Idiopathic intracranial hypertension; incidence, presenting features and outcome in Northern Ireland (1991-1995)

Objectives: to determine the age and sex specific incidence rates, presenti ng features, and visual outcome of idiopathic intracranial hypertension in Northern Ireland. Methods: A case-note review of all patients with idiopathic intracranial hy pertension, diagnosed at the Royal Victoria Hospital, Belfast between 1991 and 1995. Results: Forty-two patients were identified corresponding to an average ann ual incidence rate per 100,000 persons of 0.5 for the total and 0.9 for the female population. The commonest presenting symptoms were headache (84%), transient visual obscurations (61%) and sustained visual loss (34%). Impair ed Snellen visual acuity and visual field loss were documented in 21% and 6 2% of patients respectively at presentation, and ill 24% and 39% at last fo llow-up. One patient suffered deterioration in visual functioning sufficien t to interfere with normal daily activities. Conclusions: The age and sex specific incidence rates of IIH in Northern Ir eland are lower than have been reported in previous population-based series . Disabling visual loss occurs in a small number of patients despite all in terventions.