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Where does coup, contracoup injury occur?
- On site of impact, usually convex brain
- Opposite side (against skull), more severe.
What are the patterns of skull fracture?
- Comminuted: large fracture with multiple fragments
- Diastatic: Opens or reaches suture.
What is a concussion, what function is most often affected?
- Traumatically induced alterarion in mental status (+/- loss of conciousness)
What is a contusion?
- Bruise, usually on crest of gyri
- Often found in temporal or frontal lobes.
Where is, what causes an epidural hemorrhage?
- Between dura and calvarium
- Rupture of meningeal (often middle meningeal) arteries due to trauma.
What causes a subdural hematoma?
- Rupture of bridging veins
- Acceleration/deceleration injury (eg. shaken baby syndrome)
- Symptoms: nausea, vomiting, dizziness, sleepiness.
Subarachnoid hemorrhages may be caused by?
- Trauma, contusion
- Rupture of berry aneurysm
- Rupture of leptomeningeal blood vessels
- High mortality.
What causes diffuse axonal lesions?
Acceleration/deceleration result in axonal damage due to shearing stress.
What is the time course of diffuse axonal injury?
- 4-5hrs: accumulation of Amyloid Precursor Protein (APP)
- 12-24hrs: Axonal bulbs/varicosities on H&E
- 24hrs-2mo: Axonal spherules (with ubiquitin, APP, NF+)
What is the hallmark lesion of MS, what does it represent?
- Area of demyelination
- Often found in:
- -periventricular white matter
- -subcortical white matter
- -cerebral cortex and gray matter
- -optic nerves
- -spinal cord.
What stains are used for myelin?
Luxol Fast Blue: lack of staining identifies myelin loss.
What other cells may be found in active plaques, how can you stain for them?
- Macrophages- parenchymal and perivascular with myelin debris
- Lipid containing macrophages: oil-red-O.
Name three pathological processes in MS?
- Cytokines: lymphotoxin, TNFa, IL-6
- Endothelial activation: upregulation of ICAM-1 and VCAM-1.
What are the three types of cortical lesions in MS?
- Gray/white matter junction
- Within cortex: No B or T lymphocytes
- Cortex abutting the pia: Microglial activation prominent.
What do shadow plaques represent?
- Incomplete process early in MS.
What is the Marburg type of MS?
- Acute MS
- Fulminant of rapid course
- Children and young adults
- large conluent areas of demyelination
- Massive macrophage infiltration
- axonal swelling
What is tumefactive MS?
Acute inflammatory demyelinating mass presenting as a neoplasm.
What is Devic's disease?
- Neuromyelitis optica: optic neuritis + acute transverse myelitis
- CSF: Aquaforin 4 + Ig perivascular deposition.
What is acute dissmeinated encephalomyelitis (ADEM)?
- Acute, monophasic (demyelinating)
- In children
- may follow infections
- Affects white matter more.
What causes subacute sclerosing pan encephalitis (SSPE)?
Infection of oligodendrocytes by defective measles virus.
What is the clinical disease and pathology of SSPE?
- Global loss of higher brain functions and death
- Perivascular lymphoid infiltrate
- Intranuclear inclusions of measles virus.
What causes central pontine myelinolysis?
Rapid correction of hyponatremia.
What can cause toxic leukoencephalopathy?
A number of drugs, prescription and recreational.
Thymic hyperplasia or thymoma may be found in what NMJ condition?
- Myasthenia Gravis
- Women affected twice as often as men.
Is MG acquired or congenital?
- Acquired, autoimmune, humoral
- Anti-AchR antibodies bind to alpha subunit.
What is Lambert Eaton Myasthenic Syndrome (LEMS) associated with?
- Small cell lung carcinoma - paraneoplastic syndrome (60%)
- Men twice as much as women.
What is the pathology of LEMS?
- Decreased pre-synaptic release of Ach
- Antibodies against presynaptic voltage gated Ca2+ channel.
What are the clinical presentations of muscle strength in MG and LEMS?
- MG: decreased strength throughout the day, increased with rest
- LEMS: Increased strength with more contractions.
What are leukodystrophies?
- Inherited demyelinating diseases in which the clincial sympoms derive from abnormal myelin synthesis or turnover
- Mostly Autosomal Recessive, some X-linked.