SubArachnoid Cyst

[sunflowers1118]

My daughter is 7 years old and began having severe headaches about 2 months ago.  They would begin at night primarily and get so bad that she would begin throwing up.  We went to our pediatrician who sent us to get her eyes checked.  She ended up needing glasses (although she had passed her eye exam at school early in the school year).  We also started taking pariactin because she was having some allergy sinus issues too.  However, after the glasses she was still having the headaches, so we went for a CT scan.  The CT scan showed two things, 1 a severe sinus infection and two a Subarachnoid cyst on the back part of her brain.  We are scheduled for a MRI in two weeks.  I am not exactly sure of size I think he told me 1 inch in diameter or location, just that he said at the back of her head.  I have some questions and hopefully you can give me some answers.

1.  Are subarachnoid cyst and arachnoid cyst the same things?
2.  In the back part of the head what functions would the cyst affect?  Would this cyst be tied to vision changes?
3.  Does the cyst stop any activites, flying, rollarcoasters, skiing, etc?
4.  Are these considered a rare occurance?
5.  Can a CT scan show up to be a cyst and then the MRI find a tumour or another type of problem?

I appreciate any help here!  Thank you so much in advance!

[CCF-Neuro-M.D.-PW]

1) essentially yes - a cyst mean a collection of fluid material, and the word before denotes what type of cells the lining of the cyst comes from - the arachniod mater covering over the brain (part of the meninges), sub just means under this lining, that is betweem the arachnoid layer and the actual brain surface. Arachnoid could mean within the layer itself also

2) I would have to see the scan to tell you if the cyst was large enough to be causing compression of adjacent structures. The MRI will be more revealing. Usually these cysts (which are quite common in the general population and are often an incidental finding on brain scan done for eg headache) do not cause symptoms unless quite large. In the back of the brain (depending on where) they could affect vision in the occipital lobe, or lower down, the cerebellum (off balance, difficult with walking, dexterity) or top of the brainstem (double vision, facial weakness)

3) not by itself, but you should wait until the full results of the MRI are available and your neurologist clears her for this

4) see 2

5) this is possible - the MRI shows the brain in greater detail and some tumors have a cystic component - but usually there is a noncystic component that can be seen also - subarachnoid cysts are more common, and the likliehood is that this is what it is, the MRI is needed to make sure though

Good luck

[sunflowers1118]

Thank you so much for the prompt and detail response!  I really appreciate this site so much!  She has her MRI on June 2nd, so I may try to post again!

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