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sudden appearance of neurological symptoms as a result of interrupted blood flow

in most cases (70%) the middle cerebral artery (MCA)

arm/hand/face is more affected than the leg

stroke produces an infarction (area of dead tissue)

1. cerebral ischaemia
2. migraine stroke
3. haemorrhage
4. aneurysms
5. angiomas

any group of disorders in which symptoms caused by vessel blockage → insufficient blood flow to the brain

1. *thrombosis*
2. *embolism* :
3. *cerebral arteriosclerosis*

blood in vessel has coagulated to form a plug or clot (remained at the place of formation )

clot or another plus ( air bubble/oil deposit) brought through from a larger blood vessel and forced into a smaller one

narrowing by thickening and hardening of the arteries

*hippocampus is very sensitive to ischemia*

caused by vasospasm

rare compared to other types , most common in women under 40

experienced just like an ischaemic attack

: massive bleeding into the substance of the brain

onset is abrupt

bleeding may quickly prove fatal ( mostly when awake elevated blood pressure )

poor prognosis especially if person is unconscious

most frequent cause is high blood or hypertension

congenital defects in cerebral arteries, blood disorders (leukaemia), brain trauma , toxic chemicals

cases (70%) the middle cerebral artery (MCA) is affected, implying that the arm/hand/face is more affected than the leg.

congenital collections of abnormal vessels that divert normal blow of blood

capillary, venous or arteriovenous malformations (AVMs) massive enlarged and tortious cortical vessels supplied by a larger vein

cause abnormalities in the blood flow pattern

vascular dilatations resulting from localized defects in vessel's elasticity

balloon like expansions of vessels prone to rupture

the occlusion of the middle cerebral artery results in a dysfunction of the corticospinal system, also called the pyramidal tract

corticospinal system

located in the middle cerebral artery

essential for *fine motor functions* ( hand movement )

internal capsule (part of corticospinal system ) receives blood supply form middle cerebral artery, damage can affect motor functions

role of inhibition motor functions

crosses over at the medullary spinal junction

right pyramidal tract innervates the motor functions at the left side of the body

left hemisphere innervates the motor activity at the right side of the body

disinhibition of muscle tone

results in hypertonia → spasticity in contralateral arm/hand/leg

basal ganglia , putamen , caudate nucleus and globus pallidus → SUBCORTICAL SYSTEM

involved in **gross motor functions (**posture , balance, tone )

**corticobulbar**

lesions in the middle cerebral artery → pyramidal tract can lead to hypertonia or hyperreflexia

Babinsky reflex test

extension of the toes to the nose ( normal )

flexion of the toes ( von Struempell reflex) due to inhibition by motor cortex

a lesion in the central nervous system could bi signalled by an adult with Babinsky reflex

reflects the contribution of the brain areas to the functioning of the upper and lower extremities

hand and face require much larger brain regions

located in the lateral side of the cortex

lateral side of cortex receives blood form middle cerebral artery