Regional Anesthesia

Question 1

What is most ubiquitous material or layer in the epidural space?

Answer 1

FAT

Question 2

Termination of spinal cord in ADULT

Answer 2

L1

Question 3

All of the intrinsic muscles of the larynx are innervated by the RECURRENT laryngeal nerve EXCEPT

Answer 3

Cricothyroid Muscle

Question 4

The target nerve of TRANSTRACHEAL BLOCK is ___ which is done at the level of the cricothyroid membrane.

Answer 4

RECURRENT laryngeal nerve

Question 5

ANTIPLATELET DRUGS can be restarted ___ after Epidural/Continuous Spinal Catheter removal or Neuraxial procedure?

Answer 5

6 to 24 Hours

Question 6

Time after Neuraxial or Catheter Removal FOR FONDAPARINUX

Answer 6

6-12 Hours

Question 7

The Order of structures(FROM SKIN to ARACHNOID) when placing neuraxial?

Answer 7

Skin> Supraspinous ligament > Interspinous ligament > Ligamentum flavum > DURA > Arachnoid(CSF)

Question 8

The somatic and visceral sensation is from which nerve ROOT?

A. Posterior
B. Anterior

Answer 8

A. POSTERIOR

The posterior nerve root carries somatic and visceral sensation (pain).

The anterior nerve root carries motor and sympathetic outflow

Question 9

Which nerve root carries the MOTOR and SYMPATHETIC outflow?

A. Posterior Rami
B. Anterior Rami

Answer 9

B. ANTERIOR Rami

The anterior nerve root carries motor and sympathetic outflow

Question 10

Why does MORPHINE provide longer analgesia versus FENTANYL when used in NEURAXIAL?

Answer 10

By learning the difference of intrathecal fentanyl and morphine, you can essentially get a gauge of other opioids as they represent the two extremes: LIPOPHILIC (fentanyl, sufentanyl) and HYDROPHILIC (morphine). Because morphine is hydrophilic (lipophobic), it crosses the dura slower and has a much longer lifespan within the CSF than fentanyl.

Because morphine is hydrophilic (lipophobic), it crosses the dura slower and has a much longer lifespan within the CSF than fentanyl. Because of the slow clearance of the drug (and its hydrophilic properties) it has the greatest ROSTRAL spread among opioids.

This means two important (board-worthy) things: First, a lumbar intrathecal injection will produce analgesia well into high thoracic levels. More lipophilic drugs like fentanyl will create a more narrow band around the site of injection. Drugs less lipophilic than fentanyl and less hydrophilic than morphine like hydromorphone or meperidine will have an intermediate level of rostral spread

Second, because of its long duration of action and high rostral spread, respiratory depression has two peaks, an early peak and a late peak. Like all opioids, soon after intrathecal injection, opioids can be detected in the CSF surrounding the brainstem, which can lead to respiratory depression. Unlike other opioids, morphine’s slow rostral spread leads to another peak of respiratory depression at about 6 hours after injection (answer A), but can occur later. A 600 mcg dose (less than 300 mcg is typical) leads to late respiratory depression in most people. Also, because of the late peak in respiratory depression, intrathecal morphine should not be used for outpatient procedures.

Analgesia from intrathecal morphine has a slow onset (answer B) due to its hydrophilic nature and duration of action (in most cases) longer than 24 hours. Peak analgesic effects are typically at 6-12 hours after injection.

Question 11

Why does Benadryl not work for itching caused by intrathecal administration of opioids? What can you use instead?

Answer 11

Intrathecal opioid mediated itching works through a central mechanism (likely through the opioid receptor) and does not involve histamine release. Diphenhydramine is not an effective treatment for this condition, but does effectively treat annoying nurses through its sedating properties. If you should want to actually treat the patient all of the above choices are far more effective. Ondansetron can be used both to prevent and treat. Propofol needs to be very carefully titrated to be sub-hypnotic and continued on a gtt. Nalbuphine can also be sedating, but is reportedly the most effective. Naloxone doses should be very small and below the dose which would reverse analgesia. Typically 0.04-0.08 mg will do the trick.

Question 12

Which nerve block has the biggest risk for chylothorax?

A. SUPRACLAVICULAR (Landmark-based) NERVE BLOCK

B. INTERSCALENE (UTZ-guided) NERVE BLOCK

C. PARAVERTEBRAL (Fascial Plane) BLOCK

D. INFRACLAVICULAR (Landmark-based) Brachial Plexus Nerve Block

Answer 12

D. INFRACLAVICULAR (Landmark-based) Brachial Plexus Nerve Block

Infraclavicular block (without ultrasound) has the highest risk of pneumothorax. If you hear chylothorax on the boards, it probably means either a subclavian central line or infraclavicular brachial plexus block was performed (on the left side).

Question 13

Medial aspect of the knee is covered by which nerve?

A. Lateral Femoral Cutaneous Nerve

B. Obturator Nerve

C. Ilioinguinal Nerve

D. Sciatic Nerve

Answer 13

B. Obturator Nerve

Question 14

Wrist drop is an injury to which nerve?

A. Median Nerve

B. Radial Nerve

C. Ulnar Nerve

D. Musculocutaneous Nerve

Answer 14

B. Radial Nerve

Wrist drop is due to loss of wrist extensor function, which is a function of the radial nerve.

Nerve damage can occur due to surgical transection, prolonged tourniquet, positioning injury, needle transection, and intraneural injections. Needle transection and intraneural injections often result in no deficit, but in some individuals a prolonged nerve palsy is seen (rarely permanent).

Pronation instead of supination can entrap the ulnar nerve between the ulnar canal and the arm board (although in this situation it makes no sense as that arm was presumably being operated on!).

Median nerve = wrist flexion!
Ulnar Nerve = Pinch!

Question 15

TRUE or FALSE

The saphenous nerve is purely sensory

Answer 15

TRUE

Question 16

Differentiate Femoral nerve block vs adductor canal block in terms of motor and sensory block?

Answer 16

The adductor canal block has the advantage of producing less motor block (theoretically could be no motor block) as demonstrated with increased quadriceps strength and earlier mobilization. This is because the saphenous nerve is purely sensory. That being said, a large enough volume can ultimately end up blocking some motor nerves.

With the femoral nerve block, both motor and sensory fibers are blocked indiscriminately. Pain control between the two groups appears to be equivocal and its effects on actual outcome, including reducing complications, has yet to be proven.

Question 17

POTENCY of Local Anesthetic determined by:

A. pKa
B. Lipid Solubility
C. Protein binding
D. Volume of distribution

Answer 17

B. Lipid Solubility

Question 18

The rapid ONSET of Chloroprocaine is due to its:

A. Result of a high concentration
B. Low to Intermediate pKa
C. High pKa
D. Highly Lipophilic

Answer 18

A. Result of a high concentration

Question 19

The longer duration of ROPIVACAINE is mainly due to what pharmaco-property?

A. High lipid solubility

B. High protein binding

C. Low protein binding

D. Low lipid solubility

Answer 19

B. High protein binding

It means that local anesthetics with a higher affinity its for protein remain bound longer to the sodium channel. The degree of binding depends on addition of larger chemical radicals to amine or aromatic end. For example, ROPIVACAINE is 95% protein bound while Lidocaine 65% protein bound

Question 20

The faster onset of Mepivacaine is due to:

A. pKa

B. Lipid solubility

C. Protein binding

D. Volume of distribution

Answer 20

A. pKA.

The closer pKA of the local anesthetic is to tissue pH, the more RAPID the onset time.

low pKA = FAST ONSET

Question 21

The following structures are contained within the antecubital fossa EXCEPT:

a. Median nerve
b. Brachial artery
c. Basilic vein
d. Radial nerve

Answer 21

C. Basilic vein

The structures located within the antecubital fossa are the median nerve,
brachial artery, tendon of biceps and the radial nerve.

MEDIAN NERVE
RADIAL NERVE
BRACHIAL ARTERY

Question 22

The mouth is the most frequently assessed component of an airway assessment. Variations in structures within the mouth can often pose significant difficulties in obtaining an adequate airway. Which of the following statement is CORRECT regarding the clinical implication of variations in airway structure?

a. On a grade 1 laryngoscopy view, one would be able to see the palatoglossal and the palatopharyngeal arches

b. The nerve supply to muscles of the tongue is primarily from cranial nerve IX, the hypoglossal nerve

c. The anterior two-thirds of the tongue are innervated by the glossopharyngeal nerve

Answer 22

The tongue is superficially divided into an anterior two-thirds and a posterior third.
The lingual nerve, which arises from the mandibular branch of the trigeminal nerve,
supplies the anterior two-thirds of the tongue, passes through the chorda tympani and joins the facial nerve to reach the nucleus of the tractus solitarius. The posterior third of the tongue is supplied by the glossopharyngeal nerve.

Question 23

Which of the following motor response IS INCORRECTLY PAIRED when performing an axillary block?

A. Radial nerve → finger/wrist extension
B. Ulnar nerve → ulnar deviation
C. Median nerve → finger extension
D. Musculocutaneous → biceps twitch

Answer 23

C. Median nerve → finger extension - WRONG! finger FLEXION corresponds to median nerve.

These are the desired motor response when performing an axillary block:

Radial nerve → finger/wrist extension
Ulnar nerve → ulnar deviation
Median nerve → finger flexion
Musculocutaneous → biceps twitch

Question 24

A biceps twitch during a brachial plexus axillary block means you have successfully blocked which nerve?

A. Musculocutaneous Nerve

B. Ulnar Nerve

C. Median Nerve

Answer 24

A. Musculocutaneous Nerve

Question 25

Which of the following comprises the landmarks of the TAP block form the triangle of Petit:

A. External oblique muscle, Latissimus dorsi muscle, Iliac crest

B. Internal oblique muscle, iliac crest, external oblique muscle

C. rectus sheath, anterior superior iliac spine, external oblique muscle

Answer 25

A. External oblique muscle, Latissimus dorsi muscle, Iliac crest

TRIANGLE OF PETIT:

ANTERIOR: External oblique

POSTERIOR: Latissimus dorsi

INFERIOR: Iliac crest

Prior to ultrasound-guidance, the landmark-guided TAP block involved insertion of the needle posterior to the midaxillary line in the triangle of Petit. The triangle of Petit is bounded posteriorly by the latissimus dorsi, anteriorly by the external oblique, and inferiorly by the iliac crest.

This approach uses tactile pops as its endpoint. The first pop indicates penetration through the fascial extension of the external oblique muscle; the second pop indicates penetration through the fascial extension of the internal oblique muscle.

Question 26

Which of the following nerve provides sensory innervation to the DISTAL MEDIAL THIGH?

A. Obturator nerve
B. Iliohypogastric nerve
C. Ilioinguinal nerve
D. Lateral femoral cutaneous nerve

Answer 26

A. Obturator nerve

The Obturator nerve (L2-L4 (nerve roots)) provides:

• sensory innervation to the distal medial thigh
• motor innervation to the thigh adductor muscles

Question 27

Which of the following nerve provides sensory innervation to the ANTERIOR thigh?

A. Obturator nerve
B. Iliohypogastric nerve
C. Ilioinguinal nerve
D. Lateral femoral cutaneous nerve

Answer 27

D. Lateral femoral cutaneous nerve

The lateral femoral cutaneous nerve (L2-L3 (nerve roots)) provides sensory innervation to the ANTERIOR and LATERAL thigh

Question 28

Saphenous nerve is a distal branch of which major nerve of the lower extremities?

A. Sciatic nerve

B. Obturator nerve

C. Femoral nerve

Answer 28

C. Femoral nerve

Question 29

Pudendal nerve arises from which nerve root?

A. L3 - L4

B. L4 - S1

C. S2 - S4

D. L4 - S2

Answer 29

C. S2 - S4

Question 30

All of the following nerves arise from the coccygeal plexus EXCEPT?

A. Pudendal
B. Inferior anal
C. Perineal
D. Superior anal

Answer 30

D. Superior anal

Question 31

Orientation of abdominal muscles FROM superficial to deep:

A. External oblique muscle → internal oblique muscle → transverse abdominal muscle

B. Transverse abdominal muscle → internal oblique muscle → External oblique muscle

C. Transverse abdominal muscle → External oblique muscle → Internal oblique muscle

Answer 31

A. External oblique muscle → internal oblique muscle → transverse abdominal muscle

Think alphabetical:

E > I > T