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64 Cards in this Set
- Front
- Back
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Three common entities of neuromuscular disease |
Guillain-Barre Syndrome (GBS) Myasthenia Gravis (MG) Critical illness polyneuropathy / myopathy (CIP/CIM) |
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How can reflex examination help localize neuromuscular disease? |
CNS lesion - brisk SCI - initially absent Presynaptic - decreased Post-synaptic - normal Myopathy- normal |
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Pathophysiology of MG |
Autoimmune disease, T-cell dependent response targeting post-synaptic acetylcholine receptor or receptor-associated proteins |
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What is "man in a barrel" syndrome? |
MCA-ACA watershed infarction causing proximal arm and proximal leg weakness |
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Localization of weakness in carbon monoxide poisoning? |
Globes Pallidus injury |
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Localization of injury in methanol poisoning causing weakness? |
Putaminal injury |
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Typical presentation of spinal cord vascular injury in cardiothoracic / aortic surgery? |
Embolic phenomenon or watershed infarction - in the territory of artery of Adamkiewicz, spares dorsal column, greatest risk at levels T4-8 |
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Findings in cholinergic crisis |
SLUDGE Salivation, lacrimation, urination, diarrhea, GI upset, emesis |
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Findings in cholinergic crisis |
SLUDGE Salivation, lacrimation, urination, diarrhea, GI upset, emesis |
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What is Lambert-Eaton myasthenia syndrome? |
Associated in 50-70% with cancer
autoimmune attack of presynaptic voltage-gated calcium channels |
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Findings in cholinergic crisis |
SLUDGE Salivation, lacrimation, urination, diarrhea, GI upset, emesis |
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What is Lambert-Eaton myasthenia syndrome? |
Associated in 50-70% with cancer, autoimmune attack of presynaptic voltage-gated calcium channels |
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Which malignancy is typically associated with Lambert-Eaton syndrome? |
Small cell lung cancer |
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Findings in cholinergic crisis |
SLUDGE Salivation, lacrimation, urination, diarrhea, GI upset, emesis |
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What is Lambert-Eaton myasthenia syndrome? |
Associated in 50-70% with cancer, autoimmune attack of presynaptic voltage-gated calcium channels |
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Which malignancy is typically associated with Lambert-Eaton syndrome? |
Small cell lung cancer |
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Clinical findings in Lambert-Eaton syndrome |
Limb symptoms more prominent than ocular / bulbar Facilitation with exercise Autonomic dysfunction Reduced reflexes Respiratory failure uncommon |
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What causes botulism? |
Neurotoxin produced by Clostridium botulinum |
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How does botulin toxin cause paralysis? |
Toxin permanently blocks presynaptic acetylcholine release at NMJ |
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Clinical findings in botulism |
Symmetric descending paralysis with dilated pupils, dysautonomia
No sensory deficit |
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Treatment of botulism |
Trivalent equine antitoxin |
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How does tick paralysis occur? |
Toxin causes presynaptic NM blockade |
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How does tick paralysis occur? |
Toxin causes presynaptic NM blockade |
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Clinical findings in tick paralysis |
Ascending paralysis Ophthalmoparesis Bulbar dysfunction Ataxia Reduced reflexes
No sensory symptoms |
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How does snake venom cause paralysis? |
Depending on species of snake, can either cause pre- or post-synaptic blockade |
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How does snake venom cause paralysis? |
Depending on species of snake, can either cause pre- or post-synaptic blockade |
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Clinical presentation of snake venom paralysis |
Initially affects cranial nerves (ptosis, ophthalmoplegia, dysarthria, dysphasia) followed by limb weakness |
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Examples of organophosphate |
Malathion Parathion Sarin Soman |
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MOA of organophosphate |
Inactivated acetylcholinesterase |
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MOA of organophosphate |
Inactivated acetylcholinesterase |
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Clinical findings in organophosphate toxicity |
SLUDGE Miosis Bronchospasm Blurred vision Bradycardia |
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MOA of organophosphate |
Inactivated acetylcholinesterase |
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Clinical findings in organophosphate toxicity |
SLUDGE Mitosis Bronchospasm Blurred vision Bradycardia |
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Treatment of organophosphate toxicity |
Atropine Pralidoxime (2-PAM) Benzodiazepines |
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Clinical findings in GBS |
Areflexia & Ophthalmoplegia (MF variant)
Areflexia Ascending weakness Facial weakness Diplopia
*acute, symmetric, ascending weakness, often beginning in proximal legs |
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Fish neurotoxins (examples) |
Tetrodotoxin (puffer fish) Saxitoxin (red tide organisms) Ciguatera toxin (red snapper, grouper, barracuda) |
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Fish neurotoxins (examples) |
Tetrodotoxin (puffer fish) Saxitoxin (red tide organisms) Ciguatera toxin (red snapper, grouper, barracuda) |
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How do fish neurotoxins cause paralysis? |
Tetrodotoxin and saxitoxin blocks NM transmission
Ciguatera toxin affects voltage-gated Na channels of muscles and nerves |
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Unique symptoms caused by ciguatera toxin |
Produces metallic taste in the mouth Causes hot-cold reversal |
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Symptoms seen in diphtheria infection |
Pseudomembrane (pharynx) AV block Endocarditis Myocarditis LAD Neuropathy with craniopharyngeal involvement Prox to distal weakness Deceased reflexes |
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Pathophysiology of GBS |
Molecular mimicry from recent infection which produces autoimmune humoral and cell-mediated response against ganglioside surface molecules of the peripheral nerves |
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Pathophysiology of GBS |
Molecular mimicry from recent infection which produces autoimmune humoral and cell-mediated response against ganglioside surface molecules of the peripheral nerves |
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Differential diagnosis for acute neuropathy |
Acute inflammatory demyelination polyradiculoneuropathy (AIDP)
Acute motor axonal neuropathy (AMAN)
Acute sensorimotor axonal neuropathy (AMSAN)
Miller-Fisher syndrome
Pharyngeal-cervical-brachial
Paraparesis
Acute pandysautonomia
Pure sensory |
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40% of patients with AIDP will be seropositive for this infection |
Campylobacter jejuni |
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Which antibodies are seen in Miller-Fisher syndrome? |
GQ1b antibodies (95%) |
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Which antibodies are seen in Miller-Fisher syndrome? |
GQ1b antibodies (95%) |
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Give 5 examples of neuromuscular junction disease |
MG LEMS Botulism Organophosphate toxicity Fish neurotoxins |
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2 parts of the nerve conduction study? |
CMAP and SNAP
motor nerve compound muscle action potential
Sensory nerve action potential |
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What is the difference in NCS findings in axonal vs demyelinating disease? |
In axonal disease, nerve conduction amplitude is decresaed. In demyelinating disease, there is slowed conduction velocities, distal latencies, temporal dispersion and conduction block |
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What are the late responses in NCS? |
F and H waves |
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What are the late responses in NCS? |
F and H waves |
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What are F waves? |
waves generated by Supra maximal stimulation of a motor nerve while recording over a muscle
Represent the very proximal portion of the nerve |
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What are the late responses in NCS? |
F and H waves |
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What are the late responses in NCS? |
F and H waves |
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What are F waves? |
waves generated by Supra maximal stimulation of a motor nerve while recording over a muscle
Represent the very proximal portion of the nerve |
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What is an H reflex? |
Typically a tibial reflex (patellar reflex arc) Represents the sensory and motor nerves of the entire reflex arc |
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What are the parameters measures in the needle insertion? |
Insertional activity Spontaneous activity Recruitment Motor unit potential duration Motor unit potential amplitude Motor unit polyphasia |
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What are the late responses in NCS? |
F and H waves |
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MG patients who are negative for AchR Abs - what to test for? |
15-20% of MG are seronegative; of these 40-50% have MuSK antibodies |
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MuSK stands for? |
Muscle-specific kinase |
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What are the late responses in NCS? |
F and H waves |
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MG patients who are negative for AchR Abs - what to test for? |
15-20% of MG are seronegative; of these 40-50% have MuSK antibodies |
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MuSK stands for? |
Muscle-specific kinase |
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Serologic test for LEMS |
P/Q-type calcium channel binding antibodies |
