Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
58 Cards in this Set
- Front
- Back
|
which part of a transected axon undergoes Wallerian degeneration? |
distal When an axon is transected, the distal part, including its myelin sheath, undergoes a series of changes leading to its complete structural disintegration. |
|
|
loss of saltatory conduction |
Segmental demyelination |
|
|
Which is faster, remyelination or axonal regeneration? |
remyelination |
|
|
“Onion bulb” formations |
concentric layers of Schwann cell processes and collagen around an axon implies a demyelinating process (specifically repeated episodes of demyelination and remyelination) |
|
|
most common neuropathy in clinical practice |
diabetic neuropathy |
|
|
most common familial neuropathy |
Charcot-Marie-Tooth disease 1 in 2500, autosomal dominant |
|
|
duplication of part of chromosome 17 that contains the gene for the 22 kd peripheral myelin protein, PMP22 |
Charcot-Marie-Tooth disease (CMT1 – hereditary motor sensory neuropathy type 1) |
|
|
muscle wasting --> weakness, foot drop, tremor, stork leg/inverted champagne bottle loss of sensation --> spasmodic muscular contractions, pes cavus/pes planus neuropathic pain |
Charcot-Marie- Tooth disease (CMT1 – hereditary motor sensory neuropathy type 1) |
|
|
Charcot-Marie-Tooth disease (CMT1 – hereditary motor sensory neuropathy type 1) worsens with... |
stress pregnancy prolonged immobility |
|
|
Immune mediated neuropathies |
Guillain-Barré syndrome (GBS) chronic inflammatory demyelinating neuropathy (CIDP). |
|
|
Peripheral nerves show mononuclear inflammatory cells, segmental demyelination, and macrophages. Axonal damage is secondary. The pathology is most severe in spinal roots and plexi and less in distal nerves. |
Guillain-Barré syndrome (GBS) Acute inflammatory demyelinating polyneuropathy (AIDP) variant = 90% of cases |
|
|
Guillain-Barré syndrome (GBS) |
Campylobacter jejuni (20-30%) Cytomegalovirus (20-30%) Mycoplasma Other infections Vaccinations |
|
|
asymmetric polyneuropathy or distal symmetric polyneuropathy Biopsy shows necrotizing arteritis |
Vasculitic neuropathy |
|
|
Type1 fibers |
slow twitch rich in oxidative enzymes, mitochondria andmyoglobin and lipid depend on oxidative metabolism capable of protracted slow action and clonic activity |
|
|
Type 2 fibers |
fast twitch rich in glycogen and glycolytic enzymes capable of fast, powerful, tonic contraction |
|
|
Angulated atrophic myofibers |
Neuropathic changes |
|
|
Group atrophy, fiber type grouping Target fibers NADP-dark angular fibers Nuclear clumps and chains |
Neuropathic changes |
|
|
Round, atrophic fibers |
Myopathic changes |
|
|
Marked variation in myofiber size |
Myopathic changes Degenerated and regenerating myofibers |
|
|
Increased internalized nuclei Hypertrophic myofibers Myophagocytosis Fiber splitting |
Myopathic changes |
|
|
most common muscular dystrophy in all ages |
myotonic dystrophy |
|
|
most common muscular dystrophy in childhood |
Duchenne muscular dystrophy |
|
|
dystrophinopathies |
Duchenne and Becker muscular dystrophies mutations of the dystrophin gene on chromosomeXq21 |
|
|
Duchenne vs Becker muscular dystrophies |
In DMD, dystrophin is absent In BMD, it is severely reduced and of an abnormal molecular structure |
|
|
MC congenital myopathies |
characterized by structural abnormalities of muscle, caused by faulty development nemaline, centronuclear, central core myopathy |
|
|
small and disorganized myofibers which contain rod-shaped structures composed of a-actinin, the main protein of Z-bands |
Nemaline or rod body myopathy (Greek nema, thread) |
|
|
myofibers have one or more central areas of disorganized filaments without mitochondria |
central core and multi-core myopathy |
|
|
glycolytic enzyme defects that impair the use of glycogen for energy weakness, cramps and myonecrosis on exertion |
glycogenosis type 5 (phosphorylase deficiency, McArdle disease) type 7 (phosphofructokinase deficiency) |
|
|
subacute or chronic proximal weakness (without a rash) and elevated CK muscle biopsy shows endomysial mononuclear cells and myonecrosis |
Polymyositis |
|
|
cell-mediated autoimmune disorder in which T-cells attack myofibers |
Polymyositis |
|
|
edema around the eyes and mouth, skin rash on the face and extensor surfaces, weakness and stiffness of muscles, muscle pain, subcutaneous calcification, intestinal ulceration |
Dermatomyositis |
|
|
immune complex vasculitis (arteritis or phlebitis), leading to capillary loss ischemic infarction or myofiber necrosis and atrophy at the periphery of fascicles |
Dermatomyositis |
|
|
perifascicular atrophy |
Dermatomyositis |
|
|
Dermatomyositis is assoc with |
scleroderma, mixed connective tissue disease, cancer |
|
|
Patients with polymyositis and dermatomyositis may have circulating antibodies to |
macromolecular complex of tRNA synthetases |
|
|
Myasthenia gravis Weakness affects most severely ... |
muscles that are innervated by brain stem nuclei, such as extraocular and facial muscles, --> drooping of the eyelids, diplopia, inability to chew BX shows myofiber atrophy and aggregates of lymphocytes in the endomysium |
|
|
% of myasthenia gravis patients with thymoma |
10%, especially older males most other patients have follicular hyperplasia of the thymus |
|
|
Myasthenia gravis is caused by |
antibodies to acetylcholine receptor (AChR) IgG antibodies bind AChR and prevent acetylcholine from reacting with i also cause degradation of AChR and lysis of post-synaptic membranes |
|
|
selective myofiber atrophy from steroids, Cushing's, hyperPTH, collagen vascular disease, cancer, starvation which fiber type? |
Type 2 fibers |
|
|
target(oid) fibers |
clear central zone devoid of oxidative enzyme activity surrounded by densely stained area 3-4 concentric zones = TARGET = neurogenic, related to reinnervation 2 zones = TARGETOID = some myopathies |
|
|
dystrophin links what? |
amino terminal --> actin carboxyl terminal --> ECM via sarcolemmal protein dystroglycan |
|
|
function of dystrophin |
stabilizes the sarcolemma during contraction and relaxation |
|
|
hyaline (hypercontracted) fibers necrotic fibers regenerating fibers endomysial fibrosis |
dystrophic features (muscular dystrophy) |
|
|
b-dystrophin gene |
Xp21 |
|
|
ragged red fibers |
aggregates of mitochondria --> mitochondrial myopathies |
|
|
MC inflammatory myopathy in patients over age 50 |
inclusion body myositis |
|
|
vacuoles within muscle fibers, lined, festooned or rimmed by basophilic, granular material eosinophilic intracytoplasmic inclusions |
inclusion body myositis usu does not respond to steroids |
|
|
mutation of survival motor neuron gene (SMNI) degeneration of nerve cells in brainstem |
Werdnig-Hoffman/infantile spinal muscle atrophy hypotonia in early infancy, death by age 2 |
|
|
skein-like inclusions |
ubiquitinated fibrils ALS |
|
|
Bunina bodies |
ALS |
|
|
Affects ventral horns of spinal cord loss of Betz cells and degeneration of pyramidal tracts consisting of loss of axons and myelin sheaths |
ALS |
|
|
monocytes attack myelin sheaths |
Guillan-Barre |
|
|
mutations of transthyretin gene |
primary amyloidosis |
|
|
neuropathy in amyloidosis which types? which nerves are affected? |
Primary amyloidosis, not reactive forms affects unmyelinated and small fibers more severely |
|
|
MC type of neuromuscular disorder caused by exogenous toxins |
distal axonopathy affect longest nerve fibers first --> parasthesias in feet; symmetric and ascend |
|
|
spheroids (large focal axonal swellings) |
ALS disulfiram acrylamide hexacarbon solvents |
|
|
palpable enlargement of nerves |
Charcot-Marie-Tooth hypertrophic neuropathy |
|
|
only component of respiratory chain entirely encoded by nuclear DNA |
succinate dehydrogenase unaffected by mutations of mtDNA |
