AVM Survivors Network

Risk of hydrocephalus

What are the chances of developing hydrocephalus after a craniotomy? It has been three years since my craniotomy for the removal of my grade 4 AVM. The surgery was successful but my doctors are concerned about the cavity that’s in my brain after the AVM was removed. They are afraid I might develop hydrocephalus. Is there a way in which I can prevent it from developing? and is it always the case that someone gets hydrocephalus after surgery or are there cases where someone doesn’t develop it at all after surgery and they can live normal lives afterward?


I’ve not had open surgery or hydrocephalus, so I’m going on what I’ve read.

I’m pretty sure you can have surgery without hydrocephalus. It doesn’t automatically follow. What I understand is that hydrocephalus is most often associated with the production of cerebrospinal fluid not being met by its rate of absorption and that mismatch is most often caused by a bleed covering part of your brain, so the blood stops the CSF from being absorbed.

So I think you have a greater likelihood of hydrocephalus if you had a bleed at some point and it is blocking enough of the absorption to create an imbalance.

However, you can get increased intracranial pressure for a number of reasons, one of which being called “IIH” which means “idiopathic intracranial hypertension” and "idiopathic " basically means it is happening for reasons known only to itself… so it can just happen without a direct cause being identifiable.

So I think the most helpful bit of my answer is “no, it doesn’t automatically follow”. You can have surgery without hydrocephalus.

Did you have a bleed at some point?

Very best wishes for the new year,



Hey Sam,
Hydrocephalus is also known as ‘water on the brain’. Technically it’s not water, but rather a nutrient rich, clear fluid called Cerebral Spinal Fluid (CSF). On average we produce around 600ml of CSF per day. This fluid is produced by the brain, it cushions the brain and spinal cord. The fluid also helps to remove waste from the brain. Some of the fluid is absorbed by the brain and the remaining CSF drains from the skull through a small tube in the spinal cord called the aquaduct.
When too much fluid builds up, that is hydrocephalus.
I also agree with DickD’s comments ‘…you can have surgery without hydrocephalus. It doesn’t automatically follow…’ The diameter of the aquaduct is ‘usually’ between 1-3mm, so it doesn’t take much to block it. A small collection of blood can be enough to block it.

Merl from the Moderator Support Team

Hydrocephalus is a condition that can be independent of surgery or bleeding in the brain. As previously mentioned it is a buildup of intracranial pressure (ICP) of cerebral spinous fluid. While CSF is partially absorbed, it is also fluid and circulating all the way from brain down through our spinal cords. Therefore, the most common way to check a patients ICP is via a spinal tap. A needle in the lumbar spine(lower back). Our brains contain 4 ventricles that act as “drainage gutters” to circulate CSF from brain to spine. Some ventricles, however, may become dilated or blocked causing ICP to increase leading to hydrocephalus. If open surgery (craniotomy) disrupts or damages this drainage system, I could see where hydrocephalus could be a result. In my case, my acute hydrocephalus resulted after my first embolization when the occluded vessels of my avm blocked my lateral venricle from properly circulating my CSF. As a result, I was implanted with a VP shunt ten years ago that essentially maintains acceptable ICP and “shunts” or drains excess CSF from my brain to my abdomen. (Ventricular-peritoneal) Ventrical to peritoneum. I did have one shunt malfunction years ago where the hydrocephalus symptoms reappeared and needed a revision procedure. (shared in a previous post) Ten year later still doing well, minus the one hiccup, which only was a couple day stay in the hospital. Best, GK

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Yes I did have a bleed about four years ago when my AVM ruptured while I was running but that was the only bleed i ever had afterwards i never experienced any and so far my CSF has been stable from my last MRI examination. I’m just concern that could happen later in life and I did ask my neurosurgeons about it and they say that I have gone over the stage in hich it could develop, since according to their standards it would normally occur 2 to 3 years after the initial bleed. But it’ been 4 years now and my CSF is still stable. are there ways to prevent it in the future a means of a precautionary measure?

Sam, follow up MRIs can track the size and shape of your ventricles which can determine their functionality and predict your potential for hydrocephalus. Common symptoms of hydrocephalus are uncontrollable vomitting and extreme sleepiness. You don’t want to get an implant like a VP shunt until absolutely necessary. Best, GK



I don’t know about this area. What I would say is that if your doctor says you are beyond the point that you’re likely to develop hydrocephalus, then you should really relax about it and think of nicer things about the future. I do think we go through our surgery and it makes us hypersensitive to whether there is something wrong but the mind is as good an ally to us as medicine and we should be positive, believe the doctors when they encourage us and put the whole episode of having an AVM and surgery behind us.

Of course, this isn’t always easy and I’m very conscious that some people have ongoing issues from their AVM or the surgery, and that makes it difficult or impossible to be positive, but if you are generally well, I would encourage you to put worries about hydrocephalus out of your mind: as Greg says, you don’t want to be having a shunt unless absolutely necessary.

Very best wishes,