Headache, usually bilateral and pulsating, caused by persistent blood pressure elevation to 80/120 mm Hg or above and accompanied by symptoms of encephalopathy such as confusion, lethargy, visual disturbances or seizures. It improves after normalization of blood pressure.
A. Headache fulfilling criterion C
B. Hypertensive encephalopathy has been diagnosed
C. Evidence of causation demonstrated by at least two of the following:
1. headache has developed in temporal relation to the onset of the hypertensive encephalopathy
2. either or both of the following:
a) headache has significantly worsened in parallel with worsening of the hypertensive encephalopathy
b) headache has significantly improved or resolved in parallel with improvement in or resolution of the hypertensive encephalopathy
3. headache has at least two of the following three characteristics:
a) diffuse pain
b) pulsating quality
c) aggravated by physical activity
D. Not better accounted for by another ICHD-3 diagnosis.
Hypertensive encephalopathy presents with persistent elevation of blood pressure to ≥180/120 mmHg and at least two of confusion, reduced level of consciousness, visual disturbances including blindness, and seizures. It is thought to occur when compensatory cerebrovascular vasoconstriction can no longer prevent cerebral hyperperfusion as blood pressure rises. As normal cerebral autoregulation of blood flow is overwhelmed, endothelial permeability increases and cerebral oedema occurs. On MRI, this is often most prominent in the parieto-occipital white matter.
Although hypertensive encephalopathy in patients with chronic arterial hypertension is usually accompanied by a diastolic blood pressure of >120 mm Hg, and by grade III or IV hypertensive retinopathy (Keith-Wagener-Barker classification), previously normotensive individuals may develop signs of encephalopathy with blood pressures as low as 160/100 mm Hg. Hypertensive retinopathy may not be present at the time of clinical presentation.
Any cause of hypertension can lead to hypertensive encephalopathy. Headache attributed to hypertensive encephalopathy should be coded as 10.3.3 Headache attributed to hypertensive encephalopathy, regardless of the underlying cause.