The Role of Arachnoid Granulations and the Glymphatic System in the Pathophysiology of Idiopathic Intracranial Hypertension.

PURPOSE OF REVIEW: Idiopathic intracranial hypertension (IIH) is a disorder characterized by long-standing elevated intracranial pressure (ICP). As the name applies, no uniform cause has been identified. IIH is typically characterized by headaches, pulsatile tinnitus, and visual deterioration. RECENT FINDINGS: Anomalies in cerebrospinal fluid (CSF) absorption are implicated in the pathophysiology of IIH. Non-invasive imaging of the brain parenchyma and the cerebral venous sinus has improved, and research has gained a better understanding of the role of cerebral venous sinus stenosis. Both have led to a better delineation of the role of arachnoid granulations (AG) and the glymphatic system in the development of IIH. IIH may occur as a result of restrictions of CSF absorption from the venous system, and or the congestion and overflow of the glymphatic system. Elucidating these mechanisms will lead to greater understanding of its underlying pathophysiologic mechanisms.