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


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)


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)


- 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)


- 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)



- 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