what does the notochord become?
nucleus pulposus of intervertebral disc
markers for neural tube defect during pregnancy
elevated AFP in amniotic fluid and maternal serum
inc acetylcholinesterase in amniotic fluid to confirm
risk factor for anencephaly
maternal type 1 DM
Arnold Chiari malformation
herniation of cerebellar tonsils and vermis through foramen magnum > hydrocephalus and impaired coordination. Can be assoc w/ throaco-lumbar myelomeningocele
Dandy Walker malformation
agenesis of cerebellar vermis, cystic enlargement of 4th ventricle
assoc w/ hydrocephalus and spina bifida
syringomelia
cystic enlargement of central canal of spinal cord
crossing fibers of STT damaged first
nerves providing taste and pain sensation in parts of the tongue
anterior - taste is 7, pain is V3
post - both are 9
extreme posterior - both are 10
Wallerian degeneration
degeneration of neurons - allows for axonal regeneration in PNS
degen distal to injury and axonal retraction proximally
C fibers vs Adelta fibers
C - slow, unmyelinated
Adelta - fast, myelinated
Meissner’s corpuscles vs Pacinian corpuscles vs Merkel’s discs - where are they and what do they sense
Meissner - hairless skin, fine/light touch (adapt quickly)
Pacinian - deep skin, vibration/pressure
Merkel’s - hair follicles, pressure / static touch
function of perineurium
permeability barrier around nerve
where is ACh synth in CNS?
basal nucleus of Meynert
3 structures that form BBB
tight jxns of endothelial cells
basement membrane
astrocyte foot processes
2 hypothalamic input areas not contained by BBB
OVLT - senses osmolarity
area postrema - senses emetics
where are ADH and oxytocin made in brain?
ADH - supraoptic nucleus
oxytocin - paraventricular nucleus
lateral and ventromedial hypothal - fns
lateral - hunger
ventromedial - satiety
anterior and posterior hypotha - fns
ant - cooling (AC), PSNS
post - heating, SYNS
what do these thalamic nuclei connect (input/output)?
VPL, VPM, LGN, MGN, VL
VPL - STT/DC > primary somatosensory
VPM - trigeminal and gustatory pathway > primary somatosensory
LGN - CN2 > calcarine sulcus
MGN - superior olive and inf colliuclus > auditory
VL - basal ganglia > motor cortex
3 cerebellar peduncles and what they carry
superior - output to contra motor cortex
middle - input from contra cortex
inferior - input from ipsi proprioceptive pathways
cerebellar deep nuclei from lateral > medial, and what does lateral do vs medial?
Dentate, Emboliform, Globose, Fastigial (don’t eat greasy foods)
lateral - voluntary mvmt
medial - balance/coordination
what composes striatum and lentiform nucleus?
striatum - putamen + caudate
lentiform nucleus - putamen + globus pallidus
direct and indirect pathway in basal ganglia
direct - putamen (D1) > inhib GPi > disinhibition of thalamus > inc motion
indirect - putamen (D2) > inhib GPe > disinhibition of STN > stimulation of GPi > inhibition of thalamus > dec motion
result of dopamine in basal ganglia pathways
dopamine always inc motion
direct - D1 stimulates excitatory pathway
indirect - D2 inhibits inhibitory pathway
Parkinson’s dz - protein accumulations
Lewy bodies - composed of alpha synuclein
where is the lesion causing hemiballismus?
contra STN
tx of essential tremor
beta blockers, primidone
Kluver-Bucy syndrome
bilat amygdala lesions, assoc w/ HSV1
hyperorality, hypersexuality, disinhibited behavior
Wernicke-Korsakoff syndrome - sx, cause
confusion, ophthalmoplegia, ataxia, memory loss, confabulation, personality change
assoc w/ thiamine (B1) def and excessive ETOH, precipitated by giving glucose w/o B1 to B1 def pt
how to tell side of lesion based on eye direction for PPRF and FEF lesions
PPRF - eyes look away from lesion
FEF - eyes look toward lesion
conduction aphasia - what is it and what is the lesion
poor repetition but fluent and can comprehend
dmg to arcuate fasciculus
what is the primary driver behind cerebral perfusion and how can this be used to your advantage?
PCO2
therapeutic hyperventilation - dec PCO2 to dec ICP in acute cerebral edema
sx of MCA stroke
contra paralysis/loss of sensation to upper limb and face
aphasia or hemineglect based on what side (dominant/nondominant)
sx of ACA stroke
contra paralysis/ loss of sensation of lower limb
sx of lateral striate artery stroke and what usually causes it
contra hemiparesis/hemiplegia
lacunar infarcts 2/2 HTN
sx of ASA stroke
contra hemiparesis of lower limbs
dec contra proprioception
tongue deviates ipsi
sx of PICA stroke
vestibular - vomiting vertigo nystagmus cerebellar - ataxia dysmetria STT - dec pain/temp sensation in face/limbs dysphagia** hoarseness ipsi Horner's
**lateral medullary (wallenberg’s syndrome)
sx of AICA stroke
vestibular - vomiting, vertigo, nystagmus
paralysis of face** dec pain/temp sensation in face
ipsi Horner’s and dec hearing
ataxia dysmetria
sx of PCA stroke
contra hemianopsia w/ macular sparing
sx of AComm stroke
visual field defects (usually a berry aneurysm, not a stroke)
sx of PComm stroke
CN III palsy - eye down and out, ptosis, pupil dilation
MC site of berry aneuryism
AComm artery
Charcot bouchard microaneurysm - assoc w/? where?
chronic HTN
small vessel - basal ganglia, thalamus
where do hypertensive hemorrhages tend to occur?
basal ganglia and internal capsule
flow of CSF
lateral ventricles > intraventricular foramina of Monro > 3rd ventricle > cerebral aqueduct of sylvius > 4th ventricle > go to subarachnoid space via Lateral foramina of Luschka or Medial Foramen of Magendie
sx of normal pressure hydrocephalus
“wet wobbly and wacky”
urinary incontinence, ataxia, cog dysfn
2 causes of isolated LMN lesions
poliomyelitis and Wednig-Hoffman dz
genetic cause of ALS
defect in superoxide dismutase 1
Werdnig Hoffman dz
AR
congenital degernation of anterior horn of SC
floppy baby w/ marked hypotonia and tongue fasciculations, die at 7 mo
Friedreich’s ataxia - inheritance, gene, sx
AR triplet repeat
frataxin
staggering gait, frequent falling, nystagmus, dysarthria, pes cavus (high arch), hammer toe, kyphoscoliosis, hypertrophic cardiomyopathy (cause of death)
sx of Horner’s syndrome and what location of lesion causes it
ptosis, anhidrosis, miosis
lesion of SC above T1
dermatomes of - nipple, umbilicus, inguinal ligament, kneecaps
nipple T4
umbilicus T10
inguinal ligament L1
kneecap L4
myotomes of biceps, tricepss, patellar, and achilles reflexes
biceps - C5,6
triceps - C7,8
patellar - L3,4
achilles - S1,2
Parinaud syndrome
paralysis of conjugate vertical gaze due to lesion in superior colliculi like a pinealoma
nucleus where PSNS neurons synapse to cause pupillary constriction
Edinger Westphal nucleus
CN IV controls
superior oblique
where are the CN 3-12 nuclei located (which part of brainstem) and mnemonic for where they are lateral vs medial
midbrain - 3,4
pons - 5,6,7,8
medulla - 9,10,12
SC - 11
lateral - sensory
medial - motor (both M’s)
vagal nuclei fns
nucleus solitarius - visceral sensory info
nucleus ambiguus - motor innervation of pharynx/larynx/upper esophagus
dorsal motor nucleus - autonomic fibers to heart lungs upper GI
which CN pass through cavernous sinus?
3,4,V1,V2,6
with a CN V motor lesion, does jaw deviate toward or away from lesion?
toward side of lesion
which muscles open vs close the jaw?
open - lateral pterygoid
closed - masseter, temporalis, medial pterygoid
retina whitening w/ cherry red spot on fundoscopic exam
central retinal artery occlusion
Marcus gunn pupil
afferent pupillary defect - bilat dec in pupil constriction when light is shone in affected eye
in CN III, what type of nerve fibers are more vulnerable to vascular damage vs compression?
vascular - motor fibers
compression - PSNS fibers
drusen assoc w/
dry macular degeneration
Meyer’s loop
carries inf retina information, loops around inferior horn of lateral ventricle (temporal loop)
internuclear ophthalmoplegia - lesion to what structure? what does it cause?
MLF
impaired horizontal conjugate gaze beyond midline, convergence is spared
protein accumulations in alzheimer’s
extracellular amyloid plaques
intracellular tau tangles
protein accumulation in Pick’s disease
pick bodies - spherical tau protein aggregates
Lewy body dementia - unique symptom and what protein is in Lewy bodies
hallucinations
alpha synuclein
2 MC causes of dementia in elderly
1 - alzheimer’s
2 - multi-infarcts
Charcot’s classic triad of MS sx
scanning speech
intention tremor
nystagmus
other name for Guillain Barre
acute inflammatory demyelinating polyradiculopathy
CSF findings in Guillain Barre
inc protein w/ nl cell count
metachromatic leukodystrophy - what is it generally, inheritance, cause
lysosomal storage dz > impaired production of myelin
AR
arylsulfatase A def
Charcot Marie Tooth disease - what kind of disease does it cause, general pathophys
motor and sensory neuropathy
defective production of proteins needed to make myelin sheath
Krabbe’s disease - inheritance, type of disorder, protein cause > what general problem
AR
lysosomal storage disorder
galactocerebrosidase def > destroys myelin sheath
MC site of partial seizure
medial temporal lobe
MC causes of seizures in kids, adults, and elderly
kids - genetic
adults - tumors
elderly - stroke
Sturge Weber syndrome
neurocutaneous disorder
port wine stains in V1 distribution, leptomeningeal angiomas, pheochromocytomas, glaucoma, seizures, hemiparesis, MR
3 MC primary brain tumors
1 - glioblastoma
2 - meningioma
3 - schwannoma
brain tumor w/ “pseudopalisading” pleomorphic tumor cells. central areas of necrosis w/ hemorrhage
glioblastoma
brain tumor w/ spindle cells in a whorled pattern, psammoma bodies
meningioma
MC type of pituitary adenoma
prolactinoma
Rosenthal fibers assoc w/
pilocytic astrocytoma (benign childhood brain tumor)
Homer-Wright rosettes assoc w/
medulloblastoma
craniopharyngioma is derived from what?
remnants of Rathke’s pouch
MC childhood supratentorial tumor
craniopharyngioma
5 types of drugs used for glaucoma
alpha agonists - epi, brimonidine
beta blockers - timolol, betaxolol, carteolol
diuretics (CA inhibs) - acetazolamide
cholinomimetics - pilocarpine, carbachol, physostigmine, echothiophate
prostaglandins - PGF2alpha - latanoprost
mechanism of opioids
open K channels, close Ca channels > dec synaptic transmission > inhibit NT release
butorphanol
mu opioid receptor partial agonist and kappa opioid agonist > produces analgesia w/ less respiratory depression
tramadol
weak opioid agonist. also inhib serotonin and NE reuptake. used for chronic pain
1st line drug for partial seizures
carbamazepine
1st line for absense seizures
ethosuximide
1st line for status epilepticus (acute vs prophylaxis)
acute - benzos
prophylaxis - phenytoin
1st line seizure med in kids
phenobarbital
tox of carbamazepine
diplopia, ataxia, blood dyscrasias (agranulocytosis, aplastic anemia), liver tox, SIADH, Stevens Johnson syndrome, teratogen
tox of ethosuximide
GI distress, fatigue, HA, urticaria, Stevens Johnson
tox of phenytoin
nystagmus, diplopia, ataxia, sedation, gingival hyperplasia, hirsutism, megaloblastic anemia, teratogen, drug induced lupus, LAN, Stevens Johnson, osteopenia
tox of valproic acid
GI distress, fulminant hepatotox (rare), neural tube defects, tremor, wt gain
mech of phenytoin
blockade of Na channels > inhib glutamate release
mech of barbiturates
facilitate GABAa action by inc duration of Cl channel opening
barbiturates are contraindiated in what condition
porphyrias
benzos mech
facilitate GABAa action by inc frequency of Cl channel opening
what do you treat benzo OD w/?
flumazenil
zolpidem, zaleplon, eszopiclone - mech, use
nonbenzo hypnotics - act via BZI subtype of GABA receptor
tx insomnia
MAC as it relates to anesthetics
minimum alveolar conc at which 50% of population is anesthetized
inversely related to potency
which drugs can cause malignant hyperthermia?
all inhaled anesthetics except nitrous oxide
thiopental - class, use
barbiturate
IV anesthesia - used for induction and short procedures
midazoloam - class, use
benzo
IV anesthesia - MC drug used for endoscopy
arylcyclohexamines - ex, mech
ketamine
PCP analog - block NMDA receptors
propofol - mech, use
potentiates GABAa
sedation in ICU and short procedures
how to tell esters from amides in local anesthetics
amides have 2 i’s in the name, esters just have 1
tricks w/ local anesthetics - how to increase local action? using in infected areas?
local action increased by vasoconstrictors like epi
infected tissue is more acidic > anesthetics stay charged > can’t penetrate membranes > need more anesthetic
order of sensation loss w/ local anesthetics
pain > temp > touch > pressure
which type of local anesthetic tends to have allergic reactions?
esters
succinylcholine - mech and tox
depolarizing NMJ blocker
hyperCA, hyperK, malignant hyperthermia
nondepolarizing NMJ blockers naming
-cur- (ex vecuronium)
reversing NMJ blockers
use cholinesterase inhibs like neostigmine
dantrolene - mech, use
prevent release of Ca from sarcoplasmic retic
tx malignant hyperthermia and neuroleptic malignant syndrome
tx of malignant hyperthermia
dantrolene
tx modalities for parkinson’s dz
DA agonists (bromocriptine -ergot, non ergots: pramipexole, ropinirole) inc DA - carbidopa, amantadine (inc DA release) prevent DA breakdown - selegiline (MAOb inhib), entacapone/tolcapone (COMT inhib) curb excess cholinergic activity - benztropine (helps w/ tremor and rigidity but not bradykinesia)
selegiline - mech, use
MAOb inhib (preferentially reduce breakdown of DA over NE / 5-HT) parkinson's
memantine - mech, use
NMDA receptor antagonist - prevent excitotox
alzheimer’s
donepezil / galantamine / rivastigmine - mech, use
AChE inhibs
alzheimer’s
tetrabenazine / reserpine - mech, use
inhibit VMAT - limit DA vesicle packaging and release
huntington’s
tx for Huntington’s
tetrabenazine and reserpine
haloperidol
sumatriptan - mech, use, tox
5HT 1b/1d agonist, inhib trigeminal nerve activation, induce vasoconstriction
acute migraine, cluster HA
tox - coronary vasospasm