How does medication help the compression or fluid flow?? Without Surgery? and how do we know when there is a total block. What are the damages?
Medications do nothing to the Chiari. They target the symptoms. There is no way to directly affect the Chiari(anatomy) without surgery.
However, many medications can indirectly affect the Chiari. diamox reduces CSF production(and sometimes helps with head-aches). Steroids reduce inflammation(and sometimes help with head-aches). Head-aches medications are clearly meant to help the head-aches. Different medications may target different symptoms.
A cine MRI is the usual study to assess CSF flow(blockage).
I'm unclear to what the last question is referring. The best way to assess the anatomy(the risk of permanent damage) remains an MRI.
You can be diagnosed with total blockage with an MRI. The risk of total blockage is severe. You can have vision problems & vision loss from increased pressure, permanent paralysis. I about became a quadriplegic when my CM was dx'd too late. You can have permanent nerve damage and spine problems, dysphagia, cranial nerve disorders. Your heart can even stop from too much pressure on Cranial Nerve 10 the Vagus Nerve. You can have sleep apnea and quit breathing from too much pressure on the 9th cranial nerve - The Glossopharyngeal Nerve. There are many things that can happen and develop from total CSF Blockage from Herniation decention. It is a very serious situation and should not be taken lightly. There are many other complication possibilities.