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.
All user-generated information on this site is the opinion of its author only and is not a substitute for medical advice or treatment for any medical conditions. Members and guests are responsible for their own posts and the potential consequences of those posts detailed in our Terms of Service.
Add a Comment280 Comments
My son is 9yrs old diagnosed with severe Autism and intellectually disabled, Epilepsy, Arachnoid cyst of the cerebellum, he is non verbal . I see him so tired some days black around is eyes and very subdued . I'm wondering if he has headaches with vertigo he has light sensitivities etc We we toldMarch 13, 2018 - 4:07am
that his Autism isn't caused by these cysts, as he's not a typical autistic boy he has no meltdowns and goes to sleep if day overwhelmed . Is all these systems apart of the Arachnoid cysts traits for that part of the brain???
sir, I was diagnosed a cyst of size 1.3x2.1x2.8cm (APXTXCC) in size behind left cerebellar hemisphere. Plz. suggest me what to do? How dangerous is thisOctober 25, 2017 - 10:47pm
to my life? Anticipated Thanks.
Ugghhh.... I definitly feel your pain. I found out about 6 years ago about my cyst. Appearantly, I've had it since birth and never knew. After a nocturnal seizure, I went to the hospital and had a CT scan. There the posterior fossa cyst (about the size of my fist) and signs of long term hydrocephalus where discovered. I was told I probably had seizures my whole life (36 years at the time) and never knew. Anyhoo, after many tests and going to different doctors and trying different meds, I got the seizures under control --ish. Eventually, after getting massive headaches, I got a LP (not fun). My pressure was twice the norm. So, my neurologist reffered me to a neurosurgeon. He said my cyst was the biggest he'd ever seen. He decided to do a fenestration. Well, during that surgery, I was producing too mu fluid for him to perform a good fenestration. But, after that surgery, my balance was way off. When I walked, it looked like I was drunk. A month later, I woke up with a massive pressure headache and vomiting and leaking fluid from incision. One call, and I was off by ambulance to the hospital. They got me in an MRI to map my skull for a VP shunt. Now I have a lump on my head. But, even after that surgery, I still had little to no balance. So, off to balance therapy I go. After 6 months of therapy,(and out of work) I was able to walk again. Up until about a year ago, I was great. But, now I'm starting to show signs of seizures again. When I have a seizure, it messes with my balance, makes me tired, vertigo, nausia, memory issues, sometimes messes with my "filter". Some of that is just the lack of sleep, but some of it brain stuff. And to top it all off, I found out recently that my epileptologist is moving out of state. GRRRRRRR!!!!!May 4, 2017 - 9:20pm
I am ever so sorry to hear this, i came across your post as i had my babies 20 week scan today and we pointed out that at 12 weeks we noticed a third like hole just behind the cerebellum. Apparently no one knows what it is but yet they can all see it. On my notes for referal it states cystic area posterior to cerellum.
My question to you is how do you find day to day life? Are you happy? Is every day a bad day? Have they been able to treat you?
This seems to be such a grey area to which no one really knows much about yet can be picked up at such an early date. If you had known sooner would you of started treatment or would you never have started and wish you had just carried on?February 7, 2018 - 12:34pm
I'm 42 and have a large arachnoid cyst located in the left posterior fossa (bottom left). My cyst was found incidentally during an MRI for something else when I was 27. I never knew I had it. I don't seem to have any real symptoms despite the size. I've been hit in the head during childhood sports, even passed out and hit my head a few years ago, and there were no changes, the cyst stayed as-is.March 6, 2018 - 11:32am
Don't give up hope. Try a neurosurgeon in NYC...they have lots of experience because people travel to them from all over. My daughter had similar symptoms had surgery hydrocephalus is gone and her cyst is draining into her spine without a problem for the last two years. FInd a more experienced surgeon. I will pray for you.May 5, 2017 - 10:12am
What hospital/surgeon in NYC would you recommend?October 21, 2019 - 5:08pm
Dr Joshua BedersonOctober 21, 2019 - 7:17pm
Mt Sinai Hospital NYC
I feel all of your pain, i was diagnosed by the va after a tour in iraq and have been told contless times that i am too young to have any surgery done to help ease my issues. Ive had a constant headache since 2008 and havent had any help with that either. I hope everyone gets the help they need and im going to keep fighting the bureaucrats that run the va untill im blue in the face, which i am aready, well more of a purple colorApril 20, 2017 - 10:24pm
You should try Dr. Douglas Anderson from Loyola University in Maywood, IL. Look him up. He is OUTSTANDING. My son just had a suboccipital craniotomy, fenestration of pposterior fossa cyst, C1-C2 partial laminectomies, and patch dural repair. He has had this neurosurgeon for over 16 years after his first one left Loyola. He is unbelievable and has the best bed side manner. There is hope and there are answers. -Gina Wilch, Chicago ILJuly 28, 2017 - 2:06pm