Neuro 5 - PNS Flashcards
nerve ultrastructure
- myelinated and unmyelinated axons
- both supported by schwann cells
what is a motor unit
single alpha motor neuron and all of the corresponding muscle fibers it innervates
what is a lower motor neuron
efferent neuron of the PNS that connects CNS with the muscle
clinical signs of lower motor neuron disease
- paresis or paralysis
- hyporeflexia or areflexia
- hypotonia or atonia
- neurogenic atrophy
pathology of PNS disease with lesion
- wallerian degeneration
- axonal atrophy
- axonal dystrophy
- segmental demyelination
- degeneration and regeneration of unmyelinated axons
- bungner’s bands
causes of wallerian degeneration
- transection
- compression and crushing
- nerve stretching
- cell body injury (degeneration, infection)
reaction of neuronal cell body/glia cells to axonal damage (5)
- axonal degeneration
- secondary demyelination
- phagocytosis
- chromatolysis
- axonal regeneration
stages of chromatolysis
- healthy neuron
- chromatolysis
- necrosis
- liquefaction
diseases of the PNS
- traumatic lesion
- degenerative disease (nutritional, metabolic, toxic, hereditary)
- inflammatory diseases
- neoplasia
- disease of neuromuscular junction
traumatic lesions
- avulsion of brachial plexus
- cauda equina syndrome
- injection injury
- amputation neuroma
- calving paralysis/downer cows
- femoral nerve paralysis
- entrapment of suprascapular nerve
nutritional degenerative disease
- pantoghenic acid deficiency (swine)
- riboflavin deficiency (chickens)
metabolic degenerative disease
- diabetic neuropathy
- hypothyroid neuropathy
toxic degenerative disease
- lead poisoning
- mercury
- thallium
- pyridoxine (B6) poisoning
- vincristine neuropathy
- coyotillo neuropathy (poisonous plant)
- chloraquinone (malaria tx)
changes seen in hexachlorophene toxicity
- paranodal demyelination
- remyelination
- axonal degeneration
- intramyelinic edema
- separation of myelin lamellae
storage diseases
- globoid cell leukodystrophy
- canine alpha fucosidosis
- caprine mannosidosis
- feline neimann-pick disease polyneuropathy
- atypical canine GM2 gangliosidosis
inherited neuropathies
- canine inherited neuropathy and polyneuropathy
- hypertrophic polyneuropathy
- canine giant axonal neuropathy
inflammatory diseases
- 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
disorders of ANS
- grass sickness
- feline dysautonomy
diseases of neuromuscular junction
- botulism
- tentaus
- myasthenia gravis
PNS neoplasias
- peripheral nerve sheath tumor (benign, malignant)
- ganglioneuroma
- neuroblastoma
- primitive neuroectodermal tumor
- esthesioneuroblastoma
- marek’s disease
peripheral nerve sheath tumor (schwanoma/malignant schwanoma)
- 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
marek’s disease
- tumor invades nerve (sciatic) –> infiltration
- schwann cell proliferation
