Clin Med Flashcards
describe neurulation
thick ectoderm plate (neural plate) –> edges fold to form neural folds –> neural tube –> fuse in cranial and caudal regions, cranial neuropore closes day25 & caudal neuropore day27 b/c it makes open communication b/w neural tube lumen & amniotic cavity
what are NTDs? cause? risk factors?
failure of neural tube closing b/w wk3-4 in utero. multifactorial. fhx, maternal sz meds (valproate, folic acid antag: carbamazepine, phenobarbital/toin, trimetho/primidone, tramterene, sulfasalazine), maternal obesity/DM, hispanics > caucasians
how to prevent NTDs?
childbearing women take 0.4mg folic acid daily, high risk women take 4mg folic acid daily; supplement > food b/c unstable
how to screen for NTDs? how to interpret AFP lvls? when does it peak?
US = screening & diag –> 2nd trimester US/QUAD screen at 18-20wks, maternal serum AFP made by fetal yolk sac/GI tract/liver. if perform at 16-18wks –> >2.5 = abnl. 28-32wks
open spina bifida/spina/cystica. meningocele vs myelomeningocele
overlying skin not intact –> meninges and/or spinal herniate thru defect is post vert arches –> meningocele or myelomeningocele. meninges herniate thru defect –> fluid filled sac –> asx or neuro deficits vs meninges, spinal cord, CSF herniate thru defect –> organ dysfxn –> urin/fecal incont; neuro deficits depend on severity
myelomeningocele lvls sxs: high lumbar-thoracic vs low lumbar vs high sacral vs low sacral. any other sxs?
flaccid paralysis of LE –> absent DTRs, no touch/pain response, hydrocephalus, walk short distances w/ leg brace then wheelchair vs walk w/ short leg brace and forearm crutches vs urin/fec incont, perianal anesthesia, walk w/ gluteal lurch or foot & ankle brace vs no impaired motor fxn, can walk. other sxs: sacral hair patch, lipoma, hemangioma
myelomeningocele = assoc w/?
brainstem dysfxn d/t Arnold Chiari malformation –> dysphagia, vocal cord paresis causing stridor, apneic, strabismus & facial weakness, abnl ventilation response to respiratory gases, weak UE & poor tone (severe). hydrocephalus d/t Chiari II malformation
how to dx myelomeningocele? how to dx spina bifida?
PE w/ neuro exam, prenatal US, spine MRI = GOLD STANDARD, head CT to also chk hydrocephalus & chiari malformation, uro/GI eval. spine MRI = GOLD STANDARD, CT for bony abnlities, XR for vertebral defect
how to tx open spina bifida?
multidiscip, surgery, periodic ucx & bladder eval, reg bowel cleanouts, GI regimen, fxnal ambulation (wheelchair, cane, brace)
spina bifida occulta/occult spinal dysraphism
incomplete osseous fusion posterior elements of spine –> benign midline defect w/o protrusion of meninges or spinal cord b/c intact skin
occult spinal dysraphism = assoc w/?
derm sxs (sacral dimple, sacral hair patch, lipoma, skin discoloration, hemangiomas), syringomyelia, tethered cord, neuro sxs in LE, uro sxs, ortho sxs (deformities, scoliosis, kyphosis, dislocation)
sacral dimple vs dermoid sinus
<5mm benign skin dimple vs >5mm small skin opening leading to duct –> infxn; can be tethered to spinal cord; may have protruding hair, hairy patch, vascular nevus
anencephaly
failure of rostral neuropore to close day 25 –> defect in developing neuroaxis –> developing forebrain & brainstem exposed in utero –> destroyed –> open defect in calvaria, meninges, scalp
causes of anencephaly. how to tx it?
multifactorial (genetics, vit defic, folate metab, hyperthermia, low SES). none
encephalocele
sac + cerebral cortex, cerebellum, brainstem and/or meninges protruding thru midline defect in skull/cranium bifidum that’s covered in skin
risks for encephalocele. how to dx it?
hydrocephalus, visual probs, intellectual disability, sz, limited movement; Meckel-Gruber syndrome: auto rec w/ occipital encephalocele, cleft lip/palate, microcephaly, abnl genitals, polycystic dz, polydactyl. transilluminate, US, brain MRI/CT
sincipital vs basal vs occipital encephalocele. outcomes for each?
craniofacial deformities (hypertelorism, telecanthus, orbital dystopia, unilat micro/anophthalmos) vs hypertelorism, broad nose bridge, nasal or epipharyngeal mass, difficult breath, recurrent URI or meningitis, CSF leaks vs CN deficits, poor sucking/feeding, spasticity, blind, sz, developmental delay, Chiari III. craniofacial op vs blank vs depends on size, contents, hydrocephalus, infxn; LOCATION DOESN’T MATTER
hydrocephalus. major sites of CNS block in ventricular system?
impaired circ or absoprtion of CSF in lat/3rd/4th ventricles –> excess CSF in those spaces –> dilated. Monro, 3, Sylvius, apertures, subarachnoid space/cisterns
risk factors for hydrocephalus
birth wt <1500g, premature <30wks, maternal DM, low SES, X-linked for males, race/ethnic
causes of obstructive/noncommunicating vs nonobstructive/communicating of hydrocephalus
aqueduct stenosis/gliosis, vein of Galen malformation, post fossa tumors, Arnold Chiari malformation, Dandy Walker syndrome –> obstruction w/in ventricular system vs subarach hemorrhage, nonaccidental trauma, pneumococcal meningitis, TB menitiis, leukemic infiltrates –> obliteration of subarach cisterns or malfxn of arachnoid villi
sxs vs signs of hydrocephalus
irritability, listless/lethargy/fatigue, dec appetite/difficult feeding, emesis, HA, change in personality/behavior/academic performance, fail to meet developmental milestones vs inc head circumference, wide/bulging ant fontanelle, Setting Sun Eye sign, clonus/spasticity/Babinski, brisk tendon reflexes, extreme weakness, Macewen sign: percussion of skull –> “cracked pot”
how to dx vs tx vs prognosis hydrocephalus. can you do LP?
transilluminate, head US 0-18mo, brain MRI/CT (peds need to be sedated for MRI) vs mannitol, acetazolamide, furosemide, ventriculoperitoneal shunt, ventricle decompression vs at risk for developmental delays, behavior issues, vision probs, Cushings Triad (HTN, irreg respirations, bradycardia), brain herniation. NO LP not on someone w/ intracranial pressure
Dandy Walker syndrome. assoc w/?
congenital cystic expansion of 4th ventricle –> abnl cerebellar development. 3C syndrome, Walker-Warburg, Marden-Walker, Brachio-oculo-facial syndrome, Coffin-Siris, Sotos, XYY syndrome
s/s vs dx vs tx of Dandy Walker
hydrocephalus, cerebellar ataxia, cog & motor delay vs brain MRI vs early intervention, neurosurg consult, shunt cystic activity
Arnold Chiari malformations. type of cause?
hindbrain malformation affecting rlatinshp b/w cranial base, cerebell, brainstem, upper cervical cord. multifactorial affecting chrms9-15
type I vs II Chiari. sxs?
abnl shaped cerebellar tonsils, assoc w/ hydromyelia or syringomyelia (fluid filled cavity in spinal cord) vs downward displacement of cerebellar vermis, tonsils, med, 4th ventricle –> beaked midbrain –> hydrocephalus or myelomeningocele –> brainstem dysfxn, vocal cord paralysis, apneic. dysphagia, stridor, severe head/neck pain, loss of pain/temp sense, drop attacks, spasticity, bal probs, blurred vision, hypersensitivity to light
type III vs IV Chiari
both very rare, incompatible w/ life –> NICU, won’t see in office. cerebellar herniation –> congenital malformations vs cerebellar agenesis
how to dx vs tx chiari?
brain MRI > CT, brainstem auditory evoked potential, somatosensory evoked potentials vs based on sxs, decompression surgery
d/o of neuronal migration. examples?
disrupting migration of neuroblasts during neurogenesis. agenesis corpus callosum, holoprosencephaly, lissencephaly, microcephaly
agenesis corpus callosum. heredity? assoc w? tx?
largest white matter interhemispheric tracts connecting cerebral hemis for sensory, motor, visuomotor, & cog processes. can be partially (hypogenesis) or completely (agenesis) absent, X linked or auto dom. Chiari, Dandy Walker, Andermann, Aicardi, schizencephaly (division in brain tissue), holoprosencephaly. supportive
holoprosencephaly. cause? assoc w/? dx? tx?
defective cleavage of prosencephalon –> forebrain didn’t divide into 2 hemis. maternal DM. chrm d/o, single incisor, cyclopia, maxillary agenesis. fetal US, MRI. multidiscip, supportive
3 groups of holoprosencephaly: alobar vs semilobar vs lobar
complete failure to divide into L/R hemis vs partial separation vs distinct L/R ventricles but cerebral continuity across frontal cortex
lissencephaly/agyria. assoc w? dx?
failure of nuronal migration during wk12-14 –> lack gyri & sulci –> smooth brain. Miller-Dieker, microcephaly, ventriculomegaly, wide Sylvian fissures, agenesis corpus callosum, failure to thrive, developmental delay, sz. brain MRI
2 types of lissencephaly: 1 vs 2
facial dysmorphism, deletion chrm 17q13.3 => Miller-Dieker vs hydrocephaly, dysgenesis of cerebellum
microcephaly. assoc w/? tx?
<3 stdev head cirumference for mean age & sex. NTD, holoprosencephaly, lissencephaly. genetic & fam counseling, supportive
primary/genetic vs secondary/nongenetic microcephaly
abnl brain development –> dec # of neurons during neurogenesis –> affects forebrain (holoprosencephaly); familial, auto dom vs dec # of dendrites & synaptic connections d/t noxious agents in utero or 1st 2yrs of life (radiation, TORCH infxns, CMV, zika, maternal meds/drugs)