STROKE

1. STROKE • Worldwide, about 15 million people have a stroke every year, of whom 5 million die and 5 million have a permanent deficit. • sudden onset of focal neurological deficits • Accurate and prompt diagnosis is crucial : implementation of time-dependent therapies

2. Acute neurologicalsymptoms • patients with obvious stroke • patients whose cause of neurological dysfunction is clearly not stroke • patients seem to have a stroke, but in fact have a non-vascular cause (stroke mimic) • actual strokes, but whose presentations are unusual or atypical, suggesting a non-vascular cause.(stroke chameleons)

3. Non-localising symptoms • Neuropsychiatric symptoms • 3% of patients with stroke • delirium, a delusional state, acute onset of dementia, or mania mimicking a psychiatric illness • anosognosia, aphasia, akineticmutism, abulia, and aprosodia, can be misinterpreted as manifestations of depression. • right-sided (non-dominant) focal strokes in the frontal, parietal regions and caudate strokes

4. Non-localising symptoms • Acute confusional state, agitation, restlessness • hemispheric stroke; Strokes involving the right temporal gyrus, right inferior parietal lobe, or occipital lobe and rarely, vertebrobasilarischaemia leading to involvement of the thalami, particularly the paramedian nuclei, • more frequent in haemorrhagicstroke than in ischaemicstroke

5. Non-localising symptoms • Altered level of consciousness • Large strokes, particularly haemorrhages • embolic occlusion of the central artery of Percheron, • top-of-the-basilar syndrome

6. Abnormal movements or seizures

7. Abnormal movements • prevalence of a movement disorders in acute stroke is 1% • hemichorea, hemiballismus, and dystonia were the most common symptoms • Small deep strokes involving the basal ganglia • Myoclonus is particularly common in posterior circulation strokes. • palatal myoclonus: small pontinestroke • involuntary tonic spasms and hemiparesis of the limb: basis pontis

8. Limb-shaking transient ischaemic attacks • Involuntary repetitive and stereotyped limb shaking • brief and show postural dependence, being precipitated by abrupt standing up and relieved by lying down. • affect the upper limbs and spare facial • always contralateral to a tight carotid stenosis • high risk for stroke

9. alien hand syndrome • One hand acts independently of the patient’s voluntary control • corpus callosum, frontal lobe, or posterolateral parietal lobe

10. Peripheral nervous system symptoms

11. Acute vestibular syndrome • abrupt onset of dizziness, nausea, vomiting, headache, intolerance to head motion, nystagmus, and unsteady gait. • posterior circulation stroke • Misdiagnosis is more common in patients with vertebrobasilar strokes than with other stroke types.

12. Acute monoparesis and cortical hand syndrome • Cortical “hand knob” is large • small stroke affecting this region of the precentralgyrus can lead to a very targeted deficit involving only the hand, several fingers, or even just the thumb • Cortical sensations, including stereognosis, graphesthesia, and point localisation, in the affected hand are often impaired • leg monoparesis: anterior cerebral artery stroke • cortical foot syndrome: isolated foot drop mimics a peroneal nerve lesion.

13. Imaging of Acute Ischemic Stroke

14. Unenhanced Computed Tomography • The first-line diagnostic test for the emergency evaluation of acute stroke • Accuracy in detecting subarachnoid and intracranial hemorrhage • CT was equivalent to MRI in its ability to detect the earliest signs of stroke (1) • 1-Mohr J, Biller J, Hilal S, Yuh W et al (1995) Magnetic resonance versus computed tomographic imaging in acute stroke. Stroke 26:807–812

15. CT Early Ischemic Changes(EIC) • (1) loss of gray–white matter differentiation in cortical gyri,basal ganglia or insula (the so-called loss of insular ribbon sign) most important • (2) loss of cortical sulci or narrowing of the sylvian fissure • (3) compression of the ventricular system and basal cisterns • (4) hyperdensity in a Circle of Willis vessel due to the presence of occlusive thrombus, most notably in the middle cerebral artery(proximal MCA, also known as “hyperdense MCA sign,” and “MCA dot sign” )

16. EIC • In hyperacute stroke (0–3 h of stroke onset),EIC have been shown in up to 31–53% of cases. • 92% rate of lentiform nucleus obscuration within 6 h of MCA stroke • Early hypodensities have a high (87%) positive predictive value for stroke • Early low attenuation in more than 50% of the MCA territory is predictive of up to 85% mortality,with poor outcome in survivors • Hypodensity greater than one-third of the MCA territory was also an independent risk factor for symptomatic hemorrhage after thrombolysis. • Cortical swelling and sulcal effacement have not been clinically useful indicators of acute infarction.

23. Alberta Stroke Program Early CT Score (ASPECTS)

25. MRI • MR diffusion-weighted imaging (DWI) is the single most accurate method for detecting acute ischemia. • Decreased diffusion results in hyperintense signal on DW images that can be reliably detected within the first 30 minutes of stroke symptom onset. • A DWI hyperintenselesion with truly restricted diffusion will be dark on ADC maps

30. MRI • focal vessel hyperintensity on FLAIR: detection rates comparable to MR angiography (MRA) in both middle and posterior cerebral arteries. • Edema associated with infarction: earliest on FLAIR sequences ( sensitivity of 29% in the first 6 hours) • By 8 hours, hyperintense signal develops on T2-weighted images • By 16 hours, low signal intensity is noted on T1-weighted images