Contrast flow selectivity during transforaminal lumbosacral epidural steroid injections.
BACKGROUND
Lumbosacral transforaminal epidural steroid injections (LS-TFESIs) are an accepted procedure used in the comprehensive, conservative care for lumbar disc pathology and/or spinal stenosis induced low back pain with a radicular component. Historically, the terminology used to describe the transforaminal technique of instilling medications into the epidural space and/or exiting structures has varied. These procedures have also been referred to as either diagnostic or therapeutic selective nerve root blocks (SNRBs). Although this procedure is typically used to "selectively" treat isolated pathology, the "SNRB" terminology suggests that one can selectively diagnose or treat a specific nerve root as a pain generator by anesthetizing or blocking it. It has been recently demonstrated that L4 and L5 SNRBs are often non-"selective" by investigating the extent of epidural contrast flow patterns after injecting 1.0 mL of contrast. Our study attempts to identify the minimum injectate volume at which LS-TFESIs may still be considered "selective" with no injectate extending to either the adjacent (superior and/or inferior) levels or to the contralateral side.


OBJECTIVE
Quantitatively evaluate contrast flow level selectivity noted during fluoroscopically guided lumbosacral transforaminal epidural steroid injections (LS-TFESIs).


METHODS
Prospective, nonrandomized, observational human study.


METHODS
Thirty patients (female = 10, male = 20) undergoing LS-TFESIs were investigated. After confirming appropriate spinal needle position with biplanar imaging, 4.0 mL of nonionic contrast was slowly injected. Fluoroscopic images were recorded at 0.5 mL increments. These biplanar contrast flow images were evaluated to determine which 0.5 mL volume increment was no longer specific for the injected level. In particular, we documented when contrast extended either to a superior or inferior spinal segment or crossed the midline spine to the contralateral side.


RESULTS
After injecting 0.5 mL of contrast, 30% of LS-TFESIs performed in this study were no longer "selective" for the specified root level. After injecting 1.0 mL of contrast, 67% of LS-TFESIs performed in this study were no longer "selective" for the specified root level. After injecting 1.5 mL of contrast, 87% of LS-TFESIs performed in this study were no longer "selective" for the specified root level. After injecting 2.5 mL of contrast, 90% of LS-TFESIs performed in this study were no longer "selective" for the specified root level.


CONCLUSIONS
Diagnostic LS-TFESI or SNRB blocks limiting injectate to a single, ipsilateral segmental level cannot reliably be considered diagnostically selective with volumes exceeding 0.5mL. Injectate volumes greater than 0.5mL are consistently non-selective and cannot be used reliably for diagnostic block procedures in the epidural space.
Furman
Michael B
MB
Orthopaedic & Spine Specialists, York, PA 17403, USA. mbfurman@hotmail.com
Lee
Thomas S
TS
Mehta
Ariz
A
Simon
Jeremy I
JI
Cano
William G
WG
D000328:Adult; D000368:Aged; D002404:Catheterization / Q000592:standards; D003287:Contrast Media / Q000493:pharmacokinetics*; D004824:Epidural Space / Q000187:drug effects / Q000502:physiology; D005119:Extravasation of Diagnostic and Therapeutic Materials / Q000503:physiopathology; D005260:Female; D005471:Fluoroscopy / Q000379:methods*; D006801:Humans; D007268:Injections, Epidural / Q000379:methods; D007405:Intervertebral Disc Displacement / Q000150:complications; D017116:Low Back Pain / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D008159:Lumbar Vertebrae / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D009407:Nerve Block / Q000379:methods*; D011446:Prospective Studies; D011843:Radiculopathy / Q000188:drug therapy / Q000209:etiology / Q000503:physiopathology; D012447:Sacrum / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D013126:Spinal Nerve Roots / Q000187:drug effects / Q000503:physiopathology; D013130:Spinal Stenosis / Q000150:complications; D013256:Steroids / Q000008:administration & dosage*
D003287:Contrast Media; D013256:Steroids