They check an opening pressure by doing a lumbar puncture. Just say no! I had a LP a few years ago and they failed to do the opening pressure and wanted to repeat it. I sad no way. The first time was an awful experience and left me with an headache that lasted nine months and I was unable to sit up for weeks without being dizzy and having nausea and vomiting. If you have EDS a LP can cause a variety of problems. At the time I had a brain bleed and I did not know I had EDS. They can see hydrocephalous on MRI, but it can be subtle in EDS patients. I forget what one needs to look for.