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CHAPTER 23 NERVOUS SYSTEM

! ASTROCYTOMAS: THE MOST COMMON CNS NEOPLASM.3 formso Astrocytes are cells that support the neurons in the CNS.o Primary neoplasms of the brain and of course metastases to the brain

! Invlvd in healing & forming scar-like tissue in brain injury - supportive cellso Even benign tumors can result in death when in CNS b/c no room for expansiono ASTROCYTOMA: well differentiated but infiltrative. Grows slowly & persons life

span can be 5 - 10 years. Constitutes 20% of primary CNS neoplasms

! Well diff. tumor but tends to be very infiltrative (slow grwth but relentless)! Unfortunately they tend to never go away! Least aggressive of the 3 forms of astrocytoma; so long term survivability

o ANAPLASTIC ASTROCYTOMA: mod diff & more aggr w/life expect. of 3 years! More aggressive, still relatively well differentiated, or moderately

differentiated"not as differentiated as astrocytoma

! Its life span prognosis is shorter, about 3 yearso GLIOBLASTOMA MULTIFORME: poorly differentiated; most aggressive;

life span 1-1.5 yrs. 40% of primary CNS neoplasms! Most aggressive form of astrocytomas! Life span is about a year or so (most poorly differentiated)! MOST COMMON OF THE ASTROCYTOMAS

! NEOPLASMS METASTATIC TO BRAINo Leukemia, lymphoma, carcinoma of lung & breast, melanoma in decr order

! PRIMARY DISEASES OF MYELINo MULTIPLE SCLEROSIS: MOST COMMON DEMYELINATING DISEASE.

Mostly in 2nd& 3rddecades of life. Less common in Blacks & Asians. Etiology

unknown; strong immuno possibilities. Plaques (areas of demyelin.) in CNS only

! Clinical Features: blurred vision, diplopia, paresthesia, spasticity, slurredspeech, and abnormal gait. Life span unpredictable

! MOST COMMON OF THE MYELIN FORMING DISEASES! In MS, you are born with a normal CNS histology, function, and anatomy! Probably b/c of immunologic processes, T cell mediated injuring myelin

sheaths are destroyed focally in CNS, & therefore conduction of the axons

is interrupted

! Key factoid of MS is idea ofPLAQUE FORMATION You see a slice ofbrain w/big red area"PLAQUE- AN AREA OF DEMYELINIZATION &THAT WHY ITS RED. This is the gross, visible abnormality of MS

! Unfortunately, this is a permanent situation.

! Some ppl have what is referred to as ACUTE MS. They die rather quicklyusually due to respiratory failure or pneumonia, pulmonary problems that

develop from of lack of control of diaphragm & normal respiration

! In other people there will be slow progressiono LEUKODYSTROPHIES: A group of inherited problems that result in INABILITY

TO FORM NORMAL MYELIN TO BEGIN WITH.Usually seen in childhood! INABILITY TO FORM AND MAINTAIN NORMAL MYELIN TO BEGIN WITH

o Important to say that these 2 conditions are DEMYELINATING DISEASES --one where myelin formation isnt maintained and with the leukodystrophies,

myelin formation never really occurred properly to begin with

! DEGENERATIVE DISEASES: A group of disorders characterized by progressivedegeneration of neuronsin various parts of the CNS

o Problems with NEURONS, NOT THE MYELINo ALZHEIMER:Dementia is defined as the development of memory impairment

and cognitive deficits in those with a normal level of consciousness

! Dementia means gradual dvlpmnt in older adults of memory impairment& other cognitive deficits in somebody who is of normal consciousness

! No CNS depression, not comatose! MOST COMMON CAUSE OF DEMENTIA IN THE ELDERLY! Most cases are sporatic! Causation- 10% cases genetic. B-amyloid been shown toxic to neurons

There are abnormalities of a neuronal intracell protein called TAU Aggregates of TAU proteins form NEUROFIBRILLARY TANGLES

that, when combined with beta-amyloid, form SENILE PLAQUES

that are the histologic hallmark of Alzheimers

! 2 microscopic findings in the brains of all Alzheimers NEUROFIBRILLARY TANGLES SENILE PLAQUES (Histologic hallmark)

! It appears the neurofibrillary tangles are made up of these TAU proteins.! Couple neurofibriilary tangles + beta-amyloid"form senile plaques! Clinical--- Brain shrinkage, progressive cognitive impairment, death from

pneumonia and infection

o PARKINSONISM: A motor function prblm (rarely w/dementia) causingabnormal tremors & loss of muscle coordination. Expressionless, unintentional

tremors. Loss of dopamine secreting neurons in SUBSTANTIA NIGRA.

Decreased responsiveness to and production of dopamine occurs. Slow,

unremitting disease

! Degenerative NEURONALproblems! Neurons in substantia nigra form prtn inclusions called LEWY BODIES

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! The dopamine secreting neurons in this part of the brain quit forming DA.Theres decreased responsiveness to dopamine. AND Increased reduction

of dopamine is occurring in substantia nigra part of brain

! Early in Parkinsons, L-dopa is administered & tends to ameliorate symptfor awhile, but people become unresponsive to that and symptoms return

! Progression is variable! FACTOID: The neurons in the substantia nigra form protein

inclusions called LEWY BODIES

! Most cases occur in 50s & 60s. Death may occur due to inf. & accidents! Theres no particular predisposing factors that are generally identifiable

o HUNTINGTON DISEASE: A hereditary, progressive motor function disorder thatinvolves EXTRAPYRAMIDALsystem characterized by uncontrolled spastic

movements "chorea" and dementia. A TRINUCLEOTIDE REPEAT DISORDER

on chromosome #4, transmitted by the father. The gene defect produces an

abnormal protein called HUNTINGTIN. Not manifested until 30s or 40s. Suicide

common cause of death

! Enormously spastic movements - They flail. Cases where arms and legsare totally out of control

! The gene on CHROMOSOME 4produces an abnormal protein. Thatabnormal protein is called HUNTINGTIN, NOT -TON