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Pathology of the CNS: part 4, Dementia

What sorts of dementia may be reversible?

dementia due to infx, drugs, alcohol, metabolic or endocrine imbalances, vitamin imbalances, depression

DEMENTIA
10% of Americans over 65
two most common: Alzheimers and vascular

ALZHEIMER'S
progressive
death of nerve cells-->loss of fx such as memory and learning
mc reason for admission to nursing home
late onset most common
almost half of Americans over 85
familial/early onset is uncommon, dt mutations on xsomes 1, 14, 21
amyloid plaques (outside neurons) and neurofibrillary tangles (of tau prots, inside neurons)
tau proteins form insoluble twisted mess instead of normal microbular system
test available for beta amyloid precursor and for genes, but DX usu clinical
brain shrinks, deep fissures, large ventricles

VASCULAR DEMENTIA
MID = multi-infarct dementia
variable severity depends on number and locations of infarcts
infarcts may form cysts, calcifications
gliosis = atrocytes grow into empty spaces where liquid necrosis has emptied

PICK'S DZ
uncommon
looks a lot like Alzheimer's
cerebral atrophy of FRONTAL AND TEMPORAL lobes
"knife-like" atrophy
rapid onset, disturbed/inappropriate behavio
check drinking habits and keep in DDX

PARKINSON'S
death of pigmented neurons: substantia nigra and locus ceruleus
present with mvt probs: diminished voluntary mvt, slurred speech, difficult/shuffling gait
cogwheel rigidity of limbs, pill rolling tremor at rest, mask like face, drooling
forward head lean
mostly physical but some pts have dementia in addition to physical probs
characteristic lesion in cytoplasm of neurons: LEWY BODIES
rounded pink Lewy body

DEMYELINATING DZ
incl:
multiple sclerosis
progressive multifocal leukoencephalopathy
central pontine myelinosis
AML = Lou Gerig's dz

MULTIPLE SCLEROSIS
most common demyelinating dz
1/1000 in US and EUR
women 2x men
distinct episodes of neuro deficits, waxing and waning
more farther from equator
"Lew body dementia" in DDX for Alzheimer's
lecithin = myelin precursor
SX onset age 20-40, rare before 15 or after 60
etiology uncertain
pathogen triggers: EBV, HHV6, others
SX: muscle weakness, difficult to walk, loss of coordination and balance
numbness, blurred/double vision, eye pain, urinary sx, fatigue, tremors
pain, vertigo, dysphagia, incontinence, constipation, cognitive chcanges
LATE: muscle spasticity, paralysis
DX: no definitive diagnostic test, MRI for plaques, gadolinium enhancement tells new from old
focal lesions, acute inflam changes, macrophage and lymphocyte infiltration, edema, demyelinization
DX: lumbar px to measure immunoglobins, usu elevated in MS

PROGRESSIVE MULTIFOCAL LEUKOENCEPHALOPATHY
JC virus
demyelination
infiltrates of foamy macrophages and
assoc with scattered large oligodendrocytes and enlarged astrocytes
gross: sugary granular look
HISTOL: vacuoles

CENTRAL PONTINE MYELINOLYSIS
usu iatrogenic dt overly rapid correction of hyponatremia
myelin is destroyed but neurons and axons are spared
opposite pattern from infarct
no inflam
swollen brainstem
-->seizure, stroke, cessation of breathing

BRAIN TUMORS
in kids 70% below tentorium (in posterior fossa, cerebellum)
in adults 70% are above tentorium
most prevalent in kids: astrocytic tumors: glioblastomas, medulloblastomas, ependymomas, craniopharyngiomas
in adults: mets, astrocytic tumors, meningiomas
benign brain tumor mb lethal
surgical resection often difficult/impossible
even very malignant primary brain tumors rarely metastasize outside CNS
FOUR MAJOR CLASSES OF PRIMARY BRAIN TUMORS:
1) meningiomas (more in adults)
2) gliomas (from glial cells incl astrocytomas, oligodendrogliomas, ependymomas from ventricle cells)
3) neuronal tumors
4) poorly differentiated neoplasms

MENINGIOMAS
usu b9, very rare to be malignant
in adults
attached to dura, arise in arachnoid
found on external surface of brain
well circumscribed, encapsulated
usu solitary
raquet ball sized

GLIOMAS
malignant
30-40% of all primary intracranial
anywhere in brain
usu in cerebral hemispheres but in kids may be in brain stem and cerebellum
also in spinal cord
most common type: astrocytoma
danger!
grade 1: well differentiated fibrillary
grade 2: anaplastic astrocytoma
grade 3: glioblastoma multiforme (middle aged adults, frontal and temporal lobe, survive 8-10 mo after dx)
resists chemo and radiation
PATHOGNOMIC FOR GLIOBLASTOMA MULTIFORME: crosses to other hemisphere
higher grade, less differentiation more abberration badder
tumor cells resemble astrocytes, stellate or spindle-shaped wtih fiber-like processes OR
plump with large eosinophilic cytoplasmic masses
FIBRILLARY ASTROCYTOMA AND GLIOBLASTOMA are 80% of all adult primary brain tumors
usu between age 40-80
most often in cerebral hemispheres
CC: seizure, headache, focal neuro deficits related to site of involvement
OLIGODENDROGLIOMAS
5-15% of all gliomas
more in 4-5th decade
usu in white matter of cerebral hemispheres
prog better than astrocytomas (average survival time after tx 5-10 years)
EPENDYMOMAS
arise adjacent to ventricular system
in first two decades of life usu found near 4th ventricle-->hydrocephalus
after age 20 usu found in spinal cord
slow growing tumor with poor prognosis
average survival time after surgery: 4 years

NEURONAL TUMORS
several types of CNS tumors contain mature appearing neurons (ganglion cells)
if tumor cells all arise from ganglion-->"ganglioma"
more common: mix of ganglion tumor cells and glial tumor cells-->"ganglioglioma"
10% of primary brain tumors in kids are gangliogliomas
ten year survival rate when treated: 90%
most are slow growing but glial component may become aggressive-->worse prog

MEDULLOBLASTOMA
poorly differentiated, appears embryonal
20% of all brain tumors in children
in cerebellum ONLY
remember 70% of all CNS tumors in kids are infratentorial
so this tumor is 1/5 of 100%
MRI: cerebellar mass
highly radiosensitive: early DX and treatment may greatly improve life expectancy
with total excision and radiation, 5 year survival rate rapproaches 75%

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