Neuro 5 - PNS

Question 1

nerve ultrastructure

Answer 1

• myelinated and unmyelinated axons

- both supported by schwann cells

Question 2

what is a motor unit

Answer 2

single alpha motor neuron and all of the corresponding muscle fibers it innervates

Question 3

what is a lower motor neuron

Answer 3

efferent neuron of the PNS that connects CNS with the muscle

Question 4

clinical signs of lower motor neuron disease

Answer 4

• paresis or paralysis
• hyporeflexia or areflexia
• hypotonia or atonia
• neurogenic atrophy

Question 5

pathology of PNS disease with lesion

Answer 5

• wallerian degeneration
• axonal atrophy
• axonal dystrophy
• segmental demyelination
• degeneration and regeneration of unmyelinated axons
• bungner’s bands

Question 6

causes of wallerian degeneration

Answer 6

• transection
• compression and crushing
• nerve stretching
• cell body injury (degeneration, infection)

Question 7

reaction of neuronal cell body/glia cells to axonal damage (5)

Answer 7

• axonal degeneration
• secondary demyelination
• phagocytosis
• chromatolysis
• axonal regeneration

Question 8

stages of chromatolysis

Answer 8

• healthy neuron
• chromatolysis
• necrosis
• liquefaction

Question 9

diseases of the PNS

Answer 9

• traumatic lesion
• degenerative disease (nutritional, metabolic, toxic, hereditary)
• inflammatory diseases
• neoplasia
• disease of neuromuscular junction

Question 10

traumatic lesions

Answer 10

• avulsion of brachial plexus
• cauda equina syndrome
• injection injury
• amputation neuroma
• calving paralysis/downer cows
• femoral nerve paralysis
• entrapment of suprascapular nerve

Question 11

nutritional degenerative disease

Answer 11

• pantoghenic acid deficiency (swine)

- riboflavin deficiency (chickens)

Question 12

metabolic degenerative disease

Answer 12

• diabetic neuropathy

- hypothyroid neuropathy

Question 13

toxic degenerative disease

Answer 13

• lead poisoning
• mercury
• thallium
• pyridoxine (B6) poisoning
• vincristine neuropathy
• coyotillo neuropathy (poisonous plant)
• chloraquinone (malaria tx)

Question 14

changes seen in hexachlorophene toxicity

Answer 14

• paranodal demyelination
• remyelination
• axonal degeneration
• intramyelinic edema
• separation of myelin lamellae

Question 15

storage diseases

Answer 15

• globoid cell leukodystrophy
• canine alpha fucosidosis
• caprine mannosidosis
• feline neimann-pick disease polyneuropathy
• atypical canine GM2 gangliosidosis

Question 16

inherited neuropathies

Answer 16

• canine inherited neuropathy and polyneuropathy
• hypertrophic polyneuropathy
• canine giant axonal neuropathy

Question 17

inflammatory diseases

Answer 17

• acute idiopathic polyradiculatis
• chronic polyradiculitis
• brachial plexus neuritis
• canine ganglioneuritis
• enteric ganglioneurotis (pseudorabies)
• neuritis of cauda equina
• cranial neuritis with gutteral pouch mycosis and empyema

Question 18

disorders of ANS

Answer 18

• grass sickness

- feline dysautonomy

Question 19

diseases of neuromuscular junction

Answer 19

• botulism
• tentaus
• myasthenia gravis

Question 20

PNS neoplasias

Answer 20

• peripheral nerve sheath tumor (benign, malignant)
• ganglioneuroma
• neuroblastoma
• primitive neuroectodermal tumor
• esthesioneuroblastoma
• marek’s disease

Question 21

peripheral nerve sheath tumor (schwanoma/malignant schwanoma)

Answer 21

• most common in adult bovine
• gross: nodular thickenings of large nerve trunks, well demarcated, firm fibrillar to gelatinous, white/gray, mostly benign
• bovine: brachial plexus, intercostal nerves, cardiac nerves
• dogs: cranial nerve roots, spinal nerve roots, brachial plexus, skin, LI

Question 22

marek’s disease

Answer 22

• tumor invades nerve (sciatic) –> infiltration

- schwann cell proliferation