15. Summary of Major Blood Supply
Some
definitions |
1.
transient ischemic attack -
acute (< 24 hours), vascular, clears completely -
1/3 will go on to have a major stroke within 3 years -
if longer (<3 weeks) but still reversible = RIND (Reversible Ischemic Neurologic Deficit) 2.
ischemia -
loss of blood supply 3.
infarct -
area of necrosis from ischemia a.
lacunar infarct -
small circumscribed loss of brain tissue (surrounding small artery) b.
watershed infarct -
border zones between major arterial distributions (e.g. posterior parieto-occipital region) 4.
stroke a.
embolic stroke -
transported clot or vegetation b.
thrombotic stroke -
local clot c.
hemorrhagic stroke -
from rupture of a vessel 5.
aneurysm -
circumscribed dilation (most common site: Circle of Willis, arterial
junctions à subarachnoid hemorrhage) -
may impinge on III, IV, VI before rupturing -
family history -
all ages affected 6.
subarachnoid hemorrhage -
etiology: congenital aneurysm (angioma, trauma:
less common) -
symptoms: sudden “thunderclap” headache during activity, stiff neck , altered
consciousness -
bloody CSF 7.
intracerebral hemorrhage -
most common areas: cerebellum,
pons, internal capsule (hypertension à rupture of atheromatous
artery) - rupture
lenticulo-striate arteries à contralateral hemiplegia, sensory loss, corticobulbar
signs, contralateral homonymous hemianopsia |
Cerebral |
8.
middle cerebral artery syndrome - contralateral hemiparesis
(motor cortex à upper body; internal capsule à whole body) - aphasia (dominant hemisphere) - neglect (non-dominant parietal
lobe) -
homonymous hemianopsia (if internal capsule) -
conjugate eye deviation to side of lesion (Area 8 involvement) 9.
anterior cerebral artery syndrome - contralateral paralysis/paresis and/or sensory loss of
lower extremity - incontinence -
no hemianopsia or aphasia 10. posterior
cerebral artery syndrome - contralateral homonymous hemianopsia
(macular sparing) -
memory loss (old cortical structure) from hippocampus involvement - L. hippocampus:
autobiography/facts - R. hippocampus:
spatial memory - thalamic syndrome -
usually no paralysis, aphasia 11. carotid
artery syndrome -
may à
ACA or MCA syndromes - amaurosis fugax: transient
monocular blindness (carotid insufficiency à ophthalmic artery; centrifugal force: flight
blindness without loss of consciousness)
|
Brainstem |
12. medial
medullary syndrome - XII (ipsilateral tongue
deviation) - medial
lemnisicus (contra. loss of fine touch/proprio.) - pyramid-cortico-spinal
tract (contralateral hemiplegia) 13. lateral
medullary (Wallenberg or PICA) syndrome -
etiology: occlusion of vertebral a. or PICA -
VIII: vertigo, nystagmus -
IX, X: dysphagia, hoarseness, gag reflex absent
(nucleus ambiguous) ipsilateral - spinal tract of V: loss of pain and temperature in face - Horner’s syndrome: sympathetic system affected [miosis
(constriction of the pupil), ptosis (drooping of
eyelid), anydrosis (absence of sweating)] - ataxia (inferior cerebellar peduncle) - deafness (cochlear nuclei) contralateral -
lateral spinothalamic tract: pain and temperature
loss 14. pontine
syndromes -
may affect any or all: VII, VI, V (motor, facial sensory, pain and
temperature), lateral spinothalamic tract 15. midbrain
strokes a.
Weber’s syndrome -
involved penetrating branches of PCA: rostral
midbrain affected (contralateral motor/corticobulbar, ipsilateral III) b.
Benedikt’s syndrome -
penetrating branches of basilar artery: paramedian
midbrain (ipsilateral III, contralateral
rubral tremor (red nucleus), spinothalamic
(medial lemniscus), trigeminothalamic
tracts) |
Spinal Cord |
16. Spinal cord
syndrome -
rare -
anterior and posterior spinal arteries (branches of vertebral artery) -
anterior spinal artery: supplies lateral and anterior SC (lateral corticospinal tract) -
posterior spinal artery: supplies dorsal SC (dorsal columns) |
Etiology/Prevention/Treatment
- 85% of strokes caused by
ischemic events (thrombosis, embolism, diabetes)
- ischemic
stroke: zone of infarction (additional damage to surrounding tissue = penumbral region: caused
by release of glutamate à glutamate toxicity
mediated by NMDA receptors)
- giving NMDA antagonists after
stroke decreases morbidity (prevents development of penumbral region)
- 15% of strokes are caused by
intracerebral hemorrhage (hypertension, tumors, anticoagulant treatment, amyloid, stimulants, trauma, appetite
suppressants)
- left
frontal strokes à depression; right frontal strokes à mania