Successful outcome after outpatient transforaminal decompression for lumbar foraminal and lateral recess stenosis: The positive predictive value of diagnostic epidural steroid injection.

OBJECTIVE: To analyze the positive predictive value of diagnostic 1% lidocaine containing transforaminal epidural steroid injections (TESI) for successful outcome after outpatient endoscopic decompression for lumbar foraminal and lateral recess stenosis. PATIENTS AND METHODS: A retrospective study of 1839 consecutive patients with an average mean follow-up of 33 months that underwent endoscopic transforaminal decompression at 2076 lumbar levels was conducted. The sensitivity, specificity, and positive predictive value of lidocaine containing diagnostic TESI at the intended surgical level were calculated based on the recorded frequency of >50% VAS score reduction, intraoperatively visualized stenosis, and clinical outcomes assessed by Macnab criteria and VAS reduction.
RESULTS: Of the 1839 patients, 1750 had intraoperatively visualized stenosis in the lateral recess at the surgical level and 89 patients did not. Analyzing recordings of diagnostic TESI responses in patients with visualized compressive pathology: true positive (1578); false negative (172); as compared with TESI responses in patients without visualized compressive pathology: false positive (26); and true negative (63) allowed for calculation of sensitivity (90.17%), specificity (70.79%), and the positive predictive value (98.38%) of preoperative lidocaine containing TESI in relation to successful clinical outcome of the subsequent endoscopic decompression surgery.
CONCLUSIONS: The expected VAS pain reduction (>50%) from a lidocaine containing transforaminal epidural steroid injection renders it a valuable diagnostic tool in improving clinical outcome after lumbar endoscopic transforaminal decompression.