The most popular hypothesis is that IIH is a syndrome of reduced CSF absorption.
Clinical features include headaches, pulse-synchronous tinnitus, transient visual obscurations, visual loss, neck and back pain, and diplopia.
Signs include papilledema, sixth nerve paresis, and disturbances in sensory visual function. Visual field loss is ubiquitous, and the prototype pattern for early loss is enlargement of the blind spot and inferonasal loss. Diagnostic criteria are the modified Dandy criteria.
In all patients with IIH, treatment consists of first eliminating causal factors, such as drugs and other conditions known to cause increased intracranial pressure, and instituting a low-sodium weight-reduction diet plus acetazolamide when indicated. Therapy can be given to reverse and prevent loss of vision.
Idiopathic intracranial hypertension (IIH), also known as pseudotumor cerebri, is a disorder of increased intracranial pressure that occurs mainly in overweight women of childbearing years, often in the setting of weight gain.  Its cause is not known (hence the preferred name IIH). It is a syndrome characterized by increased intracranial pressure and its associated signs and symptoms in an alert and oriented patient, but without localizing neurologic ﬁndings. There is no evidence of deformity or obstruction of the ventricular system, and neurodiagnostic studies are normal except for increased CSF pressure and the related neuroimaging signs. Furthermore, no secondary cause of intracranial hypertension is apparent. IIH can either be self-limited or have a life-long chronic course.  
Department of Neurology and Department of Ophthalmology & Visual Sciences
University of Iowa Hospitals & Clinics and Iowa City VA Health Care System
MW declares that he has no competing interests.
Chief Resident in Ophthalmology
Nassau University Medical Center
MM declares that he has no competing interests.
Consultant in Neurology and Neuro-Ophthalmology
Mayo Clinic Florida
PWB declares that he has no competing interests.
Birmingham Neuro-ophthalmology Unit
University Hospital Birmingham
TDM declares that he has no competing interests.
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