LESI LESI Anatomy and Neuroanatomy 3

Question 1

Which structure must be pierced just before entering the epidural space during a loss-of-resistance technique?

Accepted Answer

Ligamentum flavum

Answer

The ligamentum flavum is the last firm structure traversed before the needle enters the epidural space, which produces the characteristic loss of resistance.

Question 2

A disc herniation at L5-S1 most commonly compresses which nerve root?

Accepted Answer

S1 nerve root

Answer

A paracentral or posterolateral disc herniation at L5-S1 typically compresses the traversing S1 nerve root.

Question 3

The epidural fat in the lumbar region serves which primary function relevant to LESI?

Accepted Answer

Acts as a medium through which injectate spreads

Answer

Epidural fat fills the space around neural structures and serves as the medium through which injected corticosteroids and local anesthetics diffuse toward inflamed nerve roots.

Question 4

Which anatomical variant can obstruct midline spread of injectate in the lumbar epidural space?

Accepted Answer

Epidural septum or plica mediana dorsalis

Answer

The plica mediana dorsalis (posterior epidural midline septum) is an anatomical variant that can restrict midline spread of epidural injectate.

Question 5

In a transforaminal LESI, the needle tip is ideally positioned in which zone of the foramen?

Accepted Answer

Superior zone (6 o'clock or 'safe triangle')

Answer

The needle is ideally placed in the superior 'safe triangle' of the foramen (below the pedicle, lateral to the nerve root, above the disc) to minimize vascular and nerve root injury.

LESI - Lumbar Epidural Steroid Injection Practice Test

LESI - Lumbar Epidural Steroid Injection Practice Test

LESI LESI Anatomy and Neuroanatomy 3