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complications,208,211 which are frequently the presenting feature, although headaches, vomiting and lethargy may also be seen frequently.204,209 Convulsions were the most frequently encountered complication in one review, occurring in more than 90% of the children.212 Facial palsy and an altered level of consciousness were each encountered in 4% Visual disturbances may be caused by retinal involvement, vitreous hemorrhage, and infarction of the anterior visual pathways.213 Cortical blindness is associated with cerebral edema, which usually resolves, leaving no residual impairment The severity of the vascular changes observed on retinal examination permits grading of hypertension in childhood Long-standing hypertension is known to be associated with retinal arteriolar narrowing.192,214 So-called grade I changes occur with mild venous narrowing at the site of arterial crossing, with slight thickening of the arterial wall Grade II changes include obvious arteriolar thickening, producing the copper wire appearance Grade III changes exist when the arteriolar wall is so thick that no column of blood is visible, this giving the silver wire appearance, with marked venous compression Grade IV changes are described when the arterioles are thin fibrous cords, with no distal flow Retinal hemorrhages and exudates are additionally present in grade III, while papilledema is a feature of grade IV, also considered to be malignant hypertension Severe retinal changes are less common in children, although papilledema is observed in hypertensive encephalopathy with headache, drowsiness, and convulsions.215 Retinal arterioles, as opposed to retinal venules, show better correlation with increasing pressures in both normotensive and hypertensive children Retinal examination, however, is often difficult in children, who may not be able to tolerate a detailed retinal examination Hypertensive retinopathy has been reported in up to 18% of children with severe hypertension.216 The development of visual disturbances may be secondary to acute encephalopathy or secondary to ophthalmic involvement (caused by retinal involvement, vitreous hemorrhage, and infarction of the anterior visual pathways) and will only be correctly identified following formal ophthalmic assessment.213,216 Rarely permanent visual loss may result,216 although more often cortical blindness is temporary associated with cerebral edema and resolves completely leaving no visual impairment Posterior reversible encephalopathy syndrome is a clinicoradiologic entity characterized by a variable combination of consciousness impairment, seizure activity, headaches, visual abnormalities, nausea/vomiting, and focal neurologic signs.217–220 The neurologic involvement is secondary to edema, involving the posterior portion of the cerebral hemispheres, especially bilaterally in the parieto-occipital regions, but this may spread to involve the cortical (frontal lobe), subcortical (basal ganglia) regions and unusually also to the brainstem and cerebellum.220 There is usually no change seen on computerized tomographic scans Magnetic resonance imaging is diagnostic and reveals increased signals predominantly involving the posterior regions of the cerebral hemispheres Vascular/angiographic imaging is not routinely performed or required in these patients, but when performed, MR angiography shows vasculopathy with multifocal areas of dilatation and narrowing matching the posterior distribution of the changes.218,220 Although uncontrolled severe hypertension is the most common trigger for posterior reversible encephalopathy syndrome, other etiologies are also well described, such as elevated calcineurin drug levels (e.g., tacrolimus) In these patients with associated etiologies, the level of hypertension may not be severe but still needs to be optimally controlled.220 In all patients with severe hypertension, it is important to carefully evaluate for any evidence of fluid overload and perform essential investigations, including chest x-ray, and obtain a detailed echocardiogram study to establish any evidence of hypertensive cardiac involvement, including evidence of left ventricular hypertrophy and systolic and diastolic ventricular function In spite of the relatively good prognosis in survivors, hypertensive encephalopathy is potentially fatal and requires urgent treatment (discussed later) At the other end of the spectrum of severity, mild hypertension, which is usually diagnosed incidentally, may produce no obvious clinical manifestations Essential hypertension is often mild, and is most commonly seen in the overweight adolescent with a family history of hypertension Diagnosis The physical examination aims to look for signs of the underlying cause of hypertension, and for evidence of damage to end organs The height and weight should be measured, and the body mass index calculated Long-standing undiagnosed hypertension may cause poor growth.222 Initial inspection of the patient may suggest syndromes known to be associated with hypertension, including Cushing syndrome, Williams syndrome,223,224 and Turner syndrome.225 Peripheral pulses should be assessed, in particular simultaneous palpation of the right brachial and the femoral pulse to exclude brachiofemoral delay as a sign of aortic coarctation Blood pressure should be measured in the right arm with the patient both lying and standing, and measured in the legs to determine if there is any difference between the upper and lower limbs, a feature again suggestive of coarctation Close inspection of the skin may reveal the caféau-lait patches and neurofibromas of neurofibromatosis type 1 Palpable kidneys suggest enlarged polycystic kidneys, especially autosomal recessive polycystic kidney disease Fundoscopy may show changes suggesting long-standing hypertension, such as narrowing or sclerosis of retinal arteries, and changes of arteriovenous crossing Severe hypertension is associated with retinal hemorrhages and papilledema A strong indication of the cause of the hypertension is often present from the history and examination As a general rule, essential hypertension is usually mild, while secondary hypertension is severe Unless the hypertension is mild, the initial investigation and control require admission to hospital Box 60.2 shows the investigations to be considered in children with confirmed hypertension.207 The approach to investigation and assessment of neonatal and childhood hypertension have recently been reviewed.36,207 Box 60.2 Investigation Workup of Children With Hypertension Investigations—Recommended in All Hypertensive Cases ■ Urine dipstick for any protein and blood ■ Urine culture for infection ■ Full blood count ■ Serum urea, creatinine, and electrolytes ■ Thyroid stimulating hormone ■ Abdominal, renal and urinary tract ultrasound ■ Echocardiography