Term
Anencephaly
(Definition
Prevalence
When in gestation?
Physiologic/Anatomic Features
Prognosis
Diagnosis
Distinguishing Characteristics
Increased geographic incidence |
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Definition
(Neural Tube Defect)
Failure of anterior end of neural tube closure
.1-.5% incidence, mostly females
Develops at Day 28 of gestation
Absence of brain and calvarium (bone)
Small disc shaped brain (AREA CEREBROVASCULOSA)
Rarely survives more than a few hours
Detected early in gestation by ultrasound scan
Detected by raised alpha-fetoprotein level in maternal serum
Protuberant eyes, short neck, low set ears
Incidence high (10x) in Ireland, Wales, France) |
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Term
Encephalocele
Definition
Common fossa region(s)
More male or female?
Associated abnormality? |
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Definition
Hernia of brain tissue thru a midline defect in the cranial cavity (mesodermal defect)
mostly located in occipital or posterior fossa; can be frontal
Mostly Female
Assoc. hydrocephalus
Its a herniated mass of neural tissue fragments covered by meninges and skin |
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Term
Myelomeningocele
What causes it?
Where is it mostly found?
What do you call it when the defect is limited to the spine?
Assoc. abnormality? |
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Definition
Failure of posterior end of NT closure
Both meninges and deformed spinal cord herniate thru defect in the vertebrae
Presents as a cystic mass covered by a delicate membrane or skin, OR an open lesion w/ a mass of vascular, CT and neural tissue
Mostly in the lumbrosacral region (motor and sensory deficits in the Lower Extremities
Assoc. w/ Chiari type II abnormality
spina bifida occulta = when defect is limited to the spine bone, spinal cord and meninges remain in place
meningocele = meninges are herniated, but spinal cord remains in place |
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Term
Holoprosencephaly
Def
Assoc w/ what chromosomal defect?
4 things that can increase its incidence
Symptoms/prognosis
Incidence
Diagnosis
Physiologic Basis |
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Definition
'One Ventricle'
Failure in outgrowth/cleavage of prosencephalic vesicle; incomplete separation of cerebral hemispheres across the midline
Results in a single ventricle w/ fused basal ganglia (holosphere, helmet shaped with minimal gyration)
1 in 16,000-30,000
Diagnosed via ultrasound
Physiologic cause: Mutations in the human sonic hedge-hog gene (synthesized and secreted by the notochord and neural plate during ventral induction)
Mutation causes excess of Bone Morphogenic Proteins locally in the region of the developing prosencephalon
Cyclopia
Severe Mental Retardation
Reduced Lifespan |
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Term
| Characteristics of Cyclopia |
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Definition
fused orbits and eyes
proboscis, fused ears
flat nose w/ single nostril
absent jaw |
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Term
Arrhinencephaly
aka?
Def:
Relative severity
Associated abnormality |
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Definition
(Olfactory Aplasia)
Agenesis of the olf bulbs and tracts
Mildest for of craniofacial anomalies
can be seen w/ holoprosencephaly |
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Term
Agyria vs. Pachygyria
What type of disorder (physiologic basis)? |
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Definition
Agyria = small brain w/ smooth cerebral surface (lissencephaly), abscence of gyri and sulci
Pachygyria = macrogyria, reduced number of broadened gyri
Due to a reduction in the number of neurons reaching the neocortex; results in simplification of gyral foldings |
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Term
Polymicrogyria
Def
Appearance
Associated events |
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Definition
small, irregularly formed, numerous thin gyri
Cobblestone appearance
Many assoc genetic syndromes
Twinning, VZW, CMV, Toxo, Syphillis |
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Term
| Nodular Ventricular Heterotopia |
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Definition
neurons are supposed to migrate out thru the cortex, but instead move the opposite direction and produce wart-like nodules in the ventricles
May present as a 'Double Cortex' |
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Term
Microcephaly
Def
Possible Causes (5) |
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Definition
abnormally small brain (less than 1000grams in adults)
Causes:
Inherited
Fetal Alcohol Syndrome
Viral Inf like Rubella, or
HIV-1
Inborn errors in metabolism, ie Phenylketoneurea |
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Term
Agenesis of Corpus Callosum
Is it sporadic or inherited?
2 assoc conditions |
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Definition
Absence of white matter bundle connecting both hemispheres
'Bat wing deformity'
can be Sporadic or Inherited
Assoc w/ holoprosencephaly, and midline tumors (lipoma, meningioma) |
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Term
Hydranencephaly
Def
3 causes
What differentiates it from Anencephaly? |
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Definition
Cerebral hemispheres are largely absent; instead fluid fills the cavity
Causes:
Fetal Hypoxia
maternal intoxication
twinning
skull present, often externally normal (not true for anencephaly)
Secondary destruction |
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Term
Arnold Chiari Malformation (Chiari type II)
What type of abnormality?
Def
Assoc abnormalities? (2) |
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Definition
(Posterior Fossa Abnormality)
Small posterior fossa with downward displacement of cerebellar tissue (VERMIS) thru the foramen magnum
Resulting caudal displacement of medulla
Assoc. w/ hydrocephalus and meningomyelocele |
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Term
Dandy-Walker malformation
Triad of Abnormalities?
Contrast w/ Chiari Type II |
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Definition
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Term
2 Causes of Perinatal Damage
Which is more important/common? |
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Definition
Physical Trauma - less common
Hemorrhage
laceration of dural sinuses
spinal cord injury following vigorus traction
Hypoxia - more important than trauma
Premature newborns w/ resp. distress |
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Term
Germinal Matrix Hemorrhage
Cause/association?
Why does it happen? |
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Definition
Acquired disorder
Prematurity is most common assoc
Hemorrhage may be localized or spread into ventricles and beyond
Happens because the germinal matrix is packed w/ cells but very little CT so BV's are not supported |
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Term
Periventricular Leukomalacia (PVL)
Def/Presentation
Common assoc?
When does it occur in gestation?
What is ulegyria? |
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Definition
Periventricular white matter necrosis and mineralization/calcification (chalky yellow spots)
Assoc w/ prematurity; usually a hypotensive mechanism of injury
Injury occurs between 24-32 weeks gestation
Ulegyria = thinned out mushroom shaped gyri (its damage to the cortex as a result of ischemia); involves depths of sulci
Children are often wheelchair bound |
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Term
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Definition
Described as 'focal hydranencephaly'
Smooth-walled cyst w/ communication between ventrical and the subarachnoid space
May be assoc w/ polymicrogyria |
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Term
| What are 2 possible end results of Perinatal Damage? |
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Definition
1. Death
2. In survivors, Cerebral Palsy |
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Term
Cerebral Palsy
4 Causes
Typical age of onset
Name and Describe 3 associated motor disorders (are these progressive or nonprogressive)
2 associated neurological problems |
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Definition
Neonatal hypoxia (due to premature birth) - frequent
Trauma
Kernicterus (bilirubin encephalopathy)
Neonatal meningitis
Early onset (before age 2)
Non-progressive motor disorders: (because its a white matter disease)
corticospinal - paresis, paralysis
extrapyramidal - athetosis (a continuous stream of slow, sinuous, writhing movements, typically of the hands and feet)
cerebellar - unsteadiness, ataxia
Assoc Problems:
Mental retardation - 50% (but others have normal IQ)
Seizures in 35% |
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