Neurology Flashcards
In which part of the brain is atrophy most pronounced in Alzheimer’s
Hippocampus and frontal lobe
CNS/PNS cells that originate from Neuroectoderm
- CNS neurons
- ependymal cells (make CSF)
- Oligodendroglia
- Astrocytes
CNS/PNS cells that originate from Neural Crest:
- Schwann cells
- PNS neurons
CNS/PNS cells that originate from Mesoderm:
- Microglia
* **note: microglia=macrophages of the brain!
Nissl substance
RER in cell body, dendrites of neurons; NOT in axons
GFAP
astrocyte marker
–>so, also a marker for astrocyte tumors: glioblastoma and pilocytic astrocytoma
Astrocytes:
- roles?
- marker for astrocytes?
physical support and repair; maintain BBB; create scar tissue in response to injury
*GFAP = astrocyte marker (elevated in astrocyte tumors: glioblastoma and pilocytic astrocytoma)
macrophages/phagocytes of the CNS?
- ->Microglia
- mesodermal origin
- when tissue damage, microglia respond by differentiating into large phagocytic cells
- HIV-infected microglia fuse to form giant cells in CNS
oligodendrocytes:
produce myelin in the CNS
- one oligodendrocyte can myelinat many CNS axons (up to 30!)
- destroyed in MS!
- Look like fried eggs on histology
Schwann cells
produce myelin in the PNS
-one Schwann cell only myelinates one PNS axon
Cell types that look like fried eggs on histology (various, not just neuro):
- Oligodendrocytes
- Koilocytes (HPV)
- Seminomas
Type of cells that are destroyed in MS?
Oligodendrocytes
Type of cells destroyed in Guillain-Barre syndrome?
Schwann cells
Acoustic neuroma:
type of Schwannoma; usually located in internal acoustic meatus (CN VIII)
–>see bilateral acoustic schwannomas in NF 2)
Endoneurium, Perineurium, Epineurium
Endoneurium: surrounds single nerve fibers
Perineurium: surrounds a fascicle of nerve fibers
Epineurium: dense connective tissue that surrounds an entire nerve
Diseases with increased NE?
- ->Anxiety
- ->Mania
Disease with decreased NE?
Depression
Disease associated with increased dopamine?
Schizophrenia
Diseases with decreased dopamine?
- Parkinson’s
- Depression
Diseases with decreased serotonin (5-HT)?
- Anxiety
- Depression
Diseases with decreased Ach?
- Alzheimer’s
- Huntington’s
Disease with increased ACh?
- Parkinson’s
- Also: increased ACh in REM sleep (b/c ACh is the principal neurotransmitter in REM sleep)
Diseases with decreased GABA?
- Anxiety
- Huntington’s
What is synthesized in Locus ceruleus?
- ->location of NE synthesis
- stress and panic! (elevated NE)
What is synthesized in Raphe nucleus?
location of serotonin synthesis
What is synthesized in Nucleus Accumbens?
- GABA
- ->nucelus accumbens and septal nucleus = reward center, pleasure, addiction, fear
What is synthesized in the ventral tegmentum?
Dopamine
What is synthesized in the basal nucleus of Meynert?
ACh
What vitamin is used in GABA synthesis? What is the precursor to GABA?
Glutamate is the precursor to GABA
–>Vitamin B6 = cofactor in GABA synthesis from Glutamate
3 structures that form the blood-brain-barrier:
- tight junctions (b/w endothelial cells)
- basement membrane
- astrocyte processes
What types of substances can cross the BBB rapidly via diffusion?
Nonpolar/Lipid-soluble substance (lots of anesthetic agents are lipid-soluble!)
What substances can cross the BBB slowly by carrier-mediated transport?
glucose and amino acids
How does glucose get across the BBB?
glucose crosses the BBB slowly by carrier-mediated transport mechanism
Area postrema of the brain
–>area of the brain that has fenestrated capillaries and no BBB; crossing of substances into this area is what results in vomiting post chemo
*Area postrema inputs info into the hypothalamus
OVLT = organum vasculosum of lamina terminalis
area of the brain that has fenestrated endothelium and lacks BBB (like the area postrema)
–>can sense osmolarity of the blood and respond (ie by regulating ADH-releasing neurons)….
supraoptic nucleus of the hypothalamus:
makes ADH
paraventricular nucleus of the hypothalamus:
makes oxytocin
Functions of the Hypothalamus:
“Hypothalamus wears TAN HATS”
- Thirst and water balance
- Adenohypophysis regulation
- Neurohypophysis releases hormones from the hypothalamus (ADH, oxytocin)
- Hunger
- Autonomic regulation
- Temperature regulation
- Sexual urges
Lateral area/nucleus of the hypothalamus:
- role?
- if destroyed?
- inhibited by?
- ->responsible for hunger
- if destroyed, get anorexia, FTT in infants
- inhibited by leptin (leptin–>decreased hunger)
“if zap the lateral nucleus, you shrink laterally!”
Ventromedial area/nucleus of the hypothalamus:
- role?
- if destroyed?
- stimulated by?
- involved in satiety
- if destroyed (ie craniopharyngoma) –> don’t get full, eat more = hyperphagia
- stimulated by leptin
“if zap ventromedial nucleus, you grow ventrally and medially”
Anterior hypothalamic nucleus:
-Role?
Involved in cooling the body
“Anterior Cools like an A/C”
Posterior hypothalamic nucleus:
involved in heating the body
Suprachiasmatic nucleus:
-role?
involved in the circadian rhythm
Which hypothalamic nuclei send axonal projections to the post pituitary?
- supraoptic nucleus –> ADH
- paraventricular nucleus –> oxytocin
VPL (Ventral Posterolateral) Nucleus of the Thalamus:
-role?
- Roles in:
- pain and temperature
- pressure
- touch
- vibration
- proprioception
*where the dorsal column and spinothalamic tracts have their 2nd synapses!
VPM (Ventral Posteromedial) nucleus of the thalamus:
-role?
“Make-up goes on the face; vpM”
–>face sensation and taste
LGN (lateral geniculate) nucleus of the thalamus:
“L for Light”
–>involved in relaying vision
MGN (medial geniculate nucleus) of the thalamus:
“M for Music”
–>involved in relaying Hearing
What is the function of the thalamus?
Thalamus is the major relay center for all ascending sensory information, except olfaction
–>relays sensory and motor information to the cerebral cortex
Thalamic syndrome: Vascular lesion to the thalamus (from ischemic or hemorrhagic stroke) - what are the results/symptoms?
–>damage to VPL and VPM nuclei; so get complete CONTRALATERAL SENSORY loss. may also have proprioceptive defects. NO motor deficits.
What structures make up the Limbic System?
- Hippocampus
- Cingulate gyrus
- Fornix
- Mammillary bodies
- Septal nucleus (reward center, pleasure, addiction, fear)
What are the Functions of the Limbic System?
5 F’s - all are primitive functions:
- Feeding
- Fleeing
- Fighting
- Feeling
- sex
What information does the cerebellum receive contralaterally? ipsilaterally?
Cerebellum receives:
- contralateral cortical input
- ipsilateral proprioceptive information
Deep nuclei of the cerebellum (from Lateral to Medial):
“Dentists Embody Global Fasts”
- Dentate
- Emboliform
- Globose
- Fastigial
*note: Emboliform and Globose nuclei = “interposed nuclei”
Main function of Basal Ganglia?
–>Voluntary movements and making postural adjustments
Depigmentation of substantia nigra pars compacta? What role does the substantia nigra normally play?
Parkinson’s syndrome:
–>the substantia nigra is part of the basal ganglia, and normally facilitates movement. But, in Parkinson’s get loss of dopaminergic neurons, so get inhibition of movement from basal ganglia.
Main symptoms of Parkinson’s:
“TRAP”
- Tremor at rest (“pill-rolling tremor”)
- cogwheel Rigidity
- Akinesia
- Postural instability
*have decreased dopamine, increased ACh
Hemiballismus
- sudden, wild flailing of 1 arm +/- leg
- ->get this with contralateral subthalamic nucleus lesion (like a lacunar stroke in a pt with HTN hx)
- ->loss of inhibition of thalamus through the globus pallidus (of the basal ganglia)
Neuronal death via NMDA-R binding and glutamate toxicity; and, atrophy of striatal nuclei in what disease?
Huntington’s disease
C’s of Huntington’s disease:
- Chorea (b/c atrophy of striatal nuclei, which normally inhibits movement; so, get increased movement)
- Caudate nucleus degeneration
- Crazy (dementia)
- CAG repeats
- decreased ACh and decreased GABA
“CAG –> Caudate loses ACh and GABA”
(decreased GABA–>increased movement)
Chorea is seen in what types of brain injuries?
–>injuries to basal ganglia (like in Huntington’s)
Athetosis:
- what is it?
- seen in what types of brain injuries?
- ->slow, writhing movements, especially of fingers (snake-like)
- ->see in basal ganglia lesions (like Huntington’s)
Myoclonus
=sudden, quick muscle contractions; like hiccups, jerks.
Intention Tremor
slow, zigzag movement when pointing toward an object; associated with cerebellar dysfxn, MS
(vs essential/postural tremor –> familial, alcohol, beta-blockers; and resting tremor –> Parkinson’s)
Kluver-Bucy syndrome:
- presentation?
- d/t lesion in what part of brain?
- associated with what virus?
- Hyperorality, hypersexuality, disinhibited behavior
- bilateral lesion of the amygdala
- associated with HSV-1
Spatial neglect syndrome:
–>d/t lesion to what area of brain?
lesion of Right parietal lobe (assuming that Right = NON-dominant lobe)
*don’t recognize/see contralateral side of the world!
Reduced levels of arousal and wakefulness (ie coma) d/t lesion of what area of brain?
Reticular Activating System (in midbrain)
What area of the brain is lesioned in Wernicke-Korsakof syndrome?
Bilateral lesion to mammillary bodies
Presentation of Wernicke-Korsakoff syndrome?
- Wernicke: confusion, ophthalmoplegia, ataxia
* Korsakoff: memory loss, confabulation, personality changes
Tremor at rest, chorea, athetosis (snake-like mvmnts): what area of brain is lesioned?
–>Basal ganglia lesion
Truncal ataxia and dysarthria: what area of brain is lesioned?
Cerebellar vermis
*note: lesion to cerebellar hemispheres affects lateral limbs; whereas lesion to cerebellar vermis affects central body.
Contalateral hemiballismus: what area of brain is lesioned?
–>lesion to subthalamic nucleus
Anterograde amnesia=can’t make new memories: area of brain lesioned?
–>Hippocampus lesion
Eyes look AWAY from side of lesion: area of brain lesioned?
–>PPRF lesion (Paramedian Pontine Reticular Formation)
Eyes look TOWARD lesion: area of brain lesioned?
Frontal eye fields
Consequence of correcting hyponatremia too rapidly?
- ->Central Pontine Myelinolysis:
- Acute paralysis
- Dysarthria (motor inability to speak)
- Dysphagia
- Diplopia
- Loss of consciousness
- on MRI, see abnormally increased signal in pons
- IRREVERSIBLE!
Aphasia vs Dysarthria:
- Aphasia = higher-order inability to speak
- Dysarthria = motor inability to speak
Where is Broca’s area?
Inferior frontal gyrus
Where is Wernicke’s area?
Superior temporal gyrus
Conduction aphasia:
- presentation?
- cause?
–>No connection between what pt says and what pt understands (comprehension is intact, and have fluent speech, but no connection between comprehension and speech)
*caused by lesion to: Arcuate fasciculus = connects Broca’s and Wernicke’s areas
Arcuate fasciculus
connects Broca’s and Wernicke’s areas
Area supplied by the Anterior Cerebral Artery?
–>anteromedial surface
Area of brain supplied by Middle Cerebral Artery?
–>lateral surface of brain
Area of brain supplied by Posterior Cerebral Artery?
–>posterior and inferior surfaces
Which artery supplies Broca’s and Wernicke’s areas?
MCA (b/c MCA supplies lateral surface of brain…)
What drives Cerebral Perfusion Pressure, PCO2 or PO2?
- ->PCO2 normally drives the cerebral perfusion pressure
- But, in severe hypoxia (when PO2 < 50 mmHg) PO2 also drives the cerebral perfusion pressure
**Cerebral Perfusion Pressure is proportional to PCO2 until PCO2 > 90 mmHg, then cerebral perfusion pressure levels off)
Which arteries are responsible for anterior circulation? posterior circulation?
- Anterior circulation–> arteries derived from Internal Carotid: ACA, Lateral striate, MCA
- Posterior circulation–> arteries derived from Subclavian: AICA, ASA (ant spinal artery), Basilar, PICA, PCA, Vertebral
Most common sites of saccular/berry aneurysms? 2nd most common site?
#1 = AComm (ant communicating artery) #2 = PComm (post communicating artery)
What does rupture of a saccular/berry aneurysm lead to?
–>hemorrhagic stroke/subarachnoid hemorrhage
3 conditions associated with berry aneurysms?
- ADPKD
- Marfan’s syndrome
- Ehlers-Danlos syndrome
CN III palsy:
- presentation?
- cause?
- eye is “down and out”
- cause = PCOM aneurysm rupture (saccular/berry aneurysm)
Bitemporal hemianopia/visual field defects:
-cause?
–>AComm sacular/berry aneurysm rupture
Contralateral hemianopsia with macular sparing:
–>area of lesion? what artery is stroke in?
- macular sparing = hallmark of occipital lob lesions
* this is an occipital cortex, visual cortex lesion; d/t stroke in PCA
Charcot-Bouchard microaneurysms:
- associated with chronic hypertension
- affects small vessels (ie in basal ganglia, thalamus)
Cause of epidural hematoma?
–>rupture of middle meningeal artery (branch of maxillary artery), often secondary to fracture of temporal bone
Cause of subdural hematoma?
- ->rupture of bridging veins
- Seen in:
- elderly
- alcoholics
- blunt trauma
- shaken baby
Shaken baby syndrome causes what kind of intracranial hemorrhage?
–>subdural hematoma
Cause of subarachnoid hemorrhage?
–>rupture of aneurysm (ie berry aneurysm) or AVM (ArterioVenous Malformation –> problem in vein-artery connection)
Time course of a subarachnoid hemorrhage?
–>Rapid
Risks 2-3 days after a subarachnoid hemorrhage?
- ->Risk of vasospasm d/t blood breakdown (constriction of blood vessels) –> prevent vasospasm with CCB = Nimodipine
- ->Risk of rebleed
How to prevent vasospasm following a subarachnoid hemorrhage?
–> treat with Nimodipine (a CCB)
Most common sites of Intraparenchymal/Hypertensive Hemorrhage?
–>basal ganglia and internal capsule
*usually caused by hypertension, but may also be caused by amyloid angiopathy, vasculitis, and neoplasms.
Ipsilateral hypoglossal dysfunction (tongue deviates ipsilaterally); contralateral hemiparesis; pain and temp preserved: what artery is lesioned?
ASA = Anterior Spinal Artery
loss of pain and temperature sensation on ipsilateral face, but contralateral body: What artery is lesioned?
PICA (posterior inferior cerebellar artery)
- ->this is Lateral Medullary/Wallenberg’s syndrome
- **Other findings:
- dysphagia, hoarseness, decreased gag reflex, ipsilateral Horner’s syndrome, ataxia, etc…
Dysphagia, hoarseness, and decreased gag reflex; ipsilateral Horner’s syndrome: What artery is lesioned?
–>PICA (“don’t PICK A (pica) HORSE (hoarseness) that CAN’T EAT (dysphagia)!”
- ** find this in Lateral medullary / Wallenberg’s syndrome
- ->Other findings:
- decreased pain/temp sensation on ipsilateral face, contralateral body
- ataxia, dysmetria
- vomiting, vertigo, nystagmus
Lateral Medullary/Wallenberg’s syndrome:
- what artery is lesioned (where is stroke)?
- presentation?
- stroke in PICA
- presentation:
- decreased pain/temp sensation on ipsilateral face and contralateral body
- hoarseness, dysphagia, decreased gag reflex
- ataxia, dysmetria
- ipsilateral horner’s
- vomiting, vertigo, nystagmus
Paralysis of face (Facial Drooping); ipsilateral Horner’s; decreased lacrimation, salivation; decreased pain/temp sensation on face; decreased hearing ipsilaterally, vomiting, vertigo, nystagmus: What artery is lesioned/where is stroke?
–>AICA (ant inf cerebellar artery)
=Lateral Pontine Syndrome
***Facial nucleus affects = specific to AICA lesions
Contralateral hemiplegia/hemiparesis: What artery is lesioned/where is stroke?
–>Lateral striate arteries = “arteries of stroke”; usually secondary to unmanaged HTN (so area lesioned= striatum and internal capsule)
Contralateral paralysis and loss of sensation on UPPER limb and face: what artery is lesioned?
–>MCA (Middle Cerebral Artery)
Contralateral paralysis and loss of sensation on LOWER limb: what artery is lesioned/where is stroke?
–>ACA = Anterior Cerebral Artery
Areas of the brain that are most vulnerable to ischemia/irreversible injury from ischemia?
- hippocampus
- neocortex
- cerebellum
- watershed areas
Ischemic brain injury - what’s seen at each time after damage:
- 12-48 hours?
- 24-72 hours?
- 3-5 days?
- 1-2 weeks?
- after 2 weeks?
- 12-48 hours: red neurons (=neurons that are dying d/t ischemia :()
- 24-72 hours: necrosis + neutrophils
- 3-5 days: macrophages
- 1-2 weeks: reactive gliosis + vascular proliferation
- after 2 weeks: glial scar (glial cells = fibroblasts of the brain)
Treatment of an ischemic stroke?
tPA as long as it’s within 4.5 hours of stroke
Stroke imaging: CT and MRI; hemorrhagic vs ischemic strokes?
- Can see area on MRI within 3-30 minutes, and continue to see for 10 days (can see signs of ischemia on MRI)
- Can see on CT within 24 hours; but, can only see signs of hemorrhagic stroke, not ischemic…
CSF: produced by? reabsorbed by?
CSF is produced by choroid plexus
CSF is reabsorbed by venous sinuses via arachnoid granulations; arachnoid granulations drain into the superior sagittal sinus
Pathway of CSF: from lateral ventricle to subarachnoid space:
- Lateral ventricle –> 3rd ventricle via Foramen of Monro
- 3rd ventricle –> 4th ventricle via Cerebral aqueduct
- 4th ventricle to subarachnoid space via Foramina of Luschka (laterally) and Foramen of Magendie (medially)
Dementia + Ataxia + Urinary Incontinence:
Normal Pressure Hydrocephalus
–>Expansion of ventricles (see really dilated ventricles); No increase in subarachnoid space volume
*this is a cause of reversible dementia in elderly pts; why it’s so important to do a CT in a dementia work-up!!
**“Wet (incontinenc), Wobbly (ataxia), Wacky (dementia)”
Communicating Hydrocephalus:
- cause?
- presentation?
*decreased absorption of CSF by arachnoid granulations–> increased CSF within ventricles (maybe d/t arachnoid scarring, like after meningitis)
- presentation/results:
- increased ICP
- papilledema
- herniation
“communicating” –> b/c CSF still flows between ventricles
Obstructive/Non-communicating hydrocephalus:
-cause?
Blockage of CSF circulation (like d/t a brain tumor, or stenosis of the cerebral aqueduct (aqueduct of Sylvius)
Hydrocephalus ex vacuo:
Have atrophy of brain (like in Alzheimer’s, advanced HIV, Pick’s disease), so it appears like there is increased amount of CSF. But no symptoms, and ICP is normal.
Spinal Nerves:
- how many total?
- how many of each type?
- where do they exit the vertebrae?
- 31 total
- 8 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal
*C1-C7 exit through the intervertebral foramina above the corresponding vertebrae (so, C1 exits above C1 vertebrae; etc). The rest exit below the corresponding vertebrae (So, C8 exits below C8, above T12)
Vertebral disk herniation: between which vertebrae does it usually occur?
- ->usually between L5 and S1
- ->it’s the herniation of the nucleus pulposus through the annulus fibrosus.
Between what vertebrae should an LP be done?
–>b/t L3 and L5 (find ASIS and go from there; it marks L4!)
To what vertebrae does the spinal cord extend in adults? subarachnoid space?
- ->spinal cord goes to L1-L2
- ->subarachnoid space to S2 (why do LP b/w L3-L5; want to get CSF, but not damage spinal cord)
Spinothalamic Tract: information?
Ascending pain and temperature sensation