Nerve & Muscle Path (Moore) Flashcards
All of the following are examples of neurogenic neuromuscular diseases EXCEPT:
A. ALS
B. Spinal muscular atrophy
C. Myasthenia gravis
D. McArdle disease
E. Peripheral neuropathy
McArdle disease (AKA glycogen storage disease) is a type of myopathic disease.
cell body + axon + muscle fiber = ?
motor unit
process that results when a nerve fiber is cut/crushed and the part of the axon separated from the neuron’s cell body degenerates
wallerian degeneration
T/F: biopsy is the most clinically useful procedure for diagnosing distal polyneuropathy
False. Biopsy doesn’t really contribute anything helpful to a final diagnosis in addition to a good H&P. It may be helpful though in clarifying a specific diagnosis in mononeuropathy multiplex.
best nerve to use for peripheral nerve biopsy?
sural nerve
painful, asymmetrical, asynchronous sensory and motor peripheral neuropathy involving isolated damage to at least 2 separate nerve areas
Mononeuritis multiplex
*associated with systemic disorders like vasculitis, polyarteritis and amyloidosis
what process is occurring in this picture?
axonal (wallerian) degeneration
*the little bits of debris inside of the digestion chambers
rare disease that results from accumulation of inappropriately folded proteins leading to deposition in organs or tissues disrupting normal function
amyloidosis
Which of the following is NOT associated with primary amyloidosis?
A. Neuropathy in 15%
B. Myopathy less common
C. Distal and symmetric neuropathy
D. Affects legs > arms
E. Associated with APOA1 gene
E. This is familial amyloidosis. Other gene associations: TTR and GSN
this process below, showing axons surrounded by layers of demyelinating and remyelinating Schwann cells in an “onion bulb” formation is characteristic of what group of disease?
Charcot-Marie-Tooth (CMT)
T/F: Biopsy is rarely ever done for hereditary peripheral neuropathies (Charcot-Marie-Tooth disease)
True. EMG/nerve conduction studies, family history, and genetic testing are all helpful in diagnosing.
most common subtype of NMJ disorders, caused by formation of antibodies to ACh receptors
myasthenia gravis
group of conditions characterized by muscle weakness that worsens with physical exertion, due to gene mutations that impair proper functioning at the NMJ
Congenital myasthenic syndrome
*often the genes involved code for channels, receptors, extracellular matrix proteins, and glycosyltransferases
type of biopsy:
- less painful
- smaller amount of muscle may limit testing
- requires more expertise to obtain good biopsy
needle biopsy
type of biopsy:
- can be more painful
- larger amount of muscle allows for broader range of testing
open biopsy
which muscle fiber type?
- sustained force weight-bearing, slow-twitch
Type I
which muscle fiber type?
- Abundant lipids and scant glycogen
Type I
which muscle fiber type?
- NADH stains light and ATPase dark at pH 9.4
Type II
which muscle fiber type?
- associated with the mnemonic “one mighty slow fat red ox”
Type I
*lots of mitochondria, slow-twitch, full of lipids, red in color, oxidative metabolism
what pathologic process is shown here?
chronic denervation (many groups of atrophic, angular, elongated muscle fibers)
Bonus: what disease might this suggest?
*infantile spinal muscular atrophy, in which there is degeneration of lower motor neurons
Name the disease, and 4 histological findings that support it:
Muscular dystrophy
- atrophy/hypertrophy of muscle fibers
- endomysial fibrosis
- fatty replacement
- myonecrosis
inflammatory, autoimmune myopathic disease with the histopathology as shown below:
polymyositis
*lymphocytes invading muscle fiber
inflammatory, autoimmune myopathic disease with the histopathology as shown below:
dermatomyositis
*perivascular invasion of lymphocytes; you will also see perifascicular atrophy (below)
inflammatory, autoimmune myopathic disease associated with mitochondrial abnormalities and is more common in the elderly; shows the histopathology below:
inclusion body myositis
*the arrow indicates a rimmed vacuole (lyososomes), characteristic of the disease. Vacuoles are also a common finding in Pompe disease
histopathology of this acute disease shows muscle fibers that are filling up with protein-degrading macrophages
rhadomyolysis
pools of glycogen around muscle fibers indicate what disease?
glycogen storage disease (McArdle’s)
ragged red fibers on histology indicate an abnormal accumulation of what structure in the muscle fiber?
mitochondria
congenital myopathies that result from mutations in genes that encode the sarcomeric thin filaments, resulting in abnormal assembly in the muscle cell
nemaline myopathy
*note the nemaline rods seen on histo below
what congenital myopathy is this?
centronuclear myopathy
muscular dystophy is associated with protein dysfunction that affects what muscle structure?
sarcolemma
All of the following are sarcolemma proteins associated with muscular dystrophy EXCEPT:
A. Dystrophin
B. Dystroglycan/Sarcoglycan
C. Emerin
D. Dysferlin
E. Caveolin-3
C.
Emerin is a nuclear-envelope associated protein
Which of the following is NOT a finding you would expect in Duchenne Muscular Dystrophy?
A. Mutation at Xp21 locus
B. Loss of dystrophin
C. Loss of spectrin
D. Loss of utrophin
D. Loss of utrophin is not seen in this disease; rather there is gain of utrophin
