The document discusses carotid artery strokes, describing the anatomy of the carotid arteries and causes of stenosis like plaque buildup which can lead to emboli and blockages. Symptoms of carotid artery stenosis or occlusion include transient ischemic attacks (TIAs) or strokes, and treatment options involve lifestyle changes, medications, carotid endarterectomy surgery, or carotid stenting to reopen blocked arteries. Grades of stenosis are defined based on the percentage of blockage.

1. Carotid Artery Stroke Dr. S. Aswini kumar. MD, Professor of Medicine, Medical College Hospital, Thiruvananthapuram.

2. Introduction:

3. Anatomical Points: The internal carotid artery originates at the bifurcation of the common carotid artery at the level of the thyroid cartilage in neck. The extracranial portion of the artery passes into the carotid canal of the temporal bone without giving off any branches. The intracranial portion of the artery consists of the petrosal, cavernous ie, S-shaped carotid syphon, and supra-clinoid portions.

4. Anatomical Points: The major intracranial branches arise from the supra-clinoid portion The first one is the ophthalmic artery that enters the orbit through the optic foramen to supply the retina and optic nerve. Next, the posterior communicating artery arises just distal to the ophthalmic artery and joins the posterior cerebral artery to form the circle of Willis

5. Carotid Artery Circulation: The common carotid (CCA) divides into external carotid artery (ECA) and internal carotid artery (ICA). The ECA has many branches which supply structures of head neck. The ICA has no branches in the neck, but proceeds directly towards base of the brain. Its terminal branches at the base of the brain comprise the "anterior circulation" of the circle of Willis.

6. Carotid Stenosis - Pathogenesis: When fatty and inflammatory tissue builds up on the inside surface of an artery, it forms a plaque . Platelets, fibrin and other blood products can stick to this and form a clot ( thrombus ). This leads to blockage of flow through the artery, which is known as carotid stenosis .

7. Carotid Stenosis: Embolization Sometimes, a fragment of the plaque ( embolus ) can break off and "seed" the distant circulation leading to a transient ischemic attack ( TIA or a evolving or completed stroke. Symptoms of a TIA or stroke include sudden disorders of the speech ( dysarthria or aphasia ), vision ( amaurosis fugax ), limb power( paralysis ), sensation ( hypesthesia ).

8. Grades of Carotid Stenosis: The stenosis is mild if the obstruction is < 40%. There is said to be moderate stenosis if the blockage is to be 40-69%. If the plaque build up involves 70% or more of the luminal diameter of the internal carotid artery the stenosis is referred to as &quot; high grade “. High grade stenosis results in only a trickle of flow in ICA distal to the blockage.

9. Investigations: On a carotid ultrasound , the blockage can be seen and it may create a jet effect that results in an abnormally high flow velocity . Another way blockage can be detected is using oculoplethysmography ( OPG ), where the eye pressures are recorded and found to be abnormal. On a MR angiogram or CT angiogram , this trickle may appear as a &quot; string sign &quot; because it looks like a string of remaining flow.

10. Medical Treatment: Treatment is carried out to prevent stroke , or if a limited stroke has occurred, to prevent further debilitating stroke . Medical treatment options include life-style (risk factor) modification more exercise, better diet, quitting smoking, anticholesterol drugs anti-hypertensive agents, antiplatelet agents

11. Surgical Treatment: The surgical treatment option is carotid endarterectomy Here, a surgeon makes an incision in the neck, accesses the carotid arteries as shown, opens them and cleans out the plaque. The vessel is then sewn closed with or without a synthetic patch graft (goretex or an equivalent biocompatible fabric).

12. Carotid endarterectomy: The carotid artery is accessed through an incision in neck (A). Pressure inside the vessel is measured to assess the degree of blockage (B). The carotid is clamped above and below the incision, and a shunt is inserted to maintain blood flow (C). Plaque removed (D). Shunt taken out (E) Incisions repaired (F)

13. The risks of Surgery: The risks of surgery: Peri-operative mortality: Up to 4% in large trials If stroke included-5% risk of stroke risk of an MI risk of infection and Hematoma in the neck injury to cranial nerves IX X XII

14. Carotid Stenting: The endovascular alternative to surgery is carotid stenting Here, a catheter is passed through the femoral artery up into the neck A stent is deployed to &quot;jimmy&quot; (ie. wedge or compress) the plaque against the artery wall to create a bigger opening for blood to flow in the center of the diseased internal carotid artery

15. Risk of Stenting: There is no surgery involved, and usually little risk of myocardial infarction. But some studies suggest that the risk of stroke from embolism during stenting is increased. The risk of significant complication with stenting is probably around 5% The chances of recurrent stenosis are also higher with stenting.

16. Carotid Occlusion – Atherosclerosis: Carotid artery stenosis can predispose towards platelets sticking to the abnormal or raw segment, especially if it has an ulcerated region. This leads to formation of a thrombus which can block off flow distant to the diseased segment. This is referred to a carotid occlusion. It may be asymptomatic in about 25% or it may cause (TIA) or completed stroke.

17. Treatment of Carotid Occlusion: Treatment of carotid occlusion may include one of the following Direct endovascular thrombolysis (clot-dissolving medicines through a catheter) with, e.g., tPA Surgical revascularization : urgent carotid endarterectomy and thrombectomy EC-IC (brain) bypass : used depending on many factors.

18. Carotid Dissection - Early Dissection: Carotid dissection refers to a tear between the layers of the carotid artery wall. Risk factors: direct mechanical injury e.g., external trauma Endovascular procedures where a catheter is navigated Vigorous neck turning Chiropractic manipulation Prolonged bouts of coughing and crying

19. Carotid Dissection - Presentation: Sudden or gradually worsening headache especially on same side Sudden neurological impairment TIA or stroke Pain in the neck over the dissected carotid artery ( carotidynia ), Horner's syndrome . This is a subintimal dissection . There may alternatively or in addition be medial or &quot; subadventitial &quot; dissection

20. Carotid Dissection - Large Dissection: The main complication of carotid dissection is stroke from carotid occlusion. The investigations include: CT or MRI scan to rule out a stroke, a CT angiogram or MR angiogram. Patients with Fibromuscular dysplasia. Marfan syndrome, Takayasu's arteritis, Moya Moya, and (PAN) polyarteritis nodosa are at higher risk.

21. Carotid Dissection - Dissecting Aneurysm The other complication of a carotid dissection is the formation of a dissecting aneurysm . The torn carotid artery wall leads to escape of blood through the inner wall and into a pocket under the outer wall. When it occurs into the surrounding tissue it is caleed a pseudoaneurysm because its wall is made up of nonvascular tissue.

22. Dissecting Aneurysm – Treatment: Aneurysm formation here is a surgical emergency Its treatment involves surgical reconstruction of the carotid artery Sometimes even need carotid artery sacrifice Carotid artery ligation or endovascular occlusion may be required as part of carotid artery sacrifice .

23. Occlusion of Common Carotid: All symptoms and signs of internal carotid occlusion may also be present with occlusion of the common carotid artery. Bilateral common carotid artery occlusions at their origin may occur in Takayasu's arteritis .

24. Common causes of ischemic stroke and TIA

25. Causes of Stroke:

26. Internal Carotid Occlusion The clinical picture varies depending on whether the cause of ischemia is propagated thrombus, embolism, or low flow. The cortex supplied by MCA territory is affected most often. With a competent circle of Willis, occlusion may go unnoticed. If the thrombus propagates up the internal carotid artery into the MCA or embolizes it, symptoms are identical to proximal MCA occlusion. Sometimes there is massive infarction of the entire deep white matter and cortical surface. When the origins of both the ACA and MCA are occluded at the top of the carotid artery, abulia or stupor occurs with hemiplegia, hemianesthesia, and aphasia or anosognosia. When PCA arises from the ICA (a configuration called a fetal posterior cerebral artery), it may also become occluded and give rise to symptoms referable to its peripheral territory.

27. Amaurosis Fugax: In addition to supplying the ipsilateral brain, the internal carotid artery perfuses the optic nerve and retina via the ophthalmic artery. In about 25% of symptomatic internal carotid disease, recurrent transient monocular blindness (amaurosis fugax) warns of the lesion. Patients typically describe a horizontal shade that sweeps down or up across the field of vision. They may also complain that their vision was blurred in that eye or that the upper or lower half of vision disappeared. In most cases, these symptoms last only a few minutes. Rarely, ischemia or infarction of the ophthalmic artery or central retinal arteries occurs at the time of cerebral TIA or infarction.

28. Symptoms:

29. Palpation of carotids: The carotid artery is palpated in the neck by gentle compression with one or two fingers The volume of the pulse is assessed and compared with the volume of the opposite side Never ever the carotids are palpated together for very obvious reason The palpation shall never be too strong as to precipitate a cardiac arrest

30. Carotid Bruit A carotid bruit is auscultated with diaphragm of stethoscope at the level of thyroid cartilage. A high-pitched prolonged carotid bruit fading into diastole is often associated with tightly stenotic lesions. As the stenosis grows tighter and flow distal to the stenosis becomes reduced. The bruit becomes fainter and may disappear when occlusion is imminent.

31. Symptomatic and Asymptomatic Stenosis:

32. Risk of Ipsilateral Stroke in Unilateral ACS:

33. Management Principles:

34. Summary of Management:

35. Summary of the Treatment:

36. Thank you for the patient listening