Case: 45-year-old Man Presenting with a Stroke

00:01 In this talk, we're going to review determining the cause of an ischemic stroke.

00:06 This is a really important component of evaluating patients with stroke.

00:11 So let's start with a case.

00:13 This is a 45-year-old man presenting with a stroke.

00:16 A 45-year-old man with a history of hypertension, hyperlipidemia and diabetes mellitus, not on antiplatelet treatment, presents for right-sided weakness and speech dysfunction.

00:28 The patient went to bed last night in his normal health.

00:31 When the patient awoke this morning, his wife says that he did not have symptoms and was able to speak normally.

00:37 Around 10:30 AM, he went to the shed to work in his shop.

00:41 At around 11:30 AM, she found him in the shed on the ground without the ability to move his right side and mumbling.

00:51 Examination shows a left MCA syndrome with right hemiplegia, an expressive more than receptive aphasia.

01:00 CT head is without intracranial hemorrhage and CTA shows left MCA occlusion.

01:06 The patient receives IV tPA, followed by thrombectomy to remove the clot and is monitored in the ICU for 24 hours.

01:15 He's transitioned to the floor for further workup.

01:18 So what's the next step in his workup? Well first, let's talk about some of the key features in this case.

01:26 First, we want to make note of the symptom onset.

01:29 This was sudden, abrupt or acute in onset.

01:32 His wife found him in the shed lying on the ground with these new symptoms.

01:38 Second is the evolution of the symptoms over time.

01:41 This is what we would call an acute fixed deficit.

01:45 It began suddenly abruptly and symptoms have persisted in the same way since that time.

01:51 That's what we see with a stroke.

01:54 And then the last is the localization.

01:57 The patient has a right hemiplegia and significant aphasia, and we see that with left cortical left hemisphere problems.

02:08 And then there's an important wildcard here.

02:11 The patient's last known normal is 10:30 AM.

02:15 The concept of last known normal is very important when evaluating patients with stroke.

02:20 The stroke symptoms did not begin at 11:30am when she found him, but really we mark them at the last known normal which is 10:30am.

02:31 So we did some imaging for this patient, and here we see this patient's imaging on the left, we have a CT without contrast.

02:38 And this is a normal head CT.

02:40 There's no hemorrhage which is really the most important thing we're evaluating in a patient who presents with concerns for an acute ischemic stroke.

02:47 Is it hemorrhagic or is it likely ischemic? And this supports the potential for an ischemic etiology.

02:53 On the right, we see this patient's CTA or a CT of the arteries, a CT angiography, lighting up the blood vessels in the brain.

03:02 We see the right MCA is full.

03:04 It's opacified and we can see good contrast in the right MCA, but there's an occlusion in the left MCA.

03:11 And that's a clot that's causing his left MCA syndrome and right hemibody symptoms.

03:18 So here we can take a closer look at this patient CTA and we're looking at the Circle of Willis that connection of blood vessels that supply the brain with blood.

03:30 On the right, we see the ICA.

03:31 And there are two internal carotid arteries, one on the right and one on the left, and they give blood supply to the anterior portions of the brain.

03:39 Coming off of the ICA, we have an MCA or the Middle Cerebral Artery providing the middle parts of the brain with blood.

03:47 Here we see a well formed right MCA and an occluded left middle cerebral artery.

03:54 You can see that blood clot with an abrupt ending of the left MCA.

03:59 Also coming off the ICA or the ACAs are the anterior cerebral arteries, one on the right and one on the left.

04:07 And then there's the posterior circulation providing the brainstem and the occipital lobes with blood.

04:13 Those are supplied by the basilar artery, the most important posterior artery of the brain and giving off two PCAs or Posterior Cerebral Arteries.

04:24 And together those vessels supply the brain with blood.

04:29 So in this patient with an acute left MCA syndrome, what's the best next step in workup? Is it an MRI of the brain? To repeat the CTA of the head neck? To start Clopidogrel or Plavix for secondary stroke prevention? Or evaluate for obstructive sleep apnea? Well, we don't need to repeat the CTA we just saw that and there's an acute obstruction of the left MCA branch.

04:54 There's been no change in the patient's clinical status and no reason to repeat this imaging study.

05:02 We don't need to start clopidogrel Clopidogrel is used for secondary stroke prevention.

05:07 But we often begin with aspirin.

05:09 And at this point we need to understand the cause of this patient's stroke before initiating secondary stroke prevention.

05:18 We don't need to first evaluate for obstructive sleep apnea.

05:22 Obstructive sleep apnea is associated with stroke.

05:24 Evaluating obstructive sleep apnea is a part of our stroke workup.

05:28 But that's not the best next step.

05:32 For this patient, we would proceed with an MRI of the brain.

05:35 This will help us to evaluate the extent and distribution of the stroke and understanding the distribution will help us to figure out what the cause is.

05:46 In this patient, we did perform an MRI of the brain and we're looking at that here.

05:50 This is the diffusion weighted MRI, which is evaluating cytotoxic edema that occurs in the brain immediately after a stroke.

05:57 And we see a large area of restricted diffusion, reduced diffusion in the left MCA territory consistent with an acute ischemic infarct of the left MCA.

06:10 We could see other findings.

06:11 And the MRI is really important for evaluating the distribution of stroke and understanding what the potential cause is.

06:18 Here we're looking at a diffusion weighted MRI showing multifocal regions of restricted diffusion.

06:25 In the right and left MCA territories and potentially even back in the PCA territories.

06:31 This multifocal pattern is suggestive of a cardioembolic source emboli that originated from the heart and showered up into the brain.

06:41 Sometimes on MRI we see small punctate subcortical strokes and you can see that here.

06:47 This is a diffusion weighted image showing two small punctate infarcts in the internal capsule of the left hemisphere.

06:54 These we call the lacunes or small islands of stroke in the deep subcortical regions of the brain.

07:00 And this is suggestive of a lacunar infarct which we see from long standing hypertension.

07:06 In addition to the diffusion weighted image, we can also we can also look at the FLAIR or fluid-attenuated inversion recovery image, and those looks at edema, vasogenic edema that can occur after a stroke and corresponds to the area of acute infarct or restricted diffusion.