Chapter 23 - Neurological complications of systemic hypertension

Abstract

Systemic hypertension is the most common, most easily diagnosed, and one of the most reversible risk factors for neurologic pathology. Acute severe hypertension above a mean arterial pressure of approximately 150mmHg exceeds the brain's autoregulatory capacity and results in increased cerebral blood flow leading to hypertensive encephalopathy. Chronic hypertension predisposes to cerebral vasculature atherosclerosis, medial hypertrophy, luminal narrowing, endothelial dysfunction, impaired arterial relaxation, and decreased ability to augment cerebral blood flow at low blood pressures. The pathologic effects of hypertension increase stroke risk by three- to fivefold. With three-fourths of strokes incident events, primary prevention is essential. Multiple studies have demonstrated the benefit of blood pressure lowering in reducing incident and recurrent strokes. Even more, hypertension is a risk factor for cognitive impairment and dementia through multifactorial mechanisms including vascular compromise, cerebral small vessel disease, white matter disease (leukoaraiosis), cerebral microbleeds, cerebral atrophy, amyloid plaque deposition, and neurofibrillary tangles. In patients without hypotension, treatment with antihypertensives slows progression and assuages the degree of cognitive decline. While the choice of antihypertensive did not make a significant difference in most cognitive outcome studies, some large meta-analyses have pointed to angiotensin receptor blockers as the favored agent. Because of the well-documented morbidity and mortality associated with unchecked hypertension, treating and preventing hypertension are universally critical pillars in healthcare.