11 Neuropath Muscle and Nerve Flashcards
T-F– all muscle fibers in the motor unit are the same type and do not mix with other motor unit fibers?
False- same type per motor unit, but muscle fibers from diff. motor units can intermix with each other.
T-F– all muscle fibers in the motor unit are the same type and do not mix with other motor unit fibers?
False- same type per motor unit, but muscle fibers from diff. motor units can intermix with each other.
What are the 2 types of axonal degeneration?
- Classic Wallerian degeneration
2. Distal axonopathy
What are the 2 main causes of classic wallerian degeneration?
Trauma and vascular disease
What causes distal axonopathy? 3
- systemic metabolic disease
- toxins
- Some genetic diseases
What are the two types of peripheral neuropathy?
axonal degeneration and demyelination
Review the 4 main types of axonal degeneration- ischemic neuropathies?
- Vasculitis
- Collagen VascularDisease
- Paraneoplastic Microvasculitis
- Diabetic symmetrical sensorimotor neuropathy
What are we looking for in vasculitis on microscopic imaging?
fibrinoid necrosis of vessel walls
What is distinct about vasculitic neuropathy that we can see on microscopic imaging?
- fascicle to fascicle variation in degree of axon loss
[in the image, the one with the most loss has less black looking axons)
What is distinct about vasculitic neuropathy that we can see on microscopic imaging?
- fascicle to fascicle variation in degree of axon loss
[in the image, the one with the most loss has less black looking axons)
What type of neuropathy has both metabolic and toxic neuropathy?
is it predominantly axonal degeneration or demyelination?
What type of ischemic component do we see?
- diabetic neuropathy\
- axonal degeneration
- vascular hyalinization- endoneurial microvasculature thickening
What type of neuropathy has both metabolic and toxic neuropathy?
is it predominantly axonal degeneration or demyelination?
What type of ischemic component do we see?
- diabetic neuropathy\
- axonal degeneration
- vascular hyalinization- endoneurial microvasculature thickening
On microscopic view of diabetic neuropathy, what do we readily see?
Axonal loss (lack of black circular axons) and vascular thickening.
On microscopic view of diabetic neuropathy, what do we readily see?
Axonal loss (lack of black circular axons) and vascular thickening.
What neuropathy has a segmental pattern of injury? What is the etiology 3?
- demyelinating neuropathy
2. Inflammatory (guillain-barre), Toxins, Genetics (Charcot-marie-tooth)
The genetic disease charcot-marie-tooth disease causes what type of neuropathy?
demyelinating- segmental
What 4 things are found in Guillain-barre syndrome clinical presentation?
- Ascending Paralysis
- Can involve respiratory muscles
- slowed conduction
- elevated CSF protein
What 4 things are found in Guillain-barre syndrome clinical presentation?
- Ascending Paralysis
- Can involve respiratory muscles
- slowed conduction
- elevated CSF protein
Is guillain barre a antibody mediated disease or T-cell mediated>
T-cell mediated with macrophages
[endoneurial and perineurial]
T-F- demyelination of naked axons results in a thicker sheath?
Fasle- thinner and internal length changes
T-F- demyelination of naked axons results in a thicker sheath?
Fasle- thinner and internal length changes
Cross section microscopy of a segment of nerve undergoing demyelination will show what?
myelin debris surrounding a naked axon
What is the most common hereditary peripheral neuropathy?
hereditary motor and sensory neuropathy type 1- charcot-marie-tooth disease
What is the most common hereditary peripheral neuropathy? Where do we see muscular atrophy?
- hereditary motor and sensory neuropathy type 1- charcot-marie-tooth disease
- progressive atrophy of calves-weakness
What disease has repetitive demyelination and remyelination?
hereditary motor and sensory neuropathy type 1- charcot-marie-tooth disease
What disease has repetitive demyelination and remyelination?
hereditary motor and sensory neuropathy type 1- charcot-marie-tooth disease
In charcot marie tooth, what do we see on microscopic pathology?
- Thinly myelinated axons
2. Hypertrophic “onion-bulb” neuropathy
In charcot marie tooth, what do we see on microscopic pathology?
- Thinly myelinated axons
2. Hypertrophic “onion-bulb” neuropathy
Chronic demyelination and demyelination results in what?
onion-bulbs- concentric rings of schwann cell processes.
Chronic demyelination and demyelination results in what?
onion-bulbs- concentric rings of schwann cell processes.
What muscle fiber type is for sustained force and weight bearing? What is the nadh and atpase content? are lipids or glycogen abundant? slow twitch or fast twitch? color?
- Type 1
- NADH dark, ATPase light
- lipids are abundant
- slow-twitch
- red
What muscle fiber type is for sustained force and weight bearing? What is the nadh and atpase content? are lipids or glycogen abundant? slow twitch or fast twitch? color?
- Type 1
- NADH dark, ATPase light
- lipids are abundant
- slow-twitch
- red
What muscle fiber type is for sudden movement? What is the nadh and atpase content? are lipids or glycogen abundant? slow twitch or fast twitch? color?
- Type II
- NADH light, ATPase dark
- Glycogen are abundant
- fast twitch
- white
What muscle fiber type is for sudden movement? What is the nadh and atpase content? are lipids or glycogen abundant? slow twitch or fast twitch? color?
- Type II
- NADH light, ATPase dark
- Glycogen are abundant
- fast twitch
- white
When we stain muscle fibers for ATPase…what type of fibers are dark?
Type II– (remember that their overall color is white but they are ATPase dark and TYPE I are atpase light and appear whiter)
When we stain muscle fibers for ATPase…what type of fibers are dark?
Type II– (remember that their overall color is white but they are ATPase dark and TYPE I are atpase light and appear whiter)
What are the two main classifications of muscle disease?
Neurogenic and myopathic
What are the two main classifications of muscle disease?
- Neurogenic [motor neuron disease, peripheral neuropathy, neuromuscular junction]
- myopathic [dystrophy, inflammatory, metabolic, congenital]
What are the two main classifications of muscle disease?
- Neurogenic [motor neuron disease, peripheral neuropathy, neuromuscular junction]
- myopathic [dystrophy, inflammatory, metabolic, congenital]
In neurogenic muscle disease where is the site of weakness? is there pain? fasciculations? serum enzyme changes? EMG signs? nerve conduction?
- distal
- absent
- present
- normal
- EMG fibrillation potentials
- Variable conduction
In myopathic muscle disease where is the site of weakness? is there pain? fasciculations? serum enzyme changes? EMG signs? nerve conduction?
- proximal
- variable
- absent
- elevated
- EMG polyphasic potentials
- normal
In myopathic muscle disease where is the site of weakness? is there pain? fasciculations? serum enzyme changes? EMG signs? nerve conduction?
- proximal
- variable
- absent
- elevated
- EMG polyphasic potentials
- normal
What is the difference in histological atrophy between neuropathy and myopathy?
in neuropathy the fibers are angular and in groups, while in myopathy the fibers are rounded and scattered.
What is the difference in histological atrophy between neuropathy and myopathy?
in neuropathy the fibers are angular and in groups, while in myopathy the fibers are rounded and scattered.
What type of muscle disease results in fiber type grouping
neuropathy- nerve loss is followed by regeneration leads to larger motor units and fiber type grouping
Review the myopathic diseases-
Dystrophy= duchenne, Becker, limb-girdle, myotonic.
Metabolic=mitoch. myopathy, inborn errors of metabolism, hormonal abnormalities, alcohol rhabdo
Inflammatory= polymyosits, dermatomyositis, inclusion body myositis
Congenital= centronuclear myopathy, nemaline myopathy, central core disease
Review the myopathic diseases-
Dystrophy= duchenne, Becker, limb-girdle, myotonic.
Metabolic=mitoch. myopathy, inborn errors of metabolism, hormonal abnormalities, alcohol rhabdo
Inflammatory= polymyosits, dermatomyositis, inclusion body myositis
Congenital= centronuclear myopathy, nemaline myopathy, central core disease
Is duchenne’s x linked?
YEs
What does dystrophin do?
links cytoplasmic actin to the cytoskeleton
What do we see histologically in muscular dystrophy early in the disease?
myocyte necrosis
with atrophy and hypertrophy
What do we see histologically in muscular dystrophy early in the disease?
myocyte necrosis
with atrophy and hypertrophy
What do we see histologically in muscular dystrophy late in the disease?
endomysial fibrosis and fatty replacement
What do we see histologically in muscular dystrophy late in the disease?
endomysial fibrosis and fatty replacement
What disease is autosomal dominant, trinucleotide, and has multiple internal nuclei and occasional ring fibers?
myotonic dystrophy
What do we see histologically in polymyositis early in the disease?
inflammation and muscle fiber necrosis
What do we see histologically in polymyosits later in the disease?
regenerating muscle, inflammation, and scarring fibrosis
What do we see histologically in polymyosits later in the disease?
regenerating muscle, inflammation, and scarring fibrosis
What disease is described as gradual onset, male predominance after age 50. proximal and distal weakness. Lymphocystic inflammation, angular and round atrophy, autophagic “rimmed” vacuoles?
inflammatory myopathy- inclusion body myositis
What do the rimmed vacuoles look like on stain?
stain is blue overall, clear vacuoles with purple surrounding
What do the rimmed vacuoles look like on stain?
stain is blue overall, clear vacuoles with purple surrounding
pompe’s deficiency is in what enzyme? McArdles disease?
- lysosomal a1,4-glucosidase
2. myophosphorylase
What is highly indicative of mitochondrial myopathy?
ragged red fibers
How many mitochondrial genes are there?
37
22 tRNA
2 ribosomal RNA
13 polypeptide subunits of respiratory chain
How many mitochondrial genes are there?
37
22 tRNA
2 ribosomal RNA
13 polypeptide subunits of respiratory chain
What are the ragged red fibers?
areas of mitochondrial proliferation with paracrystalline inclusions
