Neuromuscular Disease Flashcards
Two components of the motor unit
1) motor neuron
2) skeletal muscle fibers it innervates
Name the 4 important parts of the NMJ
presynaptic membrane
Synaptic cleft
Postsynaptic membrane
Muscle fiber
Briefly describe how muscle contraction occurs
nerve impulse reaches presynaptic terminal causing voltage-gated Ca channels to open–>Ca causes ACh vessicles to empty into synaptic cleft–>ACh binds nicotinic receptors on postsynaptic membrane–>opens Na channels–>depolarization
A stiff, stilited gait with no ataxia or proprioceptive deficits fits with?
Myopathy
The majority of the myopathies are diagnosed using?
Elevated CK levels
EMG
Muscle biopsy
A unique feature of labrador retriever myopathy that’s seen on muscle biopsy
centronuclear myopathy (centrally located nuclei)
First step in diagnosing Cushing’s myopathy
confirm presence of hyperadrenocoritcism (cushing’s)
A unique diagnostic test for masticatory muscle myositis?
2M antibody tiers (autoimmune disease against 2M muscles)
When tentatively diagnosing autoimmune polymyositis, what should you first rule out?
infectious causes
Name the cause of congenital vs. acquired myasthenia gravis?
Congenital–low number of ACh receptors
Acquired–Abs against the ACh receptor (autoimmune)
Congenital myasthenia gravis:
1) age of onset
2) typical breeds
1) 6-9 weeks (early)
2) jack russell, samoyeds, mini doxen
Botulism MOA?
Blocks ACh release at NMJ
How long must tick be on for paralysis to become a problem?
5-9 days
This disease of middle age to older dogs presents with CNN (V, VII, VIII) deficits and LMN paresis of the limbs; can also see laryngeal paralysis & megaesophagus
Hypothyroid neuropathy
Best way to diagnose paraneoplastic neuropathy (insulinoma)
paired insulin/glucose blood levels after 24hr fasting
This neuropathy has been associated with raccoon saliva and can cause rapidly ascending quadraplegia but lacks CNN involvement; normal tail movements
Acute idiopathic polyradiculoneuritis
This disease primarily affects dogs 6-7 years old and is characterized by LMN paresis and abnormal proprioception with intact sensation
Chronic inflammatory demyelinating Polyneuropathy
Causative agents of Protozoal polyradiculoneuritis
Toxoplasma & Neospora
Example of a toxic neuropathy?
Organophosphate toxicity in cats
This disease has a specific geographic distribution and can affects both dogs and cats; typical signs are megaesophagus, abdominal pain, urine retention, and dry mouth, nose, and eyes
Dysautonomia
Only definitive way to diagnose Dysautonomia
biopsy of parasympathetic nervous system
