Benign Intercranial Hypertension
Benign Intracranial Hypertension is essentially raised intracranial pressure with papilloedema (swelling of the optic discs, which is the point where the optic nerves enter the back of the eye). It is a diagnosis arrived at when all other conditions such as brain tumours or vascular abnormalities have been excluded. In order to arrive at the diagnosis, the brain scans and measurements of the contents of the brain and spinal cord fluid should be entirely normal.
The condition causes severe headaches that are not life threatening but more worryingly can cause an insidious onset of blindness that in the majority can be permanent even with treatment. It is therefore essential to detect this early and treat early to prevent the blindness occurring. It can happen in all age groups and is far more common in females but in the teenage group has an equal prevalence in males and females. The person tends to be grossly overweight.
The incidence in the general population is said to be 1 to 2 in 100,000 but in overweight women in the child bearing years it is said to be 19 to 20 in 100,000. The peak incidence occurs in the third decade of life although thirty-seven per cent of cases have been reported in children. It is said to have been diagnosed in children as young as one but predominantly will be diagnosed in children in early teenage years. It is said to be a self limiting condition but there is a recurrence rate of up to forty-three per cent. The severe visual deficits involved can develop in up to 1 in 8 and these are unrelated to the previous duration of the symptoms, the degree of papilloedema, the severity of the headaches and the number of recurrences.
What are the symptoms?
The headaches are the commonest form of presentation in nearly one hundred per cent of cases. There can be dizziness, nausea, visual changes, double vision and eye pain. Papilloedema is found in all cases. Visual field defects can be detected in many. Importantly, there is normal conscious level and cognitive function despite an abnormally high intracranial pressure.
Visual loss is the most important consideration and is watched by measuring visual acuities (size of letters that can be read on a wall chart) along with visual fields. As a consequence of the visual problems being the most important, treatment is aimed at avoiding this.
Medical text written February 2006 by Mr N Buxton, Consultant Paediatric Surgeon, Alder Hey Children's Hospital, Liverpool, UK.