What are the blood supplies affected in a stroke and their manifestations?

Blood Supply Affected in Stroke and Their Manifestations

Overview of Stroke Vascular Territories

Stroke manifests differently depending on which cerebral artery is occluded, with the anterior circulation (carotid system) accounting for approximately 80-85% of ischemic strokes and the posterior circulation (vertebrobasilar system) for the remainder. 1

Anterior Circulation Strokes

Middle Cerebral Artery (MCA) Territory

The MCA is the most commonly affected vessel in ischemic stroke. 1

MCA occlusion produces:

• Contralateral hemiparesis and hemisensory loss affecting the face and upper extremity more than the lower extremity 2
• Aphasia if the dominant (usually left) hemisphere is involved 2
• Neglect and visuospatial deficits if the non-dominant hemisphere is affected 2
• Homonymous hemianopia due to involvement of the optic radiations 1
• Gaze deviation toward the side of the lesion 2

Anterior Cerebral Artery (ACA) Territory

ACA occlusion produces:

• Contralateral leg weakness greater than arm weakness (opposite pattern from MCA) 1
• Sensory loss in the contralateral leg 1
• Abulia and behavioral changes when bilateral or involving the dominant hemisphere 1
• Urinary incontinence in some cases 1

Internal Carotid Artery (ICA) Occlusion

Complete ICA occlusion can produce:

• Combined MCA and ACA territory infarction if collateral circulation is inadequate 1
• Ipsilateral monocular vision loss (amaurosis fugax) if the ophthalmic artery is involved 1
• Massive hemispheric infarction with potential for malignant cerebral edema requiring decompressive hemicraniectomy within 48 hours 2

Posterior Circulation Strokes

Posterior Cerebral Artery (PCA) Territory

PCA occlusion produces:

• Contralateral homonymous hemianopia with macular sparing 1
• Visual agnosia if bilateral occipital involvement 1
• Memory impairment if the medial temporal lobe is affected 1
• Thalamic pain syndrome if thalamic branches are involved 1

Vertebrobasilar System

Vertebrobasilar occlusion produces:

• Crossed sensory and motor deficits (ipsilateral cranial nerve findings with contralateral body findings) 1
• Ataxia and vertigo from cerebellar involvement 2
• Diplopia, dysarthria, and dysphagia from brainstem involvement 2
• Altered consciousness if the reticular activating system is affected 1
• "Locked-in syndrome" with basilar artery occlusion affecting the ventral pons 1

Cerebellar Arteries (PICA, AICA, SCA)

Cerebellar infarction produces:

• Ipsilateral limb ataxia 2
• Nystagmus and vertigo 1
• Obstructive hydrocephalus requiring ventriculostomy if symptomatic 2
• Brainstem compression necessitating decompressive suboccipital craniectomy 2

Small Vessel (Lacunar) Strokes

Small penetrating artery occlusions produce classic lacunar syndromes: 1

• Pure motor hemiparesis from internal capsule or pons involvement 1
• Pure sensory stroke from thalamic involvement 1
• Ataxic hemiparesis from pons or internal capsule 1
• Dysarthria-clumsy hand syndrome from pontine base involvement 1

These result from deep perforator arteriolosclerosis related to chronic hypertension and represent approximately 20-25% of ischemic strokes. 1

Critical Clinical Assessment

Immediate Evaluation Using NIHSS

The National Institutes of Health Stroke Scale systematically assesses stroke severity across vascular territories: 2

• Level of consciousness (0-3 points) 2
• Gaze (0-2 points) 2
• Visual fields (0-3 points) 2
• Facial palsy (0-3 points) 2
• Motor arm and leg (0-4 points each) 2
• Limb ataxia (0-2 points) 2
• Sensory (0-2 points) 2
• Language/aphasia (0-3 points) 2
• Dysarthria (0-2 points) 2
• Extinction/inattention (0-2 points) 2

Time-Critical Imaging

Non-contrast CT must be performed immediately to exclude hemorrhage before thrombolytic therapy. 2

Advanced vascular imaging (CTA or MRA) should be obtained to identify large vessel occlusions amenable to endovascular therapy, particularly in the MCA or ICA. 2

Prognostic Implications by Territory

Massive hemispheric infarction involving the MCA territory carries risk of malignant cerebral edema, with decompressive hemicraniectomy providing functional benefit if performed within 48 hours, especially in patients <60 years. 2

Cerebellar infarction with neurological deterioration, brainstem compression, or hydrocephalus requires urgent neurosurgical decompression. 2

Basilar artery occlusion has extremely high mortality without recanalization, making these patients candidates for extended-window endovascular therapy. 2

Common Pitfalls

Avoid attributing isolated vertigo or dizziness to posterior circulation stroke without additional brainstem or cerebellar signs, as peripheral vestibular disorders are far more common. 1

Do not dismiss mild symptoms in small vessel disease, as these patients remain at high risk for recurrent stroke and vascular cognitive impairment. 1

Recognize that blood pressure extremes worsen outcomes: hypertension >220/120 mm Hg or hypotension requiring vasopressors both indicate poor prognosis and require careful management. 2