Lecture 19

Question 1

Which classification of nerve do cranial nerves and spinal nerves fall into?

Answer 1

peripheral nerves

Question 2

What are the characteristics of motor neuropathy?

Answer 2

-flaccid paresis/paralysis
-decreased/absent muscle tone and reflexes
-neurogenic muscle atrophy; quick, significant loss

Question 3

What are the characteristics of sensory neuropathy?

Answer 3

-abnormal sensation, including hypalgesia, hyperesthesia, or paresthesia
-postural reaction deficits
-decreased/absent reflexes

Question 4

Why is it important to recognize that most peripheral nerves are mixed nerves?

Answer 4

contain both motor and sensory fibers

Question 5

What is hypalgesia?

Answer 5

decreased pain/not feeling pain

Question 6

What is hyperesthesia?

Answer 6

increased pain sensation

Question 7

What is paresthesia?

Answer 7

abnormal pain/pins and needles feeling

Question 8

How can specific nerves be tested?

Answer 8

-palpate for muscle symmetry and regional atrophy
-check spinal reflexes and cranial nerve reflexes
-test autonomous zones for sensation; esp. with sensory issues

Question 9

What is the cutaneous area?

Answer 9

area of skin supplied by a cutaneous nerve

Question 10

What is an overlap zone?

Answer 10

area supplied by 2 or more cutaneous nerves

Question 11

What is an autonomous zone?

Answer 11

area supplied by only one cutaneous nerve

Question 12

Which nerves are tested via the thoracic limb withdrawal reflex?

Answer 12

-axillary nerve for shoulder flexion
-musculocutaneous nerve for elbow flexion
-median and ulnar nerves for carpal flexion

Question 13

What are the autonomous zones for the thoracic limb?

Answer 13

-dorsum of paw: radial nerve
-caudal antebrachium: ulnar nerve
-medial antebrachium: musculocutaneous nerve

Question 14

Which nerve is tested via the patellar reflex?

Answer 14

femoral nerve

Question 15

Which nerves are tested via the pelvic limb withdrawal reflex?

Answer 15

-femoral nerve for hip flexion
-sciatic nerve for stifle flexion
-peroneal nerve for hock flexion

Question 16

What are the autonomous zones for the pelvic limb?

Answer 16

-dorsum of paw: peroneal nerve
-bottom of paw: tibial nerve
-medial crus: femoral nerve

Question 17

What are the characteristics of acute idiopathic polyradiculoneuritis?

Answer 17

-aka coonhound paralysis
-immune-mediated reaction to raccoon saliva, raw chicken, vaccines, or unknown antigens
-directed against ventral nerve roots and peripheral nerves (affects motor function)

Question 18

What are the clinical signs of acute idiopathic polyradiculoneuritis?

Answer 18

-onset 1 to 2 weeks after immune trigger
-ascending flaccid paralysis that can progress to tetraplegia and respiratory paralysis
-bark change/laryngeal weakness
-possible facial weakness
-hyperesthesia

Question 19

How is acute idiopathic polyradiculoneuritis diagnosed?

Answer 19

-history
-clinical signs
-CSF analysis/increased protein in lumbar CSF

Question 20

What is the treatment for acute idiopathic polyradiculoneuritis?

Answer 20

-supportive care that may be intensive
-physical therapy
-NO immunosuppressives

Question 21

What is the prognosis for acute idiopathic polyradiculoneuritis?

Answer 21

-usually good after weeks to months
-relapses can occur with re-exposure to immune stimulus

Question 22

What is trigeminal neuritis?

Answer 22

bilateral inflammation of the trigeminal nerves

Question 23

What are the signs of acute/subacute onset trigeminal neuritis?

Answer 23

-dropped jaw
-possible sensory deficits (can lead to corneal ulcers)
-possible Horner’s syndrome

Question 24

What are possible differential diagnoses for trigeminal neuritis?

Answer 24

-masticatory muscle myopathy
-rabies

Question 25

What is the treatment for trigeminal neuritis?

Answer 25

-fluids -nutritional support -PT for jaw -spontaneous recovery in 2 to 3 weeks

Question 26

What are the characteristics of diabetic neuropathy?

Answer 26

-pathogenesis not understood -occurs in ~ 8% of cats with DM; uncommon in dogs -causes plantigrade stance and reluctance to jump -may precede clinical signs of DM -treated via glycemic control -residual weakness may remain even with treatment

Question 27

What are the characteristics of hypothyroid neuropathy?

Answer 27

*pathogenesis not understood *older, large-breed dogs *several syndromes: -generalized polyneuropathy -multiple cranial nerve deficits -megaesophagus -laryngeal paralysis *vestibular presentation is most common *diagnosed by documenting hypothyroidism and ruling out other causes *treat by supplementing thyroid

Question 28

What are the characteristics of peripheral nerve sheath tumors?

Answer 28

-include schwannoma and neurofibroma -brachial plexus and trigeminal nerves are predilection sites -typically unilateral -MRI is best way to diagnose -treated with surgery, radiation therapy, or steroids for palliative care -amputation of affected limbs can be done -local recurrence in > 70% of cases

Question 29

What are the characteristics of degenerative neuropathy?

Answer 29

-old, large-breed dogs -dying-back neuropathy; longest nerves affected first -recurrent laryngeal nerve and sciatic nerve commonly affected -often have abnormal esophageal motility -rarely progresses to non-ambulatory -also known as GOLPP/geriatric onset laryngeal paralysis polyneuropathy -NOT treated with tie-back procedure

Question 30

What is the presentation and clinical signs of brachial plexus avulsion?

Answer 30

-animal with extreme abduction of limb -LMN weakness -possible sensory deficits -possible Horner's -possible abnormal cutaneous trunci reaction -muscle atrophy in 1 to 2 weeks -contracture -ulceration -self-mutilation

Question 31

What are the characteristics of brachial plexus avulsion prognosis?

Answer 31

-pain perception is most important factor -can take 2 to 3 months to be able to accurately assess

Question 32

What is the treatment for brachial plexus avulsion?

Answer 32

-time -physical therapy -protect limb -amputation if poor prognosis

Question 33

What are the characteristics of tail avulsion in cats?

Answer 33

-sacrocaudal subluxation -damages cauda equina -usually develop reflex dyssynergia -leads to flaccid tail

Question 34

What is the treatment for tail avulsion?

Answer 34

-bladder management -pain management; may require amputation

Question 35

What are the characteristics of tail avulsion prognosis?

Answer 35

-based on tail base sensation and bladder function -no bladder function in 30 days indicates grave prognosis

Question 36

What are possible iatrogenic nerve injuries?

Answer 36

*sciatic nerve: -injection in caudal thigh muscles -IM pins in femur -total hip replacement *peroneal nerve: -entrapment by lateral suture -laceration during TPLO *radial nerve: -compression by tourniquet

Question 37

What are the characteristics of wallerian degeneration?

Answer 37

-occurs when axon is damaged along its length -trophic degeneration -takes around 3 days to occur