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what is the most common cause of CNS problems?
% 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
what are the different types of CNS injuries that usually result from trauma to the skull?
- subarachnoid hemorrhage
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
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
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
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
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
what is a subarachnoid hemorrhage?
bleeding into the subarachnoid space (any etiology)
what causes a subarachnoid hemorrhage?
commonly caused by trauma or rupture of a pre-existing arterial aneurysm but can have any etiology
what are CNS vascular diseases?
- inherited disorders due to incomplete and/or abnormal resolution of embryonic vasculature
- usually consist of a mixture of veins, arteries, and arterialized veins usually located in brain hemispheres ("arteriovenous malformations)
what are CNS vascular diseases likely to cause?
seizures and intracerebral hemorrhage from rupture
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
what arteries are more prone to rupture if they have saccular/berry aneurysm?
ant cerebral and ant communicating artery
what are the clinical symptoms of a saccular/berry aneurysm problem?
- rupture (most lethal)
- mass effect (compression)
what is a cerebral (non traumatic) hemorrhage?
a collection of usually bloody fluid w/in brain stem or cerebral hemispheres
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
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
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
what is hydrocephalus?
increased CSF volume causing vascular distention
what causes hydrocephalus?
- overproduction of CSP
- inability of aracnoid villi to transfer CSF to venous drainage
- blockage of CSF pathways
what is noncommunicating hydrocephalus?
blockage is within the brain
what is communicating hydrocephalus?
blockage in subarachnoid space
what happens if blockage causing hydrocephalus occurs before cranial sutures close?
resultant head enlargement mostly from top of skull
what happens if blockage causing hydrocephalus occurs after cranial sutures close?
causes symptoms related to increased intracranial pressure
what types of infectious diseases affect the CNS?
- -- leptomeningitis
- -- cerebral abscess
- -- viral meningitis
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
what occurs with leptomeningitis?
- meninges become congested w/ purulent exudate
- CSF shows increased pressure, increased neutrophils and protein, dec glucose
what are the clinical symptoms of leptomeningitis?
- stiff neck
- postive meningeal signs (Brudzinki's and Kernig's)
what causes a cerebral abscess?
bacterial infection carried by the bloodstream usually from a sinus infection, ear infection, or mastoid infection
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
what are the symptoms of a cerebral abscess?
most are related to edema, incr intracranial pressure and area of involvement
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
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
what is the most common CNS demyelinating disease?
what is the etiology of MS?
- may be autoimmune reaction after a virual infection against brain cells called oligodendroglia
what occurs with MS?
numerous patches of demyelination throughout the white matter "plaque" is the hallmark of MS.
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
what are degenerative diseases of the CNS?
- amyotrophic lateral sclerosis
- huntington's disease
what are the characteristics of Alzheimer's disease?
- progressive neurologic disease
- loss of recent memory
- progressive intellectual impairment leading to inability to comprehend, communicate or care for oneself
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
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
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%)
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
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.
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)
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
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)
Are CNS neoplasms generally malignant or benign?
- malignant but rarely metastases
- "malignant by location"
what are the two different origins of CNS neoplasms?
- depends on the cells involved
- - neuroglial origin
- - meningeal origin
- - metastatic origin
what are the types of neuroglial CNS neoplasms?
what is an astrocytoma?
- CNS neoplasms of neuroglial origin
- derived from astrocytes w/ a wide spectrum of differentiation
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
what are the symptoms of an astrocytoma?
- motor deficits
- mental changes
what is an oligodendroglioma?
- a CNS neuroglial neoplasm
- derived from oligodendrocytes
- primarily turmors of adults manifested by seizures
what is an ependymoma?
- a neuroglial CNS neoplasm
- occur most frequently in 4th ventricle (hydrocephalus) during 1st and 3rd decade
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
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
what are examples of PNS disorders?
- Wallerian degeneration
- Distal axonopathy
- Segmental demyelination
- -- diabetic neuropathy (most common)
- -- Guillain-Barre disease
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
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
what is segmental demyleination?
changes that result from damage of myelin sheaths
what is diabetic neuropathy?
- most common PNS symmetrical polyneuropathy
- involve sensory and autonomic nerves w/ extensive segmental demyelination secondary to axonal degeneration
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