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what is the most common cause of CNS problems?
Trauma
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% of disabling injury, accidental death, and automobile death caused by brain injury
- 10% disabling injury
- 30% of all accidental deaths
- 70% of all automobile deaths
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what are the different types of CNS injuries that usually result from trauma to the skull?
- epidural
- subdural
- subarachnoid hemorrhage
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what is an epidural hematoma?
- very fast accumulation of blood btwn the skull and dura
- usually due to middle cerebral artery rupture
- immediate surgery is only option or person will die
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what causes an epidural hematoma?
- a blow to the side of the head that fractures the temporal bone
- can be accompanied by loss of consciousness, recovery, and progressive neurologic deterioration leading to coma
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what is a subdural hematoma?
- accumulation of blood in the subdural space
- due to rupture of bridging veins passing btwn brain and large dural sinuses
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what causes a subdural hematoma?
- inertial brain injury to frontal or occipital portion of the head w/o skull fracture
- people tend not to remember the trauma bc it seems insginificant
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what is an acute vs chronic subdural hematoma?
- acute: manifests after a few days
- chronic: manifests after weeks or months by confusion that may lead to coma
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what is a subarachnoid hemorrhage?
bleeding into the subarachnoid space (any etiology)
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what causes a subarachnoid hemorrhage?
commonly caused by trauma or rupture of a pre-existing arterial aneurysm but can have any etiology
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what are CNS vascular diseases?
- inherited disorders due to incomplete and/or abnormal resolution of embryonic vasculature
- common
- usually consist of a mixture of veins, arteries, and arterialized veins usually located in brain hemispheres ("arteriovenous malformations)
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what are CNS vascular diseases likely to cause?
seizures and intracerebral hemorrhage from rupture
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what is the most common CNS vascular disorder/arteriovenous malformation?
- saccular ("berry") aneurysms
- present in 5-6% of general population
- usually arise at the bifurcation of vessels in the middle cerebral artery and its branches
- very lethal
- typical at the base of the skull
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what arteries are more prone to rupture if they have saccular/berry aneurysm?
ant cerebral and ant communicating artery
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what are the clinical symptoms of a saccular/berry aneurysm problem?
- rupture (most lethal)
- infarction
- mass effect (compression)
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what is a cerebral (non traumatic) hemorrhage?
a collection of usually bloody fluid w/in brain stem or cerebral hemispheres
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what is a hypertensive hemorrhage?
- most common cause of non-traumatic hemorrhage
- occurs most freq in basal ganglia where walls of vessels have been damaged by chronic hypertension or hypertensive microaneurysms
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compare cerebral infarction w/ cerebral hypertensive hemorrhage
- infarction: localized to arterial distribution, destroy brain parenchyma
- hemorrhage: affects any blood vessel in the brain, compresses the brain
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what causes cerebral infarction?
- vascular thrombosis: internal carotid, vertebral artery, usually associated w/ a pre-existing atherosclerosis
- embolism: thrombi from L hrt or carotid arteries, symptoms depend on location and size
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what is hydrocephalus?
increased CSF volume causing vascular distention
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what causes hydrocephalus?
- overproduction of CSP
- inability of aracnoid villi to transfer CSF to venous drainage
- blockage of CSF pathways
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what is noncommunicating hydrocephalus?
blockage is within the brain
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what is communicating hydrocephalus?
blockage in subarachnoid space
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what happens if blockage causing hydrocephalus occurs before cranial sutures close?
resultant head enlargement mostly from top of skull
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what happens if blockage causing hydrocephalus occurs after cranial sutures close?
causes symptoms related to increased intracranial pressure
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what types of infectious diseases affect the CNS?
- bacterial
- -- leptomeningitis
- -- cerebral abscess
- viral
- -- viral meningitis
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what causes leptomeningitis?
- bacterial infection caused by
- - E. coli in newborns
- - H. influenza in infants and children
- - N. meningitis in adolesents and young adults
- - Step. pneumoniae in adults and young children
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what occurs with leptomeningitis?
- meninges become congested w/ purulent exudate
- CSF shows increased pressure, increased neutrophils and protein, dec glucose
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what are the clinical symptoms of leptomeningitis?
- agitation
- headache
- photophobia
- stiff neck
- postive meningeal signs (Brudzinki's and Kernig's)
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what causes a cerebral abscess?
bacterial infection carried by the bloodstream usually from a sinus infection, ear infection, or mastoid infection
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how does an infection progress to a cerebral abscess?
- starts as an acute inflammatory reaction w/ neutrophil infiltration and liquefactive necrosis associated w/ extensive cerebral edema
- fibroblasts attempt to wall off the necrotic area
- cavity evolves when dead tissue is removed
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what are the symptoms of a cerebral abscess?
most are related to edema, incr intracranial pressure and area of involvement
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what is viral meningitis?
- along w/ encephalitis is an important complication of systemic viral diseases and AIDS
- results from virus spread hematogenous or along peripheral nerves (rabies)
- clinical symptoms depend on virulence and site affected
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what are the different types of viruses that can lead to viral meningitis?
- poliomyelitis: any inflammation of the gray matter of SC
- rabies: causes encephalitis
- herpes simplex type I and II
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what is the most common CNS demyelinating disease?
MS
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what is the etiology of MS?
- unknown
- may be autoimmune reaction after a virual infection against brain cells called oligodendroglia
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what occurs with MS?
numerous patches of demyelination throughout the white matter "plaque" is the hallmark of MS.
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what are the symptoms of MS and its onset?
- onset in young adults (relapsing or remitting)
- symptoms relate to leasions of the optic nerve, brain stem, or SC that may progress to blindness, ataxia and paraplegia
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what are degenerative diseases of the CNS?
- alzheimers
- parkinson's
- amyotrophic lateral sclerosis
- huntington's disease
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what are the characteristics of Alzheimer's disease?
- progressive neurologic disease
- loss of recent memory
- dementia
- insomnia
- anxiety
- progressive intellectual impairment leading to inability to comprehend, communicate or care for oneself
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what occurs physiologically w/ Alzheimer's disease?
- involved of chromosome 21 and amyloid protein
- meninges are thickened, gyri atrophic w/ dilation of ventricles due to cortical atrophy
- death is often secondary to respiratory infections
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what are the characteristics of Parkinson's disease?
- onset in 5th and 6th generation
- loss of neurons in the substantia nigra, loci cerulei, and dorsal motor nucleus of the vagus
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what are the clinical signs of Parkinson's?
resting "pill-rolling" tremors and bradykinesia which progress to rigidity and postural changes, slowness of voluntary movements, poor balance, shuffling gate, mask-like faces, and dementia (50%)
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what are the characteristics of ALS?
- relatively uncommon
- onset in the 6th decade
- gradual progressive wasting of extremities and motor weakness leading to respiratory failure
- sensory and mental function remains intact
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what happens physiologically w/ ALS?
- degeneration of upper motor neurons in the SC and brain stem
- damage to the corticospinal tracts and degeneration of anterior horn cells resulting in denervation atrophy of mm groups.
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what are the characteristics of Huntingtons's disease?
- autosomal dominant inherited disease
- onset in 4th decarde
- involuntary movement of all parts of the body and facial grimaces
- (opposite of parkinson's symptoms)
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what happens physiologically w/ Huntington disease?
- marked atrophy of the caudate and putamen nucleus w/ corresponding ventricular enlargement
- onset of symptoms to death is about 15 years
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what are the signs/sx of CNS neoplastic disease?
- nothing specific
- depend on local effects (irrative, compressive, destructive effects on the the sites involved) and general effects (inc pressure, edema, hemoorhage)
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Are CNS neoplasms generally malignant or benign?
- malignant but rarely metastases
- "malignant by location"
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what are the two different origins of CNS neoplasms?
- depends on the cells involved
- - neuroglial origin
- - meningeal origin
- - metastatic origin
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what are the types of neuroglial CNS neoplasms?
- astrocytoma
- oligodendroglioma
- ependymoma
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what is an astrocytoma?
- CNS neoplasms of neuroglial origin
- derived from astrocytes w/ a wide spectrum of differentiation
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what are the grades of an astrocytoma?
- grade I: well differentiated
- grade II and II: anaplastic astrocytoma and glioblastoma which is highly malignant and the most common
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what are the symptoms of an astrocytoma?
- seizures
- motor deficits
- mental changes
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what is an oligodendroglioma?
- a CNS neuroglial neoplasm
- derived from oligodendrocytes
- primarily turmors of adults manifested by seizures
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what is an ependymoma?
- a neuroglial CNS neoplasm
- occur most frequently in 4th ventricle (hydrocephalus) during 1st and 3rd decade
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what are CNS neoplasms of meningeal origin?
- secondary tumors
- called meningioma
- generally slow growing, benign
- occur most freq in middle-aged adults
- may or may not be symptomatic
- prognosis depends on accessibility to surgical removal
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what are the primary sites of CNS neoplasms of metastatic origin?
- (in order of freq)
- lungs, breasts, melanoma, kidney, GI
- symptoms include headach, seizures.. etc
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what are examples of PNS disorders?
- Wallerian degeneration
- Distal axonopathy
- Segmental demyelination
- Neuropathies
- -- diabetic neuropathy (most common)
- -- Guillain-Barre disease
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what is Wallerian degeneration?
- a PNS disorder w/ degenerative changes in distal segment of a transected nerve
- accumulation of organelles in the proximal and distal axonal stumps
- atrophy of Schwann cells replaced by fibrose tissue
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what is Distal axonopahty?
- "dying back"
- a PNS disorder involving toxic and metabolic neuropathies proximal axon is intact
- regeneration possible if the cause is removed
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what is segmental demyleination?
changes that result from damage of myelin sheaths
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what is diabetic neuropathy?
- most common PNS symmetrical polyneuropathy
- involve sensory and autonomic nerves w/ extensive segmental demyelination secondary to axonal degeneration
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what is Guillain-Barre disease?
- an autoimmune PNS neuropathy
- progressive ascending motor paralysis
- may affect spinal and cranial nerves
- preceded by viral infection
- characterized by segmental demyelination
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