Noninflammatory Muscle Disorders (Bertorini) Flashcards
type to neuropathy that causes sensory or autonomic problems.
peripheral
Gower’s sign
Myopathy
the patient needs to use his hands to raise from the floor and then ”climb over his legs” in figures to achieve the standing position
In what type of neuropathy will pts have sensory deficits
peripheral neuropathy
- have proximal muscle atrophy and weakness
2. have distal muscle atrophy and weakenss
myopathy
Peripheral neuopathy
winging of the scapula
myopathy
*occurs because the weak muscles cannot fix the scapula to the rib cage.
Some neuropathies affect individual nerves and these are called_________
mononeuropathies
In what type of neuropathy is muscle fatigue a hallmark
disease of neuromuscular transmission
involves fasciculations
motor neuron disease
sometimes in peripheral neuropathy/polyneuropathy
development of droopy eyelids or ptosis (arrows) after sustained upward gaze
disease of neuromuscular transmission
i.e. myasthenia gravis
Decreased or absent muscle stretch reflexes
peripheral neuropathy/polyneuropathy
motor neuron dz (most, but not all)
*in late stage myopathy, these are gone/decreased
proximal muscle weakness
disease of neuromuscular transmission
myopathy
weakness fluctuates
disease of neuromuscular transmission
sensory loss
peripheral neuropathy/polyneuropathy
distal muscle weakness
peripheral neuropathy/polyneuropathy
increased muscle stretch reflex
ALS (motor neuron dz)
*** this is an exception, most motor neuron dz has decreased muscle stretch reflexe
often involves extraocular muscles
disease of neuromuscular transmission
When the motor neuron depolarizes, it causes the muscle fibers of that motor unit to also depolarize and their individual action potentials summate (A+B+C+D) forming the potentials that are called …
motor unit action potentials (MUAPs)
describe normal muscle fiber type distribution
motor neurons innervate either type I or type II muscle fibers (only fibers of one type are innervated by each motor neuron) they are intermixed with fibers from other motor neurons in an almost “checkerboard” pattern
atrophic fibers stain dark with many stain, but in particular _____ stain
nonspecific esterase
Trauma –> periph neuropathy/motot neuron dz –> atrophy/weakness and stains with NON-SPECIFIC ESTERASE
atrophic and angular fibers
periph neuropathy
motor neuron dz
Sprouting of axons from the other intact neurons take over and reinnervate previously denervated fibers, thus more fibers of single neurons remain, forming groups of both fiber types seen histologically. This is called …
fiber type grouping
fiber type grouping results in what changes on an EMG
- larger AP
(bc more fibers are innervated by a single neuron - decreased # of AP
(bc there are fewer motor neurons)
Recall, fiber type grouping occurs after neuronal or axon damage –> sprouting of axons to reinnervate
lost checkerbaord pattern is the result of
sprouting (fiber type grouping)
Larger Motor Unit Action Potentials on EMG
motor neuron dz
periph neuron dz
elevated CK or CPK
myopathy
*necrotic muscle fibers leak some of the sarcoplasmic components
asynchronous depolarization of individual fibers of the motor unit causes ______ AP on EMG
What neuromuscular dz type causes it?
polyphasic
myopathy
when the muscle contraction is very weak, there is a (normal or decreased) number of motor unit action potentials
normal
fewer fibers innervated by a motor neuron registers on EMG as ….
more fibers innvervated by a motor neuron registers on EMG as…
smaller AP
Larger AP
How is the motor unit potential altered in myopathes
small in size and short in duration
MUP = summation of AP for each fiber in a motor unit
pale muscle fibers in picture micrograph
= necrotic fiber = myopathy
slow conduction velocitys or low AP amplitude
peripheral neuropathy
smaller AP and normal # AP
Why?
myopathy
smaller AP bc muscle fibers dysfunction
normal # AP bc neurons/axons in tact
very slow prolonged latency and small compound muscle action potential in a…
demyelinating neuopathy
normal conduction studies/velocity
everything but peripheral neuropathy
increased number of motor unit action potentials as compared to the strength of contraction
myopathy