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169 Cards in this Set
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meningeal layers
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skull - (epidural space) - dura - (subdural space) - arachnoid - (subarachnoid space) - pia
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Meningioma Origin
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arachnoidal/meningiothelial cells on top of arachanoid granulations
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Aging arachnoid
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deposition of collagen
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Virchow-Robin space
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pia layer surrounding vessels which is continuous with the subarachnoid space
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Nissl substance
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endoplasmic reticulum in neurons
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Cortical layers
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1. molecular
2. external granular 3. external pyramidal 4. internal granular 5. internal pyramidal 6. plexiform |
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Brain areas most sensitive to hypoxic injury
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CA1 region of the hippocampus
Purkinje cells in the cerebellum |
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Lipofuscin
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oxidized fatty acids that accumulate in motor neurons.
normal aging process |
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Reactive astrocytes
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activated astrocytes that respond to injury
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Position of oligodendrocytes
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in white matter: parallel sheets to axons
in grey matter: round neuronal cell bodies |
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Perivascular spaces
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outside the virchow-robin space
common site for gliomas |
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Ependymal cells
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line brain ventricles and central canal
cuboidal w/tight junctions no basal lamina |
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Multiple Sclerosis
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CNS demyelinating disease
episodic neurologic dysfunction eventual persistent neuro deficits |
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MS epidemiology
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onset btwn 15-45
Women 2:1 higher prevalence in temperate regions |
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MS symptoms
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focal weakness (UMN signs)
paresthesias dyscoordination, tremors bladder spasticity |
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clinical progressions of MS
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relapsing remitting
- eventually becomes 2dary progressive Primary progressive (smooth progression) |
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MS characteristic lesions
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acute: gadolinium-enhancing lesion
chronic: black hole |
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MS lesion types
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Type1/Type2: perivenular myelin loss, preservation of oligodendrocytes
type 2-IgG/complement deposition Type3/Type4: macrophage and T cell infiltration, no preservation of oligodrendrocytes |
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MS dopplegangers
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Lyme disease
sarcoidosis B12 deficiency HIV |
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Dawson's fingers
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perivenular demyelination perpendicularly oriented to ventricles in MS
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MS spinal cord lesions
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1-2 segments long
sensory symptomes ambulation difficulty loss of arm coordination |
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Evoked responses
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Measured velocities of visual pathway action potentials
Slowed in MS |
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Oligoclonal IgG bands
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IgG which is present in CSF but not in sera
present in 80-90% of MS cases |
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Steps of MS neuropathogenesis
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CNS entry of activated Tcells, monocytes
Neuroinflammation Axonal Degeneration |
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Gender incidence in Brain tumors
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Gliomas and embryonal tumors occur more in males
Meningiomas occur more in females |
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Environmental Risk Factors for brain tumors
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Radiation exposure
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Consequences of brain herniation
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blood vessel compression --> infarction and edema
Duret hemorrhages:stretching and tearing of brainstem vasculature Nerve compression |
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Gliomas
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tumors of neuroepithelial origin
Astrocytomas Oligodendrogliomas Ependymomas |
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Infiltrating Astrocytomas
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Diffuse (grade II)
Anaplastic (grade III) Glioblastoma (grade IV) |
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Diffuse Astrocytoma
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Grade II tumor
diffusely invades the cerebrum hypercellular, but nomitoses visible |
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Gemistocytic Astrocytoma
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A diffuse astrocytoma containing plump cells with glassy pink cytoplasm
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Anaplastic Astrocytoma
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Grade III tumor
Increased cell density and pleomorphism mitotic figures are now seen can arise from diffuse tumor or be de novo |
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Glioblastoma
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grade IV tumor
Areas of pseudopalisading necrosis glomeruloid vascular changes |
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Glioblastoma genes
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EGFR amplification: seen in primary GBM
TP53 mutation: seen in primary and secondary GBM |
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Pilocytic Astrocytoma
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Mostly in kids, good prognosis
biphasic architecture: microcystic and solid compartments Rosenthal fibers seen w/in astrocytes |
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Oligodendroglioma
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Fried-egg cells with chicken-wire capillaries
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Ependymoma
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ependymal cell tumor
pseudorosettes around vessels |
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Embryonal Tumors
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Malignant Grade IV tumors seen in kids. Includes medulloblastoma
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Medulloblastoma
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cerebellar tumor
"round blue" tumor (due to cell appearance) rosettes may be present |
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Meningioma
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Mostly benign and arise from meninges
may arise in NF1 and NF2 |
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Schwannoma
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in cranial nerves, most commonly affects CN VIII
bilateral vestibular schwannomas indicate NF2 |
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Neurofibroma
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may be dermal or intraneural
occurs in periphery multiple tumors indicates NF1 wavy nuclei and comma-shaped cells |
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Cephalhematoma
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bleed above the bone
doesn't cross suture lines |
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Linear Fracture
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secondary to contact with large flat object
Facture begins along inner table |
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Compound Fracture
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fracture associated with scalp laceration
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Complex fracture
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Fracture involving multiple bones
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Depressed Fracture
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secondary to contact with small objects
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Contrecoup fracture
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located distant from point of injury
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Hinge Fracture
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A francture extending across skull base
typically from car accidents lethal |
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Contusion
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a surface injury
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Coup contusions
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caused by bending at site of injury
moving object strikes stationary but movable head |
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Contre coup contusions
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located distant from impact
Mechanisms: 1. impact -moving head strikes fixed object 2. impulsive loading-head set in motion/moving head is stopped |
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Types of DIffuse Brain Injury
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Diffuse axonal injury
Concussion Brain Swelling |
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Retraction Balls
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ends of cut axons
Evidence of axonal injury from trauma |
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Severe Concussion effects
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high glu, lactate, and intracellular calcium
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Hyperextension of head
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transects the caudal pons
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Optic nerve sheath hemorrhages
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often found in shaken baby syndrome
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Total CSF Volume
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Adult: 90-150 ml
neonate: 10-60 ml |
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Rate of CSF formation
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500 ml per day
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Difference between plasma and CSF
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CSF has much lower protein, glucose, and potassium content
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Arachnoid granulations
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absorb CSF from subarachnoid space into venous circulation
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Physiologic Roles of CSF
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physical support
protection extracellular homeostasis excretory waste function |
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CSF formation
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Ultrafiltration of plasma across capillary wall
then, choroid epithelial cells transport components into the ventricle |
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Blood-brain barrier
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tight junctions between endothelial cells
thick basement membrane astrocyte endfoots |
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Blood-brain permeability
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permeable to water, uncharged lipid-soluble molecules
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Circumventricular organs
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exceptions to blood-brain barrier
sample the plasma and release hormones into blood |
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When to do a lumbar puncture
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CNS infection
Subarachnoid hemorrhage CNS malignancy Demyelinating disease |
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Normal CSF opening pressure
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Adult: 90-200 mm water
child: 10-100 mm water if elevated, may be infection |
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Lumbar puncture contraindication
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raised intracranial pressure
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Lumbar punture side effects
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headache for 2-14 days
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Normal CSF cell counts
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WBCs: 0-5 cell/ul
too many neutrophils, could be bacteria too many lymphocytes, could be viral RBS: 0 cell/ul Pleocytosis: elevation of cell counts, often due to infection |
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Normal CSF glucose
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60 mg/dl
if decreased, due to increased anaerobic glycolysis by parenchyma and leukocytes |
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CSF protein
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Normal: 30 mg/dL
increased CSF protein: increased permeability, IgG synthesis |
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Meningitis presentation
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fever, headache
altered mental status stiff neck photophobia |
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Viral meningitis families
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Enteroviruses
Herpesviruses Arboviruses |
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Transport of infection to CNS
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hematogenous spread
local extension for paranasal sinuses retrograde transport from PNS direct implantation |
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pachymeningitis
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infection of dura mater
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leptomeningitis
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inflammation of pia and arachnoid
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encephalitis
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inflammation of brain parenchyma diffusely
often viral |
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cerebritis
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inflammation of brain parenchyma focally
often bacterial |
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myelitis
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inflammation of spinal cord
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poliomyelitis
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inflammation of spinal grey matter
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ganglionitis
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inflammation of dorsal root ganglia
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radiculitis
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inflammation of intradural spinal nerve roots
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Cryptococcal meningitis
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most common fungal CNS infection
usually immunosuppresse invade virchow-robin spaces attach endothelium |
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Zygomycosis (Mucor)
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often in diabetic ketoacidosis
basal brain and olfactory bulbs medical emergency |
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Blastomycosis
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spreads from lungs to brain
endemic in SE USA |
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Candidiasis
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Opportunistic CNS infection
hemorrhagic infarcts absesses |
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TB in CNS
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forms granulomas in brain and spinal cord
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Neuroborreliosis
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lyme disease in the brain
causes aseptic meningitis |
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Brain Absesses
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often Staph or strep
surrounded by fibrotic capsule |
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Toxoplasmosis
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opportunistic infection
creates brain absesses |
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Entamoeba histolitica
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an amoeba causing brain abscesses
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Cysticercosis
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injestion of tapeworm eggs can lead to chronic abscesses in brain
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Empyema
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subdural abscess.
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Epidural Abscess
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ex. Pott's disease (TB in spine)
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Pathologic features of viral encephalitis
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perivascular/parenchymal lymphocytic infiltrates
scattered glial nodules neuronophagia viral inclusion bodies |
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HSV-1 encephalitis
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bilateral temporal lobe infection
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Negri Bodies
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red inclusions found w/rabies in neurons
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Poliomyelitis
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infection of anterior horns
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Naegleria fowleri
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amoeba that lives in soid, water
causes acute meningoencephalitis netty pot disease |
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Cerebral malaria
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causes circulation problem in brain
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HIV encephalitis
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HIV infects microglia
multinucleated giant cells |
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Progressive Multifocal Leukoencephalopathy
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caused by JC virus
white matter disease |
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Contact loading results
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contusion and hematoma
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Inertial loading
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head rotation
midline injury diffuse asxonal injury shrinking of tissue |
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TBI recovery
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spatial memory often recovered
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Seizure definition
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transient dysfunction of all/part of brain due to excessive discharge of neurons, causing sudden and transient symptoms
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Epilepsy definition
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recurrent unprovoked seizures
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Phenobarbital
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Barbituate used to treat epilepsy
activates GABA-A receptors |
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Electroencephalography
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surface readings of brain's extra-cellular current
mainly reflects summed excitatory/inhibitory synaptic input to pyramidal cells |
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Overall Seizure Types
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Generalized
Focal |
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Types of Generalized seizures
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Absence
Myoclonic Tonic-clonic tonic clonic atonic |
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Absence seizure
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sudden arrest of activity, staring, and unresponsiveness
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Myoclonic seizure
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quick muscle jerks involving shoulders and arms
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Tonic-clonic seizure
(grand mal) |
generalized convulsion
bilateral extremity extension and muscle stiffening, then progression to bilateral extremity rhythmic shaking |
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Tonic seizure
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bilateral extremity extension and muscle stiffening
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Clonic seizure
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bilateral extremity rhythmic shaking
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Atonic seizure
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sudden loss of neck/trunk tone, usually associated with falling
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Seizure symmetry
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generalized: symmetric
focal: begin asymmetrically |
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Focal seizure types
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without impairment of awareness
with impairment of awareness evolving to bilateral convulsive seizure |
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Frontal Lobe focal seizures
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motor cortex: clonic shaking of contralateral limb
premotor: complex, bilateral motor activity broca's: epresive language dysfunction fronto-polar: absence |
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Temporal lob focal seizure
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aura, arrest of activity, unresponsiveness, motor automatisms
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Parietal lobe focal seizure
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no typical form
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occipital lobe focal seizure
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visual signs, positive or negative
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Childhood absence epilepsy
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absence seizures presenting in childhood
treated with ethosuximide hight risk of psychologic comorbidities |
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paroxysmal depolarization shift
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abnormally prolonged calcium-dependent depolarization
causes a burst of depolarizations possible origin of focal seizure |
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Repetitive EPSPs and IPSPs
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EPSP: sum over time
IPSP: decline over time |
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Sustained Repetitive Firing
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Inward sodium current causes bursts of action potentials
(similar to PDS, but with Na instead of Ca) |
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Generalized seizure mechanisms
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Thalamocortical tracts
T-type Ca channels create generalized bursts (separate channel from PDS) |
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Mechanisms of Early Onset Epilepsies
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GABA is excitatory in development, and NMDA receptors develop before AMPA receptors
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Sodium channel blockers
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phenytoin, carbamazepine, oxcarbazepine, lamotrigine
inhibits sustained repetitive firing -> epilepsy drug |
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GABA agonists
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Barbiturates and Benzodiazepines
can be used as epilepsy treatment |
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Barbiturates
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prolong GABA channel openings
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Benzodiazepines
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increase frequency of GABA-mediated chloride channel openings
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T-type calcium channel blockers
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ethosuximide, valproic acid
effective at treating specific epileptic subtypes |
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Excitatory Amino Acid Transmitter Antagonists
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AMPA antagonist: topiramate
voltage-dependent Ca and Na: zonisamide NMDA antagonist: felbamate |
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Axonal Stretch Injury
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breaks microtubules
eventual degradation of microtubules sodium channel opening, Na and Ca influx |
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repetitive TBI effects
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massive Ca influx leads to increased Na channel density -> axon dysfunction and degeneration
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30% of TBI injuries result in amyloid plaques extracellularly
Increased risk of Alzheimer's |
n/a
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Dementia pugilistica
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Professional football player dementia
increased neurofibrillary tangles |
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Master Biological Clock
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Suprachiasmatic Nucleus
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Circadian clock adjustors
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retinal receptors -> detect light levels -> low = melatonin
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Polysomnography
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EEG and other recordings during sleep
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Cetacean Sleep
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marine mammals sleep one brain-hemisphere at a time
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VLPO
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the sleep switch in the hypothalamus
sends GABA signals to arousatory centers |
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Sleep changes across the lifespan
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as you age, more time awake and in stage 1 sleep
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Sleep latency
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the amount of time it takes to fall asleep
becomes shorter under sleep deprivation |
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Blink Speed
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measures sleepiness
slower blink = more sleepy |
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Sleep debt
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Neurobehavioral deficits accumulate linearly with sleep deficits
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Actigraphy
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patient wears a motion-detecting bracelet while asleep
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Narcolepsy tetrad
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hypersomnolence
cataplexy hypnogogic/hypnopompic hallucinations sleep paralysis |
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sleep latency
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amount of time needed to fall asleep
normal = 10 minutes |
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Multiple Sleep Latency Test
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4-5 20 minute naps at 2-hour intervals
typically no REM sleep |
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Cataplexy
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sudden loss of muscle tone triggered by emotions
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Narcolepsy Pathophysiology
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Boundaries between wakefulness and REM sleep are not well-maintained
Due to reduced hypocretinergic neurons |
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Modafinil/armodafinil
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Narcolepsy drugs
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Cataplexy drugs
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Tricylic antidepressents
SSRIs gamma hydroxybutyrate |
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Parasomnia
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an undesirable behavioral, motor, or sensory phenomenon which occurs intermittently during sleep
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Disorders of Arousal
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Confusional Arousals
Sleepwalking Sleep Terrors |
All occure in non-REM sleep
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Treatment for disorders of arousal
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Mostly non-pharmacological
benzodiazepines |
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REM Sleep Behavior DIsorder (RBD)
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violent dream-enacting w/tonic activity in REM sleep
Likely a pontine dysfunction |
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RBD causes
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Narcolepsy
Neurodegenerative disease (parkinsonisms) Anti-depressants |
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RBD treatment
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Clonazepam suppresses behaviors
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Restless Legs vs. Periodic Limb Movements
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Restless legs: awake sensory phenomenon w/volitional motor response
PLM: involuntary sleep-related motor phenomenon |
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RLS exacerbations
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psychological stress
physical confinement caffeine poor sleep |
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Secondary RLS associated conditions
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Iron deficiency anemia
Pregnancy Chronic Renal Failure |
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RLS pathophysiology
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low Fe availability in brain -> impaired dopamine tranmission -> lowered supra-spinal inhibition
(speculation) |
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RLS treatments
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Dopamine Agonists
Opiates gabapentin iron benzodiazepines |
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