CNS Study Guide (JR)

zoyogasa's version from 2016-04-14 02:06


Question Answer
UMNBrisk Deep tendon Reflexes
UMNCereberospinal tract
UMNSpastic Paralysis
UMNIncreased Tone
UMNUpgoing plantar Reflux (Babinski)
LMNMotor neurons of Anterior Horn
LMNPoliomyeitis & Werdnig Hoffman
LMNFlaccid Paralysis
UMN & LMNAmyotrophic Lateral Sclerosis

Brain Lesions

Question Answer
Paramedian Pontine Reticular FormationEyes look away from the side of lesion
HippocampusAnterograde amnesia - inability to make new memories
Subthalamic nucleusContralateral Hemiballismus
Cerebellar VermisTruncal ataxia /Dysarthria
Basal GangliaTremor at rest, choreea or athetosis
Mammilary BodiesWernicke Korsakoff- Confusion, Opthalmoplegia, ataxia. Korsakoff - Memory Loss, Confabulation, Personality changes
Reticular Activiating SystemReduced levels of arousal and wakefulness(Coma)
Right parietal LobeSpatial Neglect

CNS PNS origins

Question Answer
Neuroectoderm (4)CNS neurons
Ependymal cells (inner lining of ventricles, make CSF)
Oligodendroglia(MS - Fried egg appearance)
Neural crest (2)PNS neurons
Schwann cells)Guillain Barre Syndrome)
Mesoderm (1)Microglia (like Macrophages, originate from Mesoderm)

Bleeding of brain

Question Answer
Most vulnerable areas of brain to ischemic damage?hippocampus, neocortex, cerebellum, watershed areas
Irreversible5 minutes of hypoxia
Red neurons(12-48 hrs)
Necrosis + neutros(24-72 hrs)
Macrophages(3-5 days)
Reactive gliosis + vascular proliferation(1-2 wks)
Glial scar(>2 wks)
Stroke imagingbright on diffusion-weighted MRI in 3-30 min and remains bright for 10 days, dark on CT in 24 hrs
Venous sinusesrun in dura mater where meningeal/periosteal layers separate, cerebral veins-->sinuses-->IJV
Bright areas on noncontrast CThemorrhage (tPA is contraindicated)
Cystic cavity with reactive gliosisAtherosclerosis - thrombi lead to ischemic stroke w subsequent necrosis
Type of necrosis seen with brain infarctionliquifactive

CN pathways

Question Answer
cribriform plateCN I
middle cranial fossa through sphenoid boneCN II-VI
optic canalCN II, ophthalmic artery, central retinal vein
superior orbital fissureIII, IV, V1, VI, ophthalmic vein, sympathetic fibers
foramen rotundumV2
foramen ovaleCN V3
foramen spinosummiddle meningeal artery
posterior cranial fossa through temporal or occipital boneVII-XII
internal auditory meatusVII, VIII
jugular foramenIX, X, XI, jugular vein
hypoglossal canalXII
foramen magnumspinal roots of XI, brain stem, vertebral arteries
Great mnemonic for CN exit sitesCarl only swims south. Silly Roger only swims in infinity jaccuzzi's. Jane just hitchhikes
passage of blood through venous sinusblood from eye and superficial cortex -> cavernous sinus -> internal jugular
things that run through cavernous sinusII, IV, V1, V2, VI, postganglionic sympathetics, internal carotid
cavernous sinus syndromeophthalmoplegia and decreased corneal and maxillary sensation, normal vision


Question Answer
Ventricle pathwaylateral-->3rd via foramen of monro--> cerebral aqueduct-->4th-->SA space via Luschka (lateral) and Magendie (medial)
Normal pressure hydrocephaluswacky/wobbly/wet
NO increase in SA space volume, expansion of ventricles disrupts fibers of corona radiata → dementia, ataxia, urinary incontinence
Communicating hydrocephalusless CSF absorption by arachnoid granulations → increased icp → papilledema and herniation
Hydrocephalus ex vacuoincreased CSF in atrophy (Alzheimers, advanced HIV, picks), ICP is normal and triad not seen
Noncommunicating hydrocephalusStructural blockage (stenosis of aqueduct of sylvius)


Question Answer
NorepinephrineLocus ceruleus (pons) (since this location mediates stress)
DopamineVentral tegmentum and SNc (midbrain) (Increase In Schizophrenia Decrease in Parkinsons and Depression)
5-HTRaphe nucleus (pons, medulla, midbrain)
AChBasal nucleus of Meynert
GABANucleus accumbens
Locus ceruleusPons - stress and panic
Nucleus accumbens and septal nucleus (4)Reward center, pleasure, addiction, fear
Anxiety↑ NE (since you're all stressed out)
↓ 5-HT, GABA
Depression↓ NE, Dopamine, 5-HT (everything goes down)
HuntingtoN↑ Dopamine
Parkinson↑ Ach, 5-HT
↓ Dopamine
Alzheimer↓ Ach
Free Nerve EndingPain and Temperature
Meissners CorpusclesPosition sense, Fine touch
Pacinian corpusclesVibration pressure
Merkels DisksPosition sense, static touch

Sensory Corpuscles

Question Answer
C-fibersslow, unmyelinated fiber
Aδ-fibersfast, myelinated fibers
Pacinianin Dermis (deep layer) (VIBRATION + PRESSURE) (onion like)
Meissner'sSuperficial skin w/o HAIR (DYNAMIC/CHANGING LIGHT TOUCH)
MerkelSuperficial skin everywhere (STATIC/UNCHANGING LIGHT TOUCH) (look like melanocytes)
Intrafusal Muscle spindlemuscle length
Golgi Tendonmuscle tension

Hearing loss & facial lesions

Question Answer
Order of testsWeber(Forehead) then Rine(Mastoid & outer ear)
Conduction Right ear SxWeber -Hears better right ear / Rinne -Hears better when on the mastoidprocess(-Rinne)
Sensonuronal Right ear SxWeber -Hears better left ear / Rinne -Hears better when on the outside of ear(+Rinne)
noise-induced hearing loss damagestereocilliated cells in organ of Corti; high-frequency lost first
UMN lesionLesion between motor cortex and facial nucleus
Contra paralysis of lower face
forehead spared d/t bilateral innervation by UMNs
LMN lesionIpsi paralysis of upper & lower face
Facial nerve palsyIpsi facial paralysis w inability to close eye on involved side
Occurs in: AIDS, Lyme disease, HSV, sarcoid, tumors, and diabetes
Weber test256 Hz tuning fork is placed on the forehead
Rinne test512Hz tuning fork placed on mastoid bone. Once the vibration is no longer heard, quickly move tuning fork to just outside the ear canal.

Spinal cord lesions

DiseaseArea of destructionCharacteristics
Polio & Werdnig-Hoffman diseaseanterior horns
LMN lesions only, flaccid paralysis
MSWhite matter of cervical region, random and asymmetric lesions
scanning speech
intention tremor
ALSUMN and LMN defecits in anterior horns and lateral corticospinal tractsUMN & LMN signs
Caused by defect in superoxide dismutase 1
Fasciculations with eventual atrophy
Tx with Riluzole (modest ↑ in survival with ↓ presynaptic glutamate release)
Complete occlusion of anterior spinal arteryEverything but dorsal columns and Lissauer's tract
Can feel things, but no movement
lesion and deficits above T8 usually d/t lack of collateral blood supply above T8
Tabes dorsalisdorsal columns
Caused by 3° syphilis
Impaired sensation/proprioception and progressive sensory ataxia (no DTRs and positive Romberg)
Assoc w. Charcot's joints, shooting pain, Argyll Robertson pupils (small, bilateral pupils that react to accommodation but not light)
SyringomyeliaAnterior white commissure of spinothalamic tract (2nd order neurons)
bilateral loss of pain/temp (usually C8-T1)
Seen with Chiari 1 malformation
It can expand
Vitamin B12 or Vit E deficiencyDemyelination of dorsal columns, lateral corticospinal tracts, and spinocerebellar tracts
ataxic gait
impaired position and vibration sense


Question Answer
Friedreich AtaxiaGAA, staggering gait, falling, nystagmus,Hypertrophic cardiomyopathy(DEATH)
Brown-Sequard Syndromehemisection of spinal cord (PAIN + TEMP loss on opposite side, PTV loss on same side, motor loss same side)
Horner's Syndromeptosis, miosis, anhidrosis (of ↓Symp, lesion above T1)
Internuclear OphthalmoplegiaMLF defect. CN VII & III. Ipsilateral eye can't adduct, Contralateral eye nystagmus.
Guillain-Barre SyndromeCampylobacter jujini or CMV, DESTRUCTION of schwann cells --> bilateral ascending muscle weakness.
Myasthenia Gravisautoantibodies against ACh receptor, weakness worsens w/ use, descending weakness
Lambert-Eaton Syndromeautoantibodies against presynaptic Ca2+, ↓ACh , weakness improves w/ use
Botulismblock ACh release, flaccid paralysis, descending paralysis
PML (Progressive Multifocal Leukoencephalopathy)destruction of oligodendrocytes, JC virus in AIDS ptx
Acute Disseminated Encephalomyelitisdemyelination after infection (measles or VZV)
Parkinson's Disease↓DA (from Substantia Nigra pars compacta), TRAP (Tremor (at rest), Rigidity (cogwheel), Akinesia, Postural Instability), lewy body, α-synuclein,
Lewy BodyDimentiadementia + hallucinations + falls + syncopal episodes
Huntington's Disease↓ACh, ↓GABA,↑DA. C's = CAG, chorea, crazy (dementia), chromosome 4, Depression, agression(Mistaken for substance abuse) Striatal Nuclei Atrophy(Basal ganglia lesion)
Hemibalasmuslesion in contralateral SubThalamic Nucleus --> wild, flailing arm (Lacunar stroke in hypertension)
Alzheimer's Disease↓ACh, cortical atrophy, e4, presenilin-1, Aβ-amyloid (Trisomy 21), senile plaques, neurofibrillary tangle, hyperphosphorylated tau
Pick's Diseasepicks frontal + temporal lobe, round tau protein, like parkinson's
Essential TremorFamilial/use alcohol and find relief. Tx b BLOCKERS
Resting TremorParknsons (pill-rolling)
Locked-in syndromefrom Central Pontine Myelinolysis (rapid hyponatremia correction), Superior Pons (basilar artery)
Wernickie-Korsakoff syndromeThiamine (B1) deficiency, Mamillary bodies, confusion + ophthalmoplegia + ataxia + memory loss + confabulation
Kluver-Bucy syndromehyperorality + hypersex + disinhibited behavior (lesion of amygdala). HSV-1
Epidural hematomaMiddle Meningeal Artery (from maxillary a.), lucid interval. Can cross Falx,tentorium. CN III Palsy
Subdural hematomaBridging Veins. Cant cross Falx,tentorium
Subarachnoid hemorrhageCircle of Willis (Berry aneurysm - anterior communicating artery), ADPKD, EHLERS, MARFANS
"Worst headache of my life"
Intraparynchemal hemorrhageCharcot-Bouchard Microaneurysms from HTN
Intraventricular Hemmorrhage(Germinal Matrix)Complication of Prematurity,decrease age & birthweight. <32weeks, bulging anterior frontanelle, hypotonia and hypotension

Adults Brain tumors

TumorAgeCell TypeDetailsPicture
Glioblastoma MultiformeAdult (supratentorial)Astrocytes

pseudopalisading, GFAP+
malignant, most common, in cerebral hemispheres, crosses the corpus callosum - butterfly lesion. pseudopalisading and endothelial cells. GFAP +, poor prognosis
MeningiomaAdult (supratentorial)Arachnoid cells

benign, women. round mass attached to the dura, seizures, tumor compresses but NO INVASION of cortex, whorled pattern + psaMmoma bodies
SchwannomaAdult (supratentorial)Schwann cells

benign, NERVES = cranial nerves or spinal nerves involved. loss of hearing and tinnitus. S-100 POSITIVE. Neurofibromatosis Type 2
OligodenrogliomaAdult (supratentorial)Oligodendrocytes

malignant, calcified tumor in white matter, frontal lobe. Fried-egg appearance.

Peds CNS Tumors

TumorAgeCell TypeDetailsPicture
Pilocytic AstrocytomaChildren (infratentorial)Astrocytes

benign, most common in children, in cerebellum, cyst + nodule. Rosenthal fibers (thick eosinophiln processes of astrocytes). GFAP+

MedulloblastomaChildren (infratentorial)Granular cells of cerebellum (Neuroectoderm)

Homer Wright Rossette
malignant, small, round-blue cells. HOMER-WRIGHT Rosettes. Can metastasize via CSF to cauda equina (DROP METASTASIS)

**Homer Wright Rosettes found in neuroblastoma, medulloblastoma and retinoblastoma.

EpendymomaChildren (infratentorial)Ependymal cells

Perivascular Pseudorosettes
malignant, in 4th ventricle = hydrocephalus, PERIVASCULAR PSEUDOROSETTES
CraniopharyngiomaChildren (infratentorial)Epithelial remnants of Rathke's pouch

calcifications = teeth
SUPRATENTORIAL mass, compress optic chiasm --> bilateral hemianopia in a child. calcifications

* anatomically = in the same place as the pituitary