Pathology Flashcards
What is a lesion?
A zone of localized dysfunction within the nervous system
What are the 2 classifications of lesions?
- Anatomic: Structural
- Physiologic: Dysfunction, but no structural lesion
What are symptoms?
Subjective sensations resulting from a disorder
What are signs?
Objective abnormalities detected on exam.
Is a headache a symptom or sign?
Symptom
Is hyperreflexia a symptom or sign?
Sign
What is a syndrome?
A constellation of signs and symptoms associated with each other, suggesting a common origin
What are negative and postive neurological manifestations of lesions?
Negative: Loss of function
Positive: Result from inappropriate exciitation
What neurological senses are required for gait?
- Sensory
- Cerebellar
- Visual
- Vestibular
Do neurogenic diseases tend to be more distal or more proximal?
- Distal
What type of distribution do neurogenic diseases tend to have?
- Glove/ stocking distribution
What are the 2 types of neurogenic diseases?
- Motor neuron
- Peripheral neuropathies
What are the 2 signs/ symptoms of neurogenic disease of the motor unit?
- Fasciculation (visible)
- Fibrillations (not visible)
What are “diseases of the muscle” called?
Myopathies
What is the primary problem of myopathies?
Muscle weakness
Do myopathies tend to be proximal or distal?
Proximal
What are muscular dystrophies?
Myopathies with special characteristics such as:
- Heredity
- Progressive weakness and wasting
Which muscle system tends to cause death in myopathies?
Respiratory system
What is a myotonic disorder?
An abnormality of the muscle fiber membrane
How is the muscle affected by a myotonic disorder?
- Marked delay in relaxation
- Increased stiffness for an extended period of time
What is the pathogenesis of Myansthenia Gravis?
- Autoimmune disorder where antibodies attach the acetycholine receptor
What is the progression of Myasthenia Gravis?
- Slow, progressive
How are the muscles affected by Myasthenia Gravis? What are the 2 major symptoms?
- Weakness is patchy, and not related to the distribution of any single nerve
- Weakness fluates
- Decreased muscular endurance
What age and gender are affected by Myasthenia Gravis?
- Any age
- More common in females
What is it called when the eye is half open (common in Myasthenia Gravis)?
Ptosis
At what level is the motor unit affected by Myasthenia Gravis?
The synapse
Describe the 4-step process of Wallerian Degeneration.
Less than 24 hours: Neurofilaments break up; axons break up into short lengths
Within 10 days: Myelin sheath breaks down into lipid droplets around axon
Within Month: Myelin denatures
Within 3 Months: Macrophages from endoneurium invage myelin sheath and axis cyclinder and phagocytize everything
Where are fat droplets found in relation to the lesion in Wallernian Degeneration?
- Distal to lesion
- One or 2 nodes proximal to lesion
What is chromatolysis?
- When an axon is damaged, the cell swells, nucleus swells, and protein substances move to one side producing protein, and sending it down to the site of injury
How are muscles and nerves affected when healing of an axon begin?
- Muscle is no longer innervated and atrophies
- Nerves synapsing on axon atrophy
What type of injury will cause Wallerian Degeneration/ Chromatolysis?
Axonotemesis
What must occur before healing of a nerve begins in the periphery?
- Degeneration/ myelin removal
What protective coating must remain for nerve eregeneration to occur?
Neurolemma
What are the structures that sprout from proximal nerves in a damaged peripheral nerve during healing?
- Filopodia
How do filopodia help a nerve regenerate?
- The filopodia attach to the schwann cell and provide a scaffolding for other filopodia to grow
- The filopodia then become myelinated
At what rate do nerve regenrate?
1 mm/day
What are 2 methods of neural plasticity in an axonal/ neuronal injury?
- An axon may shoot a collateral to plug a hole
- A glia cell may plug the hole
What is apoptosis?
Orderly, genetically programmed cell death
What synaptic stripping?
- Synaptic terminals withdraw from neuron, and are replaced by processes of glia cells
What substance from schwann cells attract neurons?
- Chemotropic factors
Why may a neurolemma or cell die in the periphery?
- If the filopodia do not reach a schwann cell
What inside the perineurium can prevent the regenerating axons from going astray?
Inhibitory molecules
What 4 factors contribute to poor central NS regeneration?
- Glial scars
- Growth inhibition from Oligodendroglia
- Do not have trophic factors required for regeneration
- No neurolemma sheath
