Lecture: Neuromuscular Syndromes Flashcards
1
Q
Motor unit
A
- Lower Motor Neuron
- Neuromuscular Junction
- Muscle
2
Q
Maintenance of motor unit
A
- Maintenance by tonic inputs from LMN
3
Q
Denervation atrophy
A
rapid and severe (5-7 days)
4
Q
LMN signs
A
- Paresis to plegia
- Muscle atrophy
- poor/loss muscle tone
- weakness to loss of reflexes
- exercise intolerance
- paretic, stiff gait
5
Q
Ataxia and LMN dz
A
- ataxia is an ulikely sign of LMN dz
6
Q
LMN DZs
Tetanus
A
Happens at level of spinal cord
7
Q
DZs of LMN
Nerve root
A
Polyradiculoneuritis
8
Q
DZs of LMN
Nerve
A
- (poly)Neuropathies
- Axon
- Myelin
9
Q
DZs of LMN
Junction
A
- Tick Paralysis
- Botulism
- Myasthenia Gravis
- Snakes
10
Q
DZs of LMN Muscle
A
- Inflammatory
- Infectious
- Neoplastic
- Snakes
11
Q
Polyradiculoneuritis
Coonhound Paralysis, Guillan-Barre syndrome
A
- Poly = multiple
- Radiculo = root
- Neuritis = inflammation of the nerve
12
Q
Polyradiculoneuritis
About
A
- Racoon saliva?
- Demyelinating dz - rapid recovery
- can get distal axonal degeneration
- Root & proximal nerve disorder
- mildly delayed nerve conduction velocity (NCV)
- Albuminocytologic dissociation on CSF
13
Q
Polyradiculoneuritis
CS
A
- Acute, ascending flaccid paralysis
- LOSS of reflexes and tone
- motor, not sensory
- atrophy
- CN deficits common
- CN VII, gag
14
Q
Polyradiculoneuritis
TX
A
- Variable dz course
- may require ventilation
- supportive care
- aggressive physical therapy to avoid joint fibrosis
15
Q
Polyneuropathy
A
- Degenerative
- Paraneoplastic
- Endocrine
- Genetic/heritable
- Infectious
- Toxic: Vincristine (microtubule disruptor)
16
Q
Degenerative Polyneuropathies
Labrador retrievers
A
- 10+ yo
- Laryngeal paresis/paralysis
- Dysphonia (bark change)
- Esophageal dysfunction
- Paresis worse in pelvic limbs
- abnormal gait
*affects myelin & axons
17
Q
Inherited polyneuropathy
A
Leonbergers
18
Q
Endocrine Neuropathies
A
- Paraneoplastic - insulinoma
- Hypothyroidism
- Diabetic neuropathy - feline
- plantigrade posture
19
Q
Tick Paralysis
A
- Presynaptic neuromuscular blockade
- Dermacentor & Amblyomma most common
- Dogs flaccid 5-9 days after tick attachement
- cats resistent
- +/- megaesophagus
- In Australia
- Ixodes holocyclus, Argasid ticks
- MUCH Worse
20
Q
Tetanus
about
A
- Tetanospasmin must be cleaved to be activated
- absorbed at the NMJ and travels retrograde to spinal cord
- Inhibits glycine/GABA release at SPINAL CORD
- leads to hyperactive alpha motor neurons = constant muscle contraction
21
Q
Tetanus
CS
A
- 5-10 days after infection
- increased tone, stiffness, risus sardonicus, elevated tail, sawhorse stance, elevated nictitans
- Extensors are stronger than flexors
- external stimuli may exacerbate spasticity
22
Q
Tetanus
TX
A
- Vaccination
- Tetanus toxoid in horses
- Antitoxin
- Antibiotics and wound debridement
- penicillin G, tetracycline, metranidazole
- Sedatives
- Phenothiazines, benzodiazepines, barbiturates
- Supportive care
- dark, quit, well padded, feeding tube
23
Q
Tetany
A
- Hyperexcitability of membrane due to electrolyte imbalance
- Na+, K+, Ca+, Cl-
- Hypocalcemia
- Hypomagnesemia
- Strychnine
24
Q
Botulism
about
A
- Presynaptic neuromuscular blockade
- Ingest preformed toxin
- destroyed at 100 degrees
- resistant to proteases
- Toxin imported, blocks presynaptic release of ACh from nerve terminal
25
Botulism
CS
* 12 hrs-6 days
* progressive, symmetric ascending paresis/paralysis
* reflexes and tone are lost
* CN VII, megaesophagus, decreased gag and jaw tone
* +/- mydriasis, KCS, constipation, urinary retention
26
Botulism
DX
* Very difficult
* detection of organism in ingesta, serum, vomit
27
Botulism
Prognosis
* Improvement in 1-3 weeks
* must regenerate new motor endplates
* 2-4 months in mammalian species
28
Myasthenia Gravis
Congenital
* Insufficient receptors
* Negative AChRAb titer
* rare
* jack/parsons russel terriers
* signs from birth
* generalized weakness
29
Myasthenia Gravis
Acquired
* Autoantibodies against nicotinic acethylcholine receptors on post-synaptic membrane
* receptor is blocked, causing muscle weakness
30
Acquired Myasthenia Gravis
three forms
* Focal: typically esophageal muscle weakness
* dogs only; cats have smooth muscle
* Generalized: exercise intolerance
* Fulminant: 1/4 of the generalized patients
* Grave
31
Myasthenia Gravis
CS
* Exercise intolerance
* progressively stiff, stilted gait, crap walking, crouched
* Postural rxns should be intact
* Reflexes present/ withdrawels can tire
* No CN deficits
* may have weak gag, ptyalism, ptosis
* Megaesophagus
32
Acquired Myasthenia Gravis
Distribution
* Bimodal
* osteosarc is also bimodal
* \< 5 yrs old: immune mediated
* \> 7 yrs old
* para/pre-neoplastic
* treat/remove primary source to ease tx
33
Myasthenia Gravis
DX
* Tensilon test: edrophonium
* ultra-short acting acetylcholinesterase inhibitor
* **Acetylcholine receptor antibody titer** (GOLD STANDARD)
* Electrodiagnostics: repetitive nerve stimulation (RNS)
34
Myasthenia Gravis
TX
* Acetylcholinesterase inhibitor
* increases ACh at the NMJ
* Immunosuppression
* stops Ab production
* Treatment of underlying dz
* eliminates trigger
35
Generalized Myopathy
* Immune-mediated
* Infectious
* neospora caninum, Hepatozoon americanum
* Pre-/Para-neoplastic
* lymphoma
* Dermatomyositis
* Congenital
* muscular dystrophies
36
Generalized polymyositis
* Generalized weakness, stilted gait, dysphagia, muscle atrophy
* Myalgia is rare
* DO NOT LOSE REFLEXES
* Boxers and Newfies
* Boxers: preneoplastic
* Newfies: breed specific
37
Masticatory myositis
DX
Acute
Chronic
TX
Type 2M and Type 1 variant muscle fibers
* Autoantibodies to type 2M fibers (only expressed in masticatory mm)
Serum 2M antibody titer (easy dx)
Acute
* pain opening mouth
* mild exophthalmia
Chronic
* masticatory m atrophy
* not painful to open mouth
* fibrosis of masticatory mm
TX
* immunosuppression
38
Extraocular Myositis
Acute phase: ze eyeballz don't move
39
Neospora caninum
* Prenatal exposure
* Polyradiculoneuritis and polymyositis
* encephalomyelitis
* Muscle atrophy
* Contracture of Pelvic Limbs
\*Spay the mom
40
Endocrine Myopathies
* Type 2 myofibers more affected
* Hypothyroidism-dogs
* Hyperthyroidism-cats
* Glucocorticoid excess-dogs
* Electrolyte derangements
41
Cushing's Myopathy
Stiff, not flexing, hypertrophic, stiff muscles
42
Cat anatomical anomaly
No nuchal ligament
43
Feline Hyperthyroidism
* T3 & T4 effects on sarcoplasm
* CS
* Paresis
* ventroflexion
* tremors
* abnormal gait
44
Feline: Toxoplasma gondii
Brain and systemic infection
45
Rattlesnake Envenomation
| (pit vipers)
* Mentation, paresis/plegia, rigidity, CP deficits
46
Southern Pacific, Timber, Western Diamondback envenomation
* Myokymia
* Ca interference on nerve membrane
* looks like a moving nerve under skin I think
47
Mojave rattlesnake envenomation
* Neurotoxins
* inhibits Ach release at presynaptic terminal of NMJ leading to complete neuromuscular blockade
48
Coral Snake envenomation
| (Elapid snake)
* Venom has many components
* postsynaptic alpha-neurotoxins
* neuromuscular blockade
* Generalized LMN weakness
* respiratory paralysis
49
Congenital myopathies
* Muscular dystrophy: golden retrievers
* Myotonia congenita
* Hyperkalemic periodic paralysis
50
Exercise Induced Collapse
* labrador retrievers
* collapse, hyperthermia, loss patellar reflexes
* DNM1 mutation
51
Myoclonus
* Sudden contraction-relaxation of muscles
* LMN abnormality
* Distemper
