Clinical Aspects of Intracerebral Hemorrhage

Introduction

Stroke is the second most frequent cause of death in the world, with 6.7 million globally documented cases in 2012 alone. This chapter focuses on intracerebral hemorrhage (ICH), the least common type of stroke, accounting for about 13% of all stroke victims, occurring at an annual rate of about 12–15 cases per 100,000 people. Despite having the lowest incidence of any type of stroke, the mortality rate exceeds 30% and only one-fifth of patients make a meaningful recovery to independence , making this an incredibly morbid, costly, and high impact disease. In this chapter we review the basic classification, clinical presentation, radiographic findings, and management of patients with ICH.

Classification

Strokes are divided into two main categories: ischemic and hemorrhagic. In ischemic stroke, diminished blood flow leads to inadequate oxygenation of brain parenchyma and neuronal infarction. Hemorrhagic stroke occurs most often due to vascular injury resulting in hematoma formation and local mass effect on surrounding neural tissue.

ICH is made up of a range of pathologies with different natural courses, workup, and management ( Table 92.1 ). It is important for clinicians to recognize the major types of ICH in order to choose the appropriate diagnostic studies and treatment options.

ICH is categorized as primary or secondary depending on etiology. Primary ICH has a higher incidence and consists of two major diseases: cerebral amyloid angiopathy (CAA) and hypertensive hemorrhage. Together these two entities are responsible for greater than 80% of ICH, with hypertensive hemorrhage implicated in about 55% of total ICH cases.

Hypertensive hemorrhage occurs most often in the deep regions of the brain such as the basal ganglia, thalamus, pons, and cerebellum ( Fig. 92.1 ). Chronic hypertension causes lipohyalinosis of small arteries and arterioles. Hyaline, collagen, protein, and fat replace arterial smooth muscle, thin the adventitia, and eventually form atheromas. The stiffened and narrowed lumen results in small areas of brain ischemia followed by encephalomalacia known as lacunes. This term is derived from the Latin word “lacunae,” which appropriately means “lake.” In addition to an increased risk of ischemic events, weakening of the tunica media at vessel bifurcations leads to a 2% annual risk of hemorrhage in patients with chronic hypertension . Furthermore, the weakened muscular layer is unable to vasoconstrict in response to local hemorrhage, resulting in continued bleeding and ICH progression. Previously it was thought that weakened arterial walls form “Charcot–Bouchard microaneurysms” that rupture leading to hemorrhage. However, it has since been shown by electron microscopy that these “microaneurysms” are actually miniature hematomas located in the subadventitial or extravascular spaces.

CAA results from deposition of beta-amyloid proteins into the media of small meningeal and cortical vessels. These proteins exhibit “apple-green birefringence,” upon exposure to Congo red stain under polarized light. Cerebral amyloid deposition occurs over time and has been found in about half of all patients over 70 years of age . Over time, the amyloid proteins replace the smooth muscle cells found in arteries leading to decreased compliance and an increased bleeding risk. The annual recurrent hemorrhage rate is as high as 10.5% . Apoprotein E2 and E4 are two alleles that have been implicated in predisposition to amyloid angiopathy, with the E4 allele being associated with increased mortality and a younger age of initial ICH.

Secondary ICH encompasses a wide range of pathologies, as reviewed in Table 92.1 . Although it encompasses many more diseases, the overall incidence of secondary ICH is much lower than primary ICH. Each of these diseases has a unique presentation, workup, and management.

Traumatic ICH or “hemorrhagic cerebral contusion” occurs most commonly in the frontal, temporal, or occipital poles due to acceleration/deceleration injuries that cause these regions to strike against the bony prominences of the cranium. In patients with severe contusions, there is a risk of delayed “blossoming” of the ICH, which may occur within 72 h of the injury, leading to mass effect, edema, and rapid neurological deterioration due to elevated intracranial pressure (ICP).

The presence of a tumor can drastically alter diagnosis and management of ICH. The frequency of spontaneous ICH from a cerebral neoplasm averages 2–3%; however, this can be much higher with certain types of tumors. Intraparenchymal hemorrhage from vascular lesions is most often caused by arteriovenous malformations (AVMs) or cavernous malformations. The annual hemorrhage risk of an un-ruptured AVM is about 2–4%, and as high as 7.45% in patients who have bled previously . Cavernous malformations have a lower propensity for bleeding with annual rates of <1% for incidentally found lesions, 2% for symptomatic lesions not related to hemorrhage, and 4.5% for lesions with symptomatic hemorrhage .

Anticoagulation is often used to reduce venous and arterial thromboembolic risk in patients with certain cardiac, stroke, or malignancy histories. Common conditions include atrial fibrillation, implanted vascular stents, prior strokes, deep vein thrombosis, pulmonary embolism, and inherited or acquired coagulopathic states. Oral anticoagulants have been associated with a 10-fold increased risk of ICH in patients over 50 years , of which 60% are fatal . These hematomas have a larger volume and risk of continued expansion when compared with other causes of ICH ( Fig. 92.2 ). Novel oral anticoagulants appear to have a more favorable profile of reduced hemorrhagic risk , but have yet to be as frequently prescribed as traditional vitamin K antagonists.