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46 Cards in this Set

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  • Back
What are 3 major brain divisions and their subdivisions and components?
1. Prosencephalon
a. Telencephalon - cortex, amygdala, caudate, putamen
b. Diencephalon - thalamus, hypothalamus, globus pallidus
2. Mesencephalon - midbrain
3. Rhombencephalon
a. Metencephalon - pons, cerebellum
b. Myelencephalon - medulla
What is derived from the basal plate
Anterior horn cells and motor nuclei of cranial nerves
What is derived from the alar plate?
Dorsal sensory horn, sensory nuclei of the brain stem, cerebellum, inferior olive, quadrigeminal plate (superior and inferior colliculi), red nucleus
What is the sulcus limitans?
Boundary between basal and alar plates.
What is the sequence of events in neural tube formation
Fusion begins at day 22 in region of lower medulla (fourth somite).
Anterior neuropore closes on day 25
Posterior neuropore closes on day 27
Caudal neural tube (2ndary neurulations) forms on days 28-32.
What do neural crests cells give rise to?
Doral root ganglion, melanocytes, sensory ganglia of cranial nerves, adrenal medulla, autonomic ganglia, cells of pia and arachnoid, schwann cells, preganglionic sympathetic neurons
What are disorders of primary neurulation?
Anencephaly, Myeloschsis, Encephalocele, Myelmeningocele, Arnold Chiari Malformations, Meckel's Syndrome, Neural tube defects
What is anencephaly?
Failure of anterior neuropore closure.
Effects forebrain and variable portions of brain stem:
a. holoacrania - to foramen magnum
b. meroacrania - slightly higher than foramen magnum
75% stillborn
Most common in whites, Irish, females, children born to either very old or very young mothers.
Risk in subsequent pregnancies is 5% to 7%
What is myeloshisis?
Disorder of primary neurulation.
Failure of posterior neuropore closure.
Associated with iniencephaly - malformation of the skull base.
Most are stillborn
What is an encephalocele?
Restricted defect in anterior neural tube closure.
75% occipital
50% with hydrocephalus
What is myelomeningocele?
Restricted defect in posterior neural tube closure.
80% lumbar
90% have hydrocephalus if lumbar region involved.
50% w. hydro if other region.
Symptoms include motor, sensory, sphincter dysfunction.
What is type I Arnold Chiari malformation?
Isolated displacement of cerebellar tonsils into the cervical canal.
Kinked cervical cord.
What is type II Arnold Chiari malformation?
Displacement of cerebellum into cervical canal.
Displacement of medulla and fourth ventricle into cervical canal.
Long, thin medulla and pons and tectal deformity.
Skull base and upper cervical spine malformations.
Hydrocephalus due to fourth ventricle deformity or aqueductal stenosis.
100% with myelomeningocele.
96% with cortex malformations (heterotopias, polymicrogyria).
76% with brain stem malformations (hypoplasia of cranial nerves, pons).
72% with cerebellar dysplasia.
30% with thoracolumbar kyphoscoliosis.
30% with diastematomyelia (bifid cord).
What is type III Arnold Chiari malformation?
All of what is true for Type II plus encephalocele (occipital)
What is Meckel's Syndrome
Associated with maternal hyperthermia on day 20 - 26.
Includes encephalocele, microcephaly, microphthalmia, cleft lip, polydactyly, polycystic kidneys, ambiguous genitalia.
What are causes of neural tube defects?
Chromosomal abnormalities - trisomy 13, 18.
teratogens (thalidomide, valproate, phenytoin).
Single mutant gene (Meckel's syndrome)
How diagnose neural tube defects?
Increase alpha-fetoprotein.
Increased acetylcholinesterase.
How prevent neural tube defects?
What is recurrence rate of neural tube defects?
2 - 3%
What is another name for disorders of secondary neurulation?
Occult dysraphic states.
What happens in occult dysraphic states.
Problem with secondary neurulation.
Intact dermal layer over lesion.
80% have overlying derman lesion (dimple, hairy tuft, lipoma, hemangioma).
Frequently have tethered cord.
100% have abn. conus and filum.
90% have vertebral defects.
4% have siblings with disorder of primary neurulation.
What is caudal regression syndrome?
Disorder of secondary neurulation.
20% are infants of diabetic mothers.
Characterized by dysraphic sacrum and coccyx with atrophic muscles and bone.
Sx include delayed sphincter control and walking, back and leg pain, scoliosis, pes cavus, leg asymmetry.
What is a myelocystocele
Disorder of secondary neurulation.
Cystic central canal.
What is diastematomyelia?
Disorder of secondary neurulation.
Bifid cord.
What are disorders of secondary neurulation?
Caudal regression syndrome.
Subcutaneous lipoma/teratoma.
Dermal sinus.
Name some disorders of prosencephalic development.
Aprosencephaly - absence of tele and diencephalon.
Atelencephaly - ansence of tele but normal diencephalon. Intact skull and skin. Associated cyclopia, absent eyes, abn limbs and genitalia.
Agenesis of corpus callosum.
Describe findings in holoprosencephaly.
Defect in prosencepahlic cleavage.
100% anosmic b/c absent olfactory bulbs and tracts.
Single lobed cerebrum and ventricle.
Hypoplastic or single optic nerve.
Absent corpus callosum.
Facial defects - hypertelorism, single nostril, single eye, cleft lip.
What are clinical sx of holoprosencephaly?
Seizures, apnea, decreased hypothalamic function, developemental delay, anosmia, single maxillary incisor.
What are causes of holoprosencephaly?
Trisomy 13
Ring 13

Recurrence rate 6%
2% are infants of diabetic mothers.
What is agenesis of the corpus callosum associated with?
Absent septum pellucidum
Neuronal migration disorders (schizencephaly)
Chiari II malformation
Aicardi syndrome
What are X-linked dominant disorders?
Aicardi Syndrome.
Incontinentia pigmenti.
Rett's syndrome.
What is Aicardi syndrome?
X-linked dominant disorder.
Agenesis of corpus callosum.
Neuronal migration defects.
Chorioretinal lacunae.
What are causes of congenital hydrocephalus?
33% - Aqueductal stenosis.
28% - Arnold Chiari malformation.
22% - Communicating hydrocephalus.
7% - Dandy Walker malformation.
Other (tumor, cein of galen, X-linked aqueductal stenosis).
What is Dandy-Walker malformation?
Secondary to failed or delayed development of foramen of Magendie causing cystic dilation of 4th ventricle.
Cerebellar agenesis and maldevelopment of the cerebellar vermis.
Associated with - agenesis of corpus callosum, neuronal migration disorders (70%), large inion, large posterior fossa, cardiac abn, urinary tract abn.
What are some disorder of neuronal proliferation?
Microcephaly - decreased size of proliferating units.
Radial microbrain - decreased number of proliferating units.
Macrencephaly - well formed but large.
Hemimegencephaly - unilateral.
What are some disorders of neuronal migration?
Schizencephaly - clefts, spaces between ventricles and subarachnoid space. No gliosis. Heterotopias in cleft wall.
Porencephaly - variable communication between ventricles and subarachnoid space. Gliosis. 2nd to ischemia late in gestation.
Lissencephaly - few or no gyri.
Pachygyria - few, broad, thick gyri.
Polymicogyria - to many small gyri.
Heterotopias - nests of neurons in white matter 2nd to arrested radial migration. Assoc. w/ sz. (periventricular, laminar, bandlike).
What is Miller-Dieker Syndrome?
Associated with lissencephaly.
Chromosome 17 deletion in 90%.
Clinically - microcephaly, sz, hypotonia, poor feeding, craniofacial defects, cardiac defects, genital abn.
What is Walker-Warburg syndrome?
Associated with Fukuyama congenital muscular dystrophy, cerebellar malformation, retinal malformation, macrocephaly.
What is Zellwger's syndrome?
Cerebro-hepato-renal syndrome.
Autosomal recessive.
Peroxisomal disorder (increase long-chain fatty acids).
Polymicrogyria, heterotopias, sz, hepatomegaly, renal cysts.
What is most common form of mental retardation?
Fragile X syndrome.
Triplet repeat disease.
Has abnormal dendrites.
What is chromosal problem and some clinical features of Angelman's syndrome?
Deletion of chromosome 15q11-13 (mother).
Mental retardation, ataxia, seizures, microencephaly, "hapy puppet".
What is chromosomal problem and some clinical features of Prader-Willi syndrome?
Deletion of chromosome 15q11-13 (father).
Hypotonia, hypogonadism, eating disorder.
What is order of myelination in the nervous system?
Peripheral nervous system myelinates before CNS.
Motor before sensory.
in CNS - sensory before motor and association areas last. Most rapid phase from 0-2 yrs.
What are some disorders of myelination?
Aminoacidurias/organic acidopathies (ketotic hyperglycemia, nonketotic hyperglycemia, PKU, MSUD, homocysteinuria.
Periventricular leukomalacia.
For the following reflexes give time of onset (in gestational age) and when it disappears.

Suck, Grasp (hand, foot), Moro, Tonic neck, Landau, Placing, Parachute, Babinski.
Suck 32-34 wks, 4 mo
Grasp (hand) 32-34 wks, 6 mo
Grasp (foot) 32-34 weeks, 10 mo
Moro 34 wks, 3 mo
Tonic neck 34 wks, 6 mo
Landau 3 mo after birth, 24 mo
Placing 35 wks, 6 wks
Parachute 9 mo after birth, persists
Babinski birth, 10 mo
What are normal deve milestones for

smiles, visual tracking, rolls over, reaches, sits, thumb finger grasp, crawls, walks, pincer, walks alone, 3 words, climbs steps, tricycle.
smiles 1 mo
visual tracking 2-3 mo
rolls over 3 mo
reaches 3-4 mo
sits 6 mo
thumb finger grasp 8 mo
crawls 9 mo
walks 10 mo
pincer 12 mo
walks alone 12-14 mo
3 words 13 mo
climbs steps 17 mo
tricycle 3 yrs.