Acute and chronic neurological complications of hypertension in patients younger than 21 years were reviewed in the literature, 1980-2010, by researchers at Maimonides Childrens' Hospital, State University and Mount Sinai School of Medicine, New York; and UCL Institute of Child Health, London, UK. Childhood hypertension is underdiagnosed and is defined as an average pressure above the 95th percentile for sex, age, and height on 3 occasions. In a series of 212 pediatric patients with arterial ischemic stroke, systolic BP at immediate follow-up was >90th percentile in 54% with symptomatic stroke and in 46% with cryptogenic stroke. Children with moya-moya disease and stroke were 3-4 times more likely to have hypertension than those with normal vessels. Masked hypertension may be an unrecognized risk factor for cerebrovascular disease. In a Chinese study only 4 of 251 patients with stroke had hypertension. Hypertension is an identified factor in stroke with sickle cell disease, but with this exception, there is no definite consensus for an association of hypertension and ischemic stroke in children. Hemorrhagic stroke with hypertension was reported in 15 patients with sickle cell disease, and 6-8% of hemorrhagic stroke in children were associated with hypertension. Posterior reversible encephalopathy syndrome (PRES) arises with acute severe hypertension and is characterized by headaches, blindness, confusion, and seizures, and evidence of reversible posterior leukoencephalopathy with edema on MRI. The cause is a breakdown of autoregulation and endothelial dysfunction.
Chronic effects of hypertension include cognitive dysfunction affecting attention, learning and memory, reversible with antihypertensive treatment. Hypertension might predispose to endothelial damage and atherosclerosis, as suggested by carotid ultrasound measurements of intima-media thickness, a biomarker of hypertensive vascular damage. Retrospective review of neurological symptoms in 409 children with hypertension aged 7-17 years, and compared with 150 healthy controls, showed 54% had significantly more complaints of pain, sleep disturbance, fatigue, or lack of concentration. Headache incidence of 42% before antihypertensive treatment fell to 6-9% after treatment.  Future studies should standardize the definition and monitoring of hypertension in children, investigate transcranial doppler changes correlated with cognitive decline, and investigate the value of MRI in definition of subtle infarcts and small vessel disease. 
COMMENT. The authors find pediatric hypertension is underdiagnosed and except for hypertensive encephalopathy, the neurological effects are under-recognized. With the increased incidence of obesity and diabetes type 2 in children, hypertension has become more prevalent. Patients at risk of hypertension should receive more frequent monitoring, so that chronic effects of hypertension on cognition and memory may be avoided.