Stroke: Work-up and Etiology

00:01 Now let's talk about the work-up for ischemic stroke and evaluating the causes of the stroke.

00:07 And again, we think about strokes coming from three areas.

00:10 They can come from the heart, the blood vessels in the neck, or the blood vessels in the brain.

00:15 And so we do diagnostic testing to work up each of those areas.

00:19 First, let's talk about how we evaluate the blood vessels in the neck.

00:23 And there's really two studies that we can use to do that.

00:25 The carotid ultrasound or the (CTA) CT angiography.

00:30 Carotid ultrasound uses ultrasound or sonography to evaluate the blood vessels in the neck, and we often combine it with transcranial doppler or TCD to evaluate the blood vessels in the brain.

00:43 We can also do a CTA or CT angiography of the head and neck, which also evaluates the patency or openness of the blood vessels in the neck and the head.

00:53 We're looking for carotid artery stenosis in carotid artery stenosis more than 70% where the lumen of the carotid artery is narrowed by at least 70% in narrowed by at least 70% in a symptomatic patient warrants surgical consideration.

01:08 Carotid artery stenosis more than 60% in an asymptomatic individual, particularly men with diabetes also warrants surgical consideration.

01:16 Those patients are at higher risk of stroke.

01:18 And in those patients we want to intervene to prevent stroke before it happens.

01:24 What about evaluating the heart? Well, for there we really use two tests, the transthoracic echocardiogram or EKG to evaluate the heart and its function.

01:34 EKG and telemetry evaluate for paroxysmal atrial fibrillation, which increases the likelihood or risk of cardiac embolic strokes.

01:43 The transthoracic echocardiogram looks at the ejection fraction and atrial size.

01:48 Patients with reduced ejection fraction are at risk for blood clot development in the heart which can embolize to the brain.

01:54 Enlarged atrial size, increases the risk of paroxysmal Afib and would warrant further evaluation for afib in those patients.

02:03 We can also perform a bubble study where we use bubbles injected into the veins to evaluate a hole in the heart patent foramen ovale.

02:12 This is a symptomatic very small hole from a vestigial structure that exists in the heart and can be a nidus for right to left transfer of a blood clot.

02:22 Patients who may have venous thromboembolism or a DVT that embolizes can pass through the PFO and then travel to the brain and cause a stroke.

02:31 So the presence of a PFO warrants further evaluation for a DVT in those patients.

02:37 And then lastly, we want to evaluate potential risk factors for stroke when we perform a TSH to evaluate for hyper or hypothyroidism.

02:47 Hyperthyroidism is associated with atrial fibrillation risk.

02:51 Hypothyroidism is associated with hypertriglyceridemia.

02:55 We can work up for diabetes and A1C of greater than 7 raises risk for stroke.

03:01 And really the goal is an A1C less than 7.

03:04 This is one of the most important risk factors to modify in addition to blood pressure and LDL.

03:12 LDL or low-density lipoprotein is one of the important cholesterol measures.

03:18 There's a linear risk with reduction in LDL and reduction in stroke.

03:23 And we'd like to see a low LDL and a high HDL.

03:27 Our LDL goal for patients who have had a stroke is than less than 100 unless the patient has diabetes where the goal is less than 70.

03:36 And then also important is managing blood pressure, high blood pressure hypertension during the acute or hyper acute period right when patients present with a stroke, we allow permissive hypertension.

03:46 And that's a little bit of increased blood pressure right at that early period of time to perfuse that area of penumbra around the ischemic infarct.

03:55 But ultimately we want to move to normalization of the patient's blood pressure with a goal blood pressure of 120 over 70 and we use medicines like ACE inhibitors, diuretics, beta blockers, calcium channel blockers and others.