Biomarkers in the Etiology of Idiopathic Intracranial Hypertension

Idiopathic intracranial hypertension (IIH) is a condition characterized by an increase in intracranial pressure (ICP), papilledema with a risk of permanent visual loss, and severe headaches that profoundly affect quality of life. To date the exact pathophysiology of IIH remains unknown. IIH is considered a complex neurometabolic and neuroendocrine disorder, favored by female gender, and obesity. In the majority of patients (80% of the cases) IIH is associated with obstruction of cerebral venous drainage with stenosis of the transverse sinus. This stenosis may be the main underlying cause in the so-called "venogenic" form of IIH. Equally, in the absence of a stenosis, obstruction may occur when otherwise normal venous sinuses are compressed by the increased ICP, the so-called "non-venogenic" form of IIH. An innovative treatment of IIH with associated venous stenosis includes stenting of the transverse sinus stenosis. This strategy may allow resolution of papilledema and ICP reduction rates up to 80%. Although the pathogenesis of IIH is still poorly understood, inflammatory mechanisms, autoimmune reactions, and hormonal abnormalities of notably androgens, have been proposed to contribute to its pathophysiology. The function of the blood-brain barrier (BBB) has been studied by determining the prevalence of extravasation of endogenous proteins such as fibrinogen. A growing body of the literature shows a correlation between increased ICP and metabolic/hormonal changes. The improvement of IIH treated with acetazolamide and/or stenting appears to correlate with the reduction of ICP. Yet the association of this reduction with metabolic changes at the peripheral and central blood level as well as the CSF remains unclear. The search for specific inflammatory, immunological and hormonal biomarkers in patients with IIH and their variation in relation to the ICP should provide a better understanding of its etiology.