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Neuroanatomy and Neurophysiology: Key Concepts and Clinical Applications, Study Guides, Projects, Research of Neurology

Kansas Wesleyan University (KWU)Neurology

A comprehensive overview of key concepts in neuroanatomy and neurophysiology, covering topics such as brain structures, neuronal function, neurotransmitters, and clinical conditions. It includes detailed explanations, diagrams, and clinical examples, making it a valuable resource for students and professionals in the field.

Typology: Study Guides, Projects, Research

2023/2024

Available from 10/31/2024

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USMLE STEP 1 Neurology
Exam Review 2023
The notochord induces what to differentiate into what? - Answer-Induces overlying
ECTODERM to differentiate into NEUROECTODERM and form NUERAL PLATE
Neural plate then gives rise to? - Answer-Neural tube and neural crest cells
Notochord becomes what? - Answer-Nucleus pulposus of the intervertebral disks in
adults
Alar Plate - Answer-Dorsal [Sensory]
Same orientation as spinal cord
Basal Plate - Answer-Ventral [Motor]
Same orientation as the spinal cord
How does FGF affect chordin and noggin? - Answer-FGF regulates chordin and noggin
to down regulate BMP which leads to neural plate induction
Three Primary Vesicles - Answer-1. Forebrain [Prosencephalon]
2. Midbrain [Mesencephalon]
3. Hindbrain [Rhombencphaln]
The Forebrain gives rise to: - Answer-1. Telencephalon [Cerebral hemispheres, lateral
ventricles]
2. Diencephalon [Thalamus, Third Ventricle]
The Midbrain gives rise to: - Answer-1. Mesencephalon [Midbrain, aqueduct]
The Hindbrain gives rise to: - Answer-1. Metencephalon [Pons, cerebellum, upper part
of the fourth ventricle]
2. Myelencephalon [Medulla, Lower part of the fourth ventricle]
CNS/PNS Origins - Answer-Neuroectoderm = CNS neurons, ependymal cell [Inner
lining of ventricles, makes CSF], oligodendrocytes, astrocytes
Neural crest cells = PNS, schwann cells
Mesoderm = Microglia [Like Macrophages, originate from Mesoderm]
Neural tube defects - Answer-NEUROPORES fail to fuse [4th week] → Persistent
connection between amniotic cavity and spinal canal
Associated with:
1. Low folate levels before conception and during pregnancy
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USMLE STEP 1 Neurology

Exam Review 2023

The notochord induces what to differentiate into what? - Answer-Induces overlying ECTODERM to differentiate into NEUROECTODERM and form NUERAL PLATE Neural plate then gives rise to? - Answer-Neural tube and neural crest cells Notochord becomes what? - Answer-Nucleus pulposus of the intervertebral disks in adults Alar Plate - Answer-Dorsal [Sensory] Same orientation as spinal cord Basal Plate - Answer-Ventral [Motor] Same orientation as the spinal cord How does FGF affect chordin and noggin? - Answer-FGF regulates chordin and noggin to down regulate BMP which leads to neural plate induction Three Primary Vesicles - Answer-1. Forebrain [Prosencephalon]

  1. Midbrain [Mesencephalon]
  2. Hindbrain [Rhombencphaln] The Forebrain gives rise to: - Answer-1. Telencephalon [Cerebral hemispheres, lateral ventricles]
  3. Diencephalon [Thalamus, Third Ventricle] The Midbrain gives rise to: - Answer-1. Mesencephalon [Midbrain, aqueduct] The Hindbrain gives rise to: - Answer-1. Metencephalon [Pons, cerebellum, upper part of the fourth ventricle]
  4. Myelencephalon [Medulla, Lower part of the fourth ventricle] CNS/PNS Origins - Answer-Neuroectoderm = CNS neurons, ependymal cell [Inner lining of ventricles, makes CSF], oligodendrocytes, astrocytes Neural crest cells = PNS, schwann cells Mesoderm = Microglia [Like Macrophages, originate from Mesoderm] Neural tube defects - Answer-NEUROPORES fail to fuse [4th week] → Persistent connection between amniotic cavity and spinal canal Associated with:
  5. Low folate levels before conception and during pregnancy
  1. ↑ a-fetoprotein levels [AFP] in amniotic and maternal serum
  2. ↑ AChE in amniotic fluid [Helpful confirmatory test] -- Fetal AChe in CSF transudates across defect into amniotic fluid Spina bifida occulta - Answer-Failure of bony spinal canal to close, NO STRUCTURAL HERNIATION Usually seen at lower vertebral levels DURA INTACT Associated w/ tuft of hair or skin dimple at level of bony defect NORMAL AFP Meningocele - Answer-Meninges [BUT NO NEURAL TISSUES] herniates through bony defect Meningomyelocele - Answer-Meninges and neural tissue herniate through bony defect Associated w/ Arnold-Chiari Type II Malformation Anencephaly - Answer-Malformation of the ANTERIOR NEURAL TUBE →
  3. No forebrain
  4. Open calvarium Clinical Findings:
  5. ↑ a-fetoprotein levels [AFP]
  6. Polyhydramnios [No swallowing center in brain]
  7. Associated w/ MATERNAL TYPE I DIABETES
  8. Maternal folate supplementation ↓ risk Holoprosencephaly - Answer-Failure of LEFT AND RIGHT HEMISPHERES TO SEPARATE Usually occurs during the 5th and 6th week May be related to mutations in the SONIC HEDGEHOG signaling pathway Moderate form = Cleft lip/palate Severe form = Cyclopia Seen in:
  9. PATAU SYNDROME
  10. FETAL ALCOHOL SYNDROME Chiari Type II Malformation - Answer-Posterior fossa malformation Significant HERNIATION of the CEREBELLAR TONSILS and VERMIS through FORAMEN MAGNUM with AQUEDUCTAL STENOSIS and HYDROCEPHALUS Patients often present w/:
  11. Lumbosacral meningomyelocele
  12. Paralysis below the defect Dandy-Walker Malformation - Answer-AGENESIS of CEREBELLAR VERMIS with CYSTIC ENLARGEMENT of the 4th ventricle Fills enlarged posterior fossa

Loss of Nissle substance indicates - Answer-Irreversible hypoxic damage = Red neuron Injury to axon results in what? - Answer-Wallerian degeneration →

  1. Degeneration distal to the injury
  2. Axonal retraction proximally
  3. Allows for regeneration of axon [If in PNS] Astrocytes - Answer-Functions:
  4. Physical support
  5. Repair
  6. K+ metabolism
  7. Removal of excess neurotransmitter
  8. Component of the blood brain barrier via foot process interaction w/ perivascular space
  9. Glycogen fuel reserve buffer
  10. Reactive gliosis in response to neural injury
  11. DERIVED FROM NEUROECTODERM Astrocyte Marker - Answer-GFAP Microglia - Answer-Phagocytic scavenger cells of CNS [Mesodermal, mononuclear origin] Activated in response to tissue damage NOT READILY DISCERNIBLE BY NISSL stain HIV-INFECTED MICROGLIA FUSE TO FORM MULTINUCLEATED GIANT CELLS IN CNS Myelin - Answer-↑ Conduction velocity of signals transmitted down axons → Saltatory conduction of action potential at nodes of Ranvier [HIGH CONCENTRATIONS of Na+ channels] CNS = Oligodendrocyte [Single sheath, 50 axons] PNS = Schwann cells [Single sheath, single axon] Wraps and insulates axons ↑ Space constant and ↑ Conduction velocity Schwann cells - Answer-Each Schwann cells myelinates only 1 PNS aon Also promotes axonal regeneration Derived from NEURAL CREST ↑ Conduction velocity of signals transmitted down axons → Saltatory conduction of action potential at nodes of Ranvier [HIGH CONCENTRATIONS of Na+ channels] May be INJURED IN GUILLAIN-BARRE SYNDROME

Acoustic Schwannoma - Answer-Typically located in the internal acoustic meatus [CN VIII] If BILATERAL, strongly associated with NEUROFIBROMATOSIS TYPE 2 Oligodendroglia - Answer-Myelinated axons of neurons in CNS Each oligodendrocyte can myelinate ~30 axons PREDOMINANT TYPE OF GLIAL CELL IN WHITE MATTER Derived from NEUROECTODERM FRIED EGG appearance histologically Injured in:

  1. Multiple Sclerosis
  2. Multifocal progressive leukoencephalopathy [PML]
  3. Leukodystrophies Free nerve endings - Answer-C = Slow, unmyelinated fibers Aδ = Fast, myelinated fibers Location: All skin, epidermis, some viscera Sense: Pain, temperature Meissner Corpuscles - Answer-Large myelinated fibers, adapt quickly Location: Glabrous [Hairless] skin Senses: Dynamic, light touch/position sense Pacinian Corpuscles - Answer-Large, myelinated fibers, adapt quickly Location: Deep skin layers, ligaments, joints Senses: Vibration, pressure Merkel Discs - Answer-Large, myelinated fibers, adapt quickly Location: Fingertips, superficial skin Senses: Pressure, deep static touch [Shapes, edges], position sense Ruffini Corpuscles - Answer-Dendritic endings w/ CAPSULE ADAPT SLOWLY Location: Fingertips and joints Senses: Pressure, slippage of objects along surface of skin, joint angle change Endoneurium - Answer-Invests single nerve fiber layers [INFLAMMATORY INFILTRATE IN GUILLAIN BARRE SYNDROME] Inner Perineurium - Answer-PERMEABILITY BARRIER Surrounds fascicle of nerve fibers MUST BE REJOINED IN MICROSURGERY FOR LIMB REATTACHMENT

Infarction and/or neoplas destroys what to cause vasogenic edema? - Answer- Endothelial tight junction → vasogenic edema Blood barriers: - Answer-1. Blood brain barrier

  1. Blood testis barrier
  2. Maternal-fetal blood barrier of placenta Hypothalamus - Answer-Wears TAN HATS
  3. Thirst and water balance
  4. Adenohypophysis control [Regulates anterior pituitary]
  5. Neurohypophysis [Releases hormones in hypothalamus]
  6. Hunger
  7. Autonomic regulation
  8. Temperature
  9. Sexual urges Inputs [AREAS NOT PROTECTED BY BBB]
  10. OVLT = Organum vasculosum of the lamina terminalis -- Senses changes in osmolality
  11. Area Postrema [Responds to emetics] Vasopressin [ADH] is produced where? - Answer-Supraoptic nucleus of the hypothalamus Oxytocin is produced where? - Answer-Paraventricular nucleus Lateral Area of the Hypothalamus - Answer-1. Hunger
  12. Destruction → Anorexia, failure to thrive
  13. INHIBITED BY LEPTIN If you zap your lateral, you shrink laterally Ventromedial Area of the Hypothalamus - Answer-1. Satiety
  14. Destruction [Craniopharyngioma] → Hyperphagia
  15. STIMULATED BY LEPTIN Anterior Hypothalamus - Answer-Cooling, parasympathetic A/C = Anterior, cooling Posterior Hypothalamus - Answer-Heating, sympathetic If you zap your Posterior hypothalamus, you become a Poikilothermic [Cold-blooded, like a snake] Suprachiasmatic Nucleus - Answer-CIRCADIAN RHYTHMS You sleep to be charismatic

Sleep cycle is regulated by what? - Answer-Sleep cycle is regulated by the circadian rhythm [Driven by the suprachiasmatic nucleus of the hypothalamus] SCN is regulated by the environment [Light] Circadian rhythms control nocturnal release of what? - Answer-1. ACTH

  1. Prolactin
  2. Melatonin
  3. Norepinephrine SCN → Norepinephrine release → Pineal Gland → Melatonin Two Stages of Sleep: - Answer-1. Rapid-eye movement [REM] and non-REM -- Extraocular movements during REM sleep due to activity of the PPRF [Paramedian pontine reticular formation/conjugate gaze center] -- Occurs every 90 minutes, duration ↑ throughout the night At night, BATS, Drink Blood Awake [Eyes open] = Beta Awake [Eyes closed] = Alpha Non-REM N1 =Theta Non-REM N2 = Spindle and K complex Non-REM N3 = Delta REM = Beta What is associated w/ ↓ REM sleep and delta wave sleep? - Answer-1. Alcohol
  4. Benzodiazepines
  5. Barbiturates
  6. Norepinephrine Treatment for bedwetting [Enuresis] - Answer-Oral desmopressin [ADH analog] Preferred over imipramine [Due to adverse effects] Treatment for night terrors and sleep-walking - Answer-Benzodiazepine Awake [Eye's open] - Answer-Alert, active mental concentration Beta [Highest frequency, lowest amplitude] Awake [Eye's closed] - Answer-Alpha waves Non-REM Sleep: Stage N1 [5%] - Answer-Light sleep Theta waves Non-REM Sleep: Stage N2 [45%] - Answer-Deeper sleep, when bruxism occurs Sleep spindles and K complexes
  1. ANS function STRUCTURES:
  2. Hippocampus
  3. Amygdala
  4. Fornix
  5. Mammillary bodies
  6. Cingulate gyrus RESPONSIBLE FOR [5 F's]:
  7. Feeding
  8. Fleeing
  9. Fightin
  10. Feeling
  11. Sex Osmotic Demyelination Syndrome [Central pontine myelinolysis] - Answer-Clinical Manifestations:
  12. Acute paralysis
  13. Dysarthria
  14. Dysphagia
  15. Diplopia
  16. LOC
  17. Can cause locked-in syndrome MASSIVE AXONAL DEMYELINATION IN PONTINE WHITE MATTER 2° to osmotic changes [Commonly iatrogenic, can be due to overly rapid correction of hyponatremia] -- Results in cerebral edema/herniation Correcting serum Na+ too fast:
  18. From low to high, your pons will die! [Osmotic Demyelination Syndrome]
  19. From high to low, your brains will blow! [Cerebral edema/herniation] Cerebellum - Answer-Modulates movement, aids in coordination and balance Input:
  20. Contralateral cortex via middle cerebellar peduncle
  21. Ipsilateral proprIoceptive Information via Inferior cerebellar peduncle from spInal cord Output:
  22. Sends information to the contralateral cortex to modulate movement -- Output nerves = Purkinje cells → Deep nuclei of the cerebellum → Contralateral cortex via superior cerebellar peduncle Deep nuclei [Lateral to medial] = Don't Eat Greasy Foods
  23. Dentate
  24. Emboliform
  1. Globose
  2. Fastigial Lateral Lesions to the Cerebellum - Answer-Voluntary movement of extremities PROPENSITY TO FALL TOWARD IPSILATERAL SIDE Medial Lesions to the Cerebellum - Answer-Lesions involving midline structures [Vermal cortex, fastigial nuclei] and/or flocculonodular lobe →
  3. Truncal ataxia [Wide-based cerebellar gait]
  4. Nystagmus
  5. Head tilting
  6. Generally, midline lesions result in BILATERAL MOTOR DEFICITS affect AXIAL and PROXIMAL LIMB MUSCULATURE Basal Ganglia - Answer-Important in voluntary movements and making postural adjustments Receives cortical input, provides negative feedback to cortex to modulate movement Striatum = Putamen [Motor] + Caudate [Cognitive] Lentiform = Putamen + Globus pallidus D1 receptor = DIrect pathway Indirect = Inhibitory Excitatory pathway in the basal ganglia - Answer-Cortical inputs stimulate striatum, stimulating release of GABA [Disinhibits the thalamus via the GPi/SNr] = ↑ Motion Inhibitory pathway in the basal ganglia - Answer-Cortical inputs stimulate the striatum [Disinhibits STN via GPe, STN stimulates GPi/SNr to inhibit thalamus] = ↓ Motion Dopamine binds to what in the basal ganglia - Answer-D1 receptors stimulating the excitatory [Direct pathways] D2 inhibiting the inhibitory pathway → ↑ Motion Athetosis - Answer-Slow, writhing movements, ESPECIALLY SEEN IN FINGERS Locations of Lesion: Basal ganglia [Huntington] WRITHING, SNAKE-LIKE MOVEMENT Chorea - Answer-Sudden, jerky, purposeless movements Location of Lesion: Basal ganglia [Huntington] CHOREA = Dance-like Dystonia - Answer-Sudden, involuntary muscle contractions Example: Writer's cramp
  1. ↓ ACh
  2. ↓ GABA Neuronal cell death via NMDA-R binding and GLUTAMATE TOXICITY ATROPHY OF CAUDATE NUCLEI w/ ex vacuo DILATION OF FRONTAL HORNS Cerebral Cortex - Answer- Aphasia - Answer-Higher-order inability to speak [Language deficit] Dysarthria - Answer-Motor inability to speak [Movement deficit] Broca's Area - Answer-NONFLUENT aphasia Intact comprehension with IMPAIRED REPETITION INFERIOR FRONTAL GYRUS OF FRONTAL LOBE Wernicke' Area - Answer-FLUENT aphasia with IMPAIRED COMPREHENSION and REPETITION SUPERIOR TEMPORAL GYRUS OF TEMPORAL LOBE Wernick is Wordy but makes no sense Conduction Aphasia - Answer-Poor repetition but fluent speech, INTACT COMPREHENSION Caused by damage to the arcuate fasciculus Can't repeat phrases like "NO, IFS, ANDS, or BUTS" Global - Answer-NONFLUENT APHASIA WITH IMPAIRED COMPREHENSION Arcuate fasciculus, Broca's, and Wernicke's areas affected Transcortical motor - Answer-Nonfluent aphasia with good comprehension and intact repetition Transcortical sensory - Answer-Poor comprehension with fluent speech and intact repetition Mixed transcortical - Answer-Nonfluent speech, poor comprehension, INTACT REPEPTITON Amygdala Lesion [Bilateral] - Answer-Kluver-Bucy Syndrome = Disinhibited behavior [Hyperphagia, hypersexuality, hyperorality] Associated w/ HSV- 1 Frontal lobe Lesion - Answer-Disinhibition and deficits in concentration, orientation, judgement May have a reemergence of primitive reflexes

Nondominant parietal-temporal cortex Lesion - Answer-HEMISPATIAL NEGLECT [Agnosia of the contralateral side of the world] Dominant parietal-temporal cortex Lesion - Answer-1. Agraphia

  1. Acalculia
  2. Finger agnosia
  3. Left-right disorientation GESTERMANN SYNDROME Reticular Activating System [Midbrain] Lesion - Answer-Reduced levels of arousal and wakefulness [Coma] Mammillary Bodies [Bilateral] Lesion - Answer-Wernicke-Korsakoff Syndrome
  4. Confusion
  5. Ophthalmoplegia
  6. Ataxia
  7. Memory loss [Anterograde and retrograde amnesia]
  8. Confabulation
  9. Personality changes Associated w/ B1 [Thiamine] Deficiency and excessive EtOH use Can be precipitated by GLUCOSE w/out B1 to a B1-deficient patient Wernicke problems in a can of beer:
  10. Confusion
  11. Ataxia
  12. Nystagmus Basal Ganglia Lesion - Answer-May result in a tremor at rest, chorea, athetosis Parkinson's Disease Huntington's Disease Cerebellar Hemisphere Lesion - Answer-1. Intention tremor
  13. Limb ataxia
  14. Loss of balance
  15. Damage to cerebellum → Ipsilateral deficits FALL TOWARD THE SIDE OF THE LESION Cerebellar hemispheres are LATERALLY LOCATED and affect the LATERAL LIMBS Cerebellar Vermis Lesion - Answer-1. Truncal ataxia
  16. Dysarthria Vermis is CENTRALLY LOCATION affects the CENTRAL LIMBs Subthalamic Nucleus Lesion - Answer-CONTRALATERAL hemiballismus
  1. Temporal lobe = Wernicke Area
  2. Frontal lobe = Broca's Area APHASIA IF IN DOMINANT [Usually left hemisphere] HEMINEGLECT IF IN NONDOMINANT [Usually right hemisphere] ACA Lesion - Answer-1. Motor cortex = Lower limb [Contralateral paralysis]
  3. Sensory cortex = Lower limb [Contralateral loss of sensation] Lenticulostriate Artery Lesion - Answer-Striatum [Putamen = Motor, Caudate = Cognitive, Internal capsule Contralateral hemiparesis/hemiplegia COMMON LOCATION OF LACUNAR INFARCTS, 2° to unmanaged hypertension Anterior Spinal [ASA] - Answer-1. Lateral corticospinal tract = Contralateral hemiparesis [Upper and lower limbs]
  4. Medial lemniscus = ↓ Contralateral proprioception
  5. Caudal medulla = Hypoglossal nerve [Ipsilateral hypoglossal dysfunction = Tongue licks the lesion] STROKE COMMONLY BILATERAL Medial Medullary Syndrome - Answer-Caused by infarct of paramedian branches of ASA and vertebral arteries PICA Lesion - Answer-1. Lateral medulla -- Vestibular Nuclei -- Lateral Spinothalamic tract -- Spinal trigeminal nucleus -- Nucleus ambiguus -- Sympathetic fibers -- Inferior cerebellar peduncle [Proprioceptive information] Clinical Manifestations:
  6. Vomiting
  7. Vertigo
  8. Nystagmus
  9. ↓ Pain and temperature sensation from IPSILATERAL FACE and CONTRALATERAL BODY
  10. DYSPHAGIA
  11. HOARSENESS
  12. ↓ Gag reflex
  13. Ipsilateral horner syndrome
  14. Ataxia
  15. Dysmetria

Lateral Medullary [Wallenberg Syndrome] Lesion - Answer-Nucleus ambiguus effects are SPECIFIC TO PICA lesion "Don't PICA Horse [Hoarseness] that can't eat [Dysphasia] ACA - Answer-LATERAL PONS

  1. Cranial facial nerve
  2. Vestibular nuclei
  3. Facial nuclei
  4. Spinal trigeminal nuclei
  5. Cochlear nuclei
  6. Sympathetic fibers MIDDLE AND INFERIOR CEREBELLAR PEDUNCLES
  7. Ataxia
  8. Dysmetria Clinical Manifestations:
  9. Vomiting
  10. Vertigo
  11. Nystagmus
  12. PARALYSIS OF FACE
  13. ↓ Lacrimation, salivation
  14. ↓ Taste from anterior 2/3rd of tongue
  15. IPSILATERAL ↓ pain and temperature
  16. CONTRALATERAL ↓ pain and temperature Lateral Pontine Syndrome - Answer-Facial nucleus effects are specific to AICA lesions FACIAL DROOP means AICA's pooped PCA - Answer-1. Occipital cortex
  17. Visual cortex [CONTRALATERAL hemianopia w/ macular sparing] Basilar Artery - Answer-1. Pons
  18. Medulla
  19. Lower Midbrain
  20. Corticospinal and corticobulbar tracts
  21. Ocular cranial nerve nuclei
  22. Paramedian pontine reticular formation Clinical Manifestation [LOCKED IN SYNDROME]:
  23. Preserved consciousness and blinking
  24. Quadriplegia
  25. Loss of voluntary facial, mouth, and tongue movement
  26. Locked-in syndrome Anterior Communicating Artery [ACom] - Answer-Most common lesion is ANEURYSM

Can cross FALX and TENTORIUM Subdural hematoma - Answer-Rupture of BRIDGING VEINS SLOW VENOUS BLEED [Less pressure =Hematoma develops over time] Seen in:

  1. Elderly
  2. Alcoholics
  3. Blunt trauma
  4. SHAKEN BABY SYNDROME [Predisposing factors = Brain atrophy, shaking, whiplash] CRESCENT-SHAPED hemorrhage that CROSSES SUTURE LINES MIDLINE SHIFT Cannot cross falx, tentorium Subarachnoid hemorrhage - Answer-Rupture of ANEURYSM [Berry/saccular aneurysm in Ehlers-Danlos and ADPKD] or ARTERIOVENOUS MALFORMATION Rapid time course WORST HEADACHE OF MY LIFE Bloody or yellow spinal tap [Xanthochromia] 2 - 3 days afterward, risk of vasospasm due to blood breakdown [Not visible on CT, treat w/ NIMODIPINE] and rebleed [Visible on CT] Intraparenchymal [Hypertensive] Hemorrhage - Answer-Commonly caused by SYSTEMIC HTN Also seen w/
  5. AMYLOID ANGIOPATHY [Recurrent lobar hemorrhagic stroke in elderly
  6. Vasculitis
  7. Neoplasm Typically occurs in BASAL GANGLIA, INTERNAL CAPSULE [Charcot-Bouchard Aneurysm of lenticulostriate vessels] Ischemic Brain Disease/Stroke - Answer-Irreversible damage begins after 5 minutes of hypoxia [Due to glucose dependence] Most vulnerable:
  8. Hippocampus
  9. Neocortex
  10. Cerebellum
  11. Watershed areas Ischemic HYPOxia = HYPOcampus most vulnerable Stroke Imaging - Answer-Noncontrast CT to exclude hemorrhage [Before tPA can be given] CT detects changes in 6-24 hours Diffusion weighed MRI can detect ischemia w/in 3-30 minutes

Time since ischemia event and histologic factors - Answer- 12 - 48 hours = Red neurons 48 - 72 hours = Necrosis + neutrophils 3 - 5 days = Macrophages [Microglia] 1 - 2 weeks = Reactive gliosis + vascular proliferation

2 weeks = Glial scar Hemorrhagic Stroke [15%] - Answer-Intracerebral bleeding, often due to:

  1. HTN
  2. Anticoagulation
  3. Cancer [Abnormal vessels can bleed] May be 2° to ischemic stroke followed by reperfusion [↑ Vessel fragility] BASAL GANGLIA ARE THE MOST COMMON SITE OF INTRACRANIAL HEMORRHAGE Ischemic Stroke [85%] - Answer-Acute blockage of vessels → Disruption of blood flow and subsequent ischemia → LIQUEFACTIVE NECROSIS Three Types
  4. Thrombotic = Clot forms directly at site of infarction [Commonly MCA]
  5. Embolic = Embolus from another part of the body obstructs vessel -- Can affect multiple vascular territories -- Examples: Atrial fibrillation, DVT w/ patent foramen ovale
  6. Hypoxic = Hypoperfusion or hypoxemia -- Common during CARDIOVASCULAR SURGERIES -- TENDS TO AFFECT WATERSHED AREAS Treatment: tPA [If w/in 3-4.5 hours of onset and no hemorrhage/risk of hemorrhage] Reduce risk w/ medical therapy:
  7. Aspirin
  8. Clopidogrel
  9. Optimum control of BP, blood sugars, lipids
  10. Treat conditions that ↑ atrial fibrillation Transient Ischemic Attack [TIA] - Answer-Brief, reversible episode of focal neurologic dysfunction without acute infarction [- MRI] Majority resolves in < 15 minutes, deficits due to FOCAL ISCHEMIA Dural Venous Sinuses - Answer-Large venous channels that run through the dura Drain blood from cerebral veins and receive CSF from arachnoid granulation EMPTIES INTO JUGULAR VEINS Ventricular System - Answer-Lateral ventricle → 3rd ventricle via right and left interventricular foramen of Monro 3rd ventricle → 4th ventricle via cerebral aqueduct [of Sylvius] 4th ventricle → Subarachnoid space via
  11. Formina of Luschka [Lateral]
  12. Foramina of Magendie [Medial]