1-8-07

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What are the most important factors of CNS malformations?: Timing of lesion & what is going on at that time

...not so much the agent
Name the 6 stages of Neurological maturation: 1) Neurogenesis

2) Apoptosis

3) Neuronal Migration

4) Cytodifferentiation (axon and dendritic growth)

5) Synpatogenesis

6) Myelination of axons
When is neurogenesis completed? Name the two regions that exceptions to this and are capable of regeneration postnatally?: By birth

1) External granular layer of the cerebellum

2) Primary olfactory neurons
Difference b/w mature neuron and neurblast (2)?: 1) electrical activity

2) secratory fxn

only neurons have both
Pattern neuronal migration of cerebrum?...cerebellum?: cerebrum: from ventricles out

cerebellum: from surface in
Failure of the mechanism fo apoptosis results in? Name of disease?: Spinal muscluar atrophy

Werdnig-Hoffmann Dz
-hereditary dz, infants severely weak and developmentally delayted but of normal intelligence
Failure of glial apoptosis results in?: Agenesis of corpus callosum
What cells guide neurons to their mature sites during migration?: Radial glial fibers
Cytodifferentiation involves the formation of what 2 things?: Axons - cone growth

Dendrites - spine growth
Is the nerve cell capable of reorienting its axon? Dendritic tree?: axons = yes

dendrites = no
Down syndrome results from defect in what process: Faulty synaptogenesis (and perhaps cytodifferentiation...script and outline contradict)
When is the most active period of proliferation of dendritic spines and synapse formation in the cerebral cortex?: After 28 weeks
When does the myelination of the optic begin and end? corpus callosum? ending of frontotemporal association bundle: optic n = birth to 3 months

corpus c = 4 months to 16 years

frontotemporal = ends at **32 years**
Hypothyroidism causes what neuronal defect?: Delayed myelination
Neural tube defects are from genetic or environmental origins?: BOTH - multifactorial
Major events of dorsal induction (Neuraltion)? Timing?: Neural tube closure - Skull & spinal column

3-4 weeks
Cranioraischisis: incomplete closure of the skull AND spinal column (neural plate open throughout its length)
Ancephaly is a defect in?: Dorsal Induction - still have brainstem
Myelocahcisis: Spinal cord remains open througout its length

-kinda like a cranioraischisis w/out the skull defect
Common effect of myelomeningocele?: Hydrocephalus (90% affected)
Major events of Ventral induction (Neuraltion)? Timing?: Cleavage of prosencephalon - face and brain formation

5-6 weeks
Micrencephaly is what? a defect in? occurs when Associated with?: Small brain

Neuronal Proliferation (neurogenesis)

2-4 months

Polymicroglia (migrational defect - small irregular gyri)
Holoprosencephaly is a defect in?: Ventral induction
Porencephaly: cavity that communicates between a lateral ventricle and subarachnoid space
More severe form of porencephaly: Schizecephaly
Schizecephaly caused by?: Stroke in MCA in early pregnancy
What is Lissencephaly? Defect in? Baby's signs of having?: Absence of sulcal adn gyral development (SMOOTH BRAIN)

Migration

1)lack of eye contact
2)stiffness
3)seizures
4)developmental delays
Pachygyria? Defect in? Associated symptoms?: Thick gyri

Error in migration

Seizures
Neuronal heteropias (periventricular heteropias)? Unique propertycompared to other migrational disorders?: Displaced masses of gray matte within white matter - Seizures

Unilateral (nonsymmetric) developement
Leukodystrophies are a defect in?: Myelination

White matter distrubances
Brain accounts for what percent of total body weight? What percent of Cardiac Output?: 2.5%

15%
What is the main blood supply for the suptratentorial tissue?: Internal carotid system
What is the main blood supply for the subtentorial nervous tissue?: Vertebro-basilar system
Internal Carotid system (supratentorial) consists of what vessels?: long circumferential vessels (ACA, MCA, PCA) = supply cortex

short circumferential vessels = supply Thalamus, Internal Capsule, & Basal Ganglia

Paramedian vessels = base of brain near midline
Vertebro-basilar system (infratentorial) consists of what arteries?: Superior cerebellar artery

AICA

PICA
Ophthalmic artery anastomoses?: External and Internal carotids
Leptomengeal vessels anastomose?: branches of the major cerebral arteries
Intraparenchymal vessels anastomose?: short and long circumferential vessels
Neural parenchyma that receive input from the distal portions of two major arteries: Watershed region
T/F In contrast to the arterial system, the venous drainage of the CNS is less often a cause of CNS pathology: True
Final common pathway of superficial and deep CNS veins: Dural sinuses
What is the most common pathologic event in the CNS? leads to the production of?: Arterial cerebral (ischemic) infarction

Pale (white) infarcts
Occurrence and extent of cerebral infarction is determine by what three basic factors: 1) Site of arterial occlusion

2) Rapidity of arterial occlusion

3) The presence or absence of collateral circulation
Describe the temporal evolution of an infarct (3): 1) Acute (1 day - 1 week): soft and edematous with blurring of anatomic detail

2) Subacute (1 week - 1 month): obvious tissue destruction and liquefactive necrosis

3) Chronic (>1 month): damaged tissue ahs been phagocytized and there is cavitation with surrounding gliosis
Microscopic temporal evolution of cerebral infarcts?: 1) 0-48 hours: chromatolysis and shrunken eosinophilic neurons

2) 24-72 hours: neuronal cell necrosis and acute inflammatory response

3) 3-5 days: influx of mononuclear cells, begin to phagocytize necrotic debris

4) 1-2 weeks: vascular proliferation and reactive astrocytosis

5) >1 month: necrotic tissue will be comletely removed and cystic cavity surrounded by a glial scar will be formed
Lacunar infarcts are found where? Size by definition?: Basal ganglia and Pons

< 1.5 cm in diameter
Most common cause of thrombotic occlusion?: Atherosclerosis
Artherosclerosis typically affects what?: Large arterial vessls at the base of brain (Circle of Willis)
Second cause of thrombotic occlusion?: Group of diseases collecively termed ARTERITIS

-usually affect multiple, SMALL-medium sized arteries and cause focal hemorrhages

Examples: collagen-vascular disease, fungal infections, TB, syphilis, sarcoidosis, and meningitis
Third cause of thrombotic occlusion?: Systemic disease - Sickle cell anemia & polycythemia
Herniation of what results in fatal Duret hemorrhages?: Herniation of temporal cortex (uncus) under the tentorium
What event may occur after Subarachnoid hemorrhages (or meningitis) and produce cerebral infarctions?: Vascular spasms
Non-occlusive causes of arterial cerebral infarction (3)? What area is particularly susceptible?: 1) Systemic hypotension

2) Cardiac arrest

3) Septic shock

Watershed zone
Non-occlusive causes of arterial cerebral infarction?.. with selecive neuronal damage where?: Hypoxia/hypoglycemia

Selective neuron loss..
1)cerebral cortical neurons (esp layers 3 & 5)
2)pyramidal neurons in the hippocampus
3)Purkinje cells of cerebellum (Bergmann gliosis)
Hemorrhagic infarct from venous thrombosis = ?: Occlusion fo VEINS
Interacerebral hemorrhage secondary to hypertension referred to as? Occurs where?: Charcot-Couchard aneurysms

Short circumferential vessels supplying Basal Ganglia (80%), pons (10%)
Subdural hemorrhage of Perinatal period usually caused by (3)?: Forceps delivery

Cephalopelvic disproportion

Breech deliveries

Subdural hemorrahge is rarely a cause of infant death
Which Perinatal hemorrhage is fairly common but clinically silent? If extensive then?: Subarachnoid Hemorrhage

may result in obstruction of arachnoid granulations (cause hydrocephalus)
Perinatal CNS vascular problem that is a frequent cause of death in premature infants?: Intraventricular hemorrhage (IVH) **(esp 26-28 weekers)
When you see 1)Alteration of consciousness 2)Hemiplegia 3)3rd nerve palsy think..: Uncla Herneation
Type of hemorrhage where blood spreads and sticks intimately w/ brain: SAH

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Deck Info

Number of cards 61