Ch.73 Diagnostic & regional Anaesthesia of the Limbs & Axial Skeleton

Question 1

Which of the following is true regarding regional anaesthesia of the limbs

a. C and A-delta fibers are non-myelinated

b. A-delta fibers conduct dull diffuse pain whilst C fibers conduct sharp fast pain

c. The majority of fibers concerned with nociceptive transmission are C-fibers

d. all of the above

Answer 1

c. The majority of fibers concerned with nociceptive transmission are C-fibers

sparsely myelinated A-δ-
and nonmyelinated C-fibers

A-δ-fibers tend to be responsible for conduction of fast, sharp pain and
C-fibers for dull, diffuse pain

A delta are sparsly myelinated

Question 2

Which of the following statements is true

a. Local anesthetics block nerve conduction by preventing the increase in membrane permeability to sodium ions that occurs when nerves are stimulated

b. Local anesthetics block nerve conduction by preventing the increase in membrane permeability to potassium ions that occurs when nerves are stimulated

c.Local anesthetics block nerve conduction by enhancing rapid inward flow of Na+, thereby inhibiting depolarization of the membrane

d.Local anesthetics block nerve conduction by enhancing rapid inward flow of K+, thereby inhibiting depolarization of the membrane

Answer 2

a. Local anesthetics block nerve conduction by preventing the increase in membrane permeability to sodium ions that occurs when nerves are stimulated

inhibiting the rapid inward flow of Na+, thereby inhibiting depolarization of the membrane.

Question 3

Which of the following is true regarding regional anaesthesia

a. The first nerve fibers blocked are the C fibers

b. The first nerve fibers blocked are the B fibers

c. The last nerve fibers blocked are the B fibers

d. The first nerve fibers blocked are the A-δ- fibers

Answer 3

b. The first nerve fibers blocked are the B fibers

first nerve fibers blocked are the B-fibers;
the
A-δ- and C-fibers are next;
and the
last nerve fibers blocked are A-γ-, A-β-, and A-α3-fibers

Question 4

Which is true regarding the order of development of blockade

a. sympathetic function first, followed by pin-prick sensation, touch, temperature, and
finally motor function.

b. temperature first, sympathetic function,
followed by pin-prick sensation, touch and
finally motor function.

c. pin-prick sensation, motor function, sympathetic, motor function and finally temperature

d. sympathetic function first, followed by pin-prick sensation, touch, temperature but no motor function.

Answer 4

a. sympathetic function first, followed by pin-prick sensation, touch, temperature, and
finally motor function.

Question 5

Effective time of 2% lidocaine

Answer 5

30mins-3hours

Question 6

Which of the following is true regarding duration of efficacy of local anaesthetics

a. Lidocaine 30 minutes to 1 hour
Mepivacaine 90 minutes to 5 hours
Bupivacaine from 6 to 8 hours
Ropivacaine 8 hours
Liposomal bupivicane >24 hours

b. Lidocaine 30 minutes to 3 hours
Mepivacaine 90 minutes to 3 hours
Bupivacaine from 3 to 8 hours
Ropivacaine 3 hours
Liposomal bupivicane >24 hours

c. Lidocaine 90 minutes to 3 hours
Mepivacaine 90 minutes to 3 hours
Bupivacaine from 90 minutes to 8 hours
Ropivacaine 3 hours
Liposomal bupivicane >24 hours

d. Lidocaine 30 minutes to 3 hours
Mepivacaine 90 minutes to 3 hours
Bupivacaine from 3 to 8 hours
Ropivacaine 3 hours
Liposomal bupivicane >12 hours

Answer 6

b. Lidocaine 30 minutes to 3 hours
Mepivacaine 90 minutes to 3 hours
Bupivacaine from 3 to 8 hours
Ropivacaine 3 hours
Liposomal bupivicane >24 hours

Question 7

Duration of effect - 0.5/0.75% Ropivacane

Answer 7

3 hours

Question 8

Duration of effect of - liposomal lidocaoine in human sx

Answer 8

24 hours

Question 9

How long does a bottle of a bottle of local anaesthetic remain stable once opened

Answer 9

16 months

Question 10

What preservative is used in local anaesthetics

Answer 10

Methylparaben

Question 11

Epinephrine can be added to local anaesthetic to prolong the duration and increase the intensity, what dose should be used

Answer 11

1:200,000
5ug/ml
0.1ml of 1:1000 epi added to 20cc of local

Question 12

Risks of using epinephrine in local

Answer 12

Skin necrosis
White hairs
Tissue swelling

Question 13

a. Chondrocyte death following local admin is more pronounced in osteoarthritis

b. 2% mepivicane has shown questionable efficacy in PD nerve block

c. Addition of epinephrine prolongs activity of Ropivacane for 3 hours

d. All of the above

Answer 13

a. Chondrocyte death following local admin is more pronounced in osteoarthritis

2% lidocaine has shown questionable efficacy in PD nerve block

Addition of epinephrine does not prolongs activity of Ropivacane because it already has vasconstrictive properties

Question 14

a. A positive response of 75% is deemed diagnostic when performing intrasynovial block

b. Rate of sepsis following synoviocenthesis is 9 per 1000

c. Spacing between nodes of Ranvier is responsible for longer time for block to become effective in proximal limb

d. distal limb blocks should be checked after 5 mins whilst proximal limb blocks should be checked after 15mins

Answer 14

c. Spacing between nodes of Ranvier is responsible for longer time for block to become effective in proximal limb

50%

9 per 10,000

5 mins distal, 30 mins proximal

Question 15

a. Polysulfated glycosaminoglycans and corticosteroids are medications have been most commonly associated with synovial sepsis

b. Horses receiving intraarticular 0.5% bupivicane are at risk of showing clinical signs and synovial fluid parameters mimicking those of septic synovitis

c. The carpal sheath is most easily accessed using a medial approach with the limb held in a slightly flexed position

d. The axial sesamoidean approach to the DFTS is more likely to result in retrieval of synovial fluid to verify accuracy of centesis than the basilar sesamoidean approach

Answer 15

a. Polysulfated glycosaminoglycans and corticosteroids are medications have been most commonly associated with synovial sepsis

horses receiving intraarticular lidocaine are at risk of showing clinical signs and synovial fluid parameters mimicking those of septic synovitis.

The carpal sheath is most easily accessed using a lateral approach with the limb held in a slightly flexed position

A basilar sesamoidean approach is more likely to result in retrieval of synovial fluid to verify accuracy of centesis than the axial sesamoidean approach

Question 16

When performing standing sx on the forelimb, what additional nerve should be anaesthetized to block the skin

Answer 16

Medial cutaneous antebrachial n.
&
Dorsal branch of ulnar nerve

Question 17

Branch which selectively blocks the navicular apparatus

Answer 17

Ramus tori digitalis (ramus pulvinus)

Prox margin of collateral cartilage, palmar to DDFT

Question 18

What does the Wheat block anaesthetise

Answer 18

Lateral palmar nerve before it gives off deep br. that splits into lat and med

Question 19

Perform a wheat block

Answer 19

Distopalmar accessory carpal bone
Palmarlat to Dorsomedial
Leur lock
5cc while withdrawing

Risk: inadvertant inj of carpal canal

Question 20

Perform medial approach to lateral palmar nerve. Risks..

Answer 20

As it courses medial to accesory carpal bone
Longintudal groove medial distal third of accessory cb.
1.5 - 2ml

Can hit nerve - violent rxn & extensive proximal diffusion but doesnt risk inj carpal canal

Question 21

Site for ulnar nerve block

Answer 21

10cm prox to accessory cb.
Groove separating ulnaris lateralis and flexor carpi ulnaris muscles

Question 22

Vol for ulnar nerve block

Answer 22

10ml

Question 23

Site for median nerve block

Answer 23

Junction of caudimedial border of radius
&
Ventral superfic. pectoral

Question 24

Vol for median n block

Answer 24

10 -15ml

Question 25

a. Refrigeration of local anaesthetics is contraindicated because refrigeration inactivates the drugs ability to block Na+ channels

b. Once refrigerated local anesthetics used in equine practice are extremely stable for at least 16 months after opening the vial

c. Epinephrine can be added to local anesthetic solutions to increase not only the duration of anesthesia, but also the intensity of anesthesia

d. Epinephrine is particularly effective in prolonging the activity of ropivicane sometimes to 24 hours

Answer 25

c. Epinephrine can be added to local anesthetic solutions to increase not only the duration of anesthesia, but also the intensity of anesthesia

local anesthetics used in equine practice are extremely stable for at least 16 months after opening the vial

Refrigeration of local anesthetic solution to increase its length of potency is contraindicated because refrigeration inactivates a preservative (methylparaben) that prevents bacterial growth in the solution

Epinephrine does not prolong the activity of ropivacaine,

Question 26

a. 0.5% bupivicane is far less chondrotoxic than 2% mepivicaine or 2% lidocaine

b. 2% mepivacaine is far less chondrotoxic than 0.5% bupivacaine or 2% lidocaine

c. ramus tori digitalis (ramus pulvinus), may result in selective desensitization of the proximal sesamoids without loss of skin sensation

d. A major advantage of the Wheat block is that inadvertent injection of the carpal sheath does not occur

Answer 26

b. 2% mepivacaine is far less chondrotoxic than 0.5% bupivacaine or 2% lidocaine

ramus tori digitalis (ramus pulvinus), may result in selective desensitization of the navicular apparatus without loss of skin sensation in the heel region of the foot

A major advantage of medial approach to lateral palmar nerve block over the Wheat block is that inadvertent injection of the carpal sheath does not occur.

Question 27

a. Ulnar nerve is found between the ulnaris lateralis and the flexor carpi ulnaris

b. Median nerve is located in the ventral border of the superficial pectoral muscle

c. For surgical procedures performed further proximally on the limb, the medial cutaneous antebrachial (musculocutaneous) nerve as well as the median and ulnar nerves are anesthetized

d. all of the above

Answer 27

d. all of the above

Question 28

Which of the following statements is true

a. Injecting greater than 12 mL may result in rupture of the navicular bursa

b. PIPJ - Synovial fluid is frequently observed with the
dorsal approach but is rarely observed using the palmaroproximal and
lateral approaches

c. The palmar/plantar axial sesamoidean approach is rarely accurate unless the DFTS is distended with synovial fluid

d. none of the above

Answer 28

d. none of the above

Injecting greater than 5 mL may result in rupture of the bursa

Synovial fluid is frequently observed with the
palmaroproximal and lateral approaches but is rarely observed using the other approaches

The palmar/plantar axial sesamoidean approach is very accurate even when the DFTS is not distended with synovial fluid

Question 29

a. A cranial transtendinous approach to the bicipital bursa has shown to have a limited chance of success unless performed with ultrasound guidance

b. Scapulohumeral Joint - Periarticular deposition of local anesthetic may result in paralysis of the supraspinatus and infraspinatus muscles by means of blocking the suprascapular nerve

c. Inadvertent periarticular administration of local anesthetic during attempted centesis of the cubital joint may result in anesthesia of the superficial branch of the radial nerve, which causes paralysis of the extensor carpi radialis and common digital extensor muscles

d. Communication exists between the scapulohumeral joint and the bicipital bursa of all horses.

Answer 29

b. Scapulohumeral Joint - Periarticular deposition of local anesthetic may result in paralysis of the supraspinatus and infraspinatus muscles by means of blocking the suprascapular nerve

A cranial transtendinous approach to the bicipital bursa is highly accurate and likely to yield synovial fluid to confirm accuracy.

Inadvertent periarticular administration of local anesthetic during attempted centesis of the cubital joint may result in anesthesia of the deep branch of the radial nerve, which causes paralysis of the extensor carpi radialis and common digital extensor muscles

communication exists between the scapulohumeral joint and the bicipital bursa of some horses.

Question 30

a. the distal portion of the pelvic limb is innervated by two additional nerves, the medial and lateral dorsal metatarsal nerves, which are branches of the deep peroneal (fibular) nerve

b. The communicating branch (ramus communicans) that connects the lateral and medial plantar nerves is usually either rudimentary or nonexistent in the pelvic limb

c. The deep branch of the lateral plantar nerve divides to form the medial and lateral plantar metatarsal nerves and nerves that supply sensation to the proximal portion of the suspensory ligament.

d. all of the above

Answer 30

d. all of the above

Question 31

a. The medial and lateral dorsal metatarsal nerves, are branches of the tibial nerve

b. The peroneal nerve gives off the medial and lateral plantar nerves

c. Blocking the tibial nerve will improve or abolish lameness caused by proximal suspensory desmitis

d. All of the above

Answer 31

c. Blocking the tibial nerve will improve or abolish lameness caused by proximal suspensory desmitis

the medial and lateral dorsal metatarsal nerves, are branches of the deep peroneal (fibular) nerve

The tibial nerve gives off the medial and lateral plantar nerves, and because
the deep branch of the lateral plantar nerve supplies sensory innervation to the suspensory ligament, blocking the tibial nerve will improve or abolish lameness caused by proximal suspensory desmitis

Question 32

a. After a tibial nerve block the horse may buckle at the MTP joint as a sign of extensor muscle paralysis, which may necessitate discontinuation of the lameness examination

b. The TMT and DIT joints have been shown in all horses to communicate functionally (i.e., by diffusion) when mepivacaine HCl or methylprednisolone acetate was injected into the TMT joint

c. The intertendinous calcaneal bursa and the gastrocnemius calcaneal bursa, rarely communicate

d. All of the above

Answer 32

b. The TMT and DIT joints have been shown in all horses to communicate functionally (i.e., by diffusion) when mepivacaine HCl or methylprednisolone acetate was injected into the TMT join

After a peroneal nerve block the horse may buckle at the MTP joint as a sign of extensor muscle paralysis, which may necessitate discontinuation of the lameness examination

the two compartments of the deep portion, the intertendinous calcaneal bursa and the gastrocnemius calcaneal bursa, always communicate

Question 33

a. The subcutaneous and deep portion of the calcaneal bursa always communicate

b. When ultrasonographic guidance is not available, a cranial approach to the SI joint should not be used for administration of local anesthetic solution because of the danger of paresis caused by inadvertent anesthesia of the sciatic nerve

c. Scapulohumeral Joint - Periarticular deposition of local anesthetic may result in paralysis of the supraspinatus and infraspinatus muscles by means of blocking the deep branch of the radial nerve

d. none of the above

Answer 33

d. None of the above

The subcutaneous and deep portion of the calcaneal bursa often communicate

When ultrasonographic guidance is not available, a caudal approach to the SI joint should not be used for administration of local anesthetic solution because of the danger of paresis caused by inadvertent anesthesia of the sciatic nerve

Periarticular deposition of local anesthetic may result in paralysis of the supraspinatus and infraspinatus muscles by means of blocking the suprascapular nerve