Increased CSF pressure in IIH may result from a rise in venous sagittal sinus pressure secondary to extracellular edema causing venous obstruction, or from low conductance for CSF reabsorption producing a compensatory increase in CSF pressure. Patients were Epidemiology and Risk Factors. IIH with papilledema occurs with a frequency of about one case per 100,000 per year in the general population and 19.3 cases per 100,000 per year in obese women aged 20 to 44. Clinical Features and Associated Disorders. The symptoms of IIH consist of generalized increased intracranial pressure, with headache occurring in most, but not all, patients.
Bifrontotemporal headache is most common.
Unilateral headache with increased CSF pressure due to IIH may be an exacerbation of migraine or a new local phenomenon. Transient visual obscuration, an episode of visual clouding in one or both eyes usually lasting seconds, occurs with all forms of increased intracranial pressure with papilledema but is not a specific symptom. Transient visual obscurations can occur in patients without increased intracranial pressure who have elevated optic discs from other causes. Persons without papilledema do not have transient visual obscurations. Pulsatile tinnitus, diplopia, and visual loss can occur.