Orlando, Fla.—The presence of a novel complex of fibronectin and aggrecan predicted whether patients with lumbar radiculopathy responded to an epidural steroid injection (ESI), according to a prospective study presented at the 25th annual meeting of the North American Spine Society. The investigators found that assaying the epidural space lavage for the biomarkers prior to receiving an ESI lowered patients’ risks for infection, postprocedure dural puncture headache and epidural hematoma.

According to Sukdeb Datta, MD, this test may become useful in optimizing ESI therapy. “With the widespread availability of ELISA [enzyme-linked immunosorbent assay] techniques, such a test may become routine and help in ‘staging’ patients in terms of different mediators present in the epidural fluid,” said Dr. Datta, chief of the Pain Medicine Division and associate professor in the Department of Anesthesiology at Vanderbilt University Medical Center in Nashville, Tenn., who was not involved in the research. “Perhaps this test may also allow physicians to quantify the natural milieu of the intervertebral disc in a patient undergoing ESI. This is important because we know very well that if such a milieu is not addressed or optimized, interventions such as ESIs will be suboptimal.”

This study follows on the heels of previous research conducted by Gaetano Scuderi, MD, clinical assistant professor of Spine Service in the Department of Orthopaedics at Stanford University in Palo Alto, Calif., who examined the diagnostic value of immunoreactive epidural interferon-γ in patients with radiculopathy (Spine 2009;34:2311-2317).

In the current investigation, Dr. Scuderi’s team prospectively examined epidural lavage samples from 26 patients with radiculopathic pain and herniated nucleus pulposus. Patients were a mean age of 46 years and 19 were male. The subjects had symptoms consistent with dermatomal radiculopathy in one or more lumbar nerves. Twenty-four patients had one vertebral level affected, whereas two patients had two symptomatic levels. Herniation was present in the L3-L4 disc in four patients, the L4-L5 disc in 15 patients and the L5-S1 disc in seven patients. In most cases, pain was unilateral. Seventeen of the 26 patients had private insurance and nine were receiving workers compensation.

Using an ELISA, Dr. Scuderi and his colleagues assayed the lavage fluid for the fibronectin–aggrecan complexes. They then administered an ESI and measured symptoms both prior to and following the procedure using the short-form 36 (SF-36), specifically comparing the 35-item physical component summary (PCS) of the SF-36.

The researchers found that the two biomarkers were present in 14 patients. Twelve of those 14 responded to ESI treatment, reporting statistically significant improvements in the PCS component of the SF-36. Specifically, the mean improvement from baseline PCS in patients with the fibronectin–aggrecan complex was 22.9 compared with 0.64 for those without the complex (P<0.001). Among the 12 patients who did not have the fibronectin–aggrecan complex, one responded to the ESI.

An area under the curve (AUC) analysis revealed that biomarker complex predicted whether patients would respond to an ESI (AUC=0.97; P=0.001). There was no significant difference in age (P=0.25), gender (P=0.84), laterality (P=0.06), lumbar spinal level (P=0.75) or payer type (workers compensation vs. private insurance, P=0.90) between groups with and without the biomarker.

“Our results show the subset of patients with this biomarker complex are more likely to respond vigorously and have improved functional outcome after ESI,” Dr. Scuderi told meeting attendees. “Our investigation is one step toward establishing a set of tools that can be used to predict and potentially improve response to ESI for patients with radiculopathy.”