Although transforaminal lumbar epidural steroid injections remain popular because of their long-term pain relief, it is becoming increasingly clear that they carry the potential for "catastrophic consequences," he said.

"When people perform transforaminal administration of primarily particulate glucocorticoid medications, there is an indeterminate but finite risk of causing paralysis or death," Dr. Candido explained. "The reason is because the particulate glucocorticoid medications get into the intermedullary or radicular feeding arteries, they go up to the spine, and they cause a catastrophic infarction of the spinal cord."

He said there are currently "several hundred" case reports of permanent paralysis and death resulting from the transforaminal technique — both in the cervical spine and the lumbar spine.

The alternative midline approach reduces this risk, "because the medullary arteries are found laterally; you don't encounter them when you do an interlaminar technique," Dr. Candido explained.

Pain relief is generally not as effective with the midline approach, but in a poster that he presented at the meeting, Dr. Candido reports that modifying the midline technique to incorporate a parasagittal approach seems to improve pain relief.

The study involved 44 patients scheduled for lumbar epidural steroid injections who were randomized to either the midline approach (n = 22) or the parasagittal approach (n = 22).

All patients received 120 mg of methylprednisolone acetate plus 1 mL normal saline solution and 1 mL 1% lidocaine.

The patients completed the Oswestry Low Back Pain (OLBP) questionnaire before injection and on days 1, 7, and 28 after the procedure.

Although patients in both groups had similar OLBP scores at baseline and showed improvement after the procedure, these improvements were statistically significant only in the parasagittal group (P = .037).

Patients also completed the 11-point Numeric Rating Scale (NRS) for pain, both at rest and during movement.

At baseline, the average NRS score of patients in the midline group was 5.4 at rest and 7.1 with movement; in the parasagittal group, the average score was 5.1 and 7.2, respectively.

Both groups experienced statistically significant improvements in both scores on days 1, 7, and 28 after treatment; however, this improvement was more pronounced in the parasagittal group than in the midline group at rest (P = .026 vs .044) and with movement (P = .005 vs .019).

By moving the needle placement from the midline to the lateral recess, there is "a greater likelihood of getting the medication into the ventral compartment of the epidural space, which is where the pain generators, the nociceptors, are. The nociceptors are found at the interface between a degenerated disk and the exiting nerve root, so applying the greatest concentration and bolus of medication at that interface is logically an extension of what we're trying to accomplish with the transforaminal techniques," said Dr. Candido.

"We're essentially doing what I call "the poor man's transforaminal technique," because this requires less fluoroscopic time. There is therefore less risk to the patient in terms of x-ray exposure, and certainly less risk to the interventionalists, who are bombarded by ionizing radiation throughout the day."

Asked to comment on the study, Jie Zhu, MD, attending physician at Mid Atlantic Spine and Pain Physicians, in Newark, Delaware, and Elkton, Maryland, said he has used the parasagittal approach a few times with mixed results. He used "the optimal oblique view after reviewing the lumbar spine MRI to ensure adequate epidural space in the parasagittal plane."

Dr. Zhu said the parasagittal approach might reduce the risk for spinal artery injury, but might also increase the risk for thecal sac puncture because "the space between the thecal sac and the ligamentum flavum in the parasagittal plane is usually smaller than it is in the midline."

In a recent paper (Pain Physician. 2011;14:331-341), Dr. Zhu and colleagues describe an alternative to the traditional transforaminal superoanterior approach: a dorsal approach in which the tip of the needle is placed immediately dorsal to the dorsal root ganglion.

"The primary goal of this approach is to minimize the risk of puncturing the spinal radicular artery, minimize nerve root penetrations, and effectively deliver medications into the epidural space through the neuroforamen. This modified approach is potentially safer than the traditional superoanterior ones currently in use," they write.

Dr. Candido and Dr. Zhu have disclosed no relevant financial relationships.

6th World Congress of the World Institute of Pain: Abstract 176. Presented February 4, 2012.


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