LESI LESI Techniques and Approaches 2

Question 1

During transforaminal LESI, which fluoroscopic view is used to confirm the needle tip is in the posterior (not anterior) epidural space?

Accepted Answer

Lateral view confirming the needle tip is posterior to the posterior vertebral body line

Answer

AP view showing the needle at the 6 o'clock position of the foramen

Answer

Ipsilateral oblique view showing the 'Scotty dog' eye

Answer

Caudal tilt AP view

Question 2

The paramedian interlaminar approach to lumbar epidural injection differs from the midline approach primarily in that:

Accepted Answer

The needle is angled medially and cephalad, bypassing the spinous process

Answer

It accesses the epidural space through the neural foramen

Answer

It is performed without fluoroscopic guidance as standard of care

Answer

It requires a larger-gauge needle for reliable loss of resistance

Question 3

An inadvertent subdural injection during LESI differs clinically from an intrathecal injection because:

Accepted Answer

It deposits injectate between the dura and arachnoid, not within the CSF

Answer

It immediately produces total spinal anesthesia due to direct CSF dilution

Answer

It is easily identified by free aspiration of cerebrospinal fluid

Answer

It has no clinical significance and self-resolves within minutes

Question 4

When performing a caudal epidural injection, the 'pop' or loss of resistance typically occurs as the needle passes through which structure?

Accepted Answer

The sacrococcygeal membrane covering the sacral hiatus

Answer

The posterior sacral ligament overlying the sacrum

Answer

The sacrococcygeal ligament connecting the coccyx to the sacrum

Answer

The posterior longitudinal ligament of the lower sacrum

Question 5

Which fluoroscopic view is most useful for identifying the sacral hiatus before performing a caudal epidural injection?

Accepted Answer

Lateral view

Answer

Anteroposterior (AP) view

Answer

Ipsilateral oblique view

Answer

Caudal tilt AP view

Question 6

During transforaminal LESI setup, the C-arm is obliqued ipsilaterally until which classic landmark is visualized?

Accepted Answer

The 'Scotty dog' silhouette of the vertebra with the pedicle as the eye

Answer

The spinous process is centered over the disc space

Answer

The interlaminar space reaches its maximum opening

Answer

The contralateral pedicle overlaps the midline

Question 7

What is the primary advantage of the interlaminar approach over the transforaminal approach for LESI when bilateral radiculopathy is present?

Accepted Answer

Better bilateral spread of injectate to cover both sides simultaneously

Answer

More precise delivery to a single targeted nerve root

Answer

Lower risk of intravascular injection into radicular arteries

Answer

Easier visualization of correct needle placement under fluoroscopy