LESI LESI Fluoroscopy and Imaging Guidance 1 — Questions and Answers
Question 1: Fluoroscopic guidance for LESI is recommended over blind (landmark-based) injections primarily because:
- It is faster than the blind technique
- It confirms accurate needle placement and reduces the rate of inaccurate injections from approximately 30-40% to near zero (Correct answer)
- It eliminates all risk of complications
- Insurance requires fluoroscopy for reimbursement only
Correct answer: It confirms accurate needle placement and reduces the rate of inaccurate injections from approximately 30-40% to near zero
Studies show that blind epidural injections have inaccurate placement rates of 30-40%; real-time fluoroscopy with contrast confirmation reduces inaccurate placement rates to near zero.
Question 2: In fluoroscopic interlaminar LESI, the AP (anteroposterior) view is used primarily to:
- Confirm absence of intravascular injection
- Verify midline or paramedian needle position between the laminae (Correct answer)
- Assess disc morphology
- Measure epidural space depth
Correct answer: Verify midline or paramedian needle position between the laminae
The AP fluoroscopic view confirms that the needle tip is positioned midline or paramedian between the target laminae before advancing to the epidural space.
Question 3: A 'Christmas tree' pattern of contrast spread on fluoroscopy during interlaminar LESI indicates:
- Intravascular injection
- Intrathecal injection
- Appropriate epidural spread along nerve roots (Correct answer)
- Subdural injection
Correct answer: Appropriate epidural spread along nerve roots
Epidural contrast spread radiating along multiple nerve root sleeves in a symmetrical pattern resembling a Christmas tree confirms proper epidural placement of the needle.
Question 4: Rapid disappearance of contrast on fluoroscopy during ESI, without epidural spread pattern, indicates:
- Correct epidural placement
- Intravascular injection — injection should be stopped immediately (Correct answer)
- Intrathecal injection
- Air in the epidural space
Correct answer: Intravascular injection — injection should be stopped immediately
Rapid vascular washout of contrast (disappearing within seconds without epidural spread) indicates intravascular needle placement; the procedure must be stopped, the needle repositioned, and contrast re-injected to confirm epidural placement.
Question 5: The lateral fluoroscopic view during interlaminar LESI is used primarily to confirm:
- Bilateral spread of contrast
- Needle depth (anterior-posterior positioning in the spinal canal) (Correct answer)
- Level identification
- Absence of spondylolisthesis
Correct answer: Needle depth (anterior-posterior positioning in the spinal canal)
The lateral view confirms that the needle tip is at the appropriate depth within the posterior epidural space and has not advanced too far anteriorly toward the intrathecal space or nerve roots.
Question 6: In transforaminal LESI under fluoroscopy, the oblique view is used to identify which landmark for needle placement?
- The disc space
- The 'Scotty dog' silhouette to target the superior foramen (eye of the Scotty dog) (Correct answer)
- The spinous process
- The sacral hiatus
Correct answer: The 'Scotty dog' silhouette to target the superior foramen (eye of the Scotty dog)
The oblique fluoroscopic view creates the 'Scotty dog' silhouette of the lumbar vertebra; the eye of the dog represents the pedicle, and the needle is targeted to the 6 o'clock position below the pedicle (superior foramen).
LESI LESI Fluoroscopy and Imaging Guidance 1
Fluoroscopic guidance for LESI is recommended over blind (landmark-based) injections primarily because: