Flashcards in Principles in Neurology_1 Deck (351):
what happens in neural development between day 18 and day 21?
neural plate + notochord → neural crest → neural tube and neural crest cells
notochord induces overlying ectoderm to differentiate into what?
neuroectoderm and form the neural plate
neural plate gives rise to what?
the neural tube and neural crest cells
notochord becomes what in adults?
nucleus pulposus of the intervertebral disc
what are the name and function of the dorsal part of the neural tube?
Alar plate: sensory
what are the name and function of the ventral part of the neural tube?
Basal plate: motor
what are the three primary vesicles of the developing brain?
1. Forebrain (prosencephalon) • 2. Midbrain (mesencephalon) • 3. Hindbrain (rhombencephalon)
what are the five secondary vesicles of the developing brain?
1. telencephalon • 2. Diencephalon • 3. Mesencephalon • 4. Metencephalon • 5. Myelencephalon
the Forebrain (prosencephalon) gives rise to which secondary vesicles?
1. Telencephalon • 2. Diencephalon
the Midbrain (mesencephalon) gives rise to which secondary vesicles?
the Hindbrain (rhombencephalon) gives rise to which secondary vesicles?
1. Metencephalon • 2. Myelencephalon
the walls of the telencephalon give rise to what?
the cavities of the telencephalon give rise to what?
the walls of the diencephalon give rise to what?
the cavities of the diencephalon give rise to what?
the walls of the mesencephalon give rise to what?
the cavities of the mesencephalon give rise to what?
the walls of the metencephalon give rise to what?
Pons and Cerebellum
the cavities of the metencephalon give rise to what?
upper part of fourth ventricle
the walls of the myelencephalon give rise to what?
the cavities of the myelencephalon give rise to what?
lower part of the fourth ventricle
what happens in neural tube defect?
neuropores fail to fuse (4th week) → persistent connection between amniotic cavity and spinal canal
neural tube defects are associated with what?
low folic acid intake before conception and during pregnancy
what are the lab levels in neural tube defect?
1. ↑ AFP in amniotic fluid and maternal serum • 2. ↑ AChE in amniotic fluid is a helpful confirmatory test
why is it that AChE can be measured in NTD?
fetal AChE in CSF transudates across defect into the amniotic fluid
what is spina bifida occulta?
failure of bony canal to close, but no structural herniation
spina bifida occulta is usually seen where?
lower vertebral levels
status of dura in spina bifida occulta?
spina bifida occulta is associated with what?
tuft of hair or skin dimple at level of bony defect
what is meningocele?
meninges (but not the spinal cord) herniate through spinal canal defect
what is meningomyelocele?
meninges and spinal cord herniate through spinal canal defect
what are the types of forebrain anomalies?
anencephaly • holoprosencephaly
what happens in anencephaly?
malformation of anterior neural tube resulting in no forebrain, open calvarium (frog like appearance)
what are the clinical findings in anencephaly?
why is there polyhydramnios in anencephaly?
no swallowing center in the brain
anencephaly is associated with what?
maternal diabetes type I
what decreases the risk of anencephaly?
what is holoprosencephaly?
failure of left and right hemispheres to separate
when does holoprosencephaly happen?
usually occurs during weeks 5-6
what is the etiology of holoprosencephaly?
complex multifactorial etiology that may be related to mutations in sonic hedgehog signaling pathway
what is the spectrum of severity of holoprosencephaly?
moderate form has celf lip/palate, most severe form results in cyclopia
what are the posterior fossa malformations?
Chiari II (Arnold-Chiari malformation) • Dandy Walker
what is an Arnold Chiari malformation?
Significant cerebellar tonsillar and vermian herniation through foramen magnum with aqueductal stenosis and hydrocephalus
Chiari II (Arnold-Chiari) malformation often presents with what?
thoraco-lumbar myelomeningocele and paralysis below the defect
what is a Dandy-Walker malformation?
Agenesis of cerebellar vermis with cystic enlargement of 4th ventricle (fills the enlarged posterior fossa)
Dandy Walker malformation is associated with what?
hydrocephalus and spina bifida
what is syringomyelia?
cystic enlargement of central canal of spinal cord
which fibers of spinal cord are damaged first in syringomyelia?
crossing fibers of spinothalamic tract
syringomyelia results in what?
cape like bilateral loss of pain and temperature sensation in upper extremities (fine touch sensation is preserved)
syringomyelia is associated with what?
Chiari I malformation
what is Chiari I malformation?
>3-5mm cerebellar tonsillar ectopia
where is syringomyelia most common?
which embryonic structures form the tongue?
1st branchial arch forms anterior 2/3 • 3rd and 4th branchial arches form posterior 1/3
muscles of the tongue are derived from what?
which nerves carry taste?
CN VII, IX, X (solitary nucleus)
which nerves carry tongue pain?
CN V3 (ant 2/3), IX, X
which nerve is responsible for motor function of tongue?
neuroectoderm gives rise to which neural tissue?
CNS neurons • ependymal cells • oligodendroglia • astrocytes
neural crest gives rise to which neural tissue?
PNS neurons • schwann cells
mesoderm gives rise to which neural tissue?
which are the signal transmitting cells of the nervous system?
how often do neurons divide?
permanent cells- do not divide in adulthood (and, as a general rule, have no progenitor stem cell population)
what are neurons?
signal relaying cells with dendrites (receive input), cell bodies, and axons (send output)
cell bodies and dendrites of neurons can be stained how?
via the Nissl substance (stains RER)
why doesn't Nissl stain the axon?
RER is not present in the axon
what happens if an axon is injured?
undergoes Wallerian degeneration- degeneration distal to the injury and axonal retraction proximally
what are the functions of astrocytes?
Physical support • repair • K+ metabolism • removal of excess neurotransmitter, maintenance of blood-brain barrier
how do astrocytes respond to injury?
what is the astrocyte marker?
what are microglia?
CNS phagocytes • Scavenger cells of CNS
what is the germ layer origin of microglia?
how do microglia stain with Nissl?
not readily discernable in Nissl stains
what is the function of microglia?
respond to tissue damage by differentiating into large phagocytic cells
what happens to microglia in HIV?
HIV-infected microglia fuse to form multinucleated giant cells in the CNS
what is the function of myelin?
Wraps and insulates axons: ↑ space constant and ↑ conduction velocity
the function of myelin results in what action?
saltatory conduction of action potentials between nodes of Ranvier, where there are high concentrations of Na + channels
what makes myelin in the CNS?
what makes myelin in the PNS?
Each oligodendrocyte myelinates how many CNS axons?
multiple (up to 50 each)
how do oligodendroglia appear in Nissl stain?
much smaller nuclei with dark chromatin and little cytoplasm
what is the predominant type of glial cell in white matter?
oligodendroglia are destroyed in which disease?
how do oligodendroglia look in H&E stain?
like fried eggs
each Schwann cell myelinates how many PNS axons?
Schwann cells also promote what?
Scwhann cells are derived from what?
Schwann cells are destroyed in which disease?
what is Acoustic neuroma?
type of Schwannoma typically located in internal acoustic meatus CNVIII
what are the 2 types of free nerve endings?
C • Aδ
what type of fibers are C fibers?
slow, unmyelinated fibers
what type of fibers are Aδ fibers?
fast, myelinated fibers
what are the locations of C fibers and Aδ fibers?
All skin, epidermis, some viscera
what are the senses carried by C fibers and Aδ fibers?
Pain and temperature
what type of fibers are Meissner's corpuscles?
Large, myelinated fibers that adapt quickly
what is the location of Meissner's corpuscles?
glabrous (hairless) skin
what are the senses carried by Meissner's corpuscles?
dynamic, fine/light touch; position sense
what type of fibers are Pacinian corpuscles?
Large, myelinated fibers
what is the location of Pacinian corpuscles?
deep skin layers, ligaments, and joints
what are the senses carried by pacinian fibers?
vibration • pressure
what type of fibers are Merkel's discs?
Large, myelinated fibers that adapt slowly
what is the location of Merkel's discs?
what are the senses carried by Merkel's discs?
Pressure, deep static touch (shapes, edges) position sense
what is the endoneurium of a peripheral nerve?
invests single nerve fiber layers
the endoneurium of peripheral nerve contains inflammatory infiltrate in which condition?
which part of the peripheral nerve forms the permeability barrier?
the perineurium of a peripheral nerve surrounds what?
a fascicle of nerve fibers
which part of a peripheral nerve must be rejoined in microsurgery for limb reattachment?
what is the epineurium of a peripheral nerve?
dense connective tissue that surrounds the entire nerve (fascicles and blood vessels)
how does NE change in disease?
↑ in anxiety • ↓ in depression
where is NE synthesized in the brain?
Locus ceruleus (pons)
how does dopamine change in disease?
↑ in schizophrenia • ↓ in Parkinsons • ↓ in depression
where is dopamine synthesized in the brain?
Ventral tegmentum and SNc (midbrain)
how does 5-HT change in disease?
↓ in anxiety • ↓ in depression
where is 5HT synthesized in the brain?
Raphe nucleus (pons)
how does ACh change in disease?
↓ in Alzheimers • ↓ in Huntingtons • ↑ in REM sleep
where is ACh synthesized in the brain?
Basal nucleus of Meynert
how does GABA change in disease?
↓ in anxiety • ↓ in Huntingtons
where is GABA made in the brain?
Functions of the Locus ceruleus?
stress and pain
functions of the nucleus accumbens and septal nucleus?
reward center • pleasure • addiction • fear
Blood brain barrier does what?
prevents circulating blood substances from reaching the CSF/CNS
blood brain barrier is formed by which 3 structures?
1. tight junctions between nonfenestrated capillary endothelial cells • 2. basement membrane • 3. astrocyte foot processes
can glucose and amino acids cross BBB?
glucose and amino acids cross slowly by carrier mediated transport mechanism
do nonpolar/lipid soluble substances cross BBB?
cross rapidly via diffusion
what are the specialized areas of the brain with fenestrated capillaries and no BBB that allow molecules in the blood to affect brain function?
area postrema- vomiting after chemo • OVLT- osmotic sensing
what are the specialized areas of the brain with fenestrated capillaries and no BBB that allow molecules in the blood to affect neurosecretory products to enter circulation?
neurohypophysis- ADH release
besides BBB what are the other notable barriers?
blood-testis barrier • maternal-fetal blood barrier of placenta
what happens when infarction and/or neoplasm destroys endothelial cell tight junctions of the BBB?
how do hypothalamic inputs and outputs get to their target?
they permeate the BBB
BBB helps prevent what?
bacterial infection from spreading into the brain • also restricts drug delivery to the brain
what are the functions of the hypothalamus?
TAN HATS: • 1. Thirst and water balance • 2. Adenohypophysis control • 3. Neurohypophysis releases hormones produced in the hypothalamus • 4. Hunger • 5. Autonomic regulation • 6. Temperature regulation • 7. Sexual urges
what are the inputs to the hypothalamus?
OVLT (senses changes in osmolarity) • area postrema (responds to emetics)
supraoptic nucleus of the hypothalamus makes what?
paraventricular nucleus of hypothalamus makes what?
Lateral area of hypothalamus controls what?
destruction of lateral area of hypothalamus → what?
anorexia, failure to thrive
lateral area of the hypothalamus is inhibited by what?
ventromedial area of the hypothalamus controls what?
what can destroy the ventromedial nucleus of the hypothalamus?
destruction of the ventromedial area of the hypothalamus leads to what?
ventromedial area of the hypothalamus is stimulated by what?
anterior nucleus of hypothalamus controls what?
posterior nucleus of hypothalamus controls what?
the suprachiasmatic nucleus of the hypothalamus controls what?
posterior pituitary receives hypothalamic axonal projections from where?
supraoptic (ADH) and paraventricular (oxytocin) nuclei
what is the function of the thalamus?
major relay for all ascending sensory information except olfaction
what is the input to the VPL nucleus of the thalamus?
spinothalamic and dorsal columns/medial lemniscus
what is the info conveyed via the VPL of the thalamus?
pain and temperature; • pressure, touch, vibration, and proprioception
what is the destination of the information conveyed via the VPL nucleus of the thalamus?
1° somatosensory cortex
what is the input to the VPM nucleus of the thalamus?
trigeminal and gustatory pathway
what is the info conveyed via the VPM nucleus of the thalamus?
face sensation and taste
what is the destination of the information conveyed by the VPM nucleus of the thalamus?
1° somatosensory cortex
what is the input to the LGN of the thalamus?
what is the info conveyed via the LGN of the thalamus?
what is the destination of the info conveyed by the LGN of the thalamus?
what is the input to the MGN of the thalamus?
superior olive and inferior colliculus of tectum
what is the info conveyed by the MGN of the thalamus?
what is the destination of the info conveyed by the MGN of the thalamus?
auditory cortex of the temporal lobe
what is the input to the VL nucleus of the thalamus?
what is the info conveyed via the VL nucleus of the thalamus?
what is the destination of the info conveyed via the VL nucleus of the thalamus?
what is the limbic system?
collection of neural structures involved in emotion, long-term memory, olfaction, behavior modulation, ANS function
limbic system structures include what?
hippocampus • amygdala • fornix • mammillary bodies • cingulate gyrus
limbic system is responsible for what?
Feeding • Fleeing • Fighting • Feeling • Sex
cerebellum modulates what?
movement; aids in coordination and balance
what is the input to the cerebellum?
1. contralateral cortex via middle cerebellar peduncle • 2. ipsilateral proprioceptive information via inferior cerebellar peduncle from the spinal cord (input nerves=climbing and mossy fibers)
what is the output from the cerebellum?
1. purkinje fibers to deep nuclei • 2. sends information to contralateral cortex to modulate movement
what are the features of the system of output nerves emerging from the cerebellum?
output nerves= purkinje fibers send information to deep nuclei of cerebellum, which in turn sends information to the contralateral cortex via the superior cerebellar peduncle
what are the deep nuclei of the cerebellum lateral → medial?
Dentate • Emboliform • Globose • Fastigial • (don't eat greasy foods)
function of lateral cerebellar nuclei?
voluntary movement of extremities
function of the medial nuclei of cerebellum?
balance, truncal coordination
what happens when lateral nuclei of cerebellum are injured?
propensity to fall toward injured (ipsilateral) side
basal ganglia are important in what?
voluntary movements and making postural adjustments
basal ganglia do what?
receives cortical input and provides negative feedback to cortex to modulate movement
what makes up the Striatum?
putamen (motor) + caudate (cognitive)
what makes up the lentiform nucleus?
putamen + globus pallidus
what happens in the excitatory pathway of basal ganglia?
cortical inputs stimulate the striatum, stimulating the release of GABA, which disinhibits the thalamus via the Globus pallidus internus/Substantia Nigra reticulata (↑ motion)
what happens in the inhibitory pathway of basal ganglia?
cortical inputs stimulate the striatum, which disinhibits Subthalamic nucleus via Globus pallidus externus and STN stimulates GPi/SNr to inhibit the thalamus (↓ motion)
what are the effects of dopamine in the basal ganglia?
Dopamine binds to D1 receptors, stimulating the excitatory pathway, and to D2, inhibiting the inhibitory pathway → ↑ motion
what is PArkinson's disease?
degenerative disorder of the CNS associated with Lewy bodies and loss of dopaminergic neurons of the substantia nigra pars compacta
Lewy bodies in Parkinson's disease are composed of what?
α-synuclein- intracellular inclusion
what happens to your body in Parkinsons?
it becomes a TRAP • Tremor at rest • cogwheel Rigidity • Akinesia • Postural instability
what is the inheritance of Huntington's disease?
what causes Huntington's?
trinucleotide repeats • CAG • Caudate loses ACh and GABA
Huntington's is characterized by what?
chorea, agression, depression, and dementia (sometimes initially mistaken for substance abuse)
Neuronal death in Huntingtons is via what?
NMDA-R binding and glutamate toxicity
what can be seen on imaging in huntingtons?
atrophy of striatal nuclei (main inhibitors of movement)
what is the presentation of hemiballismus?
sudden, wild flailing of 1 arm +/- ipsilateral leg
what is the characteristic lesion causing hemiballismus?
contralateral subthalamic nucleus (e.g. lacunar stroke)
what is the presentation of Chorea?
sudden, jerky, purposeless movements
what is the characteristic lesion causing chorea?
Basal ganglia (e.g. Huntington's)
what is the presentation of athetosis?
slow writhing movements; epecially seenin fingers • writhing snake like movement
what is the characteristic lesion causing athetosis?
Basal ganglia (e.g. huntingtons)
what is the presentation of myoclonus?
sudden, brief, uncontrolled muscle contraction
what is the typical picture of myoclonus?
jerks; hiccups; common in metabolic abnormalities such as renal and liver failure
what is the presentation of dystonia?
sustained, involuntary muscle contractions
what are the typical pictures of dystonia?
writer's cramp; • blepharospasm (sustained eyelid twitch)
what is the presentation of essential tremor (postural tremor)?
action tremor; exacerbated by holding posture/limb position
what causes essential tremor?
patients with essential tremor typically self medicate with what?
alcohol, decreases tremor amplitude
what is the treatment for essential tremor?
β blockers, primidone
what is the presentation of Resting tremor?
uncontrolled movement of distal appendages (most noticeable in hands); tremor alleviated by intentional movement
what is the characteristic lesion causing resting tremor?
what is the presentation of intention tremor?
slow, zigzag motion when pointing/extending toward a target
what is the characteristic lesion causing intention tremor?
lower extremity deficit in sensation or movement may indicate involvement of what?
anterior cerebral artery
what are the consequences of a bilateral lesion of the amygdala?
what are the clinical features of Kluver-Bucy syndrome?
hyperorality • hypersexuality • disinhibited behavior
Kluver-Bucy syndrome is associated with what?
what are consequences of frontal lobe lesions?
disinhibition and deficits in concentration, orientation, and judgement; • may have reemergence of primitive reflexes
what is the consequence of a lesion in the right parietal lobe?
spatial neglect syndrome (agnosia of the contralateral side of the word)
what are the consequences of a lesion to the reticular activating system (midbrain)?/
reduced levels of arousal and wakefulness (coma)
what are the consequences of bilateral lesion to the mamillary bodies?
what are the clinical features of Wernicke-Korsakoff syndrome?
confusion, ophthalmoplegia, ataxia; memory loss (anterograde and retrograde amnesia), confabulation, personality changes
Wernicke Korsakoff syndrome is associated with what?
thiamine deficiency and excessive EtOH use
how can Wernicke Korsakoff syndrome be precipitated?
giving glucose without B1 to a B1 deficient patient
what are the consequences of a basal ganglia lesion?
may result in tremor at rest, chorea, or athetosis
what are the consequences of a lesion in the cerebellar hemisphere?
intention tremor • limb ataxia • damage →ipsilateral deficit. fall toward side of lesion
what are the consequences of a lesion to the cerebellar vermis?
truncal ataxia, dysarthria
what is the difference between lesions to the cerebellar hemispheres and cerebellar vermis?
cerebellar hemispheres are laterally located- affect lateral limbs • vermis is centrally located- affects central body
what are the consequences of a lesion to the subthalamic nucleus?
what are the consequences of a lesion to the hippocampus ?
what are the consequences of a lesion to the paramedian pontine reticular formation?
eyes look away from the lesion
what are the consequences of a lesion to the frontal eye fields?
eyes look toward lesions
what are the clinical features of central pontine myelisnosis?
acute paralysis • dysarthria • dysphagia • diplopia • loss of consciousness
central pontine myelinosis can cause what?
locked in syndrome
what is central pontine myelinosis?
massive axonal demyelination in pontine white matter tracts
what causes central pontine myelinosis?
commonly iatrogenic, caused by overly rapid correction of Na levels
what is aphasia?
higher order inability to speak (language deficit)
what is dysarthria?
motor inability to speak (movement deficit)
what is Broca's aphasia?
nonfluent aphasia with intact comprehension
where is Broca's area?
inferior frontal gyrus of frontal lobe
what is Wernicke's aphasia?
fluent aphasia with impaired comprehension
where is Wernicke's area?
superior temporal gyrus of temporal lobe
what is global aphasia?
nonfluent aphasia with impaired comprehension
what areas are affected in global aphasia?
both Broca's and Wernicke's
what is conduction aphasia?
poor repetition but fluent speech, intact comprehension
conduction aphasia can be caused by what?
damage to arcuate fasciculus
anterior cerebral artery supplies what?
anteromedial surface of cortex
middle cerebral artery supplies what?
lateral surface of cortex
posterior cerebral artery supplies what?
posterior and inferior surface of cortex
where are the watershed zones in cerebral circulation?
between anterior cerebral/middle cerebral, posterior cerebral/middle cerebral arteries
watershed areas of cerebral circulation are damaged in what?
consequences for the watershed areas of cerebral circulation of severe hypotension?
upper leg/upper arm weakness, defects in higher-order visual processing
cerebral perfusion is primarily driven by what?
what is the effect of therpeutic hyperventilation on brain?
↓pCO2 helps ↓ICP in cases of acute cerebral edema (stroke, trauma) via decreasing cerebral perfusion
what are the vessels of the anterior circulation of the brain?
MCA • ACA • Lateral striate artery
what is the functional distribution of the areas supplied by the MCA?
1. Motor cortex- upper limb and face • 2. Sensory cortex- upper limb and face • 3. Temporal lobe (Wernicke's area); frontal lobe (broca's area)
what are the symptoms of a stroke to the motor cortex supplied by the MCA?
contralateral paralysis- upper limb and face
what are the symptoms of a stroke to the sensory cortex supplied by the MCA?
contralateral loss of sensation- upper limb and face
what are the symptoms of stroke to the temporal lobe and/or frontal lobe supplied by the MCA?
aphasia fi in dominant (usually left) hemisphere. • hemineglect if lesion affects nondominant (usually right) side
what are the functional distributions of the areas supplied by the ACA?
1. Motor cortex-lower limb • 2. Sensory cortex- lower limb
what are the symptoms of a stroke affecting the area of the motor cortex supplied by the ACA?
contralateral paralysis- lower limb
what are the symptoms of a stroke affecting the area of the sensory cortex supplied by the ACA?
contralateral loss of sensation- lower limb
what are the structures that are supplied by the lateral striate artery?
striatum • internal capsule
what are the symptoms of a stroke to the area supplied by the lateral striate artery?
striatum, internal capsule→ contralateral hemiparesis/hemiplegia
what are the strokes common to the area supplied by the lateral striate artery?
striatum and internal capsule are common locations of lacunar infarcts, 2° to unmanaged hypertension
what is ACA?
anterior cerebral artery
what is AComm?
Anterior Communicating Artery
what is AICA?
Anterior Inferior Cerebellar artery
what is MCA?
middle cerebral artery
what is PCA?
Posterior cerebral artery
what is PComm?
posterior communicating artery
what is PICA?
posterior inferior cerebellar artery
what are the arteries of the posterior circulation of the brain?
ASA • PICA • AICA • PCA
what are the structures supplied by the anterior spinal artery (ASA) that are vulnerable to stroke?
1. Lateral corticospinal tract • 2. Medial lemniscus • 3. Caudal medulla- hypoglossal nerve
what are the symptoms of an ASA stroke of the lateral corticospinal tract?
contralateral hemiparesis- lower limbs
what are the symptoms of an ASA stroke in the medial lemniscus?
what are the symptoms of an ASA stroke in the caudal medulla- hyposglossal nerve?
inpsilateral hypoglossal dysfunction (tongue deviates ipsilaterally)
what is the relative side frequency of ASA strokes?
Medial medullary syndrome is caused by what?
infarct of paramedian branches of ASA and vertebral arteries
what are the structures supplied by the PICA that are vulnerable to stroke?
Lateral Medulla- • - vestibular nuclei • - lateral spinothalamic tract • - spinal trigeminal nucleus • - nucleus ambiguus • - sympathetic fibers • - inferior cerebellar peduncle
what are the symptoms of a PICA stroke in the lateral medulla?
1. vomiting • 2. vertigo • 3. ↓ pain and temperature sensation to limbs/ face • 4. dysphagia • 5. hoarseness • 6. ↓ gag reflex • 7. ipsilateral horner's syndrome • 8. ataxia • 9. dysmetria
what is the name of the disease state caused by PICA stroke to lateral medulla?
Lateral medullary (Wallenberg's) syndrome
which symptoms are specific to a PICA lesion?
nucleus ambiguus effects: • "Don't pick a (PICA) horse (hoarseness) that can't eat (dysphagia)"
what are structures supplied by the AICA that are vulnerable to stroke?
1. Lateral pons- cranial nerve nuclei; vestibular nuclei, facial nucleus, spinal trigeminal nucleus, cochlear nuclei, sympathetic fibers • 2. middle and inferior cerebellar peduncles
what are the symptoms of AICA stroke in the lateral pons?
1. vomiting • 2. vertigo • 3. nystagmus • 4. paralysis of face • 5. ↓ lacrimation, salivation • 6. ↓ taste from anterior 2/3 of tongue • 7. ↓ corneal reflex • 8. Face- ↓ pain & temperature sensation • 9. Ipsilateral ↓ hearing • 10. ipsilateral horner's syndrome
what are the symptoms of AICA stroke in the middle and inferior cerebellar peduncles?
ataxia • dysmetria
what is the name of the disease state caused by a stroke of the AICA?
lateral pontine syndrome
which symptoms are specific to AICA lesions?
facial nucleus effects • "Facial droop means AICA's pooped"
what are the structures supplied by the PCA that are vulnerable to stroke?
occipital cortex • visual cortex
what are the symptoms of a PCA stroke in the occipital cortex, visual cortex?
contralateral hemianopia with macular sparing
what are the communicating arteries of the brain circulation?
AComm • PComm
lesions of AComm are typically what?
aneurysms not strokes
AComm is a commone site of what lesions?
saccular (berry) aneurysm
saccular (berry) aneurysm of AComm → what?
impingement on cranial nerves
symptoms of a berry aneurysm of AComm?
visual field defects
lesions of PComm are typically what?
aneurysms, not strokes
PComm is a common site of what lesion?
saccular (berry) aneurysm
what are the symptoms of PComm berry aneurysm?
CNIII palsy- eye is down and out with ptosis and pupil dilation
berry aneurysms occur where?
at the bifurcations in the circle of Willis
most common site of berry aneurysm?
bifurcation of AComm
what is the most common complication of berry aneurysm?
rupture of berry aneurysm leads to what?
SAH or hemorrhagic stroke
rupture of berry aneurysm can cause which symptoms?
bitemporal hemianopia via compression of optic chiasm
berry aneurysms are associated with what?
ADPKD • ED • Marfan's syndrome
other risk factors for berry aneurysm include what?
advanced age • htn • smoking • black race
Charcot-Bouchard microanerysm is associated with what?
charcot-bouchard microanerysm affects what?
small vessels in basal ganglia, thalamus
what causes epidural hematoma?
rupture of middle meningeal artery (branch of maxillary artery), often 2° to fracture of temporal bone
how does epidural hematoma present clinically?
lucid interval→ • rapid expansion under systemic arterial pressure → transtentorial herniation, CNIII palsy
CT scan of epidural hematoma shows what?
biconvex (lentiform), hyperdense blood collection not crossing suture lines. • Can cross falx, tentorium
what causes subdural hematoma?
rupture of bridging veins
how does subdural hematoma present clinically?
slow venous bleeding (less pressure= hematoma develops over time)
subdural hematoma is seen in whom?
elderly individuals • alcoholics • blunt trauma • shaken baby
predisposing factors to subdural hematoma include what?
brain atrophy • shaking • whiplash
how does subdural hematoma look on CT?
crescent shaped hemorrhage that crosses suture lines. midline shift. Cannot cross falx, tentorium
what causes subarachnoid hemorrhage?
rupture of an aneurysm (such as a berry [saccular] aneurysm, as seen in Marfan's, ED, ADPKD) or an AVM
what is the clinical presentation of subarachnoid hemorrhage?
rapid time course • WHOML • bloody or yellow spinal tap
risk 2 or 3 days after SAH?
risk of vasospasm due to blood breakdown (not visible on CT, treat ith nimodipine) and rebleed (visible on CT)
Intraparenchymal hemorrhage is most commonly caused by what?
intraparenchymal hemorrhage is also seen with what?
amyloid angiopathy • vasculitis • neoplasm
where does intraparenchymal hemorrhage typically occur?
in basal ganglia and internal capsule (Charcot-Bouchard aneurysm of lenticulostriate vessels), but can be lobar
in ischemic brain disease/stroke irreversible damage begins when?
after 5 minutes of hypoxia
which parts of the brain are most vulnerable to ischemic brain disease/stroke?
hippocampus • neocortex • cerebellum • watershed areas
what are the findings in the different stages of the progression of irreversible neuronal injury?
1. red neurons (12-48 h) • 2. necrosis and neutrophils (24-72h) • 3. macrophages (3-5 days) • 4. reactive gliosis and vascular proliferation (1-2 weeks) • 5. glial scar (>2weeks)
how does stroke look on diffusion weighted MRI?
bright in 3-30min and stays bright for 10 days
how does stroke look on noncontrast CT?
dark in ~24 h
in stroke, bight areas on noncontrast CT indicate what?
hemorrhage (tPA contraindicated)
what does atherosclerosis do to the brain?
thrombi lead to ischemic stroke with subsequent necrosis→ cystic cavity with reactive gliosis
what happens in hemorrhagic stroke?
intracerebral bleeding, often due to hypertension, anticoagulation, and cancer (abnormal vessels can bleed).
hemorrhagic stroke can be secondary to what?
ischemic stroke followed by reperfusion (↑ vessel fragility)
what happens in ischemic stroke?
atherosclerotic emboli block large vessels
etiologies of ischemic stroke include what?
atrial fibrillation • carotid dissection • patent foramen ovale • endocarditis
lacunar strokes block what?
lacunar strokes may be 2° to what?
what is the treatment for ischemic stroke?
tPA within 4.5 hours (so long as patient presents within 3 hours of onset and there is no major risk of hemorrhage)
what is a transient ischemic attack?
Brief, irreversible episode of focal neurologic dysfunction typically lasting < 1 hour without acute infarction (-) MRI
;deficits in TIA are due to what?
what are dural venous sinuses?
large venous channels that run through the dura
what do dural venous sinuses do?
drain blood from cerebral veins and receive CSF from arachnoid granulations
dural venous sinuses empty into where?
what is the main location of CSF return via arachnoid granulations?
superior sagital sinus
Inferior sagital sinus drains to what?
superior sagital sinus drains to what?
typically becomes right transverse sinus or confluence of sinuses
straight sinus drains to what?
typically becomes left transverse sinus or confluence of sinuses
occipital sinus drains to what?
confluence of sinuses
confluence of sinuses drain to what?
right and left transverse sinuses
sphenoparietal sinuses drain to what?
lateral ventricles drain to what?
3rd ventricle via right and left intraventricular foramina of Monro
3rd ventricle drains to what?
4th ventricle via cerebral aqueduct of Sylvius
4th ventricle drains to what?
subarachnoid space via: • foramina of Lushka= Lateral • foramen of Magendie= medial
CSF is made by what?
ependymal cells of choroid plexus
CSF is reabsorbed by what?
arachnoid granulations and then drains into dural venous sinuses
what are the 3 types of nonobstructive hydrocephalus?
1. Communicating hydrocephalus • 2. Normal pressure hydrocephalus • 3. Hydrocephalus ex vacuo
what happens in communicating hydrocephalus?
↓ CSF absorption by arachnoid granulations
Communicating hydrocephalus can lead to what?
↑ ICP, papilledema, herniation (e.g. arachnoid scarring post-meningitis)
normal pressure hydrocephalus results in what?
↑subarachnoid space volume but no increase in CSF pressure
in normal pressure hydrocephalus, expansion of ventricles does what?
distorts the fibers of the corona radiata and leads to the clinical triad of urinary incontinence, ataxia, cognitive dysfunction (sometimes reversible)
what is hydrocephalus ex vacuo?
appearance of ↑ CSF in atrophy (e.g. AD, HIV, Pick's disease)