STROKE SYNDROMES

Stroke Within the Anterior Circulation– Middle Cerebral Artery– Anterior Cerebral Artery– Anterior Choroidal Arteries– Internal Carotid Artery– Common Carotid Artery

Middle Cerebral Artery

• Occlusion of the proximal MCA or one of its major branches is most often due to an embolus rather than intracranial atherothrombosis

• The cortical branches of the MCA supply the lateral surface of the hemisphere

Middle Cerebral Artery• The proximal MCA (M1 segment) supplies the

following:– Putamen– Outer globus pallidus– Posterior limb of the internal capsule– Corona radiata– Most of the caudate nucleus

• In the sylvian fissure, the MCA divides into the superior and inferior divisions (M2 branches)– Inferior division supplies

• Inferior parietal and temporal cortex– Superior division supplies

• Frontal and superior parietal cortex

Middle Cerebral Artery

• entire MCA is occluded at its origin :– contralateral hemiplegia,

hemianesthesia, homonymous hemianopia, and a day or two of gaze preference to the ipsilateral side

– Dysarthria is common because of facial weakness

– global aphasia – anosognosia, constructional apraxia,

and neglect

• Middle Cerebral Artery: Partial Syndromes– Brachial syndrome : embolic occlusion of a single

branch include hand, or arm and hand, weakness alone

– Frontal Opercular Syndrome: facial weakness with nonfluent (Broca) aphasia, with or without arm weakness

– Lacunar stroke within internal capsule - pure motor stroke or sensory-motor stroke contralateral to the lesion

Middle Cerebral Artery

Stroke within the Anterior Circulation

• Anterior Cerebral Artery

Anterior Cerebral Artery

• Divided into 2 segments:– Precommunal Circle of Willis (A1)• Connects the internal carotid artery to the anterior

communicating artery

– Postcommunal segment (A2)*Pericallousal artery (A3)• Main terminal branches of the ACA

Anterior Cerebral Artery

• Supplies the anterior limb of the internal capsule, the anterior perforate substance, amygdala, anterior hypothalamus, and the inferior part of the head of the caudate nucleus

• Occlusion of the proximal ACA is usually well tolerated because of collateral flow through the anterior communicating artery and collaterals through the MCA and PCA

Anterior Cerebral Artery

• Paralysis of opposite foot and leg: Motor leg area

• A lesser degree of paresis of opposite arm: Arm area of cortex or fibers descending to corona radiata

• Cortical sensory loss over toes, foot, and leg: Sensory area for foot and leg

• Urinary incontinence: Sensorimotor area in paracentral lobule

Anterior Cerebral Artery

Anterior Cerebral Artery

• Abulia (akinetic mutism), slowness, delay, intermittent interruption, lack of spontaneity, whispering, reflex distraction to sights and sounds: Uncertain localization—probably cingulate gyrus and medial inferior portion of frontal, parietal, and temporal lobes

• Impairment of gait and stance (gait apraxia): Frontal cortex near leg motor area

• Dyspraxia of left limbs, tactile aphasia in left limbs: Corpus callosum

Stroke within the Posterior Circulation

– Posterior Cerebral Artery– Vertebral Artery– Posterior Inferior Cerebellar Artery– Basilar Artery

Stroke within the Posterior Circulation

• Posterior Cerebral Artery– result from atheroma formation or emboli that

lodge at the top of the basilar artery– May also be caused by dissection of the vertebral

artery or fibromuscular dysplasia

Posterior Cerebral Artery

• (1) P1 syndrome: midbrain, subthalamic, and thalamic signs, which are due to disease of the proximal P1 segment of the PCA or its penetrating branches

• (2) P2 syndrome: cortical temporal and occipital lobe signs, due to occlusion of the P2 segment distal to the junction of the PCA with the posterior communicating artery.

Posterior Cerebral Artery

• P1 Syndromes• third nerve palsy with contralateral ataxia (Claude's

syndrome) or with contralateral hemiplegia (Weber's syndrome)• contralateral hemiballismus (if subthalamic nucleus is

involved)• thalamic Déjerine-Roussy syndrome - contralateral

hemisensory loss followed later by an agonizing, searing or burning pain in the affected areas

Posterior Cerebral Artery

• P2 Syndromes• Occulsion of the PCA causes infarction of the medial

temporal and occipital lobes• Contralateral homonymous hemianopia with macula

sparing is the usual manifestation• acute disturbance in memory (hippocampus)• peduncular hallucinosis - visual hallucinations of

brightly colored scenes and objects• infarction in the distal PCAs produces cortical blindness

(blindness with preserved PLR) • Anton's syndrome – unaware of blindness and in denial

Basilar Artery

• Atheromatous lesions are most frequent in the proximal basilar and the distal vertebral segments

• Complete basilar occlusion :• a constellation of bilateral long tract signs (sensory and

motor) with signs of cranial nerve and cerebellar dysfunction

• “locked-in" state of preserved consciousness with quadriplegia and cranial nerve signs suggests complete pontine and lower midbrain infarction

Basilar Artery

• TIAs in the proximal basilar distribution may produce vertigo

• Occlusion of the superior cerebellar artery results in– Ipsilateral cerebellar ataxia, nausea and vomiting,

dysarthria, contralateral loss of pain and temp sensation• Occusion of the anterior inferior cerebellar artery

results in– Ipsilateral deafness, facial weakness, vertigo, nausea and

vomiting, nystagmus, tinnitus and contralateral loss of pain and temperature sensation

Imaging

• CT Scan• identify or exclude hemorrhage as the cause of stroke• the infarct may not be seen reliably for 24–48 h• may fail to show small ischemic strokes in the posterior

fossa

• MRI• reliably documents the extent and location of

infarction in all areas of the brain• less sensitive than CT for detecting acute blood

Imaging

• Cerebral Angiography• "gold standard" for identifying and quantifying

atherosclerotic stenoses of the cerebral arteries • used to deploy stents within delicate intracranial vessels• intraarterial delivery of thrombolytic agents• Carries the risk for arterial damage, groin hemorrhage,

embolic stroke, embolic stroke, and renal failure

• Carotid Doppler

• For the next meeting, read on Disturbances of Vision, Ocular Movement, and Hearing

• Harrison’s Principles of Internal Medicine 17th edition