Neuromuscular Disease in Small Animals

Question 1

what is the motor unit?

Answer 1

cell body in spinal cord
nerve root
spinal nerve
specific named nerve
synapse/junction
muscle fibers

Question 2

what does it mean that myelinated nerves have saltatory conduction?

Answer 2

jump from one node of ranvier to the next

Question 3

what is the rate of action potential travel influenced by?

Answer 3

diameter of axon and degree of myelination

Question 4

how do the amount of acetylcholine receptors compare to the amount needed to generate an end-plate potential?

Answer 4

many more than required to reach action potential in the myofiber

Question 5

how aree myofibers innervated?

Answer 5

each one innervated by only on axon of one motor neuron

Question 6

what are some diseases that have an acute presentation?

Answer 6

myasthenia gravis
idiopathic polyradiculoneuritis

Question 7

what is important about signalment?

Answer 7

breed
specific age groups

Question 8

what are gait and posture like with neuromuscular disease?

Answer 8

lower motor neuron paresis without ataxia
crouched or plantigrade stance
cervical ventroflexion in cats
maybe worsens with exercise

Question 9

should proprioception be normal or abnormal with neuromuscular disease?

Answer 9

normal with weight support

Question 10

what are the goals of a workup for neuromuscular disease?

Answer 10

confirm neuromuscular localization
find level of lesion
define cause of lesion
determine treatment plan

Question 11

what is important on a chem for diagnostics?

Answer 11

CK/AST

Question 12

what does electrodiagnostic testing have a high degree of sensitivity for?

Answer 12

axonal dysfunction

Question 13

what does electromyography record and study?

Answer 13

insertional, spontaneous and voluntary electrical activity of muscle

Question 14

what can electromyography give insights into?

Answer 14

myopathies and neuropathies

Question 15

what are abnormal electromyography findings?

Answer 15

spontaneous activity seen with no movement of the needle

Question 16

what is evaluated for motor nerve conduction velocity?

Answer 16

CMAP amplitude: health of axons
nerve conduction velocity: degree of myelination

Question 17

what are F waves?

Answer 17

antidromic motor nerve activation

Question 18

what are diagnostics useful for in neuromuscular disease?

Answer 18

differentiate between denervation atrophy (axonal disease) and disuse atrophy

Question 19

what is the other name of idiopathic polyradiculoneuritis?

Answer 19

coonhound paralysis

Question 20

how can you diagnose idiopathic polyradiculoneuritis?

Answer 20

absent F waves

Question 21

which nerves are affected first by geriatric onset laryngeal paralysis polyneuropathy?

Answer 21

longest ones: sciatic nerve and recurrent laryngeal nerve

Question 22

what is the focal form or myasthenia gravis?

Answer 22

megaesophagus

Question 23

what is the generalized form of myasthenia gravis?

Answer 23

megaesophagus
appendicular muscle weakness, exercise intolerance
normal spinal reflexes and muscle tone

Question 24

what does acetylcholinesterase do?

Answer 24

enzymatic hydrolysis of unbound acetylcholine: rapid termination to ready muscle for next signal

Question 25

what is the end-plate potential like at a normal neuromuscular junction?

Answer 25

several times larger than that required to reach action potential in the myofiber

Question 26

what does the strength of muscle contraction depend on?

Answer 26

number of motor units activated in a muscle

Question 27

what are some nerve changes due to damage?

Answer 27

demyelination axonopathy axonopath with secondary demyelination wallerian degeneration

Question 28

what is a polyneuropathy with acute presentation?

Answer 28

idiopathic polyradiculoneuritis

Question 29

where in the neuromuscular junction is the problem in myasthenia gravis?

Answer 29

postsynaptic membrane

Question 30

what does finding an elevated temperature, increased respiratory rate and/or effort, reduced chest excursions, or a palpable mass raise concern for?

Answer 30

aspiration pneumonia hypoventilation megaesophagus

Question 31

what findings on physical exam would suggest cranial nerve deficits?

Answer 31

fatiguing or absent palpebral reflex dysphagia megaesophagus voice change inspiratory noise/stridor

Question 32

what diagnostics for electrodiagnostic testing are useful for neuromuscular disease?

Answer 32

EMG nerve conduction

Question 33

what are myotonic discharges on EMG like?

Answer 33

waxing and waning

Question 34

what is the most common cause of myotonic discharges on EMG?

Answer 34

myotonia congenita

Question 35

what is motor nerve conduction velocity used in conjunction with?

Answer 35

EMG to differentiate neuropathies from myopathies

Question 36

what does CMAP amplitude in motor nerve conduction velocity reflect?

Answer 36

health of the axons

Question 37

what is repetitive nerve stimulation used to evaluate?

Answer 37

neuromuscular junction

Question 38

what in repetitive nerve stimulation suggests myasthenia gravis?

Answer 38

decrement of greater than 10% of CMAP

Question 39

what are the clinical signs of idiopathic polyradiculoneuritis?

Answer 39

reduced or absent spinal reflexes reduced muscle tone

Question 40

who does geriatric onset laryngeal paralysis polyneuropathy usually occur in?

Answer 40

geriatric (8-13) large breed dogs

Question 41

what is the result of geriatric onset laryngal paralysis polyneuropathy?

Answer 41

distal axonopathy with secondary demyelination

Question 42

what are the late clinical signs of geriatric onset laryngeal paralysis polyneuropathy?

Answer 42

laryngeal weakness or paralysis paraparesis abnormal withdrawal reflex

Question 43

what are the acquired forms of myasthenia gravis?

Answer 43

idiopathic paraneoplastic: thymoma

Question 44

what is the acute, fulminating form of myasthenia gravis?

Answer 44

megaesophagus appendicular muscle weakness, exercise intolerance decreased or absent spinal reflexes, decreased muscle tone hypoventilation, respiratory failure