Congenital, Perinatal, and Developmental Pathology Flashcards
What are neural tube defects and when do they usually arise?
Neural tube defects usually result from the failure of the neural tube to fully form a closed tube during primary neurulation or from disordered differentiation of the caudal cell mass into the conus medullaris and film terminale during secondary neurulation.
What are some neural tube defects?
Cranioraschisis totalis, Anencephaly, Encephalocele, Myelomeningocele, Meningocele, Lipomeningocele, Lipomyelomeningocele, Dorsal Dermal Sinus Tract, Spina Bifida Occulta.
What is “tethering”?
Tethering is a neural tube defect that keeps the conus medullaris in place lower in the spine and prevents the spinal cord from gradually ascending as it normally does. This can result in pain, UMN signs like spasticity and hyper-reflexia, and urinary incontinence.
How is a Chiari II malformation associated with a myelomeningocele?
A myelomeningocele consists of a hole through the epidermis which the spinal cord and CSF may protrude. The Chiari II malformation is almost always seen with a myelomeningocele at the thoraco-lumbar level, and this hole may allow the escape of CSF, which then allows the collapse of the ventricles and overgrowth of the cerebellum.
How is a Chiari I malformation associated with syringomyelia?
In the Chiari I malformation, the cerebellar tonsils are elongated and pushed through the foramen magnum, blocking the flow of the CSF. This blocked flow may build up in the central canal causing hydromyelia, or form a CSF-filled cyst that breaks out of the central canal and dissects into the substance of the cord, a syringomyelia.
What is holoprosencephaly?
Holoprosencephaly is the failure of the prosencephalon to form properly into its three ventricles. It occurs during the fifth week. There are three degrees of severity: Alobar - no evidence of any division, Semilobar - partial cleavage, horseshoe shaped frontal lobe, Lobar - cerebral hemispheres separate anteriorly and posteriorly with some degree of fusion.
What does holoprosencephaly lead to?
This primary embryological defect in the forebrain leads to microcephaly, absent olfactory and optic nerves, and midline facial defects. Alobar is fatal within first year of life, Semilobar infants may survive but have poor prognosis. Lobar may have a normal life expectancy, but with severe mental and physical impairment.
Where do most perinatal strokes occur in preterm infants?
The periventricular, subependymal germinal matrix, which serves as a “growth plate” for neurons and glia, is highly vascular and largely void of cells by the age of 32-34 weeks. These subependymal hemorrhages (SEH), also called Germinal Matrix Hemorrhages (GMH), are a major cause of morbidity and mortality in the pre-term infant population.
What is a common natural history of perinatal stroke in full term infants?
Birth trauma leads to stretching of the carotid arteries and vascular insufficiency. Resulting infarcts are often in the watershed zones between the anterior, middle, and posterior cerebral arteries because of hypoperfusion. The infant brain is still capable of growing, so the less injured crest of the gyro develop but the injured sulci would not, resulting in mushroom shaped gyri - “ulegyria”. These are commonly associated with cerebral palsy.
What are the signs and symptoms of cerebral palsy?
CP patients have motor disorders including weakness and hypertonia (spasticity, rigidity), and may also have movement disorders including athetosis (writhing movement) and dystonia (simultaneous co-contraction of opposing muscle groups, usually associated with damage to the basal ganglia).
