Brain Abnormality (developmental/genetic & metabolic disorders)

Question 1

what is the most common cause of CNS malformation?

Answer 1

neural tube defects

Question 2

anencephaly

Answer 2

absence of brain except basal ganglia, cerebellum, brainstem

ant. neuropore failure to close

usually an absent skull too

Question 3

Myelomeningocele

Answer 3

meninges + spinal cord protrude through vertebral column defect

• often presents with hydrocephalus and Arnold-chiari malformation
• most common non-lethal malformation

Question 4

encephalocele

Answer 4

meninges + brain through skull

-less serious, sinus probs

Question 5

polymicrogyria

Answer 5

increased # of small, irregular gyri

4 cortical layers instead of the usual 6

Question 6

pachygyria

Answer 6

flat, thick gyri

due to a migratory problem; usually results in mental retardation

Question 7

heterotopias

Answer 7

Abnormal clusters of neurons due to a partially failed migration from subependymal (germinal) matrix

Seizures often occur

usually due to DCX (doublecortin) gene mutation

Question 8

holoprosencephaly

Answer 8

failure of hemispheres to separate (resulting in frontal lobe fusion)

Sonic hedgehog defect

sometimes no corpus callosum either

Question 9

Arnold-chiari malformation

Answer 9

SMALL posterior fossa resulting in a slightly deformed brain stem (type 2 most common)

associated with meningomyelocele and hydrocephalus due to aqueductal stenosis

Question 10

Dandy-walker malformation

Answer 10

LARGE posterior fossa (foxc1 gene mutation)

Cerebellar vermis replaced with midline cyst

lateral displacement of cerebellar hemispheres

also can cause hydrocephalus

Question 11

Syringomyelia

Answer 11

a cavity that forms in the spinal cord (usually cervical)

onset at ANY age

presents as loss of PTT symetrically in hands with hand muscle wasting (C8ish)

Question 12

Cerebral Palsy

Answer 12

Non-progressive neurologic MOTOR deficits

90% congenital, 10% acquired

Can NOT be diagnosed in utero nor at birth:

• floppy/stiff arms legs in first months
• poor head control at 5 mo
• inability to sit after 8mo
• difficulty standing 12mo
• probs walking 12-18 mo

Question 13

What are the 3 types of cerebral palsy and what is characteristic of each?

Answer 13

1) Spastic = stiff and jerky movements
2) ataxic = decreased muscle tone and poor coordination
3) athetoid = difficulty maintaing posture & involuntary movements (usually due to hyperbilirubinemia)

Question 14

Germinal Matrix Hemorrhage

Answer 14

attributed to cerebral hypoxia

usually occurs between 25-35 weeks gestation

preemie baby with blood in CSF

Question 15

Periventricular leukomalacia

Answer 15

INFARCTS in periventricular white matter of cerebral hemispheres.

cyst formation may occur

Question 16

Non-ketotic hyperglycinemia

Answer 16

causes imprecise eye movements/nystagmus

Question 17

Freidrich Ataxia

Answer 17

MOST common inherited ataxia

due to frataxin gene defect

onset 2-16yrs

95% show first sign being “clumsiness”, slurred speech follows, and 55% form pes cavus deformity

hypertrophic cardiomyopathy key sign

Question 18

Tay-Sachs disease

Answer 18

neuronal storage disease caused by accumulation of GM2 gangliosides

hexosaminidase A deficiency

3-8months onset, “cherry red spot” in macula, exaggerated startle reflex

Question 19

Krabbe Disease

Answer 19

aka globoid cell leukodystrophy

galactocerebroside B-galactosidase deficiency***

accumulation of psychosine

motor decline, and difficulty feeding

onste at 3-6months with mult-nucleated Macrophages!!!

Question 20

Metachromatic leukodystrophy

Answer 20

arylsulfatase A deficiency —> accumulation of sulfatide

onset usually in later infant years (6-8)

presents as mental & motor decline with peripheral neuropathy (widespread myelin deficit in white matter)

Question 21

leukocoria (white pupil)

Answer 21

No red reflex… infantile cataract is most common (galactosemia)

but could be a RB1 mutation resulting in retinoblastoma

Question 22

Adrenoleukodystrophy

Answer 22

x-linked

presents in early school years (with adrenal insufficiency too)

rapid/progressive and fatal

Question 23

pelizaeus-merzbacher disease

Answer 23

x-linked, fatal leukodystrophy

-proteolipid protein deficit (PLP gene important for CNS myelin)