Peripheral nerves and muscles Flashcards
PNS injuries typically cause what effect?
Injuries causing flacid and hyptotonia
Typically CNS injuries cause what effect?
spasticity and overactivity
True or false; the neuron is the parenchyma of the PNS
true
What is axonal neuropathology
direct injury to axon, degeneration of peripheral segment
Repair from axonal neuropathy involves what?
axonal regrowth and remyelination
True or false when an axon repairs following axonal neuropathy there is a decrease in amplitude
true
Demyelinating neuropathy causes damage to what?
Schwann cell or myelin (spares axon)
True or false; demyelinating neuropathy causes damage uniformly along total nerve
false
What is mononeuropathy and what is a common example?
single nerve effected
Entrapment: carpal tunnel syndrome
Is mononeuropathy asymmetric?
yes
Diffuse/symmetric axonal loss best describes what?
polyneuropathy
“stocking and glove” appearance commonly appears with what pathology?
polyneuropathy
What is polyneuritis multiplex?
damage randomly affecting portions of individual nerves
True or false; polyneuritis multiplex is a autoimmune disorder
true
A common acute motor neuron demyelination causing ascending paralysis
Guillain-Barre syndrome (GBS)
True or false; there appears to be a autoimmune function with Guillain-Barre syndrome (GBS) - with macrophages near nerve roots
true
What is relapsing or chronic Guillain-Barre syndrome (GBS)
Chronic inflammatory demyelinating polyneuropathy (CIDP)
A 50 year old male presents with ataxia (poorly coordinated movements) and onion-skin Schwann cells - what is the patient most likely suffering from
Chronic inflammatory demyelinating polyneuropathy (CIDP)
What is the #1 cause of peripheral neuropathy
Diabetic peripheral neuropathy (50% diabetes myletis)
True or false; environmental toxins typically damaged very short neurons
false; typically effect longest neurons
True or false; 1/3 of all vasculitis patients have peripheral neuropathy
true
PMP22 gene mutations can typically lead to what?
peripheral neuropathy (Charcot-Marie-tooth disease)
What is Myasthenia gravis?
Auto-immune disorder degrading post-synaptic ACh receptors
What symptoms are associated with myasthenia gravis?
Diplopia (double vision) and ptosis (drooping eyelid)
True or false; Myasthenia gravis is commonly associated with thymic lesions
true (60% hyperplasia - thymoma 20%)
True or false; symptoms with myasthenia gravis typically get worse as the day goes on
true
Is myasthenia gravis more common in one sex?
yes - females
What is Lambert-Eaton syndrome?
Autoimmune disorder - autoantibodies inhibit pre-synaptic Ca++ channels - decreasing ACh release
True or false; a thymectomy can sometimes help patients with Myasthenia gravis
true
Lambert-Eaton syndrome and Myasthenia gravis are both autoimmune disorders effecting ACh receptors - which has a worse prognosis
Lambert-Eaton syndrome - Myasthenia gravis has a 95% 5-year survival rate
True or false; a thymectomy can greatly help a patient with Lambert-Eaton syndrome
false; it can help those with Myasthenia gravis though
What is the difference between myasthenia gravis and lambert-eaton syndrome
Myasthenia gravis is autoimmune disease effecting post-synaptic ACh receptors
Lambert-Eaton- autoimmune disease effecting pre-synaptic ACh receptors
What does a Tetanus infection cause in human body
Increased ACh release
What does a botulism infection cause in human body
decreased ACh release
True or false; Botulism causes ascending paralysis
false; it causes descending paralysis (eyes-throat-respiration)
Guillian-Barre syndrome causes ascending paralysis
What kind of fibers are muscle fiber type 1? What about type 2?
Type 1: slow twitch, dark, aerobic, fat metabolism
Type 2: fast twitch, white, anaerobic, glycogen metabolism
Grouped atrophy causing fewer and larger motor units is characteristic of what?
neuropathic changes
Disuse atrophy primarily effects what kind muscle tissue?
Primarily type 2 fibers (following localized fracture - or generalized disuse from quadriplegia)
Glucocorticoid atrophy primarily effects what kind of muscle tissue? How does this kind of atrophy typically occur?
Primarily effects type 2 fibers
Typically occurs because of exogenous reasons (mis-use of corticosteriods - steroids used to inhibit inflammation)
Can also occur by endogenous reasons like Cushing disease
True or false; muscular dystrophy is typically congenital?
false; it is rarely congenital - typically occurs after ~5 years of age
What is muscular dystrophy?
An inherited, progressive disorder - MC due to dystrophinopathies (not producing dystrophin)
What is dystrophin? What are the two common disorders dealing with it?
Dystrophin is one of the longest genes in human genome; codes for protein vital in cytoskeleton
Duchenne Muscular dystrophy and Becker muscular dystrophy
What is the difference between Duchenne muscular dystrophy and Becker?
Duchenne is more severe - dystrophin gene completely absent - fatal by early adulthood
Becker just abnormal dystrophin - possible normal lifespan
What are some keynote symptoms to muscular dystrophy
Clumsiness, “can’t keep up”, pseudohypertrophy of calf muscles and “Gower sign” (using hands to push on legs to stand)
What is polymyositis?
Autoimmune disorder (T cells attack endomysium) causes dysphagia (difficulty swallowing), proximal muscle weakness (45-60 yrs old)
True or false; polymyositis, Dermatomyositis, and Inclusion body myositis are all examples of inflammatory myopathies
true
What is the MC inflammatory myopathy in elderly
Inclusion body myositis (tau proteins in cytoplasm, progressive weakness, dysphagia)
What is the MC inflammatory myopathy in children
Dermatomytositis; autoimmune, muscle & skin inflammation, proximal muscle weakness
True or false; thyrotoxic myopathy, ethanol myopathy, and drug myopathy are all examples of toxic myopathies
true
Overproduction of thyroxine, goiter or Graves disease, acute or chronic best describes what?
Thyrotoxic myopathy
True or false; peripheral nerve sheath tumors are MC in adults
true
True or false; schwannomas are commonly malignant
false; they are almost always benign (1% malignant)
Schwannomas are benign peripheral nerve sheath tumors, they are MC involved with which C.N.?
VIII (vestibular schwannoma)
What is the difference between Neurofibromatosis 1 & 2
1 - causes neurofibromas all over body (very pronounced)
2 - Bilateral vestibular schwannomas (vision and hearing problems)
Both are autosomal dominant
What is a neurofibroma
benign nerve sheath tumor
True or false; 50% of all cases of malignant peripheral nerve sheath tumors arise in neurofibromatosis type 1 patients
true
