The controversial entity of brain herniations into arachnoid granulations: A report of three cases with literature review

Brain herniation into arachnoid granulation (BHAG) is a quite recently described controversial entity in terms of both etiology and clinical significance. It comprises a herniation of brain tissue into a presumed preexisting arachnoid granulation in dural venous sinuses, calvarium, meningeal or diploic veins. Most often described as an incidental finding in patients examined for unrelated pathologies, some BHAGs can possibly be related to headache, epilepsy or conditions with increased intracranial pressure such as idiopathic intracranial hypertension (IIH) or pseudotumor cerebri (PTC). The number of reported cases is low and there are only three more recently published observational studies on this subject with results lacking statistical significance due to relatively few BHAGs analyzed. Therefore, BHAGs still need an increased focus from both the radiologists and clinicians and more published studies and cases are necessary to help in understanding their factual meaning, clinical and treatment implications. In this article we describe three new cases of BHAGs to the literature, with patients presenting with different symptoms.