An arachnoid cyst is a fluid filled sac that develops primarily in the uterus during the development of the brain and skull. The arachnoid membrane of the brain splits, and the split space fills with fluid known as cerebral spinal fluid. The fluid will enter the split area, but it cannot escape at the same rate as it enters. Because of this, the cyst will grow over time. The growth rate depends on many factors, but even as it grows, more times than not, the cyst will remain asymptomatic. This means that generally, an arachnoid cyst will not cause any symptoms.
Arachnoid cysts can grow anywhere on the brain with the primary areas being the side of the brain, and the top of the brain. When a cyst forms on the back of the brain, this is called a posterior fossa arachnoid cyst. A posterior fossa arachnoid cyst can create pressure on the brain stem and the cerebellum. These are extremely vital organs of the brain and they both produce tremendous functions that are required to live.
The brain stem controls a lot of our everyday functions that we do not even think about. One thing it controls is our body temperature. It controls our diaphragm for breathing, and it is where our hunger and thirst are controlled. It is also the path in which all our nerves leave the brain and travel throughout the body. The brain stem controls our pain, it is also where the nausea center is based, and it plays a role in the regulation of our hearts.
The cerebellum; on the other hand, helps control our balance. It plays a role in the reflex of our muscles, and plays a major role in our motor skills. Both parts of the brain have their very specific tasks, and when either one is compromised, it can reek havoc on the entire body.
If treatment is needed for an arachnoid cyst, usually the first choice is a fenestration of the cyst. This means going into the brain with a wand and opening up any walls that may have formed inside the cyst. These walls trap the fluid inside the cyst. The idea of this procedure is to get all the cerebral spinal fluid flowing in and out of the cyst efficiently so that the cyst does not continue to grow. If this procedure does not work, a neurosurgeon may decide to put a shunt in. A shunt helps to keep the cyst draining and not allow fluid to build up inside. If the cyst is small enough and in a space on the brain that is not too dangerous to remove, the neurosurgeon may be able to remove it altogether.
Symptoms can show themselves in many ways; from balance problems, nausea, vomiting, headaches, even seizures. Many cysts are discovered on accident when having a scan for another reason. They can be seen on Cat Scan, but the preferred diagnostic test for a brain cyst, is an MRI.
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Hi Melanie, I am sooo sorry to hear about all your trouble, but I have to say that your medical problems and length of them, remind me of myself. Even how you have questioned God about "hasn't He given you enough?" I have asked that often myself, believe me. I was born with a neurological (hereditary from my mother) disease called Charcot-Marie-Tooth. I had many surgeries on my feet up until the age of 18. I felt like that was enough...not being able to always walk good, let alone run well and balance problems. My feet always hurt, starting way back as a child. I got made fun of with my run all through elementary school which was torment for a little girl.
I have had kidney stones that I had bilateral lithotripsy for in '01, I also then had one when I came home from my shunt surgery that I had to pass on my own. The placement of the shunt knocked one loose and down the ureter. I have a right kidney full of them which I've been told are mostly big ones and if one of the big ones gets into the ureter, I could be in trouble. But I just cannot tolerate any more procedures right now. I have this brain sagging and chiari and a shunt that will eventually need replacing. I've torn the ligaments in both ankles which increases my difficulties with balance and walking. I often ask God when is enough, enough? You hear as a Christian that God only gives you as much as you can handle, and I have told Him countless times, that He is pushing it with me. lol
I needed the shunt because of where my large cyst sits (which is so large, takes up a third of my brain). Right at the base and moves up the back of the brain. But it blocks the channels for the CSF to flow down my spine. On scan you can only see part of my brain because the cyst blocks a very large portion of my brain from sight on film. It's enormous. It is pushing my cerebellum and brain stem downward, along with the top of my brain sagging, or drooping downward on top. I live with pain every day in and on my head. The sagging I have been told, causes the brain to tug on vessels and nerves up there, which causes my awful pain on top of my head.....like someone has just hit me in the head with a shovel. Especially first thing in the morn., if I don't eat enough or at all, and at night at the end of a long day. Dizziness from the chiari is horrible. I feel like I am on a boat all the time...trying to get my balance. I am weak, fatigued, and lose energy quickly. It is hard now, for me to bend to get things off the floor or anything. I have to have my boys help me a lot. I get double vision a lot and have to close one eye to get it to stop, and my right eyelid still droops. Greatly when I am tired. My husband of 13 years, just moved out last week. We have been having difficulties, and he admittingly said that he has lost compassion for my situation. So I will be trying to raise the boys, essentially on my own. I am taking an online medical billing course and am supposed to be done in May. I hope to start my own medical billing practice so I can work from home. I just hope I have the energy to do this. I freelance write from home too. It brings in a little money but not much. Writing is my passion...it's a good release. I have also written my autobiography about my situation and am almost ready to start peddling it out to publishers. Fingers crossed. I have titled it, "It's all in Your Head" because the play on words is exactly what I lived. Everyone...doctors included, used to tell me all my symptoms were just all in my head. Well, the cyst proved that yes, in fact it was "All in my Head!" : )
I wish you the best of luck. It is not always easy staying positive, but it is important because it plays a role in your recovery as well as how you view life. I will keep you in my prayers.
God bless-
January 15, 2010 - 4:59pmMaria
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Formerly Anon - i have now created an account. I'm sure that i will not have the results from my MRI anytime soon, but i will certainly touch base once i have, and what my doctor feels the next course of action is. I would imagine that since it is on the brain i would have to see a neurosurgeon......Hopefully the same one that did the surgery on my back can do this too, if required.....will check in again. Thanks Pat
January 13, 2010 - 6:33amThis Comment
I was in an ER for 4 hours with a migrane headache that there was no explaination for. I have never ever had such a headache in my life. It was after a CT scan i was told that there was "something" on the scan and an MRI would be required to verify. Well I was out of the state on vacation at the time, so i opted to have the MRI when i got home. It is scheduled for 1/13/10.
January 12, 2010 - 1:46pmI was told that this was either a 25mm x 25mm epidermoid, or arachnoid cyst (Images through the posterior fossa show an unexplained low density process at the inferior margin of the fourth ventricle and just below the obex, between the cerebellar tonsils). Now mind you i am a little nervous at this point, even thought i was told that neither one of these types of cysts are life threatening. There is so much that i need to know.....i am raising my 1 year old grandson so my life is complicated at this moment and this was just the icing on the cake......
anyone out there know what the terms above mean? Is this in a dangerous place to operate on? Does it HAVE to be operated on? I have absolutely no sick time, no disability, no nothing at work. If i have no choice, what is the recovery time....days, weeks, months etc.? Anyone out there that can help me? In case it matters - i am 42.......
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Hi Anon - Thank you for writing to us and sharing your story. It's easy to see why getting this type of information would concern you and spark a lot of questions.
First, you asked about some definitions. An epidermoid brain cyst is an uncommon, benign cyst. Surgery is usually needed for large epidermoid tumors that are causing symptoms for the patient. Chemotherapy and radiotherapy are generally not used for treating epidermoid cysts.
An arachnoid cyst is also a benign cyst and most are developmental anomalies. In most cases there are no symptoms even when the arachnoid cysts are quite large. There is disagreement within the medical community about treatment. Some advocate that asymptomatic cysts do not need to be removed. Others believe all such cysts should be removed to avoid future complications.
Each person's experience is going to be unique, so it's hard to predict what yours will be. You can learn more about EmpowHer member Maria Richmond's experience with an arachnoic cyst, and her advice for others, here:
https://www.empowher.com/community/share/rare-brain-condition-called-posterior-fossa-arachnoid-cyst-has-wreaked-havoc-my-life
Obviously the type of cyst you're dealing with, as well as the size and location, won't be clear until after you have the MRI. Will you write back to us with that information? Until we know more about exactly what you're dealing with it will be difficult to research information for you or help you locate resources.
Good luck to you as you go through the exam. We will be waiting to hear back from you and are here to help you so you're not going through this alone.
Take good care,
January 12, 2010 - 6:24pmPat
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My brother is 11 years old and they just found one of these on him a couple of days ago and im soooo scared ..i would like to learn more about this from people who have had this done. Is it very dangerous and are there any negative results after the surgery???
December 8, 2009 - 10:00amThis Comment
I was diagnosed with a Posterior Fossa Arachnoid Cyst in 2006. My symptoms included mainly imbalance, but also nausea and pressure pain at the back of my head and across my eyes. I had a Postior Foss Craniotomy May/06. It took about three months to tell if it was successful, and I DID have 18 months symptom free. The symptoms have slowly come back and are now worse than before the first surgery. My neurosurgeon has declined to do further surgery, because of how quickly the symptoms recurred. A shunt was suggested but because I am also Type 1 Diabetic for 38 years now, that also does not seem to be an option because of risk of infection. I am wondering if anyone may know of any other treatment that again would give me my life back. Thanks, Monica Anderson
November 1, 2009 - 3:13pmThis Comment
I had a mri scan for problems i have been having with my ear and although my ear looks fine they told me i had an arachnoid cyst on the left posterior fossa casuing minor displacement of the cerebellum. I also have Marfan syndrome (connective tissue disorder) and wondered if the 2 could be related. I ve heard of people with marfans having cysts on their spine i think its called dura ecstasia due to the elasticity of the dura. Are these things similar. I wasnt told the size of the cyst. Do you know if cysts are usual in this part of the brain?
October 5, 2009 - 4:34amThis Comment
Update: I have seen a neurosurgeon who was very helpful and informative. I feel relieved to have some answers, I also know the size its 6cm by 2cm. Basically as long as my symptoms dont change and the size and disruption to the chiari malformation dont alter then there is no need to go in there and mess with it. I was told the arachnoid cyst in this part of the brain is not common place but arachnoid cysts in general occur in about 1% of the UK population. A quick google search by the surgeon on marfans and cysts suggests there could be a link but i suppose without scanning everyone with marfans then there will be no clear evidence and im not sure what good it would do anyway. I have a scan in 4 months and they are going to check my spine as well so overall i am happy as I have answers. Good luck and fingers crossed for good news and answers for everyone else x
January 22, 2010 - 6:38amThis Comment
it's your right to know the size of the cyst you should call the dr that stated you have a cyst and advise that you want to know the size also request the mri report and keep it for your records...my son's dr didnt tell us a size either just stated small..i had to request the info which to me is bull...an the cyst isn't small it's the size of a lemon...
December 5, 2009 - 7:07amThis Comment
Thank you for sharing your stories. I hope you all find solace in this site and sharing the great stories on here. We all can certainly learn from each other.
September 26, 2009 - 8:37amThis Comment