Neuraxial Indications/CI/NeuroAnatomy- ChatGPT

Question 1

What are common clinical indications for neuraxial anesthesia?

Answer 1

Surgeries involving the lower abdomen, perineum, lower extremities, orthopedic and vascular leg surgeries, and as an adjunct in thoracic surgery.

Question 2

What are some benefits of neuraxial anesthesia?

Answer 2

• Mental alertness
• less urinary retention
• quicker recovery (eat, void, ambulate),
• reduced general anesthesia complications
• faster PACU discharge
• blunted surgical stress response.

Question 3

Name 4 relative contraindications to neuraxial anesthesia.

Answer 3

• Spinal deformities (e.g., scoliosis)
• pre-existing spinal cord disease
• chronic headache/back pain
• more than 3 failed attempts at placement

Question 4

What are key lab-based contraindications to neuraxial anesthesia?

Answer 4

• INR > 1.5
• platelets < 100k
• anticoagulation use
• abnormal PT/aPTT

Question 5

Seven

What are the absolute contraindications to neuraxial anesthesia?

Answer 5

• Patient refusal
• local infection/sepsis
• severe aortic/mitral stenosis
• increased ICP
• severe CHF
• preload dependence
• high-risk cardiac disease (e.g., HSS)

Question 6

How many vertebrae are in the spine and how are they distributed?

Answer 6

33 total: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral (fused), 4 coccygeal.

Question 7

What are the two main segments of a vertebra?

Answer 7

Anterior body and posterior vertebral arch (formed by pedicles and laminae).

Question 8

What is the vertebral foramen and its contents?

Answer 8

The canal formed by vertebrae that houses the spinal cord, nerve roots, and epidural space.

Question 9

What anatomical structure is used to locate midline during neuraxial anesthesia?

Answer 9

The spinous process.

Question 10

How do lumbar spinous processes differ from thoracic/cervical?

Answer 10

Lumbar spinous processes project straight posteriorly, making access easier; thoracic/cervical tilt caudally.

Question 11

What is the function of intervertebral discs?

Answer 11

To act as shock absorbers between vertebrae.

Question 12

What structures form the intervertebral foramina?

Answer 12

• Anterior: vertebral body + disc
• Posterior: facet joints.

Question 13

What happens when intervertebral discs degenerate?

Answer 13

The foramina narrow, potentially compressing spinal nerves.

Question 14

What forms a facet joint and what is its function?

Answer 14

Formed by the inferior articular process of one vertebra and the superior of the next; guides and limits spinal movement.

Question 15

What surface landmark correlates with the L4 vertebral level?

Answer 15

The top of the iliac crests (Tuffier’s line/intercristal line).

Question 16

What vertebral level does the posterior superior iliac spine correlate with?

Answer 16

S2.

Question 17

What are the sacral hiatus and sacral cornu?

Answer 17

• Sacral hiatus: opening at S5 for caudal anesthesia;
• cornu: bony landmarks adjacent to the hiatus.

Question 18

At what vertebral level does the spinal cord end in adults? In infants?

Answer 18

• Adults: L1–L2;
• Infants: L3.

Question 19

What is the cauda equina?

Answer 19

A bundle of nerve roots from L2–S5 and the coccygeal nerve that extends below the conus medullaris.

Question 20

Where does the dural sac end in adults?

Answer 20

S2.

Question 21

How many vertebrae are in the spine, and how are they distributed?

Answer 21

33 total: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral (fused), 4 coccygeal.

Question 22

Which vertebra lacks a vertebral body and why is this important?

Answer 22

C1 (atlas); it supports the skull and allows for nodding motion.

Question 23

What is the function of transverse processes and spinous processes?

Answer 23

Serve as attachment sites for muscles and ligaments, and help guide spinal motion.

Question 24

Why are lumbar spinous processes favorable for neuraxial anesthesia?

Answer 24

They project straight posteriorly, creating easier access compared to the caudally-angled cervical/thoracic spinous processes.

Question 25

What forms the intervertebral foramina and what passes through them?

Answer 25

Formed by vertebral bodies, discs, and facet joints; spinal nerves exit through them.

Question 26

What symptoms can disc degeneration and foraminal narrowing cause?

Answer 26

Nerve compression leading to pain, numbness, or weakness.

Question 27

What forms a facet joint and what is its function?

Answer 27

Inferior articular process of one vertebra + superior articular process of the next; it guides and limits spinal motion.

Question 28

What vertebral levels correspond to the iliac crest and posterior superior iliac spine?

Answer 28

Iliac crest = L4; Posterior superior iliac spine = S2.

Question 29

What is Tuffier’s line and what is its clinical use?

Answer 29

A horizontal line across the iliac crests aligning with L4; used to find L3–L4 or L4–L5 for lumbar puncture.

Question 30

How does Tuffier’s line differ in infants under one year?

Answer 30

It aligns with the L5–S1 interspace.

Question 31

What is the sacral hiatus and why is it important?

Answer 31

An opening at S5 covered by the sacrococcygeal ligament; used for caudal anesthesia.

Question 32

What are the sacral cornua?

Answer 32

Bony projections that flank the sacral hiatus; important landmarks for caudal blocks.

Question 33

At what level does the spinal cord end in adults and infants?

Answer 33

Adults: L1–L2; Infants: L3.

Question 34

What is the cauda equina and where does it extend?

Answer 34

A bundle of nerve roots (L2–S5 + coccygeal nerve) extending from the conus medullaris.

Question 35

Where does the dural sac end in adults and infants?

Answer 35

Adults: S2; Infants: S3.

Question 36

What is the filum terminale and its function?

Answer 36

A pia mater extension that anchors the spinal cord to the coccyx.

Question 37

Differentiate internal and external filum terminale.

Answer 37

- Internal: from conus medullaris to dural sac; - External: dural sac to sacrum.

Question 38

Which arteries supply the spinal cord?

Answer 38

One anterior spinal artery (motor) and two posterior spinal arteries (sensory).

Question 39

Why is the anterior spinal cord more susceptible to ischemia?

Answer 39

The anterior spinal artery is a single vessel with fewer collateral connections.

Question 40

What is anterior spinal artery syndrome?

Answer 40

Paralysis and loss of pain/temperature below lesion; preserved proprioception and vibration.

Question 41

What is the Artery of Adamkiewicz?

Answer 41

A major feeder artery to the anterior spinal artery, often arising between T7–L2.

Question 42

What are the 5 major spinal ligaments relevant to neuraxial procedures?

Answer 42

Supraspinous, interspinous, ligamentum flavum, posterior longitudinal, anterior longitudinal.

Question 43

What does the ligamentum flavum indicate during epidural placement?

Answer 43

Loss of resistance signals entry into the epidural space.

Question 44

What layers are traversed during midline spinal approach?

Answer 44

Skin → subcutaneous fat → supraspinous → interspinous → ligamentum flavum → dura → arachnoid → subarachnoid space.

Question 45

What is different about the paramedian approach?

Answer 45

Avoids interspinous ligament; insert needle 1 cm lateral and 1 cm caudal at 15° angle.

Question 46

Name the meningeal layers from outermost to innermost.

Answer 46

Dura mater → arachnoid mater → pia mater.

Question 47

What does the epidural space contain?

Answer 47

Fat, lymphatics, venous plexus (Batson’s), spinal nerve roots.

Question 48

What is the subdural space and why is it clinically important?

Answer 48

A potential space between dura and arachnoid; can cause high block if LA is misdirected.

Question 49

What is the subarachnoid space and what does it contain?

Answer 49

Space between arachnoid and pia mater; contains CSF, spinal cord, and nerve roots.

Question 50

What are the borders of the epidural space?

Answer 50

- Cranial: foramen magnum; - caudal: sacrococcygeal ligament; - anterior: posterior longitudinal ligament; - posterior: ligamentum flavum.

Question 51

What is the Plica Mediana Dorsalis and why is it controversial?

Answer 51

* A theorized band of tissue possibly affecting epidural spread and catheter insertion. * Thought to divide the right and left epidural space

Question 52

What are the three meningeal layers and their functions?

Answer 52

- Dura (tough outer layer) - Arachnoid (middle protective layer) - Pia (vascular inner layer).

Question 53

How many pairs of spinal nerves are there?

Answer 53

31 total: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal.

Question 54

What is unique about the C8 spinal nerve?

Answer 54

It exits below the C7 vertebra, despite being a cervical nerve.

Question 55

What is a dermatome?

Answer 55

A skin area innervated by the sensory fibers of a single spinal nerve root.

Question 56

What spinal level corresponds with the umbilicus dermatome?

Answer 56

T10.

Question 57

What nerve provides sensory innervation to the face?

Answer 57

The trigeminal nerve (CN V), not spinal nerves.

Question 58

What are the three branches of the trigeminal nerve and their sensory areas?

Answer 58

V1 (forehead, scalp), V2 (cheeks, upper lip/teeth), V3 (jaw, lower teeth, part of tongue).

Question 59

Why is dermatomal level knowledge important for surgery?

Answer 59

To match the block level with the surgical site for adequate anesthesia.

Question 60

What is Batson’s venous plexus and why is it clinically important?

Answer 60

* A valveless network of veins in the epidural space that drains blood from the cord and it's linings * becomes engorged in pregnancy, increasing the risk of vascular puncture during epidural placement

Question 61

How does neuraxial anatomy differ in infants compared to adults?

Answer 61

In infants, the spinal cord ends at L3, the dural sac at S3, there is less epidural fat, and landmarks are less defined — increasing the risk of cord injury during neuraxial procedures.

Question 62

Why is the thickness of the ligamentum flavum clinically important in epidural placement?

Answer 62

It is thickest in the midline, providing a distinct 'pop' sensation for identifying the epidural space; thinner laterally, making off-midline approaches less reliable for tactile feedback.

Question 63

What is the Plica Mediana Dorsalis and its possible impact on epidural spread?

Answer 63

A proposed midline septum in the posterior epidural space that might cause a unilateral block or restrict catheter advancement — its existence remains debated.

Question 64

What is the clinical significance of the Artery of Adamkiewicz?

Answer 64

Injury to this artery can cause anterior spinal artery syndrome, leading to bilateral motor paralysis and loss of pain and temperature sensation, while sparing proprioception and vibration.

Question 65

What dermatome level is needed for cesarean section anesthesia?

Answer 65

T4 (nipple line).

Question 66

What dermatomes must be blocked for lower abdominal surgery (e.g., appendectomy)?

Answer 66

T6

Question 67

What dermatomal level is targeted for TURP procedures?

Answer 67

T10

Question 68

What is the target dermatome for vaginal delivery anesthesia?

Answer 68

T10

Question 69

What dermatome range should be blocked for lower extremity surgery?

Answer 69

L1–L4 or higher depending on tourniquet use.

Question 70

What does the valveless nature of Batson’s plexus allow in pathological states?

Answer 70

Facilitates the spread of cancer or infection from the pelvis to the vertebral column or brain via retrograde flow.

Question 71

What dermatome level is appropriate for lower extremity surgery such as thigh, lower leg, and knee?

Answer 71

L1

Question 72

What dermatome level is required for foot and ankle surgery?

Answer 72

L4

Question 73

What dermatome levels are needed for perineal or anorectal procedures? "Saddle block"

Answer 73

S2–S5

Question 74

What dermatome level is the umbilicus, and what surgeries might require blockade to this level?

Answer 74

T10 Vaginal delivery, uterine, hip procedure, tournequet, TURP

Question 75

What dermatome level needs to be blocked for urologic/gynecologic (hysterectomy), and lower abdominal surgeries?

Answer 75

T6