Neuroembryology and Child Neurology Flashcards
Main embryonal layer giving rise to nervous system
ectoderm
this give rise to vertebral column
notochord
induces formation of neural plate from ectoderm and later signals differentiation of various cell types
notochord (a layer of mesodermal cells in contact with ectoderm)
process at which neural plate forms a structure known as neural tube
neurulation
neurulation occur at which week of gestation
3-6th wk of AOG
abnormal rostral fusion at the anterior pore leads to
anencephaly
abnormal caudal fusion at the posterior pore leads to
spina bifida
after neurulation, neural tube undergoes segmentation into 3 vesicles. what is this process called?
specification
3 vesicles formed from neural tube
prosencephalon
mesencephalon
rhombencephalon
Prosencephalon eventually becomes…
telencephalon
diencephalon
Telencephalon give rise to..
cerebral hemispheres
Diencephalon give rise to…
thalamus
hypothalamus
epithalamus
Mesencephalon give rise to…
midbrain
Rhombencephalon eventually becomes
myelencephalon
metencephalon
Peripheral nervous system (including autonomic ganglia) arise from…
neural crest cells
Neural crest cells give rise to….
peripheral nervous system
autonomic ganglia
chromaffin tissue of the adrenal medulla
melanocytes
Galactosemia mode of inheritance
Autosomal Recessive disorder
3 enzyme defects in galactosemia
galactose-1-phosphate uridyl transferase deficiency (GALT gene) galactokinase deficiency (GALK gene) urindine diphosphate galactose 4'epimerase deficiecy (GALE gene)
What is the most common cause of galactosemia?
galactose-1-phosphate uridyl transferase deficiency (GALT gene)
This type of galactosemia is associated with intellectual impairment.
galactose-1-phosphate uridyl transferase deficiency (GALT gene)
At first days of life, patient presents with feeding difficulties, vomiting, diarrhea and jaundice; with hepatomegaly, failure to thrive, lethargy and hypotonia; detection of reducing substances in the urine. What is the diagnosis and deficiency?
galactosemia (galactose-1-phosphate uridyl transferase deficiency (GALT gene - most common)
cataract in galactosemia results from…
accumulation of galactitol
Treatment of Galactosemia
Restriction of lactose and galactose
What are the late neurologic sequelae of galactosemia?
developmental delay
cognitive impairment
ataxia
tremor
Pyruvate Dehydrogenase is responsible for..
oxidative decarboxylation of pyruvate to carbon dioxide and acetyl coenzyme A
Pyruvate dehydrogenase complex have 3 main components. Which is the most common?
E1 (alpha and beta subunits) - most common;
E2 and E3
E1 defect is inherited via..
X-linked fashion
E2 and E3 defect are inherited via…
autosomal recessive
Management of PDH deficiency
ketogenic diet
thiamine supplementation
Patient presents with severe neonatal acidosis, with episode of progressive ataxia, nystagmus, dysarthria, lethargy, weakness, areflexia, hypotonia and psychomotor retardation. Diagnosis?
Pyruvate dehydrogenase deficiency
Majority of patients with neurofibromatosis 1 has severe developmental delay, true or false?
False. Majority of patients with NF1 have normal cognition or mild developmental delay
An infant with epileptic encephalopathy is brought for evaluation. He has microcephaly and prominent developmental delay. On cerebrospinal fluid (CSF) analysis, it was noticed that the level of glucose was 30 mg/dL while the serum glucose was 112 mg/dL. Other CSF tests are normal. Diagnosis?
Glucose Transporter Type 1 (GLUT-1) Deficiency
GLUT-1 is a membrane bound protein that is encoded by..
SLC2A1 gene on chromosome 1p34.2
SLC2A1 mutation is inherited via..
autosomal dominant pattern
Chromosomal Aberration commonly seen in patients with encephalocoele
Trisomy 13 and Trisomy 18
What is the deficiency in phenylketonuria?
Deficiency in phenylalamine hydroxylase
What is the function of phenylalamine hydroxylase?
converts phenylalamine to tyrosine (thus deficiency leads to phenylalamine accumulation)
What is responsible for the musty odor of sweat and urine in PKU patients?
phenylacetic acid
What is the mode of inheritance of PKU?
Autosomal recessive
Baby presented with seizure. He has significant developmental delay, is hypotonic, has failure to thrive, and is microcephalic. His urine has a musty odor. Diagnosis and deficiency?
Phenylketonuria (deficiency in phenylalamine hydroxylase)
A 1-week-old baby was admitted to the hospital with altered sensorium, opisthotonic posture, and abnormal movements. He is now intubated, comatose, and began having seizures last night. A specimen of his urine smells like maple syrup. Diagnosis and Deficiency?
maple syrup urine disease (branched chain alpha-ketoacid dehydrogenase complex deficiency)
What is the most common and severe form of maple syrup urine disease?
Classic Type
Define sacral agenesis
absence of the sacrum
Define meningocele
isolated protrusion of the meninges into a bony defect within the vertebral column
Define myelomeningocele
protrusion of potentially all layers of intraspinal contents through a bony defect: spinal cord, nerve roots, and meninges. Also known as dysraphism or rachischisis.
Define diastomyelia
splitting of the spinal cord into two portions by a midline septum
Define diplomyelia
duplication of the spinal cord. presence of two central canals each surrounded by gray and white matter as in a normal spinal cord
Single or multiple cardiac rhabdomyomas occur in more than half of patients with tuberous sclerosis complex . It undergoess malignant transformation. True or False?
False. The majority of them regress over time, and they are often clinically irrelevant over the long term.
Define Renal angiomyolipomas in TSC
benign tumors consisting of vessels, smooth muscle, and fat. this can be single or bilateral and multiple.
Lymphangiomyomatosis most common in…
female patients with TSC
A newborn baby is being evaluated for encephalopathy in the setting of metabolic acidosis and hyperammonemia. There is also ketoacidosis and elevated blood propionic acid and glycine levels with normal methylmalonic acid levels. Diagnosis and defect?
Propionic acidemia (deficiency of propionyl-CoA carboxylase)
What is the role of propionyl coA carboxylase?
participates in the carboxylation of propionyl-CoA to D- methylmalonyl-CoA. It requires biotin as co-enzyme.
Tuft of hair over the lower lumbar region
Spina bifida occulta
Define spina bifida occulta
Defect in the bony components along the posterior aspect of the vertebral column.
The presence of a tuft of hair, associated with underlying spina bifida occulta, does not necessarily imply impending cognitive or motor delay. True or False?
True
Define occult spinal dysraphism
associated neurologic dysfunction in a child with a tuft of hair over the lumbar region but with no other evidence of NTD
3-year-old boy is brought for follow-up evaluation. He has had developmental delay and intellectual impairment since early in life and has developed torticollis and spasticity in his limbs. He also has a history of seizures and aggressive behavior. His mother reports that he began biting himself to the point of bleeding and constantly self-inflicts injuries. He has had kidney stones and hyperuricemia. Diagnosis and defect?
Lesch–Nyhan disease
inherited in an X- linked fashion
deficiency of the enzyme hypoxanthine guanine phosphoribosyltransferase
What is the role of hypoxanthine guanine phosphoribosyltransferase?
It participates in the salvage pathway of purine metabolism. It is encoded by the gene HPRT1 on chromosome Xq26, and deficiency of this enzyme leads to the accumulation of purines with their subsequent conversion to uric acid.
A 10-month-old baby is brought for follow-up. He has a significant developmental delay with psychomotor retardation and failure to thrive. On examination, he also has a cherry-red spot on retinal examination and hepatosplenomegaly. The Filipin test is not abnormal. Bone marrow specimen demonstrates foam cells. Diagnosis and defect?
Niemann–Pick type A autosomal recessive
acid sphingomyelinase deficiency
What is accumulated in Niemann-Pick Type A?
Accumulation of Sphingomyelin
Niemann-Pick Type B Manifestation
Does not affect the CNS, presenting with hepatosplenomegaly and interstitial lung disease
A 6-year-old girl is evaluated for progressive neurologic deterioration, including vertical gaze apraxia, ataxia, and spasticity. A Filipin test (which demonstrates impaired ability of cultured fibroblasts to esterify cholesterol) was abnormal. Diagnosis and Defect?
Niemann–Pick type C
autosomal recessive disorder defects in intracellular cholesterol circulation
What is accumulated in Niemann-Pick Type C?
Accumulation of cholesterol in perinuclear lysosomes
What is the gene defect in NP Type C?
NPC1 located on Chromosome 18q11
Laboratory examinations in NTDs
serum maternal α-fetoprotein level is elevated
elevated amniotic α-fetoprotein
Elevations in amniotic fluid acetylcholinesterase levels
ultrasonography can also be used to detect NTDs
4-year-old boy presents with progressive neurologic deterioration. The onset of his symptoms was around the age of 1 year with hypotonia and inability to walk. Vision and hearing loss were subsequently noticed. At this point, he is unable to walk and has generalized spasticity and cognitive regression. Brain MRI shows T2 hyperintense signal changes in the periventricular and subcortical white matter sparing the U fibers. Diagnosis and defect?
Metachromatic leukodystrophy
autosomal recessive disorder deficiency of the lysosomal enzyme arylsulfatase A
What is accumulated in metachromatic leukodystrophy?
Accumulation of sulfatide resulting in demyelination of central and peripheral nervous system
What is the role of arylsulfatase A?
responsible for the breakdown of cerebroside sulfate (a major myelin glycoprotein)
What is the definition of Chiari I malformation?
displacement of the cerebellum and cerebellar tonsils downward through the foramen magnum
Chiari II malformation (Arnold–Chiari malformation)?
displacement of the cerebellar vermis and tonsils in association with a myelomeningocele.
Syringomyelia definition
fluid-filled cavity within the spinal cord that is SEPARATE from the central canal and lined by gliotic tissue
Definition of Chiari III malformation
cerebellar herniation into a cervical or occipital encephalocele.
Define Chiari IV malformation
cerebellar hypoplasia
Where is molar tooth sign observed?
- Joubert syndrome
- COACH syndrome (cerebellar vermis hypoplasia, oligophrenia, congenital ataxia, coloboma, and hepatic fibrosis)