Clinical Presentation and Diagnosis of Cerebrovascular Disease

Stroke is a common and serious disorder. Each year stroke affects almost 800,000 people in the United States, at least 16 million people globally, and is the second leading cause of death in the world (see Chapter 28 ). The associated high morbidity and mortality of stroke, combined with its high cost for acute and chronic care, provide impetus for improving the diagnosis, acute management, and prevention of strokes. A full understanding of how patients with stroke and cerebrovascular disease come to medical attention, along with a logical approach for defining the mechanism of stroke, is needed for safe and effective implementation of acute therapies and prevention strategies. This chapter will focus on clinical manifestations of all types of cerebrovascular disease and how clinicians can approach diagnostic evaluation.

Overview of clinical stroke

Stroke and cerebrovascular disease are caused by a disturbance of the cerebral vessels and/or cerebral blood flow in almost all cases. In simple terms, we can divide stroke into two major types: ischemic and hemorrhagic. Ischemic stroke is the most common variety and is responsible for 80% to 85% of all strokes; hemorrhagic stroke accounts for the remainder. On occasion, an ischemic stroke can undergo secondary hemorrhagic transformation; likewise, a cerebral hemorrhage (particularly a subarachnoid hemorrhage [SAH]) can cause a secondary ischemic stroke via vasospasm.

Ischemic stroke occurs when a blood vessel in or around the brain becomes occluded or has a high-grade stenosis that reduces the perfusion of distal cerebral tissue. A variety of mechanisms and processes can lead to such occlusions and will be discussed later in more detail. On rare occasions, thrombosis and occlusion of a cerebral vein can lead to ischemic as well as hemorrhagic strokes (venous infarction).

A hemorrhagic stroke (intracerebral hemorrhage [ICH] and SAH) occurs when a blood vessel in or around the brain ruptures or leaks blood into the brain parenchyma (ICH) or into the subarachnoid space (SAH). It is not uncommon for there to be some overlap, such as an ICH also causing some degree of SAH and/or an intraventricular hemorrhage. Likewise, an SAH can produce some elements of an ICH if the aneurysmal rupture directs blood into the brain parenchyma. As with ischemic stroke, a variety of processes and lesions can produce ICH and SAH, but most affect the integrity of the vessel wall in some way.

Clinical manifestations of stroke and cerebrovascular disease

Stroke is similar to real estate in that much of its presentation and prognosis depend on size and location. The area of brain involved by the stroke typically dictates the presenting symptoms. Furthermore, blood vessels that supply different parts of the brain are affected by different types of cerebrovascular disease and have different mechanisms (pathophysiology) for the stroke. This concept greatly influences and defines the approach a vascular neurologist or neurosurgeon uses when assessing patients with a known or suspected stroke or cerebrovascular disease.

For example, a patient with evidence of involvement of the left hemispheric cortex (e.g., aphasia, visual field defect, weakness of contralateral face and arm) is likely to have a process involving the left middle cerebral artery (MCA). If head computed tomography (CT) does not show evidence of a hemorrhage, likely etiologies would include an embolic event from the heart (e.g., atrial fibrillation) or an artery-to-artery embolism (as might be seen with a high-grade lesion at the carotid bifurcation in the neck). Another patient with a pure motor hemiparesis but no other deficits is likely to have a lesion affecting the motor pathways in the internal capsule, often due to occlusion of a small penetrating artery (lenticulostriate vessel) deep in the brain. Most ischemic strokes will respect the vascular territory of one or more arteries. Indeed, lesions that do not respect typical arterial territories lead to concern for a nonvascular process (e.g., tumor, infection), or an atypical vascular process (i.e., venous infarction, vasculitis). Common ischemic stroke syndromes can be found in Tables 29.1 and 29.2 .

Table 29.1

Common Large-Vessel Ischemic Stroke Syndromes

Syndrome	Anatomy Involved	Major Symptoms	Vessels Involved	Etiology
Left MCA	Left frontal/parietal cortex and subcortical structures	Aphasia, right visual field cut, right motor/sensory deficits; face > arm > leg weakness; left gaze preference	Left MCA or major branch; could also be left ICA or siphon	Emboli from heart or proximal lesion; intrinsic atherothrombosis
Right MCA	Right frontal/parietal cortex and subcortical structures	Neglect syndrome, agnosia, apraxia, left motor/sensory deficits, visual field deficit; right gaze preference	Right MCA or major branch; right ICA or siphon	Same as left MCA
Left ACA	Left frontal and parasagittal areas	Speech disturbance, behavioral changes, leg > arm weakness	Left ACA	Intrinsic atherothrombosis, embolic
Right ACA	Right frontal and parasagittal areas	Behavioral changes, leg > arm weakness	Right ACA	Same as left ACA
Brainstem	Pons, midbrain, medulla, cerebellum	Ophthalmoplegia, bilateral motor deficits, ataxia/dysmetria; nausea/vomiting/vertigo, coma/altered mentation	Basilar artery	Intrinsic atherothrombosis, embolism from heart or proximal vessel
PCA	Upper midbrain, occipital cortex/subcortex, thalamus, medial temporal lobes	Visual field cut, motor/sensory loss, seizures, gaze problems; third nerve deficits	Posterior cerebral artery, thalamic perforators	Embolism from proximal lesion, intrinsic atherothrombosis

ACA , Anterior cerebral artery; ICA , internal carotid artery; MCA , middle cerebral artery; PCA , posterior cerebral artery.

Table 29.2

Common Lacunar Stroke Syndromes

Syndrome	Vessel Typically Involved	Brain Location	Symptoms
Pure motor hemiparesis	Lenticulostriate or basilar/pontine perforator	Internal capsule, pons	Unilateral weakness only
Mixed motor/sensory	Lenticulostriate or thalamic perforator or deep white matter vessel	Internal capsule, deep white matter, thalamus	Motor and sensory deficits
Pure sensory	Thalamic perforator	Posterior thalamus	Loss of contralateral sensory modalities
Ataxic hemiparesis	Lenticulostriate or basilar/pontine perforator	Internal capsule, basis pontis	Unilateral weakness with prominent ataxia, leg > arm
Dysarthria/clumsy hand	Lenticulostriate or deep white matter vessel	Internal capsule, deep white matter	Prominent dysarthria with isolated hand weakness

Evaluation of a patient with a hemorrhagic stroke follows a similar logical assessment but is further complicated by spread of the initial bleed, the effects of increased intracranial pressure, and other secondary effects that lead to neurological manifestations beyond the original injury. In this case, detailed cerebral imaging is vital for understanding the mechanism of the stroke and reasons for secondary worsening. The discussions that follow offer more detailed descriptions of common hemorrhagic stroke syndromes correlated with their likely anatomy and most likely etiology and pathophysiology.

Besides the location of the stroke, the tempo of onset and progression of symptoms often provide valuable information about stroke etiology and mechanism. Stroke symptoms that progress in a casual manner with gradual onset and worsening over many minutes or longer often suggest a thrombotic process or hypoperfusion due to occlusion or stenosis of a larger proximal vessel. Such a leisurely progression can also be seen with stroke mimics such as complicated migraines or partial seizures. The converse is a stroke syndrome with sudden onset of maximal symptoms that remain stable; this suggests an embolic process such as a cardioembolic stroke due to atrial fibrillation or an artery-to-artery process (although a thrombotic occlusion is still a possibility).

Similar reasoning holds true for most cases of hemorrhagic stroke. ICH often presents with the apparent abrupt onset of symptoms, but close questioning may reveal that symptoms actually progressed over 15 to 30 minutes as the hematoma grew and expanded. SAH is often characterized by sudden onset of the worst headache of one’s life, with significant nausea, vomiting, and stiff neck in many cases. The phrase “worst headache of my life” is so characteristic of SAH that a patient who presents with that symptom complex is assumed to have a SAH until proven otherwise.

Transient Ischemic Attack

A transient ischemic attack (TIA) can be a prodrome to an ischemic stroke. Symptoms of a TIA are identical to those of a stroke but with resolution within 24 hours (according to the old definition of a TIA). In reality, most TIA syndromes last just a few minutes, not many hours. In fact, modern brain imaging using magnetic resonance imaging (MRI) with diffusion-weighted sequences has shown that 25% to 30% of patients with a TIA lasting 30 minutes to 2 hours will have a new diffusion- weighted imaging (DWI) lesion on MRI, indicating a stroke (based on a tissue definition). TIA symptoms lasting 6 hours or longer have a 50% likelihood of having a new stroke on MRI with DWI techniques. Therefore the perceived distinction between a TIA and a stroke should be viewed more as a continuum from minor transient neuronal dysfunction to actual brain infarction with permanent symptoms.

Although it was once thought that the risk of stroke after a TIA was low, new imaging studies and epidemiological studies have proven this is not the case. Based on purely clinical criteria (not MRI results), several recent studies have shown that after a TIA, 10% of patients will have a stroke within 3 months and half those strokes (5%) will occur within 48 hours of the initial TIA. Approximately 25% of patients with a TIA will have a stroke, myocardial infarction (MI), death, or recurrent TIA or be hospitalized within the next 3 months. Based on these poor outcomes, recently published guidelines recommend hospital admission for patients with a recent TIA.

Further studies have attempted to better define those patients with a TIA who are at higher risk of having a stroke within the next 2 to 7 days. Several scoring systems have been developed ( Table 29.3 ) that may be useful for assessing such risks. Of course, any such assessment tool must be tempered by good clinical judgment and consideration of all clinical factors.

Table 29.3

Transient Ischemic Attack Scoring Systems

Data from Johnston SC, Rothwell PM, Nguyen-Huynh MN, et al. Validation and refinement of scores to predict very early stroke risk after transient ischaemic attack. Lancet. 2007;369(9558):283–292; and Kiyohara T, Kamouchi M, Kumai Y, et al. ABCD3 and ABCD3-I scores are superior to ABCD2 score in the prediction of short- and long-term risks of stroke after transient ischemic attack. Stroke. 2014;45(2):418–425.

ABCD	Age, blood pressure, clinical symptoms, duration
ABCD2	Age, blood pressure, clinical symptoms, duration, diabetes
ABCD2I	Age, blood pressure, clinical symptoms, duration, diabetes, infarction
ABCD3	Age, blood pressure, clinical symptoms, duration, diabetes, dual TIAs
ABCD3-I	Age, blood pressure, clinical symptoms, duration, diabetes, dual TIAs, imaging
Age: 60 years or greater = 1 point Blood pressure: systolic 140 mm Hg or greater = 1 point or diastolic 90 mm Hg or greater = 1 point Clinical symptoms: unilateral weakness = 2 points; speech disturbance without weakness = 1 point Duration: 60 min or more = 2 points; 10–59 min = 1 point Diabetes: 1 point (on antidiabetic medications) Dual TIA: One TIA prompting medical attention plus another TIA in preceding 7 days Imaging: evidence for acute ischemic stroke on CT or MRI or > 50% ipsilateral ICA stenosis (ABCD3-I only)

CT , Computed tomography; ICA , internal carotid artery; MRI, magnetic resonance imaging; TIA , transient ischemic attack.

Several types of TIAs deserve special mention because of their unique presentations and symptom complex. One is sudden blindness in one eye, which typically occurs as a “shade coming down” over the eye. Some patients report a graying out of vision in the eye, like looking through a gray haze or cloud. This type of TIA is often referred to as amaurosis fugax . This symptom complex typically resolves in a few minutes, although it can last for several hours. There is sometimes pain in or around the eye, globe, and orbit, but patients usually do not have any other focal neurological complaints at the same time. Some cases of amaurosis are due to emboli to the retinal circulation from an ulcerated plaque in or near the carotid bifurcation in the neck. Other cases can be due to local disease in the ophthalmic artery or in the posterior ciliary artery that supplies the optic nerve. A process such as temporal arteritis can produce headaches, eye pain, and sudden loss of vision.

Another unique type of TIA is the limb-shaking TIA . This typically involves the arm or leg on one side of the body. Patients report uncontrollable shaking of a limb that can be precipitated by movement. These spells can last seconds to minutes. They are not epileptic in origin; the electroencephalogram (EEG) is unremarkable. These TIAs are associated with severe stenosis of the contralateral internal or common carotid artery. Once the carotid artery is opened (usually with an endarterectomy), the spells cease.

Lastly is the topic of crescendo TIAs . This refers to a pattern where TIAs are recurrent, last longer, and/or are progressive or more severe in nature. This is a very worrisome type of TIA and is associated with a risk of stroke as high as 25% to 50% over the next few weeks. This presentation is very worrisome for high-grade ipsilateral carotid disease that might need urgent therapy.

It is important to understand that many patients have transient episodes of apparent neurological dysfunction (disturbed speech, motor symptoms, numbness, visual changes) from nonvascular etiologies. Causes can range from metabolic disturbances to seizures, atypical migraines to hysteria. Often a detailed evaluation, including brain and vessel imaging studies, is needed to establish a correct diagnosis.

Some hemorrhagic strokes may also have a TIA equivalent, namely the sentinel headache before a SAH. The sentinel headache presents as an acute headache that is unusual in terms of its nature, severity, and onset. It typically lasts more than an hour but does not have other impressive focal neurological findings and resolves prior to the definitive SAH presentation. Sentinel headaches occur in 25% to 50% of patients with a subsequent aneurysmal SAH and typically antedate the SAH by days to weeks (average 2 weeks). It is thought that most of these headaches are due to either minor leakage from a fragile aneurysm or enlargement of the aneurysm, resulting in pressure on a nearby structure that produces pain.

Ischemic Stroke Syndromes

There are numerous manifestations of ischemic stroke, and they can be classified based on affected brain region, affected artery, disease process, or symptoms. Although modern diagnostic techniques (MRI) have altered some of the clinical rules of stroke symptoms and etiology, there are still some useful concepts that can guide us in terms of stroke location and mechanism. Tables 29.1 and 29.2 list some classic ischemic stroke syndromes with their major clinical manifestations, vascular territory, and underlying pathophysiology.

Broadly speaking, ischemic strokes typically involve one or more vessels or vascular territories and produce a focal neurological deficit. Typically, clinicians look for unilateral weakness or sensory deficits, unilateral visual field abnormalities, speech disturbance (aphasia or dysarthria), neglect syndromes, unilateral ataxia, ophthalmoplegias, gaze abnormalities, or a specific behavioral syndrome as clues of a stroke. Vague or nonfocal symptoms such as diffuse weakness alone, headaches alone, long-term memory loss, abnormal behavior, or isolated dizziness are rarely caused by an ischemic stroke. The appearance of a lesion in a typical vascular territory (based on brain imaging) is a key feature of almost all stroke syndromes.

The presence of cortical deficits (aphasia, visual field cuts, neglect syndromes) often indicates involvement of a major vessel in the cerebral hemispheres. The presence of ataxia, bilateral motor or sensory deficits, Horner syndrome, ophthalmoplegias, and crossed sensory findings (one side of the face and the other side of the body) often indicates a stroke in the posterior fossa and vertebral-basilar territory. There are specific syndromes that indicate small-vessel involvement deep in the brain. These so-called lacunar strokes are due to occlusion of small penetrating arteries that arise directly from larger parent vessels. Favored locations include the deep basal ganglia structures, thalamus, and brainstem (especially the pons). A listing of common large-vessel and lacunar syndromes appears in Tables 29.1 and 29.2 .

Atherothrombosis accounts for the majority of ischemic strokes. These lesions can occur anywhere in the cerebral vasculature, but they tend to have a preference for specific locations such as the bifurcation of the carotid artery in the neck, intracranial carotid siphons, proximal portion of the MCA, midportion of the basilar artery, and aortic arch. An atherosclerotic plaque forms over many years then ruptures, causing formation of a superimposed thrombus. This atherothrombotic lesion can totally occlude the vessel, produce severe narrowing (leading to watershed ischemia), or be a source of embolic material that embolizes to more distal parts of the cerebral vasculature (artery-to-artery emboli).

Cardiac embolism accounts for 15% to 20% of all ischemic strokes. A variety of conditions such as atrial fibrillation, endocarditis, prior MI, valvular disease, and cardiomyopathy often lead to formation of intracardiac thrombi that subsequently embolize to the brain (and other organs). Most lacunar strokes are due to either lipohyalinosis or microatheromata occluding a small penetrating artery.

Special Cases

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