Tissue Healing Flashcards
Can central nerves regenerate?
no
Can peripheral nerves regenerate?
yes, often incompletely
?
- severe contusion to nerve
- decreased conduction
- recovery takes several weeks
Neuropraxia
?
- injury to axon with wallerian degen
- recover in months-years
- crush injuries
Axonotmesis
?
- complete severence of a nerve
- irreversible damage
- nerve will never recover
- can treat neuroma
- cutting wounds
neurotmesis
- NOTES-
- axonal degeneration does not begin immediately after injury; ie can still produce ap and xmit signals
-blood brain barrier is compromised
what happens to the axon distal to the injury site?
-swells
Calpain is activated and there is Ca2+ influx during nerve injury.
What is calpain?
Protease essential for the cytoskeleton degeneration and axonal degeneration
?
- granular degeneration of cytoskeleton
- fine debris produced
- occurs within an hr
axonal degeneration
What is required for myelin sheath breakdown?
phospholipase a2
what aids in axonal regeneration, secrete trophic factors, secretes cytokines, and phagocytose myelin debris?
schwann cells
what removes myelin debris?
macrophages
What is the order of involvement of inflammatory cells during nerve inurjy?
- hours/days-neutorphils
- 3 days- t lymphocytes
- 1 week-macrophages
Why do we do manual muscle testing?
have to determine if any abnormalities are coming from the nerve, nm junction, or the muscle
?
- tap along course of the nerve
- what is it when you have pain distally and pain proximally?
Tinel’s=distal->less concerning
Valleaux=proximal -> more concerning
What do NCV studies test?
sensory component
motor component
f wave
h reflex
what is the time it takes the electricity to travel from stimulation site to the recording site?
sensory and motor latency
-change in latency or amplitude indicates nerve injury
What does the F-wave study?
- measures the resulting action potential
- not an reflex
- electrical activity travels from site of stimulation through ventral horn to muscle
- conduction velocity between the spinal cord and the limb
What does H reflex study?
- electrical discharge of muscle
- connection between the limb and the spinal cord
What occurs in rapid myonecrosis? (degeneration)
-Sarcolema disruption-> inc permeability; inc serum creatine kinase, prevelent skeletal troponin I
-increased infiltration of inflammatory cells
neutrophils then macrophages
what occurs during myogenic proliferation?
myogenic cells differentiate and fuse to existing damaged fibers
- new fibers formed->cells enlarge->nuclei move to periphery
- new fibers are identical
why can muscle cells regenerate?
undifferentiated mononuclear monogenic cells at periphery of mature skeletal fibers
What is the steriotypical blood vessel response to injury?
stimulation of smooth muscle cell growth and associated matrix synthesis that thickents the intima forming a neointima
How is neointima formed?
- defect in endothelium
- epithelial cells migrate into the area to fill the deficit
- smooth muscle cells proliferate and synthesize ecm
- neointima is formed
what happens when there is decrease in blood flow?
- local tissues become hypoxic and ischemic
- increase VEGF production
- binds to cognate recepetor tyrosine kinases
- angiogenesis
6 P’s
-signs of vascular injury
Pale, Pallor, Polar, Pulselessness, Pokilothermia, pain
what type of vascular injury is this?
- embolic shower
- crush/laceration injury
acute vascular injury
- What test is this?-
- dependent rubor
- palor with elevation
- raise legs 60 degrees x1min
Brueger’s test
- What test is this?-
- evaluates competency of valves in the veins
- elevate legs 90 degrees
- cuff around the high thigh occlude the grater saphenous vein
- have pt stand
- evaluate filling of the veins
Brodie-trendelenberg test
What different in pressure indicates pathology when using abi/pvr with segmental pressures
greater than 30mmHg
What indicates a healthy waveform?
- brisk sharp rise
- dichrotic notch
waveform pathology with absence of a dichrotic notch and gradual prolonged downstroke?
-early pathology
waveform pathology with rounded systolic peak
moderate pathology
flattened wave with slow upstroke and downstroke
severe occlusion
what is photoplethysomography?
infrared frequency is emitted and reflected by hemoglobin molecules in microcirculation to show waveforms
what are the aims for arterial duplex and when do you use it?
- assess velocity of blood flow in the LE arteries
- localize and characterize stenosis, collaterals, and occlusions
- detailed assessment of the arterial tree
-evaluation of atherosclerotic, aneurysm, bypass grafts, evaluation of arterial trauma
What is the gold standard test for DVT?
venogram
What is the difference between arterial and venous hemorrhage?
artery-pulsatile flow, bright red blood
vein-oozing, red to dark red blood
