Cerebrovascular Disease Flashcards by Berina Karisik

What deficits are caused by damaging the anterior cerebral artery (ACA)?

Upper motor neuron type weakness and cortical type sensory loss, contralateral hemiplegia initially; contralateral leg more than the face or arms; alien hand syndrome

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What is alien hand syndrome?

Semiautomatic movements of the contralateral arm not under voluntary control

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What deficits are caused with damage to the PCA?

Contralateral homonymous hemianopia (loss of vision of half of visual field of one or both eyes)

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In which artery are infarcts and ischemic events more common?

MCA

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What are the deficits caused by damage to the MCA?

Aphasia, hemineglect (lack of awareness to half of the body), face-arm or face-arm-leg sensorimotor loss; gaze preference toward side of the lesion

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What is cerebrovascular disease?

Injury to the brain as a consequence of altered blood flow; can be grouped into ischemic and hemorrhagic etiologies with tissue infarction the ultimate consequence

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What are the most common cerebrovascular disorders?

Global ischemia (whole brain), embolism, hypertensive intraparenchymal hemorrhage, ruptured aneurysm

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When blood flow is reduced, what does survival depend on?

Collateral circulation, duration of ischemia, and magnitude + rapidity of flow reduction

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What are the 2 types of reduction in blood flow?

Global ischemia (generalized reduction of perfusion due to cardiac arrest,shock, severe hypotension);
Focal ischemia in a localized area (emboliform or thrombotic arterial occlusion, vasculitides, atherosclerosis in HTN

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What are watershed infarcts?

Blood supply to two adjacent cerebral arteries compromised —> region between the 2 vessels most susceptible to ischemia and infarction; damage to this region produces a sickle shaped band of necrosis over the cerebral convexity a few cm lateral to the interhemispheric fissure

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What are the effects of an ACA-MCA watershed infarct?

Occlusion of the ICA, hypotension in pt with carotid stenosis; proximal arm and leg weakness with transcortical aphasia and language issues

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What are the effects of an MCA-PCA watershed infarct?

Higher order visual processing changes

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What are the two patterns of border zone infarcts?

Cortical border zone infarctions and internal border zone infarctions

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What are cortical border zone infarctions?

Infarctions of the cortex and adjacent subcortical white matter located at the border zone of ACA/MCA and MCA/PCA

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What are internal border zone infarctions?

Infarctions of the deep white matter of the centrum semiovale and corona radiata at the border zone between lenticulostriate perforators and the deep penetrating cortical branches of the MCA or at the border zone of deep white matter branches of the MCA and ACA

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What are risk factors for hypercoagulability?

Heritable coagulation factor disorders (protein S, C or anti thrombin III deficiencies), dehydration, adenocarcinoma/malignancies, surgery, trauma, childbirth, DIC, hematologic disorders (sickle cell, leukemia, polycythemia Vera) and vasculitis (temporal arteritis, SLE, infections, neoplasms)

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What needs to be ruled out in a young child who presents with a stroke?

Sickle cell

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What are the RF for a stroke?

HTN, DM, hypercholesterolemia, cigarette smoking, +FHx, cardiac dz (valvular dz, Afib, PFO, low ejection fraction), prior Hx of stroke or other vascular dz, hypercoagulability

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If a young pt presents with stroke what should you think of?

Arterial dissection, PFO, or hypercoagulability (also sickle cell)

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What are the 4 principle routes of CNS infections?

Hematogenous, direct implantation, local extension, PNS

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What is hematogenous spread?

MC route of infection; arterial primary but retrograde venous spread via anastomosis with facial veins possible

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What can cause direct implantation of a pathogen?

Trauma or congenital malformation (meningomyelocele)

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What can lead to local extension of a pathogen?

From infected adjacent structures such as sinuses, teeth, skull/cranial, vertebra (spinal osteomyelitis)

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Which pathogens tend to spread peripherally?

Viruses such as rabies and HSV

What is the flow of CSF?

Circulates through the foramen of Lusaka and Magendie to arachnoid space; absorbed by the arachnoid villi along superior sagittal sinus

How does tuberculus meningitis develop?

By seeding CSF from subepidural or submeningeal granulomas

Infections of the retropharyngeal, posterior mediastinal or retroperitoneal spaces may produce what?

Spinal epidural abscess since lymphatics are present in the epidural space (CSF has no lymphatics anywhere else)

Describe HSV and zoster infections

Produce latent infection of sensory ganglia, replicate in Schwann cells, and ascend to the CNS within sensory nerves

How does rabies virus affect nerves?

Binds at or near ACh receptors are the NMJ and ascends to the CNS via motor nerves

Describe capillaries in the brain

They dont have fenestrations or intracellular clefts; surrounded by foot processes of adjacent astrocytes; molecules move across mainly by active transport and lipid solubility

Capillaries in the brain have relative impermeability to what?

Immunoglobulins, complement and Abx; an important factor in the pathogenesis of CNS infection and in the selection of Abx therapy

Widespread infection involving all tissue elements are characteristic of which conditions?

Bacterial meningitis and viral encephalitides

What causes cerebral edema during infections?

Accelerated by products released by both living bacteria and abx lysed bacteria; slowed and reversed by corticosteroids

What are the effects of cerebral edema in response to an infection?

Infection and inflammation cause loss of capillary integrity (loss of BBB) with transudation of intravascular fluid into the brain or spinal cord

What is ventriculitis?

Fulminant infection where inflammation may extend to the ventricles

What is focal cerebritis?

Inflammatory cells infiltrate walls of the veins and extend in the brain substance

Phlebitis may lead to what?

Venous thrombosis and hemorrhagic infarction of the underlying brain

What are the complications of bacterial meningitis?

Seizures, encephalitis, hearing loss, blindness, paralysis, fulminant especially with meningococcemia: rash and adrenal hemorrhage which could lead to death (Waterhouse friderichsen syndrome)

If a lumbar puncture shows gram negative diplococci what is the presumptive pathogen?

N meningitidis

If a lumbar puncture shows gram positive diplococci what is the presumptive pathogen?

S pneumoniae

If a lumbar puncture shows gram negative pleomorphic organisms what is the presumptive pathogen?

H influenzae

If a lumbar puncture shows gram positive cocci what is the presumptive pathogen?

S aureus or S epi and streptococci

If a lumbar puncture shows gram negative bacilli what is the presumptive pathogen?

E. coli or other gram negative organisms

What will the lab results be for bacterial meningitis?

Gross appearance will be cloudy or turbid, increased neutrophils, decreased glucose, increased protein

What will be the lab results for viral meningitis?

Gross appearance will be clear or colorless, increased lymphocytes, normal glucose, mildly elevated protein

What are the CSF findings for viral meningitis?

NL or + pressure, clear appearance, 0-500 cell count, early dominant cell are PMNs with lymphocytes dominating late

What are CSF findings for bacterial meningitis?

++ pressure, opaque appearance, cell count 1-60,000, dominant cell is PMNs, ++ protein

What are the CSF findings for fungal meningitis?

+ pressure, clear appearance, cell count 10-500, early PMNs, late lymph’s, + to ++ protein

What factors cause an increased risk of meningitis?

Age <5 or >60 yo, DM, immunosuppression/HIV, contiguous infection (sinusitis), IVDA, bacterial endocarditis, sickle cell

What are common bacterial pathogens that cause acute meningitis in neonates?

E. coli and Group B streptococcus

What are common bacterial pathogens that cause acute meningitis in 3mo-2yo or unvaccinated children?

H influenza type B

What are common bacterial pathogens that cause acute meningitis in adolescent and young adults?

N meningitidis

What are common bacterial pathogens that cause acute meningitis in the elderly?

Strep pneumoniae and Listeria monocytogenes

Immunosuppression individuals with purulent meningitis may be infected with what pathogen?

Klebsiella or anaerobic organisms

What are common bacterial pathogens that cause acute meningitis in the immunocompromised state?

S pneumoniae, N meningitidis, L monocytogenes, aerobic gram negative bacilli (P aeruginosa)

What are common bacterial pathogens that cause acute meningitis in those with a basilar skull fracture?

S pneumoniae, H influenza, Grp A beta-hemolytic strep

What are common bacterial pathogens that cause acute meningitis in those with head trauma (post neurosurgery)?

S aureus, S epidermidis, aerobic gram negative bacilli (P aureginosa)

What are common bacterial pathogens that cause acute meningitis in those with a CSF shunt?

S aureus, S epidermidis, aerobic gram negative bacilli (P aureginosa), P acnes