Editing Idiopathic intracranial hypertension (section)

===Investigations===
[[Neuroimaging]], usually with [[computed tomography]] (CT/CAT) or [[magnetic resonance imaging]] (MRI), is used to exclude any mass lesions. In IIH these scans typically appear to be normal, although small or slit-like [[ventricular system|ventricles]], dilatation and buckling<ref>{{cite journal |vauthors=Tan YJ, Choo C| year = 2020 | title =Idiopathic Intracranial Hypertension – Characteristic MRI Features | journal = Headache | volume = 60 | issue = 9| pages = 267–8 | doi=10.1111/head.13931| pmid = 32757392| s2cid = 221014881 }}</ref> of the optic nerve sheaths and "[[Empty sella syndrome|empty sella sign]]" (flattening of the [[pituitary gland]] due to increased pressure) and enlargement of Meckel's caves may be seen.

An MR venogram is also performed in most cases to exclude the possibility of venous sinus stenosis/obstruction or [[cerebral venous sinus thrombosis]].<ref name=Binder/><ref name=Soler/><ref name=FriedmanJacobson2002/> A contrast-enhanced MRV (ATECO) scan has a high detection rate for abnormal transverse sinus stenoses.<ref name="Farb">{{cite journal|last1=Farb|first1=RI|last2=Vanek|first2=I|last3=Scott|first3=JN|last4=Mikulis|first4=DJ|last5=Willinsky|first5=RA|last6=Tomlinson|first6=G|last7=terBrugge|first7=KG|title=Idiopathic intracranial hypertension: the prevalence and morphology of sinovenous stenosis.|journal=Neurology|date=May 13, 2003|volume=60|issue=9|pages=1418–24|pmid=12743224|doi=10.1212/01.wnl.0000066683.34093.e2|s2cid=34459740}}</ref> These stenoses can be more adequately identified and assessed with catheter cerebral venography and manometry.<ref name=Ahmed/> Buckling of the bilateral optic nerves with increased perineural fluid is also often noted on MRI imaging.

[[Lumbar puncture]] is performed to measure the opening pressure, as well as to obtain [[cerebrospinal fluid]] (CSF) to exclude alternative diagnoses. If the opening pressure is increased, CSF may be removed for transient relief (see below).<ref name=FriedmanJacobson2002/> The CSF is examined for abnormal cells, infections, antibody levels, the [[glucose]] level, and [[protein]] levels. By definition, all of these are within their normal limits in IIH.<ref name=FriedmanJacobson2002/> Occasionally, the CSF pressure measurement may be normal despite very suggestive symptoms. This may be attributable to the fact that CSF pressure may fluctuate over the course of the normal day. If the suspicion of problems remains high, it may be necessary to perform more long-term monitoring of the ICP by a pressure catheter.<ref name=FriedmanJacobson2002/>