developmental disorders Flashcards
Causes, class, time course of porencephaly and hydrancephaly
causes: in-utero hypoxia/ischemia. result of major destructive brain lesions in first 6 mo. of fetal life.
secondary malformation
Porencephaly
linear or funnel-shaped defects of variable sizes that involve the whol thickness of the hemispheres
hydrancephaly
cerebral hemispheres converted to thin-walled, fluid-filled vesicles. no ependymal lining. may be from anterior circulation failures, or atresia/stenosis of the aqueduct
subependymal/germinal matrix hemorrhage: class, who gets this, when
most common intracranial complication of premature infants, esp. those with gestational age under 34 wks.
Graded I-IV, with IV being the most severe
hemorrhage
Periventricular leukomalacia
multiple, irregular foci of necrosis in the white matter, esp. in rostral frontal lobes and parieto-occipital regions.
secondary defect
Down’s syndrome pathology
brain is small and pearshaped. truncated frontal lobes. narrow gyri.
Patau syndrome pathology
trisomy 13. holophrosencephay in 2/3 of cases.
dysraphism vs. neuroschisis
dysraphism: failure of the neural tubes to close
neuroschisis: neural tube rupture
anencephaly
most common congential malformation of the brain in human fetuses.
cranioachischisis
open defect extends along the whol length of the vertebral column with degenration of the brain and spinal cord
Encephalocele
frequently occipital
brain herniating out of underdeveloped brain coverings
Tail bud defects
problems w/ secondary neurulation. grouped together as spina bifida oculta. spinal cord may sho hydromyelia (distension of the central canal), diastematomyelia (split cord), or tethering of the filum terminala. May show a tuft of hair or skin tag over the area.
tethered cord
motor and sensory deficits of lower limbs and neuropathic bladder. resutl of a spina bifida occulta.
syringomyelia
tubular cavidation of the spinal cord over many segments. kind of like hydromyelia (distenstion of the central canal), but the cavidation need not involve the central canal. often C2-upper thoracic cord. progressive. presents in 2nd or 3rd decade.
Chiari type I malformation
herniation/elongation of the cerebellar tonsils without any mass lesion or edema. aka “chronic tonsillar herniation. often asymmptomatic but may be associated with adult onset hydrocephalus. and sudden unexpected death in childhood. associated with syringomyelia and occipital skull dysplasi
Arnold-Chiari malformation
elongation and displacement of the inferior vermis and brainstem, esp. the medulla, into the cervical spinal canal. usually in infants and associated with lumbosacral myelomeningocele and hydrocephalus. beaked tectum common.
Dandy-Walker Malformation
hypoplasia of the vermis, cystic dliation of the 4th ventricle, and enlargement of the posterior fossa. hydrocephalus frequent.
characteristics of alobar holoprosencephaly
single large ventricle. fused basal ganglia. olfactoctory bulbs are abscent
causes of holoprosencephaly
maternal DM, toxoplasmosis, syphilis, rubella, fetal alcohol syndrome. Or genetic: Patau (trisomy 13),
Agyria/Pachygyria
agyria, aka lissencephaly: smooth surface of brain
pachygyria: a few broad convolutions with shallow sulci. due to problems that neuroblasts have reaching the cortex at 12th wk of gestation. thickened cortex with reduced white matter. 4 layers of cortex. may be sporatic or familial
Polymicrogyria
lots of small irregular gyri. may be focal or widespread. may be acquired from intrauterine ischemia or infection (month 4-5 of gestation), be familial, or associated with metabolic disease.
heterotopias
see irregular grey matter nodules or symmetrical layers near the ventricles. seizures are common.
Cortical dysplasia
disorderly arrangement of neurons in the cortex. not part of pre-malignant lesions. May be a minor focal problem (ie. seizure locus) or a major developmental disorder.
microcephaly
small head. related to small brain. may be sporatic, familial. often seen in fetal alcohol syndrome
