Neuraxial review question

Review questions covering anatomy, physiology, anesthesia techniques, pharmacology, complications, and systemic effects related to neuraxial anesthesia.

How many vertebrae make up the human spine?

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

What is the anatomical significance of the sacral hiatus?

It is an opening at the distal end of the sacral canal through which the caudal epidural space can be accessed.

Name the ligament that forms the dorsolateral border of the epidural space.

The ligamentum flavum.

What are the two layers of the intervertebral disc?

Annulus fibrosus and nucleus pulposus.

Where does the spinal cord terminate in adults?

L1–L2.

Where does the spinal cord terminate in infants?

L3.

What is Batson’s Plexus?

A network of valveless epidural veins that drain csf.

Why is Batson’s Plexus clinically significant?

It can engorge with increased intra-abdominal pressure, posing a risk for bleeding during neuraxial procedures.

Which artery is the largest anterior radicular branch?

The artery of Adamkiewicz or great anterior radiculomedullary artery.

What syndrome can result from the ischemia of the artery of Adamkiewicz (Largest anterior radicular branch)?

Anterior spinal artery syndrome.

What is the difference between the anterior and posterior spinal arteries in terms of spinal cord blood supply?

Anterior supplies anterior two-thirds of the spinal cord,

The two posterior spinal arteries supply the posterior one-third.

Which nerve fibers are blocked first during neuraxial anesthesia?

B fibers (preganglionic sympathetic fibers).

What are the absolute contraindications of neuraxial anesthesia?

Patient refusal, infection at the injection site, coagulopathy, sepsis, increased intracranial pressure, and severe hypovolemia.

What is the significance of baricity in spinal anesthesia?

Baricity determines the spread of local anesthetic in cerebrospinal fluid.

What is the primary determinant of block height in epidural anesthesia?

The volume of local anesthetic injected.

What is the most distal approach to the epidural space?

The caudal approach via the sacral hiatus.

What is the recommended patient position for caudal anesthesia?

The prone position, often with a pillow under the hips.

How do local anesthetics work in spinal and epidural anesthesia?

They reversibly block voltage-gated sodium channels, preventing nerve depolarization and conduction.

Name one lipophilic opioid used in neuraxial anesthesia.

Fentanyl.

Name one hydrophilic opioid used in neuraxial anesthesia.

Morphine.

Which type of neuraxial opioid has a higher risk of late respiratory depression?

Hydrophilic opioids, such as morphine.

What sensory modalities are blocked in order during differential blockade?

Sympathetic (temperature), then pain, then touch, and finally motor function.

What cardiovascular effects are commonly seen with neuraxial anesthesia?

Hypotension and bradycardia due to sympathetic blockade.

Why might a patient experience a sensation of not being able to breathe after neuraxial anesthesia?

Due to blockade of thoracic sensory nerves (particularly C4–C5).

What is the effect of neuraxial anesthesia on gastrointestinal motility?

It increases gastrointestinal motility by blocking sympathetic fibers.

What are the symptoms of a post-dural puncture headache?

Positional headache, nausea, neck stiffness, photophobia, and sometimes hearing changes.

What are the three reflex responses proposed to cause severe bradycardia after spinal anesthesia?

1. Bezold-Jarisch reflex

2. Decreased venous return

3. High sympathetic blockade.

What are the key risk factors for developing an epidural hematoma?

Coagulopathy, traumatic needle or catheter placement, anticoagulant use, and spinal canal abnormalities.

What is cauda equina syndrome?

A rare complication involving compression or injury to the cauda equina nerves.

How is cauda equina syndrome related to neuraxial anesthesia?

It can result from high concentrations of local anesthetic or maldistribution.