Stroke Pathophysiology, Etiology and Risk Factors
Stroke Pathophysiology, Etiology and Risk Factors
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Content
0 ->
0.95 -> This presentation is on stroke,
3.29 -> pathophysiology, etiology,
5.45 -> and risk factors.
6.42 ->
9.65 -> At the end of this presentation,
11.67 -> you should be able to define
13.03 -> stroke and describe
14.38 -> its underlying pathophysiology,
17.08 -> understand
17.59 -> the different etiological
18.66 -> subtypes of stroke,
19.96 -> and know the epidemiology
21.56 -> and common modifiable risk
23.44 -> factors for stroke.
24.545 ->
27.35 -> Stroke is classically defined
29.37 -> as a sudden neurologic deficit
31.43 -> of vascular etiology lasting
33.69 -> more than 24 hours.
35.9 -> However, with the advent
37.25 -> of modern imaging studies,
39.19 -> there are some modification
40.39 -> to the definition.
41.98 -> Patients with rapidly vanishing
43.53 -> symptoms and imaging
45.04 -> of an acute clinically relevant
46.77 -> brain lesion are considered
48.55 -> to have suffered from a stroke.
50.66 -> A transient ischemic attack
52.37 -> or TIA is a transient episode
54.9 -> of neurological dysfunction
57.06 -> caused by focal brain,
58.78 -> spinal cord, or retinal ischemia
61.09 -> without acute infarction.
62.32 ->
65.61 -> There are two main types
66.75 -> of stroke, ischemic stroke
68.57 -> or cerebral infarction accounts
70.39 -> for the majority of strokes,
72.23 -> about 80% to 85%.
74.76 -> This is caused by interruption
76.35 -> of the blood supply
77.19 -> to the brain or spinal cord,
79.06 -> usually an occlusion
80.34 -> by a thrombus or embolus.
82.73 -> The cerebral arterial blood
84.06 -> supply is usually involved.
85.4 -> But uncommonly, the venous
87.53 -> system is affected
89.07 -> due to venous sinus thrombosis.
91.71 -> Hemorrhagic stroke,
93.15 -> or cerebral hemorrhage,
94.36 -> accounts for about 10% to 15%
96.57 -> of all strokes.
98.24 -> This is caused by a rupture
99.58 -> of a blood vessel.
101.31 -> These may be related
102.25 -> to hypertension, aneurysm,
104.04 -> or arterial venous malformation.
106.99 -> Hemorrhage may be inside a brain
108.58 -> parenchyma, that is,
110.29 -> intracerebral
111.06 -> or outside the brain parenchyma,
113.25 -> such as a subarachnoid
114.6 -> hemorrhage.
115.7 -> Both ischemic and hemorrhagic
117.34 -> strokes can occur in the brain
118.99 -> or the spinal cord.
119.98 ->
123.65 -> The etiology of ischemic stroke
125.85 -> can be classified according
127.34 -> to the pathologic mechanism
129.039 -> involved.
130.66 -> The pathology may be related
132.25 -> to large vessel disease.
134.42 -> This may be extracranial disease
136.5 -> involving the common or internal
138.38 -> carotid arteries
139.94 -> or intracranial disease
141.8 -> involving, for example,
143.85 -> the middle cerebral and basilar
145.5 -> arteries.
147.33 -> Atherosclerosis is
148.73 -> the usual underlying pathology
150.79 -> causing plaque and thrombus
152.21 -> formation, resulting in stenosis
154.93 -> or narrowing of the blood vessel
156.69 -> lumen.
158.37 -> Another category of stroke
160.16 -> is small vessel disease
161.84 -> affecting arteries
163.03 -> of small penetrating arterials
165.22 -> supplying the deep subcortical
167.44 -> and brain stem regions causing
169.6 -> small areas of infarction
171.59 -> sometimes referred as lacunar
173.75 -> infarction.
175.67 -> The underlying pathology
177.09 -> is postulated to include
179.04 -> microatheroma, lipohyalinosis,
181.61 -> and fibrinoid necrosis.
184.74 -> Cardioembolic stroke
186.04 -> is due to a cardiac thrombus
188.02 -> embolizing to cause
189.3 -> cerebral arterial obstruction.
192.36 -> Sources of cardioembolism
193.94 -> include atrial fibrillation,
196.18 -> mechanical prosthetic valves,
198.32 -> poor cardiac ejection fraction,
200.06 -> and valvular heart disease.
203.09 -> Other known, but less common
204.56 -> etiologies of ischemic stroke
206.37 -> are autoimmune diseases,
208.14 -> like systemic lupus
209.47 -> erythematosus,
211.03 -> hypercoagulable [INAUDIBLE]
213.46 -> conditions,
214.31 -> and arterial dissection.
215.37 ->
218.29 -> Next, we will discuss
219.33 -> the etiology
219.88 -> of hemorrhagic stroke.
221.62 -> In primary hypertensive
223.16 -> intracerebral hemorrhage,
225.03 -> uncontrolled hypertension leads
226.58 -> to weakening of arterial walls,
228.58 -> causing
229.08 -> Charcot-Bouchard aneurysms,
230.99 -> which are prone to rupture
232.4 -> causing
232.9 -> intracerebral hemorrhage.
235.14 -> The most common site
236.27 -> is the basal ganglia
237.59 -> due to involvement
238.83 -> of the lenticulostriate branches
240.84 -> of the middle cerebral artery.
243.26 -> Abnormal dilatation
244.53 -> of an arterial wall
245.96 -> forming a secular aneurysm which
248.1 -> can rupture causing
249.13 -> subarachnoid, an intracerebral
251.34 -> hemorrhage.
252.6 -> Saccular aneurysms tend to occur
254.48 -> along bifurcations
255.265 -> of large cerebral arteries.
258.7 -> Arterial venous malformations
260.35 -> are abnormal connections
261.6 -> between arteries and veins
263.31 -> and are usually congenital.
265.52 -> They can rupture causing
266.75 -> cerebral hemorrhage, which
268.27 -> is usually lobar and tends
269.92 -> to affect younger individuals.
272.994 -> Other etiologies
273.66 -> of hemorrhagic stroke
274.8 -> are vascular [INAUDIBLE],
276.03 -> like amyloid angiopathy.
277.95 -> These are more
278.65 -> common among the elderly
280.17 -> and the intracerebral hemorrhage
281.94 -> seen in these cases are usually
284.11 -> located more
284.95 -> superficially in the lobar
286.67 -> regions of the brain.
287.91 ->
290.91 -> We next move
291.48 -> on to the epidemiology
292.46 -> of stroke.
294 -> This slide covers
295.04 -> the non-modifiable risk factors
296.96 -> of stroke.
297.9 -> As one gets older, the risk
300.01 -> of stroke increases.
301.7 -> In demographically developed
303.33 -> countries, the average age
305.04 -> of stroke onset is 73 years,
307.412 -> though it might be younger
308.495 -> in less developed countries.
311 -> Stroke risk doubles
312.54 -> for each decade after age 55.
316.17 -> Males have a slightly higher
317.64 -> stroke incidence compared
319.04 -> to females.
320.99 -> Race is a non-modifiable risk
323.22 -> factor with certain ethnicities
325.34 -> predisposed to certain types
326.77 -> of stroke.
327.87 -> For example, small vessel
329.51 -> arterial strokes are more
330.91 -> common among Asians,
332.68 -> and hypertensive bleeds are more
334.11 -> common among Africans
335.8 -> compared to Caucasians.
338.26 -> A positive family history
339.53 -> of stroke is also associated
341.18 -> with increased risk of stroke.
343.92 -> Some strokes subtypes are
345.38 -> from genetic disorders,
346.84 -> for example, CADASIL.
347.83 ->
351.1 -> There are a number
351.85 -> of modifiable risk factors
353.59 -> for ischemic stroke
355.35 -> wherein hypertension is the most
356.85 -> common
357.35 -> and the most important one.
359.57 -> Blood pressure of around 140
361.76 -> to 160 systolic and 90 to 94
365.1 -> diastolic increases the risk
367.04 -> of stroke by 1.5 times
369.26 -> while blood pressure of more
370.8 -> than 160
371.96 -> systolic and 95 diastolic
374.52 -> increases the risk by 3 to 4
376.57 -> times.
378.06 -> Another common risk factor
379.85 -> is diabetes mellitus.
381.6 -> It increases risk
382.68 -> of ischemic stroke
383.99 -> by about two times independent
386 -> of other associated risk.
388.52 -> Dyslipidemia is another risk
390.24 -> factor with one study showing
392.49 -> for every 1 million
393.65 -> mole per liter increase
395.08 -> in total cholesterol, that
396.84 -> is concurrent to a 5% increased
399.34 -> risk of ischemic stroke.
401.76 -> Atrial fibrillation, the most
403.49 -> common cause
404.2 -> of cardioembolic stroke,
405.9 -> increases ischemic stroke risk
407.705 -> by approximately 4 to 5 times.
411.01 -> Acute myocardial infarction
412.77 -> is also associated with 5%
414.95 -> increased risk
416.04 -> of ischemic stroke
417.41 -> within the first two weeks
418.62 -> of event with increased risk
420.78 -> of 12% if complicated
422.88 -> by presence of LV thrombus.
425.69 -> Lifestyle factors are also very
427.39 -> important as stroke risk
428.611 -> factors.
430.1 -> Cigarette smoking approximately
431.83 -> doubles the risk
432.77 -> of ischemic stroke
434.01 -> compared to nonsmokers.
436.09 -> Moderate alcohol consumption
437.67 -> is also [INAUDIBLE] with lower
439.01 -> incidence of ischemic stroke,
440.98 -> but heavy drinkers have a higher
442.85 -> chance of stroke.
444.45 -> Obesity, which is increasing
445.96 -> in prevalence,
446.95 -> is also [INAUDIBLE]
447.84 -> with coronary artery disease
449.82 -> and ischemic stroke.
451.64 -> Obese people tend to have a more
453.21 -> sedentary lifestyle
454.58 -> and eat a less healthy diet
456.28 -> than non-obese people.
458.33 -> Obesity increases risk of stroke
460.115 -> with relative risk of 1.5 times.
463.29 -> A sedentary lifestyle can also
465.09 -> affect individual risk
466.52 -> of stroke.
467.6 -> Studies have shown that there
468.92 -> are fewer strokes among more
470.44 -> active patients compared to less
472.77 -> active patients.
474.96 -> Lastly, recreational use
477.08 -> of drugs, such as cocaine
478.64 -> and methamphetamine,
479.9 -> is also associated
481.12 -> with increased risk of stroke.
482.545 ->
485.79 -> Thank you for listening.
487.2 -> We hope you have enjoyed
488.33 -> learning about stroke
489.44 -> through this presentation.
491.49 ->
Source: https://www.youtube.com/watch?v=JkY0GetkL74