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Dr. Muneeb Ali
Dr. Muneeb Ali, Intensivist
Category: Neurology
Satisfied Customers: 7454
Experience:  Experience of Neurology of over 4 years, well versed in EEG, NCS and EMG alongwith MRIs and CT scans
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MRI brain scan What is a posterior cranial fossa cyst just

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MRI brain scan
What is a posterior cranial fossa cyst just to the left of midline along the cerebellar falx causing mild mass effect on the left cerebellar hemisphere in the midline and following CSF signal intensity on all sequences mean? Cyst measuring 2.2 x 2.1 x 3.9cm....I have hearing loss and other stuff going on is why I was sent for MRI of brain...
Customer: replied 1 month ago.
I picked up my report and my doctor appt is not for 2 weeks because he is on vacation and the cyst finding have my nerves on edge. Will they need to remove it and is it safe? Also could my hearing come back and other effects stop?


Welcome to JA and thanks for this question. Im sorry to hear about your symptoms. Actually on the MRi images there is a small cyst (fluid containing lesion) inside a certain region of the brain which is known as the cerbellum. This region of the brain controls the balance, fine motor movements among other issues. A cyst in this region can cause balance issues, tremors, seizures, rigidity, dizziness, rapid eye movements among other symptoms. Now this cyst is present just to the left of the center of the cerebelum and it is large enough that it is causing pressure effects on one of the two hemispheres of the cerbellum. This is a atrachnoid cyst which is usually a benign structure and would not cause many symptoms however given that it is causing mass effects (which means pressure on the brain) then it may be responsible for your symptoms. It is less likely to be responsible for your hearing loss as the auditory nerve does not arise from this region of the brain. But if you have other effects like the ones i described above then this may be the cause.

Regarding its treatment, yes it can be removed if the symptoms are severe and there are several methods to remove the cyst, however all of them are essentially brain surgery and there are certain risks associated with any sort of brain surgery. In most cases it is a safe surgery provided it is done by a good neurosurgeon who has a plan to minimize or avoid damaging other portions of the brain. Once removed, it can help with resolution of the symptoms provided this is the cause but the hearing loss is unlikely to be due to this cause. What other symptoms do you have and i can determine if this cyst is causing those symptoms or not.

Do you have any more questions?

Please leave a POSITIVE rating by clicking on the stars above, until you do i am not compensated for my time. You can continue to ask follow-up questions even after the POSITIVE rating. You can also ask questions from me directly by going on the link below,

Customer: replied 1 month ago.
I have dizziness and some headaches... Lost sight for few days in my right eye... Balance problems and memory problems....they have suggested I have MS and said that for 7 years now and that is why I went for this Brain MRI. I totally lost all motor skills about 7years ago that lasted about a day and half amd slowly got better after that 1.5 day mark

Then the dizziness, headaches and balance issues can be associated with this cyst. However your MRI brain does not show any signs of MS, so that is less likely as a cause. The loss of vision can be amarousis fugax which can be due to small blood clots in the vessels in the brain which can lead to this problem, it would resolve by itself once the clot dislodges, however that would not be picked up on the MRI. The memory problems would also not be associated with these findings on the MRI.

There are a few conditions which we can consider,

We can consider pheochromocytoma which can cause the intermittent rises i heart rate as well as the other symptoms. this is a benign tumor of the adrenal glands which can cause surges of catecholamines including adrenaline which can be diagnosed with 24 hour urinary catecholamine levels along with VMA levels. Once diagnosed beta and alpha blockers would be necessary followed by surgery.

The adrenals should be addressed here, not because of the implant but because it could be causing the problem independently of the implant. These symptoms can occur in both adrenal excess and adrenal insufficiency as they are not specific for either one of them. If you had weight gain then cushings or adrenal excess would have been suspected and if there was weight loss then adrenal insufficiency would be more likely.

Perimenopause itself can cause this problem as well or even a hormonal imbalance inspite of the implant. At the same time the catamenial migraine should be considered here as well. Simple medications like beta blockers can be used if the problem is too frequent to prevent attacks from occurring. In catamenial migraines a drug called acetazolamide has been found to be more effective than others.

The arrhythmia option is still be considered because a 24 hour EKg would ONLY pick up on the problem if you were actually having symptoms when you were wearing the monitor, if there are no symptoms then it would miss the arrhythmia. if this occurs every 28 days like clockwork then wearing a monitor for 7 days before the event and a couple of days after could be more useful.

But we can also look into the other endocrine and metabolic issues that i have mentioned above.

Do you have any more questions?

Please leave a POSITIVE rating by clicking on the stars above, until you do i am not compensated for my time. You can continue to ask follow-up questions even after the POSITIVE rating. You can also ask questions from me directly by going on the link below,

Dr. Muneeb Ali and other Neurology Specialists are ready to help you
Customer: replied 1 month ago.
Is this something that can grow and something I should consider getting fixed sooner than later? Could it be 'life threatening' if left untreated?

Sorry for the previous response, i mistakenly sent another patients respons along with yours. Sorry about that. The portion after there are a few conditions we can consider is not meant for you.

In most cases the arachnoid cyst remains the same size and does not grow, however there are instances where it can grow in size and cause worsening of symptoms. But even if it grows in size it is rarely if ever, life threatening. It can however cause worsening of symptoms and cause serious issues with your quality of life. So if your symptoms worsen over the course of the next month or if you start getting worsening headaches then it is better to treat this earlier rather than later.

Do you have any more questions?

Please leave a POSITIVE rating by clicking on the stars above, until you do i am not compensated for my time. You can continue to ask follow-up questions even after the POSITIVE rating. You can also ask questions from me directly by going on the link below,

Customer: replied 1 month ago.
One more question because I feel like I fit a wide varietyof symptoms dealing with it possible for MRI not to show MS if it is not in the active stage or would you rule MS out entirely by the MRI findings I sent you? Thank you for your time and help :-)

With this MRI, the chances of you having MS are less likely but completely ruling it out on just a MRI is not what most physicians would consider. If the MRI findings and your general physical exam both indicate that MS is less likely then it can be completely ruled out. But in practice, when a MRI of the brain is normal or does not have lesions of MS, we effectively rule out MS.

Customer: replied 1 month ago.
What findings are usually in a physical exam on an MS person? I mean what would one neurologist typically look for.... I have had 2 say yes but one that doesnt think so...kinda confused

Usually there would be muscle weakness, twitching, numbness, tingling which can be substansiated on a clinical examination as well. A eye examination would signs of inflammation in the retina or atleast in the optic disc.

Customer: replied 1 month ago.
An eye dr recently said I had Optic Neuritsis (sp?) when I had sensitivity to light and pain in eye .....

Optic neuritis can be an indication of MS, and if it is actually present then a normal MRI brain alone would not exclude MS and you would need a spinal MRI or a spinal tap to exclude the diagnosis.

Customer: replied 1 month ago.
Thank you VERY much for all your help.... I feel more at ease because of the information you gave me and it has allowed me a better understanding of things! I appreciate it more than words can express.

You are more than welcome, happy to be off assistance.

Customer: replied 1 month ago.
Is it possible that its is tumor? The findings on the MRI suggest saying more than likely its an aracnoid cyst... how do they know by MRI what it is if they are using unsure words like 'more than likely' in the findings

Actually we never put down that the findings are conclusive of this disease, we always write it down like that it is likely to be this condition. The appearance of the lesion is indicative of a cyst however, the words CSF signal intensity basically means that the lesion contains fluid and it is unlikely to be a tumor which would have another type of appearance on the MRI. The wording is open ended because they leave the final diagnosis upto the physicians who have to correlate the MRI findings with your clinical examination. But this is not a tumor.

Customer: replied 1 month ago.
You mentioned there was ways to remove it but all involved brain surgery.... Is it possible for you to tell me the options I should have for removing it and how many options there are.
Customer: replied 1 month ago.
What options are to remove it?
The most common ones are endoscopic removal of the cyst which involves using a camera and the second one is open surgery in which the cyst is removed under direct vision.
Customer: replied 1 month ago.
I go to a Neurologist this afternoon because I got another appointment because my nerves are bad from this. Anyway, 2years ago I was thrown to where I hit tje back pf my head really hard (on corner sidewalk) & after that I started feeling like my reality was off. I actually started thinking I was loosing my mind and gonna need help. Anyway, is this something that may be relevant to the finding of the cyst that I should mention to the Neurologist or is that just inncidential and isn't relevant to this cyst?

You can certainly mention it to the neurologist but it is less likely that the arachnoid cyst is due to the trauma, but mention it nervetheless.