This chapter speaks about an 82-year-old woman who was admitted with apparently sudden-onset neurological symptoms. On examination, this patient appeared well and comfortable. The patient's clinical evolution was characterized by a relentlessly progressive course over several weeks. The visual field defect expanded into a right homonymous hemianopia, and optic ataxia also developed on the left. Dysarthria and dysphagia worsened until she was dependent on tube feeding. The human prion diseases are a comparatively rare cause of dementia, with an estimated incidence of 1 case per million people per year, although some uncorroborated reports would place the true incidence much higher. Therapeutic options for all the human prion diseases are currently limited to palliation, as there are no agents capable of reliably causing a sustained improvement in clinical course. A large and diverse selection of drugs have been tried with limited success, including antivirals, antifungals, antibiotics, antimalarials, antidepressants, antioxidants, and analgesics.

Advanced cerebral amyloid angiopathy (CAA) consists of vascular deposition of amyloid and secondary breakdown of amyloid-laden vessel walls. This chapter focuses on the pathogenesis of CAA, clinical and genetic risk factors, presentations and diagnosis, and prospects for treatment. CAA-related intracerebral hemorrhage (ICH) accounts for a substantial proportion of all spontaneous ICH in the elderly. CAA-related lobar ICH presents similarly to other types of lobar ICH with acute onset of neurological symptoms and the variable presence of headache, seizures, or decreased consciousness according to hemorrhage size and location. CAA-related hemorrhages can also be small and clinically silent. CAA can also present with transient neurological symptoms, another syndrome where diagnosis during life is of particular practical importance. Future treatments for CAA are likely to focus on preventive or protective therapy aimed at decreasing the deposition or toxicity of vascular amyloid.

The epidermal nevus syndrome refers to the association of any epidermal nevus with extracutaneous abnormalities. The most common extracutaneous abnormalities are neurologic, skeletal, and ocular, although other organs may also be involved. Widespread use of magnetic resonance imaging (MRI) has resulted in an increasing appreciation of the role of cortical malformations in patients with neurological symptoms. Strokes and vascular abnormalities have been reported in patients with the epidermal nevus syndrome. Arteriovenous malformations and leptomeningeal angiomas have been found in some patients with the epidermal nevus syndrome. Generally, the diagnosis of an epidermal nevus is not in doubt. If there are any doubts, a skin biopsy should be obtained. Treatment of the nevus with dermabrasion, diathermy, laser treatment, and cryotherapy is associated with a fairly high risk of recurrence of the nevus. Focal resection of the epidermal nevus before puberty is advised because of the increased risk of tumor development.

The underlying pathological mechanism of thrombotic thrombocytopenic purpura (TTP) is the presence of microvascular thrombi that partially occlude the vascular lumins with overlying proliferative endothelial cells. Coombs-negative hemolytic anemia and severe thrombocytopenia owing to platelet clumping in the microcirculation are the most outstanding laboratory abnormalities. Classically, TTP has been recognized by the pentad of microangiopathic hemolytic anemia, thrombocytopenia, neurological symptoms, fever, and renal involvement, though only 20 to 40 percentage of patients will manifest the classic pentad. TTP remains a life-threatening disease the mortality rate of which may be as high as 90 percentage when untreated. Diagnosis is mainly based on hematological findings and a broad variety of neurological abnormalities, including ischemic or, less often, hemorrhagic stroke. Plasma exchange (PE) is currently the mainstay of treatment; however, rapid advances in the understanding of TTP pathophysiology may offer more specific and effective therapies in the near future.

This chapter explores the complex relationship of stroke with polyarteritis nodosa (PAN) and microscopic polyangiitis (MPA). MPA is a systemic necrotizing vasculitis that clinically and histologically involves capillaries, venules, or arterioles without granulomata, and is associated with necrotizing crescentic glomerulonephritis and hemorrhagic pulmonary capillaritis, which are the main causes of mortality and morbidity. Hemorrhagic strokes occur more frequently than ischemic infarction in MPA. Immunohistochemical studies from muscle and nerve biopsies showed that macrophages and T cells, mostly CD8+, are involved in the pathogenesis of PAN. Neurological symptoms and signs are a major and common feature of PAN, occurring in nearly three-quarters of patients. A close relationship between the use of corticosteroids and stroke exists in PAN. From a therapeutic point of view, antiplatelet drugs, which inhibit platelet thromboxane production, might reduce the risk of corticosteroid-induced, antiplatelet drugs in PAN. The use of aspirin and corticosteroids prospectively prevents stroke recurrence.