Idiopathic intracranial hypertension

Idiopathic intracranial hypertension (IIH) is a disorder of increased intracranial pressure in an alert and orientated patient. The most popular hypothesis is that IIH is a syndrome of reduced cerebrospinal fluid absorption.

Clinical features include headaches, pulse-synchronous tinnitus, transient visual obscurations, visual loss, neck and back pain, and diplopia.

Signs include papilloedema, 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 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.

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.[1]Wall M. Idiopathic intracranial hypertension. Neurol Clin. 2010 Aug;28(3):593-617. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2908600 http://www.ncbi.nlm.nih.gov/pubmed/20637991?tool=bestpractice.com Its cause is unknown. It is characterised by increased intracranial pressure and its associated signs and symptoms in an alert and orientated patient but without localising neurological findings. There is no evidence of deformity or obstruction of the ventricular system, and neurodiagnostic studies are normal except for increased cerebrospinal fluid pressure and the related neuroimaging signs. Furthermore, no secondary cause of intracranial hypertension is apparent. IIH can either be self-limited or have a lifelong chronic course.[1]Wall M. Idiopathic intracranial hypertension. Neurol Clin. 2010 Aug;28(3):593-617. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2908600 http://www.ncbi.nlm.nih.gov/pubmed/20637991?tool=bestpractice.com [2]Shah VA, Kardon RH, Lee AG, et al. Long-term follow-up of idiopathic intracranial hypertension: the Iowa experience. Neurology. 2008 Feb 19;70(8):634-40. http://www.ncbi.nlm.nih.gov/pubmed/18285538?tool=bestpractice.com