If the opening pressure is increased, CSF may be removed for transient relief (see below). 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. 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. Classification
The original criteria for IIH were described by Dandy in 1937. They were modified by Smith in 1985 to become the "modified Dandy criteria". Smith included the use of more advanced imaging: Dandy had required ventriculography, but Smith replaced this with computed tomography. In a 2001 paper, Digre and Corbett amended Dandys criteria further. They added the requirement that the person is awake and alert, as coma precludes adequate neurological assessment, and require exclusion of venous sinus thrombosis as an underlying cause. Furthermore, they added the requirement that no other cause for the raised ICP is found. In a 2002 review, Friedman and Jacobson propose an alternative set of criteria, derived from Smiths. These require the absence of symptoms that could not be explained by a diagnosis of IIH, but do not require the actual presence of any symptoms (such as headache) attributable to IIH.
These criteria also require that the lumbar puncture is performed with the person lying sideways, as a lumbar puncture performed in the upright sitting position can lead to artificially high pressure measurements. Friedman and Jacobson also do not insist on MR venography for every person; rather, this is only required in atypical cases (see "diagnosis" above). Treatment
The primary goal in treatment of IIH is the prevention of visual loss and blindness, as well as symptom control. IIH is treated mainly through the reduction of CSF pressure and. IIH may resolve after initial treatment, may go into spontaneous remission (although it can still relapse at a later stage), or may continue chronically. Lumbar puncture
The first step in symptom control is drainage of cerebrospinal fluid by lumbar puncture. If necessary, this may be performed at the same time as a diagnostic LP (such as done in search of a CSF infection). In some cases, this is sufficient to control the symptoms, and no further treatment is needed.The procedure can be repeated if necessary, but this is generally taken as a clue that additional treatments may be required to control the symptoms and preserve vision. Repeated lumbar punctures are regarded as unpleasant by people, and they present a danger of introducing spinal infections if done too often. Repeated lumbar punctures are sometimes needed to control the ICP urgently if the persons vision deteriorates rapidly.