Regional Anesthesia

Question 1

Of the spinal nerve roots, what does the anterior root carry? What does the posterior root carry?

Answer 1

Anterior root: Motor and sympathetic outflow

Posterior root: Somatic and visceral sensation (pain)

Question 2

Does the posterior nerve root carry motor nerves?

Answer 2

No

Question 3

What type of block can be used for analgesia after umbilical or incisional hernia repairs and other midline surgical incisions?

Answer 3

rectus sheath block

Question 4

Rectus sheath block:

a) what nerves are blocked?
b) where do these nerves traverse?
c) what do they supply

Answer 4

Blocks 9th 10th, and 11th intercostal nerves, which run in between the internal oblique and transversus abdominus muscle.

The most widely described approach is a blind technique, passing the needle through anterior rectus sheath and through the rectus abdominis muscle and injecting the local anaesthetic on the posterior wall of the rectus sheath.

Question 5

What are the key nerves of the brachial plexus in the axilla?

Answer 5

Radial
Median
Ulnar

These nerves are located in relatively consistent positions in relation to each other and to the axillary artery.

Question 6

In relation to the axillary artery:

1- the median nerve is superior/inferior/posterior?
2- the ulnar nerve is superior/inferior/posterior?
3- The radial nerve is superior/inferior/posterior?

Answer 6

Median nerve is superior to the axillary artery
Ulnar nerve is inferior to the axillary artery
Radial nerve is posterior to the axillary artery

Question 7

US guided supraclavicular blockade is normally performed at which level of the brachial plexus?

Answer 7

At the level of the divisions

Question 8

What is the first line treatment for an acute radiculopathy?

Answer 8

NSAIDs. Epidural steroid injection may be very helpful in speeding resolution of symptoms but is not generally thought to reduce the proportion of patients who may eventually progress to surgery. Many clinicians would advocate for early surgical consultation in a patient with weakness and muscle
atrophy.

Question 9

What is the salient feature that distinguishes a complex regional pain syndrome from a neuralgia?

Answer 9

The presence of sympathetic nervous system dysfunction

Question 10

T or F: CRPS type I is diagnosed in the absence of a known nerve injury. CRPS type II is diagnosed in the presence of a known nerve injury.

Answer 10

True-

Complex regional pain syndrome (CRPS) type II can be diagnosed when a patient has a known injury
pain disproportionate to the inciting event sympathetic nervous system dysfunction including sudomotor (sweating), pilomotor (goose bumps), or vasomotor symptoms (color change, edema) at some point during the course of the disease
no other explanatory diagnosis (such as deep vein thrombosis).

Question 11

T or F: motor symptoms, while not pat of the diagnostic criteria of CRPS, are quite common.

Answer 11

True- while not part of the diagnosis, motor symptoms are quite common in CRPS. Motor symptoms in CRPS include:

reduced strength
tremor
incoordination
dystonia
muscle wasting
muscle spasm
involuntary movements

Tremor has been reported in more than 50% and incoordination in more than 82% of patients with CRPS. These motor symptoms, the sympathetic nervous system dysfunction, and the perceived sense of the pain spreading over a larger area of tissue can be understood as a set of abnormal spinal and brain responses that occur in response to the inciting peripheral injury that initiated the CRPS. The central nervous system (CNS) dysfunction initiated by the inciting peripheral trauma is the critical distinguishing feature
between CRPS and a simple neuralgia in which a nerve can be injured and cause pain but is not associated with these manifestations of CNS dysfunction.

Question 12

T or F: a superficial cervical plexus block is more likely to be associated with a horner’s syndrome.

Answer 12

True

Question 13

Which of the following nerves is typically spared during performance of an interscalene brachial plexus block?

a. median
b. axillary
c. musculocutaneous
d. ulnar

Answer 13

Ulnar- the ulnar nerve branch originates from C8-T1 nerve roots. A properly performed interscalene approach to brachial plexus blockade can provide for a dense blockade of the C5-C7 nerve roots/trunks and less consistent blockade of C8-T1 nerve roots/trunks.

Thus, an interscalene appropach may not be the best block for distal upper extremity surgery.

Question 14

What are the five roots that innervate the foot?

Answer 14

posterior tibial, sural, superificial peroneal, deep peroneal, and saphenous.

Question 15

T or F: reactivation of phantom limb sensations has been reported in patients who receive both spinal and epidural anesthetics.

Answer 15

True- in the majority of these cases (80%), phantom limb sensation persisted until the block receded. Severe phantom pain history may be a relative contraindication to neuraxial analgesia.

Question 16

Which parts of the arm are NOT innervated by the brachial plexus?

Answer 16

1- shoulder- innervated by the cervical plexus

2- posterior medial aspect of arm- supplied by the intercostobrachial nerve.

Question 17

At what anatomic structures do the various parts of the brachial plexus exist?

Answer 17

1- Roots- at the level of the ventral rami C5-T1
2- Trunks- the roots become the three trunks at the level of the scalene muscle
3- Divisions- the trunks divide into the dorsal and ventral divisions at the lateral edge of the first rib
4- Cords- when the divisions enter the axilla, they become the posterior, lateral, and medial cords
5- 5 periopheral nerves: at the lateral border of the pectoralis muscle, they become the five peripheral nerves, radial, musculocutaneous, median, ulnar, and axillary

Question 18

T or F: a cutting needle (eg Quinke) has a greater incidence of PDPH than non-cutting needles (eg Whitacre, Sprotke).

Answer 18

True

Question 19

Prolonged pressure on the medial epicondyle produces:

Answer 19

an ulnar neuropathy

Question 20

Prolonged pressure on the posterior humerus produces:

Answer 20

a radial neuropathy

Question 21

T or F: the saphenous nerve is a branch of the femoral nerve and provides sensory innervation along the medial aspect of the lower leg between the knee and medial malleolus.

Answer 21

True

Question 22

What is the most common complication of a celiac plexus block?

Answer 22

hypotension secondary to decreased preload to the heart from the produced sympathectomy. Note that celiac plexus blocks relieve constipation by interrupting the sympathetic fibers and leaving the paraysympathetic fibers unopposed..

Question 23

T or F: neurolytic blockade with phenol is painless because phenol has a dual action as both a local anesthetic and a neurolytic agent.

Answer 23

true

Question 24

The potency of local anesthetics is related to which property?

Answer 24

lipid solubility

Question 25

The speed or onset of action of local anesthetics is related to which property?

Answer 25

the pKa of the drug. drugs with lower pKas have a higher amount of non-ionized molecules at physiologic pH and penetrate the lipid portion of nerves faster.

Question 26

The duration of action of local anesthetics is related to which property?

Answer 26

protein binding- more protein binding kmeans longer duration of action

Question 27

T or F: chloroprocaine has the highest pKa of the local anesthetics.

Answer 27

True- this means a greater percentage of it will exist in the ionized form at any given pH than any of the other local anesthetics. Despite this fact, 3% chloroprocaine has a more rapid onset than 2% lidocaine, presumably because of the greater number of molecules (concentration).