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

Epidural contrast creates a characteristic 'Christmas tree' or 'celery stalk' pattern as it spreads along the epidural space around the dural sac, confirming correct placement.

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

Kambin's triangle is bounded by the pedicle above, the exiting nerve root below, and the posterior vertebral body medially; targeting this zone avoids nerve and major vessel injury.

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

One to three milliliters of contrast is sufficient to outline epidural spread and detect intravascular or intrathecal placement without overdistending the epidural space before steroid injection.

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

The L4 nerve root exits through the L4-5 foramen below the L4 pedicle; a transforaminal injection at this level targets the L4 root sleeve and the adjacent ventral epidural space.

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

Intravascular injection produces a rapid vascular runoff pattern (arterial or venous) visible in real time, allowing the physician to abort injection before steroid is delivered into the bloodstream.

LESI - Lumbar Epidural Steroid Injection Practice Test

LESI - Lumbar Epidural Steroid Injection Practice Test

LESI LESI Techniques and Approaches 3