A related discussion, cyst right temporal lobe was started.
Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with your doctor.
Without the ability to examine you and obtain a history, I can not tell you what the exact cause of your symptoms is. However I will try to provide you with some useful information.
I am not sure what is meant exactly by cyst; there are several different types of cyst that occur in the brain. However, based on the fact that you were told this cyst has likely been present since birth, the most common possibility is that it is an arachnoid cyst, so I will provide you with some information about that. Arachnoid cysts are sacs filled with cerebropsinal fluid (CSF) which is the fluid that normally bathes the brain and spine. This fluid is normally located in the part of the brain called the subarachnoid space.
Most commonly, these are primary arachnoid cysts, cysts that are present from birth and result from a minor developmental problem that occurred while the brain was developing. Secondary arachnoid cysts are those that develop secondary to trauma, infection, or after brain surgery. It is not always possible to tell if the cyst you have is primary or secondary. If the cyst is only 4 mm it would be highly unlikely to be causing neck or head pain or any other symptoms, but this would really depend on its exact location and whether or not it is present on nerves or the brain or other structures.
If an arachnoid cyst is deemed to be causing symptoms or is pressing on surrounding structures (which would most often be evident on your MRI), surgical opening (fenestration) of the cyst and other surgical interventions could be done to correct it, but this is rarely necessary because the vast majority of arachnoid cysts are benign, do not grow, and do not cause symptoms. Sometimes, re-imaging to take another look at it after a few months or years may be indicated. It is a good idea for you to ask your physicians about more information about the cyst, what the implications of having it is, so you can have a good understanding of it; continued followup with your neurologist is recommended.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.