Neuro 1.1 Midterm

nervous system development?

• wk 3-4 → notochord forms nuclues pulposus of IV disc + primitive neural tube formation

  • neural plate invaginates → neural tube (lining = CNS, lumen = ventricle, sinus)

• neural crest → PNS (DRG, symp. chain/paravertebral, prevertebral ganglia, enteric ganglia, parasympathetic CN ganglia) + non neural (melanocytes, schwann cells, pharyngeal arch, chromaffin cell of adrenal medulla)

neural tube derivates?

• forebrain = telencephalon (hemisphere, BG, lat. ventricle), diencephalon (thalamus, hypothalamus, retina, 3rd ventricle)

• midbrain = mesencephalon (midbrain, cerebral aqueduct)

• hind brain = metencephalon (pons, cerebellum, upper 4th ventricle), myelencephalon (medulla, lower 4th ventricle)

encephalocele? hydrocephalus?

• diverticulum or outpouching of malformed CNS tissue herniates thru skull (occipital region or post. fossa); ass. w/ meckel gruber (cystic kidney + polydactyl)

• inc. CSF vol (prod. in choroid plexus)

  • choroid → lat. → monro → 3rd → aqueduct → 4th → luschka/magendie → subarachnoid → granulation

  • comm. (non- obstruct) OR non comm. (obstruct)

communicating vs non communicating hydrocephalus? symptoms? treatment?

• comm. (non-obstruct) → impaired CSF absorption = hemorrhage or chronic meningitis (arachnoid gran. scarring); wet, wobbly, wacky

• non comm. (obstruct) → structural block via tumor, aqueduct stenosis (atresia), dandy-walker, chiari II (myelomeningocele)= upstream ventricle enlarge

• b4 sutures close (enlarged head, sunset gaze) vs after sutures close (intracranial pressure inc. w/o head size change)

• ventriculoperitoneal shunt (CSF to abdomen), ETV (new outflow path)

  • prenatal Tx =dec. VPS need, improve motor fxn, dec. chiari II hindbrain herniation

neural tube defect cause? prevention? diagnosis?

• folate (B9) def., maternal diabetes, obesity, teratogens (valproate, methotrexate, alcohol), radiation

• 400 mcg/4mg folic acid daily + up to 1000 mcg for high risk women/prior NTD pregnancy

• Dx in 2nd trimester via inc. AFP in maternal serum from fetal liver (16-18 wk; open NTD), inc. AChE on amniocentesis, US (18-22 wks)

spina bifida occulta? meningocele? myelomeningocele?

• vertebral arch defect only (mild) → common, hair tuft, skin dimple, normal AFP via closed defect; no Tx

• meninges herniate/protrude → CSF-filled cyst, neural tissue intact (doesn’t protrude)

• meninges + spinal cord herniate (lumbar) → motor/sensory deficit, brainstem dysfxn (apnea, dysphagia); inc. MSAFP, AChE; ass. w/ chiari II + hydrocephalus

myeloschisis/rachischisis? anencephaly?

• failure of neural plate fusion → severe, exposed bisected cord w/o skin coverage, infection risk; inc. MSAFP, AChE

• failure of ant. neural tube/neuropore closure → no forebrain/skull, empty cranial vault (frog like), polyhydramnios, high risk stillbirth/fatal; inc. MSAFP

forebrain defects? cause? features?

• microcephaly → few cortical neurons= small brain vol. (via FAS, HIV, zika)

• lissencephaly → failed neuronal cortical migration (smooth brain)= severe dev. delay, seizures, microcephaly

• polymicrogyria → many small gyri, heterotopia (neuron cluster in white matter)

• holoprosencephaly → failed prosencephalon cleavage (day 33)= fused hemispheres/no midline, cyclopia, cleft palate; ass. w/ maternal diabetes, SHH mut (cyclopamine-corn lily), FAS, patau (13) + edwards (18)

posterior fossa defects? cause? features?

• chiari I (adults) → cerebellar tonsils herniate thru. foramen mangum= headaches + syringomyelia (cape-like loss of pain/temp in upper limb via CSF filled cavity in spinal cord C4-6 damaging spinothalamic tract)

• chiari II (babies) → cerebellum + brainstem (medulla, pons, mb)= myelomeningocele, hydrocephalus, brainstem dysfxn (dysphagia, apnea via CNX)

  • risk = underdeveloped post. fossa

• dandy-walker → absent cerebellar vermis + failed f. luschka and magendie= 4th ventricle cystic dilation (enlarged post. fossa, hydrocephalus, hypotonia, ataxia)

charcot-marie tooth 1 vs 2? tethered cord syndrome?

• schwann cell myelin defect (onion bulb) vs axonal mit. defect

  • adolescents; hereditary motor/sensory neuropathy → issues w/ feet (foot drop, high arch, hammertoes, distal weakness), pes cavus (inverted champagne bottle legs)

  • genetic testing definitive

• cord fixed to tissue via stretch injury= thick/short filum terminale, low conus medullaris; ass. w/ chiari malformation

  • pain, weakness, bladder/bowel dysfxn

  • conus ends at L2-3

stroke cause? risk factors? symptoms?

• sudden focal deficit from ischemia (85%) or hemorrhage (15%)

• modifiable (smoking, obesity, alcohol), somewhat modifiable (DM, AFib, dyslipidemia), non-modifiable (age, FHx)

• BE FAST → balance loss, eyes (vision loss), face dropping/weakness, arm (+ leg) weakness, speech difficulty, time (call 911)

types of strokes? features?

• ischemic → thrombotic (atherosclerosis), embolic (AFib, carotid plaque), lacunar (small vessel; HTN/DM) → Tx = tPA, thrombectomy

  • TIA → transient neuro defect via focal ischemia w/o infarction, resolve w/in 24 hrs (usually 1 hr); warning sign for stroke

• hemorrhagic → ICH (HTN, amyloid, anticoagulation) + SAH (berry aneurysm, AVM) → Tx = neurosurgery, coiling

acute stroke treatment? prevention?

• IV tPA w/in 4.5 hrs (if no CI) + mechanical thrombectomy up to 6 hrs → trying to optimize cerebral perfusion

• antiplatelets (aspirin + clopidogrel), anticoagulation if cardioembolic (AFib, LV thrombus), statins (IS), risk factor (HTN, DM, smoking)

ischemic strokes?

• more common + less devastating than hemorrhagic → better long term survival if reperfused

• zones (normal, penumbra, infarct core)

• neuronal death mechanism = Ca influx → mit. damage → cell death → BBB break down + glial scar

• vascular dementia

cerebral venous thrombosis (CVT)

hemorrhagic strokes features?