CONGENITAL AND BRAIN MALFORMATIONS 1.2 (based on Agsa T) Flashcards
What is the most common congenital or acquired brain lesion that presents with a large head?
Hydrocephalus.
What causes hydrocephalus?
Impaired circulation and absorption of CSF.
Where is CSF formed?
Choroid plexus.
Where is CSF absorbed?
Foramen of Luschka and Magendie.
What can cause increased CSF production leading to hydrocephalus?
Choroid plexus papilloma.
What imaging findings suggest hydrocephalus?
Dilated lateral and third ventricles, dilated frontal horn of the ventricle, possible aqueductal stenosis.
What is the treatment for hydrocephalus?
Ventriculoperitoneal (VP) shunt.
How does a VP shunt work?
CSF is diverted from the ventricle to the abdomen/peritoneum for absorption and excretion.
What are the two major types of hydrocephalus?
Communicating (acquired) and non-communicating (obstructive/congenital).
What are common causes of communicating hydrocephalus?
Achondroplasia, basilar impression, benign enlargement of subarachnoid space, choroid plexus papilloma, meningeal malignancy, meningitis (most common), posthemorrhagic (most common)
What is the most common cause of non-communicating hydrocephalus?
Aqueductal stenosis.
What are some congenital causes of non-communicating hydrocephalus?
X-linked, mitochondrial, autosomal recessive, autosomal dominant, L1CAM mutations, Chiari malformation, Dandy-Walker malformation, Klippel-Feil syndrome.
What mass lesions can cause hydrocephalus?
Abscess, hematoma, tumors, neurocutaneous disorders.
What vascular malformation can lead to hydrocephalus?
Vein of Galen malformation.
What syndrome is associated with hydrocephalus and congenital muscular dystrophy?
Walker-Warburg syndrome.
Why is anthropometric measurement important in children under 3 years old?
To determine if the head is normocephalic, microcephalic, or macrocephalic.
How is microcephaly defined?
Head circumference more than 2 standard deviations (SD) below the mean for age and sex.
In which population is microcephaly relatively common?
Developmentally delayed children.
What are the two main types of microcephaly?
Primary (genetic) and secondary (nongenetic).
What is an example of primary microcephaly?
Craniosynostosis.
What causes craniosynostosis?
Early closure of cranial sutures leading to a small head.
How is craniosynostosis treated?
Surgical intervention.
How does secondary microcephaly occur?
Brain does not develop properly, causing the skull to adapt to the small brain.
What condition can cause secondary microcephaly?
Hypoxic-ischemic encephalopathy (HIE).
What neonatal finding suggests hypoxic-ischemic encephalopathy?
Low APGAR score at birth.
Why does hypoxic-ischemic encephalopathy lead to microcephaly?
Brain cells are damaged due to lack of oxygen, leading to impaired brain growth and a small skull.
What other conditions can cause secondary microcephaly?
CNS infection, metabolic disorders, brain lesions.
Why is secondary microcephaly not treatable?
It results from brain damage, not a structural skull issue.
What condition is the most common differential diagnosis for congenital hydrocephalus?
Hydranencephaly.
What is the main difference between hydrocephalus and hydranencephaly?
Hydrocephalus is due to CSF obstruction, while hydranencephaly is due to absent cerebral hemispheres.
What are the cerebral hemispheres replaced with in hydranencephaly?
Membranous sacs.
What brain structures may be present in hydranencephaly?
Remnants of the frontal, temporal, or occipital cortex.
What brain structures remain intact in hydranencephaly?
Midbrain and brainstem.
Why can hydranencephalic patients survive?
They retain brainstem functions such as heart rate and breathing.
What are common complications of hydranencephaly?
Cerebral palsy, spastic quadriplegia, developmental delay.
Why do hydranencephalic patients require lifelong care?
They lack a functional cerebral cortex and depend on caregivers for all activities.
What is the treatment for hydranencephaly?
Ventriculoperitoneal (VP) shunt for aesthetic purposes only.
Why is a VP shunt performed in hydranencephaly?
To reduce head enlargement from continuous CSF production, improving appearance.
What is a key MRI finding in hydranencephaly?
Absence of cerebral cortex with only membranous sacs and intact brainstem.
“What is craniosynostosis?”
Premature closure of the cranial sutures.
“What are the two classifications of craniosynostosis?”
Primary craniosynostosis and Secondary craniosynostosis.
“What causes primary craniosynostosis?”
Closure of one or more sutures due to abnormalities in skull development.
“What causes secondary craniosynostosis?”
Failure of brain growth and expansion.
“What is the definitive treatment for craniosynostosis?”
Surgical intervention with titanium plates to allow brain growth.
“What is a syndrome?”
A number of malformations occurring together as a group.
“What are common causes of syndromes?”
Chromosomal aneuploidy, single gene abnormalities, teratogen exposure, environmental/viral/toxin exposure.
“What is nondisjunction?”
Failure of chromosome pairs to separate properly during cell division.
“What are common chromosomal syndromes caused by nondisjunction?”
Down syndrome (Trisomy 21),
Patau syndrome (Trisomy 13),
Edwards syndrome (Trisomy 18),
Turner syndrome (Monosomy X),
Klinefelter syndrome (47, XXY).
“What is the most common recognized dysmorphic syndrome?”
Down syndrome (Trisomy 21).
“What are common physical features of Down syndrome?”
Hypotonia, epicanthal folds, flat nasal bridge, midface hypoplasia, short hands and fingers, single transverse palmar crease, Brushfield spots in eyes.
“What congenital heart defects are associated with Down syndrome?”
(V-A-T)
Ventricular septal defect (VSD),
atrial septal defect (ASD),
Tetralogy of Fallot.
“What gastrointestinal conditions are associated with Down syndrome?”
(D-H)
Duodenal atresia
Hirschsprung’s disease.
“What are characteristic hand and foot features in Down syndrome?”
Simian crease,
short fifth finger that curves inward,
widely separated first and second toes,
increased skin creases.
“What is Prader-Willi syndrome?”
A genetic disorder characterized by hyperphagia, obesity, hypotonia, developmental delay, and distinctive facial features.
“What genetic abnormality causes Prader-Willi syndrome?”
Uniparental disomy at 15q11.2.
“What are common physical features of Prader-Willi syndrome?”
Narrow temple and nasal bridge, almond-shaped eyes, mild strabismus, thin upper lip, downturned mouth, obesity.
“What are key neurodevelopmental features of Prader-Willi syndrome?”
Hypotonia, poor suck/feeding difficulties, motor developmental delay, temper outbursts, emotional lability.
“What appetite-related symptom is characteristic of Prader-Willi syndrome?”
Hyperphagia (excessive eating) leading to obesity.
“What are common sleep-related issues in Prader-Willi syndrome?”
Central sleep apnea, obstructive sleep apnea, excessive daytime sleepiness.
“What are common craniofacial abnormalities in Prader-Willi syndrome?”
Dolichocephaly, narrow bifrontal diameter, almond-shaped eyes, thin upper lip, downturned mouth.
“What is the hypothalamic dysfunction seen in Prader-Willi syndrome?”
Short stature, growth hormone deficiency, central hypothyroidism, central adrenal insufficiency.
“What is the most common congenital or acquired lesion of brain growth disorders?”
Hydrocephalus.
“What causes hydrocephalus?”
Impaired circulation and absorption of cerebrospinal fluid (CSF).
“What is the function of the choroid plexus in hydrocephalus?”
It forms CSF, which is absorbed by the foramen of Luschka and Magendie.
“What is the most common cause of communicating hydrocephalus?”
Meningitis (most common) or posthemorrhagic causes.
“What is the most common cause of non-communicating hydrocephalus?”
Aqueductal stenosis.
“What is the treatment for hydrocephalus?”
Ventriculoperitoneal (VP) shunt to divert CSF from ventricles to the peritoneum.
“What is microcephaly?”
A head circumference measuring more than 2 standard deviations below the mean for age and sex.
“What are the two main types of microcephaly?”
Primary (genetic) microcephaly and Secondary (nongenetic) microcephaly.
“What is a common genetic cause of microcephaly?”
Craniosynostosis.
“What condition results in a newborn with a very low APGAR score and secondary microcephaly?”
Hypoxic ischemic encephalopathy.
“What is the treatment for secondary microcephaly?”
There is no treatment since it is due to brain growth failure, not skull size.
“What is hydranencephaly?”
A condition where cerebral hemispheres are absent and replaced by membranous sacs.
“How is hydranencephaly different from hydrocephalus?”
In hydrocephalus, brain growth is restricted by CSF buildup; in hydranencephaly, cerebral hemispheres are absent.
“What is the treatment for hydranencephaly?”
Ventriculoperitoneal (VP) shunting for aesthetic purposes only.
“Can patients with hydranencephaly survive into adulthood?”
Yes, but they are entirely dependent on caregivers due to lack of motor cortex function.
“What is Edwards Syndrome also known as?”
Trisomy 18.
“What is the incidence of Edwards Syndrome?”
3 in 1000 newborns.
“What is the survival rate of infants with Edwards Syndrome?”
30% die in the first month; only 10% survive beyond the first year.
“What are common neurological symptoms of Edwards Syndrome?”
Hypotonia, developmental delay, and cerebral palsy.
“What diagnostic test confirms Edwards Syndrome?”
Karyotyping.
“What are common features of Edwards Syndrome?”
Weak cry, polyhydramnios, growth deficiency, low-set malformed auricles, clenched hand with overlapping fingers, rocker bottom feet, congenital heart defects.
“What are key physical findings in Edwards Syndrome?”
Small mouth, small jaw, short neck, shield chest, short/prominent sternum, wide-set nipples, prominent occiput, dysplastic ears, clenched hands with overlapping fingers.
“What is Patau Syndrome also known as?”
Trisomy 13.
“What is the incidence of Patau Syndrome?”
1 in 5000 live births.
“What diagnostic test confirms Patau Syndrome?”
Karyotyping.
“What are key clinical features of Patau Syndrome?”
Holoprosencephaly, absent corpus callosum, large single ventricle, cutis aplasia, microcephaly, microphthalmia, cleft lip +/- palate, polydactyly, congenital heart defects.
“What are key physical findings in Patau Syndrome?”
Small head, absent eyebrows, cleft lip/palate, dysplastic ears, clenched hands with polydactyly, undescended/abnormal testes.
“What causes Turner Syndrome?”
Complete or partial absence of the second sex chromosome (45,X).
“What is the incidence of Turner Syndrome?”
1 in 2500 live-born females.
“What percentage of 45,X conceptions result in miscarriage?”
Approximately 99%.
“What are common physical findings in newborns with Turner Syndrome?”
Puffy hands and feet, webbed neck, shield chest.
“When is Turner Syndrome often diagnosed?”
At 5-6 years old.
“What are common physical features in Turner Syndrome?”
Short stature, broad chest, low hairline, cubitus valgus.
“What cardiovascular and renal anomalies are associated with Turner Syndrome?”
(B-C-R)
Bicuspid aortic valve,
coarctation of the aorta,
renal anomalies.
