The Neurosurgeons cut through Jaymun's cranium yesterday, relieved some pressure, and installed a subdural drain. The fluid was CSF fluid with a slight amount of old blood. The neurosurgeon said he believed it was caused by past traumatic spinal taps causing leakage into the back, temporary low CSF pressure and slight sagging of the brain, subsequent subdural vascular tension and small tears / bleeding, follwed by accumulation of CSF fluid (local secretion) and water (osmotic pressure).
The blood formed a sort of membrane that kept the slightly richer fluid inside (building pressure). CSF fluid could cross that membrane (osmosis) but once it was there and combined with the richer proteins, it could not get out. So now that they relieved the pressure and flushed it out, the CSF fluid from the brain is continuing to slowly leak - further flushing it.
We are keeping him comfortable with pain meds while the drain is in for a few days, He has to lay at a position relative to the reservoir so as not to over/under drain. He did not have to go into intensive care - we went back to our regular room.
We will take another CT scan tomorrow to see if brain is re-expanding to fill that gap. If so, we will remove the drain and hope the problem doesn't reoccur. This works about 80% of the time - so if it reoccurs we simply do it again - eventually we get it.