Cerebrovascular Disease

1. Cerebrovascular Disease FM Brett , MD, FRCPath

2. ~ In USA 0.5 million new strokes diagnosed annually and 3 million survivors of a previous stroke ~ Stroke 3rd most frequent cause of death ~ 2nd most frequent cause of dementia ~ Major reason for severe disability and long term dependency

3. Epidemiological aspects of stroke ~ In the USA stroke is the third commonest cause of death ~ Incidence increases with age ~ Major risk factors for stroke are hypertension, cardiac disease, smoking, hyperlipidemia, and diabetes ~ Other causes OCP, sickle cell, coagulation disorders ~ In USA - brain infarction 10 times commoner than haemorrhage

4. Blood supply to the brain ~ Human brain approx 2% of body weight ~ Receives 15% of total cardiac output O2 consumption approximately 20% of whole body (i.e high metabolic rate) ~ How long would the brain survive if blood flow interrupted

6. Terminology ~ Ischaemia - arterial stenosis or occlusion Infarction - perfusion territory of the affected vessel ~ Global brain ischaemia - < CPP below the threshold for autoregulation i.e when systemic blood pressure falls very low e.g cardiac tamponade, heroin overdose, or ICP rises to a level that compromises cerebral perfusion Resultant brain damage or infarction is accentuated in the WATERSHED REGIONS

8. CPP= SAP - ICP CPP > 40 mmHg - necessary for autoregulation If CPP < 40 mmHg CBF falls dramatically

9. Principal causes of hypoxia Hypoxemic hypoxia - low O2 in blood ~ Carbon monoxide poisoning ~ Near drowning ~ Respiratory arrest ~ Prolonged status epilepticus Stagnant hypoxia - (inadequate supply of oxygenated O2 ~ Cardiac arrest ~ Rise ICP ~ Respirator brain Histotoxic hypoxia (inability of tissues to use O2) ~ Cyanide and sulphide exposure - inhibition of mitochondrial enzymes involved in oxidative respiration

10. Selectively vulnerable zones ~ Hippocampus - CA1 ~ Laminae 3 and 5 of cortex ~ Purkinje cells cerebellum

12. HYPOXIA- blood flow to the CNS may be normal or increased Damage occurs in selectively vulnerable neurones

13. Hypoxic ischaemic encephalopathy ~ Variable clinical presentation ~ Clinical recovery generally better after hypoxemic hypoxia than after global brain ischaemia ~ Severity and duration of HIE after transient cerebral hypoxia depends on I) duration of insult 2) completeness of insult 3) blood glucose level (high level poor outcome) 4) CNS temperature ~ Long term sequelae - difficult to predict

16. Infarct - region of cell death Infarct may become secondarily haemorrhagic and may mimic a primary haemorrhage STROKE - rapid onset of focal disturbance of cerebral function lasting > 24 hours TIA - less than 24 hours Infarcts may be caused by: ~ Large vessel or macrovasculature disease ~ Small vessel or microvasculature disease ~ Emboli ~ Venous thrombosis

17. Types of vascular disease Anterior circulation A. Small vessel disease – e.g microangiopathy B. Occlusive large vessel disease of pial arteries C. Occlusive large- vessel disease of brain supplying arteries in the neck D. Embolising heart disease including aortic plaques and R-L shunts

18. 1 a, b – small vessel disease 2 a,b. Atherosclerotic or embolic occlusion of cerebellar artery 3 – intracranial thrombosis 4 – atheromatosis of vertebro-basilar artery 5 – embolus sticking in mid-basilar artery • In situ thrombosis of • basilar artery

20. Thalamic infarction Sensory or sensiomotor hemi-deficits with disassociated sensory loss, hemispasticity or even severe impairment of position sense; Segmental and focal dystonia without jerks and abnormal dystonic posture of affected hand

23. ~ Large vessel disease includes atherosclerosis, fibromuscular dysplasia, arterial dissection, giant cell arteritis ATHEROSCLEROSIS IS THE COMMONEST OF THESE

26. ATHEROSCLEROSIS - leading vasculopathy producing brain infarcts. Affects intracranial and extracranial large vessels RISK FACTORS ~ Hyperlipidemia ~ Hypertension ~ Cigarette smoking ~ Obesity ~ Age ~ Sex

29. Small vessel disease includes cerebral vasulitides PACNS ~ Isolated granulomatous or primary angiitis of the CNS (PACNS)

30. PACNS ~ Recognised in the mid 1950’s ~ Diagnosis: ~ Clinical ~ Imaging ~ Biopsy

32. Case presentation

33. EMBOLIC DISEASE • Embolic stroke results when any solid material: • forms within the aterial circulation • is introduced into the arterial circulation • forms within the venous and has a conduit to the • arterial circulation ì.e right to left shunt • Resultant infarct is : • clinically abrupt • haemorrhagic

35. Autopsy of a stroke patient If infarction 1. Examine major cranial arteries i.e carotid and vertebral arteries in the neck 2. Carefully examine heart for: infective endocarditis valvular abnormalities septal defects

36. IF haemorrhage Look for evidence of: 1. Hypertension i.e cardiomegaly, LVH, nephrosclerosis 2. Neoplasia 3. Drug abuse 4. If dementia CAA

37. Blood in the cranial cavity • Source? • Spread • Occur? • Cause? • Sufficient to cause death

38. Intracranial haemorrhage • Extradural • Subdural • Subarachnoid • Intracerebral

39. SAH • Berry aneurysm • Infectious • Fusiform aneurysm • AVM • CAA

40. CIRCLE OF WILLIS

41. Berry aneurysms • Congenital • Risk of bleeding inc; • Hypertension • AVM • systemic vascular • disease • defects collagen • polcystic renal disease

42. ICH causes • Hypertension • Trauma • CAA • Berry aneurysm • AVM • Bleeding diathesis • Vasculitides • Drugs • Neoplasm • Infective

43. Hypertension - major risk factor for brain haemorrhage • Occurs due to rupture of arterioles that have become • weakened • DUE TO • Replacement of smooth muscle by fibrocartilagenous material • Fragmentation of elastic tissue • Charcot-Bouchard aneurysms

44. Haemorrhages involving the basal ganglia- putamen in particular tend to be non-traumatic and caused by hypertension

45. Chronic hypertension leads to arteriolar sclerosis resulting in small lacunar infarcts OCCUR~ BASAL GANGLIA~ PONS~ DEEP WHITE MATTER

46. AVM • Commonest 3-4th decade • Rarely familial • Rarely multiple • have a nidus • commonest vascular malformation • identified in surgical specimens

48. End result of herniation is compression and Duret haemorrhages as seen in the pons

49. Venous Thrombosis ~ Often secondary to infectious causes ~ Pregnancy ~ Puerperium ~ OCP ~ Haematological abnormalities