Neuromuscular Disorders Flashcards
How do lower motor neuron disorder present?
- Weak, wasted muscle
- Low tone
- Fasciculations
- Reduced or absent reflexes
What drugs should be avoided in myasthenia gravis?
Gentamicin
What drug is used for symptomatic treatment of myasthenia gravis?
Pyridostigmine
What is long-term management of myasthenia gravis?
Immunosuppression
- Steroids
- Azathioprine/mycophenolate (elderly especially)
Are ACh receptors inotropic or metabotropic?
Inotropic
What is the motor end plate?
The junction between motor neuron and muscle
Are pre-synaptic or post-synaptic neuromuscular disorders more common?
Post-synaptic
What organism causes botulism?
Clostridium botulinum
Who is at high risk of botulism?
IV drug users
What is the early signs of botulism?
Extra-ocular paralysis
What causes myasthenia gravis?
Antibodies to acetylcholine receptors
When do symptoms begin in myasthenia gravis?
When ACh receptors reduced to 30% of normal
There is a spike in myasthenia gravis in men and women at what ages?
Women in 20’s
Men in 50’-60’s
What are typical clinical features of myasthenia gravis?
- Fluctuating weakness
- Extraocular weakness, Facial & bulbar weakness
- Limb weakness (typically proximal)
- Fatiguability
What diagnostic tests are used in myasthenia gravis?
- Test for ACh antibodies (present in 80-90% of cases)
- EMG studies to find patterns to distinguish MG from LEMS
- CT for thyoma
What is the likelihood that there is thymus involvement in MG?
75% present with hyperplasia or thyoma
What is myotonia?
Failure of muscle relaxation after use
What causes myotnia?
Cl- channel disorder
How will a patients creatine kinase (CK) read if they have a muscle disease?
Raised CK
What are the three divisions of neuromuscular disease?
- Immune mediated
- Inherited
- Congenital
Name some immune mediated neuromuscular diseases?
- Dermatomyositis
- Polymyositis
What is the most common muscular dystrophy?
Myotonic dystrophy
Name some inherited neuromuscular diseases?
- Muscular dystrophies
- Myotonic dystrophy
- Limb girdle muscular dystrophies
What is the inheritance pattern of myotonic dystrophy?
Autosomal dominant
What is rhabdomyolysis?
Damage to skeletal muscle causing leakage of large quantities of toxic intracellular contents into plasma
How does rhabdomyolysis present?
Myalgia, muscle weakness & Myoglobinuria
Incredibly high CK
Name some pre-synaptic disorders
- Botulism
- Lambert Eaton Myasthenic Syndrome (LEMS)
What is LEMS strongly associated with?
Small cell carcinoma
How is LEMS treated?
3-4 Diaminopyridine
