Abstract
Intracerebral hemorrhage is an important and common cause of stroke, which has the most devastating consequences. Arteriovenous malformation (AVM) is the second most common vascular abnormality of the central nervous system after cerebral aneurysm. Vein of Galen aneurysmal malformations are rare anomalies of the intracranial circulation that constitute 1% of all intracranial vascular malformations. Dural arteriovenous fistula is a type of AVM in which there is a communication between dural arteries and dural venous sinuses, cortical veins, or meningeal veins. Carotid endarterectomy and carotid artery stenting are procedures done in patients with significant carotid artery stenosis to prevent disabling and fatal stroke and its devastating consequences. Moyamoya disease is a rare occlusive cerebrovascular disease causing symptoms of either vascular insufficiency or intracranial hemorrhage. Various cerebrovascular diseases are discussed in detail in this chapter.
Keywords
Anesthesia, Arteriovenous malformation, Carotid endarterectomy, Dural arteriovenous fistula, Intracerebral hemorrhage, Moyamoya disease, Vein of Galen malformation
Outline
Intracerebral Hemorrhage 346
Incidence and Risk Factors 346
Imaging 346
Clinical Presentation 346
Management of Intracerebral Hemorrhage 348
Initial Evaluation 348
Medical Management 348
Management of Anticoagulation and Antiplatelet Therapy 349
Blood Pressure Management 349
Management of Intracranial Pressure 349
Blood Sugar Management 350
Seizure Prophylaxis 350
Temperature Management 350
General Intensive Care Unit Care 350
Intraventricular Hemorrhage 350
Perihemorrhagic Edema 350
Surgical Treatment 351
Anesthetic Considerations 351
Medical Complications and Their Management 351
Arteriovenous Malformations 352
Cause and Incidence 352
Natural History 353
Pathophysiologic Effects and Clinical Presentation 353
Grading of Arteriovenous Malformations 353
Imaging 354
Cerebral Hemodynamics in Arteriovenous Malformation 354
Management 354
Surgical Resection of Arteriovenous Malformation 355
Anesthetic Considerations for Resection of Arteriovenous Malformation 355
Postoperative Management 356
Endovascular Therapy for Arteriovenous Malformations 356
Anesthetic Considerations for Arteriovenous Malformation Embolization 356
Complications During Arteriovenous Malformation Embolization 357
Pediatric Arteriovenous Malformations 357
Pregnancy and Arteriovenous Malformations 358
Vein of Galen Aneurysmal Malformations 358
Treatment Strategies for Vein of Galen Aneurysmal Malformation 359
Anesthetic Considerations for Vein of Galen Aneurysmal Malformation 360
Dural Arteriovenous Fistula 360
Clinical Presentation 360
Management 360
Carotid Endarterectomy 360
Preoperative Evaluation 362
Management of Carotid Artery Disease 362
Monitoring 362
Intraoperative Management 363
Postoperative Complications and Outcomes 363
Coronary Angioplasty and Stenting 363
Moyamoya Disease 363
Management of Moyamoya Disease 364
References 364
Intracerebral Hemorrhage
Intracerebral hemorrhage (ICH) is an important and common cause of stroke, which has the most devastating consequences. It is characterized by abrupt onset of severe headache, altered level of consciousness, or focal neurological deficit associated with focal collection of blood within the brain parenchyma. ICH can be either primary (spontaneous) or secondary. It is considered spontaneous if it results from rupture of small arteries and arterioles that have been damaged by chronic hypertension or amyloid angiopathy, whereas secondary causes include trauma, aneurysms, and vascular malformations; hemorrhagic conversion of infarct; and substance abuse.
Incidence and Risk Factors
The incidence of ICH as a cause of stroke has been reported to vary from 10% to 28%. It has been found to occur more frequently with advancing age and in black as well as Asian population. Hypertension has a strong correlation with ICH. Hypertensive patients who are young (<55 years), smokers, or those who have stopped their antihypertensive medication are at greater risk of developing ICH. The Perindopril Protection Against Recurrent Stroke Study (PROGRESS) found that antihypertensive medications resulted in decreased incidence of stroke in the elderly population with a history of cerebrovascular disease. Anticoagulants like warfarin significantly increase the risk of ICH. In a retrospective analysis, 25.8% of ICH was related to use of oral anticoagulants. The risk of ICH in patients receiving oral anticoagulation has been shown to be 8 to 11 times that in patients of similar age who are not receiving the drug. The incidence of ICH in patients receiving warfarin after myocardial infarction (MI) is approximately 1% a year. The correlation between genetic factors and ICH has not been fully understood.
ICH usually occurs in the deep parts of the brain, the most common areas being the putamen, subcortical white matter, thalamus, cerebellum, and pons. The majority of cases of ICH are manifestations of either hypertensive vasculopathy or cerebral amyloid angiopathy. The initial hemorrhage is followed by secondary arterial rupture at the periphery of the enlarging hematoma. After the initial bleed, hematoma can expand in the initial hours following the ictus. Hematoma expansion is predictive of clinical deterioration and high morbidity and mortality. Recurrence is very uncommon in ICH, unlike aneurysmal, and arteriovenous malformation (AVM) bleeds.
Imaging
Various imaging modalities are available to evaluate ICH. In fact, any patient presenting with focal neurological deficit along with high blood pressure (BP) requires noncontrast computed tomography (NCCT) Figs. 20.1 and 20.2 . Contrast-enhanced computed tomographic (CT) angiography helps in determining hemorrhage expansion. The spot sign has a good sensitivity and specificity, and its presence signifies more severe clinical presentation with poor prognosis, a high risk of clinical deterioration, extension into the intraventricular space, and high mortality. Magnetic resonance imaging (MRI) is superior in differentiating between primary hemorrhage and hemorrhage in the infarct area. It may also be able to detect the underlying pathological condition like vascular malformation, cerebral venous thrombosis, and microbleeds.
Clinical Presentation
ICH usually manifests as headache, nausea, and vomiting. In most cases (60%), there is worsening of alertness, which can progress to coma. One consistent sign associated with ICH is hypertension. Seizure is a rare presentation of ICH. Neurological symptoms like isolated limb weakness, hemiparesis, cranial nerve palsies, sensory signs, speech abnormalities, and gait abnormalities may be present depending on the location and extent of ICH. Hemphill et al. have devised the ICH Score, which is a simple clinical grading scale that allows risk stratification on presentation with ICH based on the level of consciousness at presentation, infratentorial and intraventriular hemorrhage, hemorrhage volume >30 mL, and age >80 years as independent factors predictive of outcome ( Table 20.1 ).
| Component | ICH Score Points |
|---|---|
| GCS score | |
| 3–4 | 2 |
| 5–12 | 1 |
| 13–15 | 0 |
| ICH volume, cm 3 | |
| ≥30 | 1 |
| <30 | 0 |
| IVH | |
| Yes | 1 |
| No | 0 |
| Infratentorial origin of ICH | |
| Yes | 1 |
| No | 0 |
| Age, years | |
| ≥80 | 1 |
| <80 | 0 |
| Total ICH score | 0–6 |
Management of Intracerebral Hemorrhage
Initial Evaluation
History and examination should be structured to determine the diagnosis, find out the risk factors, document current status, and monitor the progress of the patient. Systemic examination should be focused so as to also evaluate other major organ functions. Routine laboratory tests, including coagulation profile, toxicology screening, and pregnancy tests may be indicated.
Medical Management
The American Heart Association (AHA)/American Society of Anesthesiologists (ASA) has published guidelines for the management of patients with ICH.
Management of Anticoagulation and Antiplatelet Therapy
Oral Anticoagulants
Oral anticoagulants (OACs) are responsible for 12–20% of ICH, and reversal of the anticoagulation effect is justified in these cases. The most common drug used for anticoagulation is warfarin, and more than 50% mortality has been reported in patients with ICH on warfarin. Vitamin K is slow in reversing the anticoagulant effect of warfarin and is mainly used as an adjunct. Prothrombin complex concentrates (PCCs), which contain vitamin K-dependent coagulation factors II, VII, IX, and X, normalize the international normalized ratio (INR) more rapidly than fresh frozen plasma (FFP), and can be given in smaller volumes. FFP and PCCs have their own risks and benefits, and PCCs carry a higher risk for developing disseminated intravascular coagulation.
A trial, which compared FFP with four-factor PCC (4F-PCC) to reverse OACs, concluded that for patients requiring urgent vitamin K antagonist reversal, 4F-PCC had a similar safety profile to plasma, but was associated with fewer fluid overload events. Recombinant activated factor VII rapidly normalizes INR after administration in patients on OACs, but it does not replenish coagulation factors other than factor VII. Thus, in the setting of development of ICH, OACs should be stopped and their effects reversed with vitamin K and FFP as soon as possible while monitoring prothrombin time and INR. PCCs may also be used along with vitamin K.
Antiplatelet Drugs and Intracerebral Hemorrhage
The role of antiplatelet drugs in causing or worsening ICH is not well established, and there are conflicting reports. Naidech et al. found that reduced platelet activity was associated with more intraventricular hemorrhage (IVH), greater ICH scores, and increased mortality after ICH.
Blood Pressure Management
Hypertension is a usual finding in a patient with ICH, the magnitude of which is much more in comparison to ischemic stroke. While on the one hand hypertension improves cerebral perfusion pressure (CPP) and cerebral perfusion, on the other hand it can lead to hematoma expansion, perilesional edema, and rebleeding. The desired level of BP in these patients is not known, although a few studies have thrown some light on this subject.
The Intensive Blood Pressure Reduction in Acute Cerebral Haemorrhage Trial (INTERACT) demonstrated that rapid lowering of BP [target systolic blood pressure (SBP) 140 mm Hg] in patients with ICH is feasible and safe, and at the same time this strategy may limit growth of hematoma potentially improving the outcome. The INTERACT II showed that early intensive lowering of BP (<140 SBP), as compared with the more conservative level of BP control (<180 SBP), did not result in a significant reduction in the rate of the primary outcome of death or major disability.
The antihypertensive treatment of acute cerebral hemorrhage (ATACH) trial also demonstrated that rapid SBP control after ICH is feasible and safe, and after the findings of this pilot study, a large trial ATACH II is underway. The Intracerebral Hemorrhage Acutely Decreasing Arterial Pressure Trial demonstrated that relative perihematomal cerebral blood flow (CBF) is not different in patients with acute ICH (within 24 h) who were randomized to intensive SBP lowering (<150 mm Hg) or moderate SBP lowering (<180 mm Hg).
It is now being increasingly understood that ICH is not a monophasic event but is a progressive condition, and that controlling BP may limit the hematoma expansion. The AHA/ASA guidelines regarding BP management in patients with ICH are as follows.
- 1.
For patients with ICH presenting with SBP between 150 and 220 mm Hg and without contraindication to acute BP treatment, acute lowering of SBP to 140 mm Hg is safe and can be effective for improving functional outcome
- 2.
For patients with ICH presenting with SBP >220 mm Hg, it may be reasonable to consider aggressive reduction of BP with a continuous intravenous infusion and frequent BP monitoring
Management of Intracranial Pressure
Patients with ICH may have increased intracranial pressure (ICP) due to hematoma, edema, or to hydrocephalus, which can lead to further neuronal damage and herniation. There is paucity of data supporting use of ICP monitoring in ICH. Measures to reduce ICP, such as positioning, sedation, osmotic agents, mild hyperventilation, and CSF drainage are adopted, and these are based on evidence available from studies in patients with traumatic brain injury. An ICP of <20 mm Hg and CPP of 50–70 mm Hg are recommended targets.
Blood Sugar Management
The optimal glucose level in patients with ICH is not well known. High blood sugar at admission is an independent marker of poor outcome. On the other hand, tight control of sugar may lead to increased incidences of hypoglycemic attacks and higher mortality in patients in the intensive care unit (ICU). The recommended blood sugar level is less than 180 mg%.
Seizure Prophylaxis
Seizures can develop in 2.7–17% patients in the first 2 weeks of ICH. Patients with lobar ICH are at a greater risk for seizures. Since there is a high risk of early convulsive and nonconvulsive seizures after ICH, it is recommended that prophylactic anti-epileptic drugs (AED) therapy be started soon after onset of ICH. However, preventing seizures after ICH may not improve outcomes because seizures may not be independently associated with worse outcomes after adjustment for other predictors. Also, use of AED might be associated with fever, which can itself contribute to worse outcomes. The seizure prophylaxis following intracerebral hemorrhage trial, a randomized, double-blind, placebo-controlled trial is currently underway to determine whether prophylactic antiseizure prophylaxis would be beneficial in patients with ICH.
The AHA/ASA recommendations regarding management of seizures in ICH are as follows.
- 1.
Clinical seizures should be treated with antiseizure drugs
- 2.
Patients with a change in mental status who are found to have electrographic seizures on EEG should be treated with antiseizure drugs
- 3.
Continuous EEG monitoring is probably indicated in patients with ICH with depressed mental status that is out of proportion to the degree of brain injury
- 4.
Prophylactic antiseizure medication is not recommended
Temperature Management
Schwarz et al. found that the incidence of fever is high in patients with supratentorial ICH, especially those with IVH who may have pyrexia of central origin. The duration of fever is an independent prognostic factor, and therefore, aggressive normalization of temperature is warranted.
General Intensive Care Unit Care
In general, all patients with ICH require close monitoring initially as they are systematically and neurologically very unstable. Patients with ICH, if admitted in specialized neuro-ICU, have reduced mortality.
Intraventricular Hemorrhage
Intraventricular hemorrhage is seen in 45% of patients with ICH. It may be confined to ventricles (primary IVH) or more commonly, associated with ICH in basal ganglia and thalamus (secondary ICH). This is a poor prognostic sign, with an expected mortality varying between 50% and 80% and is an independent contributor to morbidity and mortality.
The removal of intraventricular blood by inserting ventricular catheter is not very successful because it can get occluded with blood, making removal of clot difficult. Intraventricular thrombolysis and endoscopic removal of hematoma have been successfully attempted, although its clinical efficacy is yet to be established.
Perihemorrhagic Edema
Perihematomal edema can develop within 3 hours of bleed and can peak at 10–20 days after the initial episode. This may be responsible for secondary injury, which can worsen clinical outcome. Hematoma evacuation may lead to a significant decrease in perihematomal edema.
Surgical Treatment
Surgical evacuation of hematoma would seem logical to decrease the effect of secondary injury ( Fig. 20.3 ). However, this surgery has its own risks and disadvantages as it may not only cause damage to uninvolved brain but also has a risk of bleeding in patients with ongoing bleeding.
The STICH-1 was an international, multicenter trial conducted in patients presenting within 72 hours of spontaneous supratentorial ICH. In an intention-to-treat analysis, early surgery was neither beneficial nor harmful as there was no statistically significant difference in either mortality or functional outcome. The investigators of the STICH-II trial that ended in 2013 have concluded that early surgery does not increase the rate of death or disability at 6 months and that there might be a small but clinically relevant survival advantage for patients with spontaneous superficial ICH without IVH.
Early surgical intervention is indicated in patients who have cerebellar bleed with clinical deterioration, those with large lobar bleeds, significant mass effect, brain stem compression, or hydrocephalus.
Anesthetic Considerations
The anesthetic considerations in these patients are similar to the management of any neurosurgical patient with intracranial hemorrhage with raised ICP and coagulation problems. The nonpharmacological methods of cerebral protection such as BP management, intracranial hypertension management, glycemic control, optimal hemoglobin levels, fluid management, temperature control, and seizure control would provide favorable conditions for the injured brain to recover and would be the mainstay of anesthetic management.
Medical Complications and Their Management
Medical complications in patients with ICH are common and may be related to poor Glasgow coma score (GCS), obtunded reflexes, prolonged use of airway devices, ventilator requirement, or systemic effects of ICH and raised ICP. Aspiration pneumonitis or pneumonia may occur due to dysphagia and obtunded airway reflexes. Cardiac complications include accelerated hypertension, MI, heart failure, ventricular arrhythmia, or even death. Neurogenic pulmonary edema has also been reported following nontraumatic ICH. Other complications in patients with ICH include acute kidney injury, hyponatremia, gastrointestinal bleeding, impaired nutritional status, urinary tract infections, and poststroke depression.
Patients with ICH may be prone to development of thromboembolic complications due to paresis and prolonged immobilization. The results of clot trials found that compression stockings are not useful in reducing the risk of deep vein thrombosis (DVT) or pulmonary embolism (PE) in patients with stroke. A meta-analysis of controlled studies that evaluated the efficacy and safety of anticoagulants in patients with acute ICH found that early use of enoxaparin or heparin led to significant reduction in PE with no significant reduction in mortality and no difference in DVT or hematoma enlargement. In cases of DVT or PE, systemic anticoagulation and/or IVC filter placement can be considered depending on the cessation of further hemorrhage, location of hematoma, and radiological findings.
Mechanical ventilation is required in one-third of patients with ICH, and a majority of these patients require tracheostomy. Yaghi et al. found that the need for tracheostomy could be predicted early in the course of ICH based on admission GCS score, the duration of intubation being another predictor. Early tracheostomy could decrease the time, and therefore risks of prolonged endotracheal intubation and length of hospital stay.
Arteriovenous Malformations
AVM is the second most common vascular abnormality of the central nervous system after cerebral aneurysm. AVMs are composed of a tangle of thin-walled blood vessels called the “nidus,” which connects the high-pressure arterial circulation to the low-pressure venous circulation bypassing the normal capillary circulation, thus creating a high-flow shunt through one or more fistulas. This may also be associated with venous hypertension. Morphologically, it resembles a tortuous agglomeration of abnormally dilated arteries that directly drain either into the superficial or deep venous system. The cerebral tissue in the nidus and adjacent areas shows signs of gliosis, and the surrounding brain may be atrophic, as a result of chronic ischemia. More than 90% of AVMs are supratentorial, the parietal regions being most commonly affected followed by the frontal and temporal regions. The middle cerebral artery (MCA) is the commonest feeding artery in >50% of cases, while in 30–50% of AVMs, the supply is by branches of more than one artery. Nearly 40% of AVMs drain into the superior sagittal vein. Cerebral AVMs may be associated with aneurysms in approximately 10% of patients, and this could be present in the nidus ( Fig. 20.4 ).
Cause and Incidence
The cause of cerebral AVMs is not known. It has always been assumed to be congenital in origin. However, there is no strong evidence to prove this theory. Predisposing genetic or triggering environmental factors are not yet clear and are being currently investigated. In a study conducted in 2000, the estimated prevalence of AVM was found to vary from less than 10 to 18 per 100,000 population and the annual incidence of hemorrhage due to AVM is 0.5 per 100,000 population. Nowadays, an increasing number of patients are being diagnosed with unruptured AVMs as an incidental finding because of technological advances and increasing use of brain MRI. Overall, men and women are equally affected, and the average age of presentation is in the third and fourth decades of life.
Natural History
It is very important to know the natural history of AVMs as that plays a crucial role in determining the treatment options being considered and offered to patients. The risk of spontaneous bleed in patients with unruptured AVM without treatment is estimated to be approximately 2–4% per year, although this also depends on the associated risk factors. A meta-analysis in 2013 of the natural history of AVMs revealed an overall annual hemorrhage rate of 3.0%, the rate of hemorrhage being 2.2% for unruptured AVMs and 4.5% for ruptured AVMs. Clinical presentation with intracranial hemorrhage appears to be the strongest predictor for future bleeds. Increasing age, initial hemorrhage presentation, deep brain location, and exclusive deep vein drainage were also found to be independent predictors of subsequent hemorrhage.
The natural history of symptomatic AVMs has been studied over a 24-year follow-up period by Ondra et al., and it was found that the likelihood of neurologic deficit developing with the initial hemorrhage is 50–80%, with a mortality of 10–11%. Da Costa et al. also found that the risk of hemorrhage continues to be present until the AVM is completely obliterated and partial endovascular obliteration does not completely reduce the risk of bleeding. In patients with AVMs, although the risk of rebleed is low after initial presentation with hemorrhage as compared with cerebral aneurysms, the morbidity and mortality after the initial bleed is high. All available natural history data are level V data.
The natural history of unruptured cerebral AVMs, on the other hand, is not very clear. The ARUBA (A Randomized Trial of Unruptured Brain Arteriovenous Malformations) trial was a randomized, multicenter trial designed to evaluate whether medical management of patients with unruptured cerebral AVMs improves long-term neurological outcome as compared to invasive management. This trial showed that medical management alone is superior to medical management with interventional therapy for the prevention of death or stroke in patients with unruptured brain AVM followed up for 33 months. The trial is continuing its observational phase to establish whether the disparities will persist over an additional 5 years of follow-up.
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