Incidence of idiopathic intracranial hypertension in Fife

Background and aims Idiopathic intracranial hypertension is a clinical syndrome of intracranial hypertension with normal cerebrospinal fluid in the absence of a mass lesion or hydrocephalus on brain imaging. Headache is the most common symptom of idiopathic intracranial hypertension, and about 10–15% of patients suffer from irreversible visual impairment. Previous estimates of the annual incidence of idiopathic intracranial hypertension vary worldwide from 0.03 to 2.2 per 100,000. The major risk factor implicated in idiopathic intracranial hypertension is body mass. Scotland has one of the worst records for obesity in the developed world, and the prevalence of obesity in Fife is higher than the Scottish average. Our aim was to record the incidence of idiopathic intracranial hypertension in NHS Fife over a one-year period. Methods and results Prospective study including every patient who was seen in the ophthalmology department in NHS Fife with a new diagnosis of idiopathic intracranial hypertension over a one-year period. Thirteen patients were seen with a new diagnosis of idiopathic intracranial hypertension from August 2013 to July 2014 giving an incidence of 3.56 per 100,000. Headache was the most common presenting symptom. Three patients were asymptomatic but were noted to have swollen optic discs during a routine sight test. One patient complained of visual symptoms. All patients were overweight. The mean BMI was 36 (range: 28–49). Conclusion The incidence of idiopathic intracranial hypertension in NHS Fife was significantly higher than previous estimates in the literature. This is probably due to a high level of obesity in Fife. Scotland is in the midst of an obesity epidemic and if this continues we may see increasing levels of idiopathic intracranial hypertension nationally with associated increasing incidence of visual impairment in young adults.