LESI LESI Techniques and Approaches 3

Question 1

Which fluoroscopic contrast pattern confirms successful epidural spread during an interlaminar LESI?

Accepted Answer

A 'Christmas tree' or 'celery stalk' pattern spreading cranially and caudally along the epidural space

Answer

A globular collection pooling at the needle tip without spread

Answer

Immediate vascular runoff showing arterial branching

Answer

A smooth oval 'column' pattern within the thecal sac

Question 2

The 'safe triangle' targeted in transforaminal LESI is bordered by which three structures?

Accepted Answer

The pedicle superiorly, the exiting nerve root inferiorly, and the vertebral body medially

Answer

The pedicle above, the pedicle below, and the posterior vertebral body line posteriorly

Answer

The spinous process medially, the lamina posteriorly, and the facet joint laterally

Answer

The transverse process superiorly, the vertebral body anteriorly, and the neural foramen posteriorly

Question 3

What volume of contrast is typically injected to confirm epidural spread during an interlaminar LESI before the therapeutic injectate?

Accepted Answer

1-3 mL

Answer

0.1-0.5 mL

Answer

5-10 mL

Answer

10-20 mL

Question 4

When performing a transforaminal LESI at the L4-5 level, which nerve root is primarily targeted?

Accepted Answer

L4 nerve root exiting below the L4 pedicle through the L4-5 foramen

Answer

L3 nerve root exiting below the L3 pedicle

Answer

L5 nerve root exiting below the L5 pedicle

Answer

S1 nerve root at the S1 foramen

Question 5

Real-time fluoroscopy during contrast injection during LESI serves what critical safety purpose beyond confirming epidural placement?

Accepted Answer

Detecting intravascular injection by identifying rapid vascular contrast washout patterns

Answer

Measuring the exact volume of injectate delivered

Answer

Confirming the gauge and bevel orientation of the needle

Answer

Measuring disc height and degree of herniation

Question 6

In digital subtraction angiography (DSA) used during LESI, what is digitally 'subtracted' from the live image?

Accepted Answer

A pre-injection mask image, highlighting only newly introduced contrast in real time

Answer

Bony anatomy, leaving only soft tissue contrast

Answer

Previous contrast injections to isolate the current spread pattern

Answer

Patient motion artifact to sharpen the needle image

Question 7

Which needle gauge is most commonly used for transforaminal lumbar epidural steroid injections?

Accepted Answer

20-22 gauge

Answer

16-18 gauge

Answer

25-27 gauge

Answer

30-32 gauge