In doing some research on recurrent meningitis (also known as Mollaret's meningitis), I found two sites that suggested there are times when a lumbar puncture would be contraindicated because of a rare possibility of brain hernia. Of course doctors should know this, but they are fallible. Also, we might forget to tell them something (such as we were recently hit on the head)--or we might be too sick to tell them and our family members might have to step in. I am not a doctor. This information was taken from two websites that appear thorough, reliable, and documented. They are listed below. From what I understand, the doctors first do an MRI or CT scan to rule out these possibilities. Obviously, each case is unique. This is simply something to be discussed with your doctor. Here is the compiled list:
-possible or recent head injury
-immune system problem
-cerebral mass lesion
-elevated/increased intracranial pressure
-localizing neurological signs
-evidence on examination of a raised intracranial pressure (ICP)
Sources: