I have several of them also. The worst is sitting on top of spine where my skull meets. Yes they are rare however common with the rare disease Adhesive arachnoidites. You should be checked for that. It's hard to be diagnosed though because radiologist aren't that familiar with it. The radiologist who did my MRI noticed right away my thecal sac had indentation and was full of nerves that were rooted. He looked it up and that is how they figured out what I had going on. I had previously had my 4th back procedure ( radio frequency nerve denervation) where they go in and burn the nerves for pain relief. The last denervation I had. I knew something terrible had happened during the procedure. I felt a sharp pain and my right leg went intoa convolution . It was so scary when I asked what was going on my surge said . It's okay! It's just letting me know im in the wrong area!! Well he had "accidentally "punctured my dura sack causing a SCFL. He decided to not tell me. I had problems from the moment it happened. Instant foot drop, horrid nerve pain shooting up my legs it felt like I was being electrocuted . My back would burn off and on like someone had just thrown a bucket of acid on me. I had the worst migraine ever. I ended up going to the ER that night. They didn't bother to do an MRI to see if I had a spinal cord leak. They should have as I just had a back procedure next to my spine Earlier that day. I guess what hurts the most is they could if given me a blood patch and it would of reversed the non curable disease I had no idea at the time I was just given. It took 9 months for me to be diagnosed with Adhesive and. My Dr. Thought I had really bad Neuropathy and started treating me for that. I lasted 9 months, then I told him one day, I can't live like this anymore. I'm done! He said let's go do an MRI and see if anything is going on. So prior to all my back procedures I HAD to get an MRI done my insurance wouldn't cover my procedures until I had one done prior. I never had Adhesive Arachnoidites in any of the past MRIs and definitely not present the one I had done the day before I had my 4th nerve denervation. The MRI showed something was definitely wrong the radiologist just had to figure out exactly what it was. And it wasn't super easy to figure out as Adhesive arachnoidites is a rare disease. But I'm grateful he did. It was just to late to reverse it. You have to get a Blood patch within 24 hours of injury. There are only a few ways people can get this disease. A misplaced epidural during child birth or any surgery or procedure done on the back,if you ever had spinal meningitis, and if you had an MRI done before 1989 back then they used an oil die that has since been linked to Adhesive arachnoidites. Since having AA as we call it. I have developed several Tarlov cysts the one sitting at the top of my spine where my skull meets is the worst. My nuero spinal surgeon said the best way to explain it to me was its like having an aneurysm but instead of the sack being full of blood it's full of spinal cord fluid. I have horribly migraines and I take imatrax ( migraine meds) daily. When there really bad I have to go to the ER. They have checked on that specific Tarlov cyst during a migraine and everytime its leaking. My nurse surgeon said I just have to live with it. I'm in a Adhesive arachnoidites group and pretty much everyone else with this disease has Tarlov cysts too so we firmly believe this rare disease comes with Tarlov cysts also. There is nothing they do for them. They just leave them alone.. my disease is listed as one of the most painful diseases there is it's right there next to stage 4 bone cancer so I am on Morphine 24-7 also roxycodone rapid release and then 3 different nerve blockers. I'm still in alot of pain but mostly lumbar ( back pain) and thoratic. So I couldn't tell you really if they cause additional pain. I also have a couple on my spine. But no my neuro spinal surgeon said they leave them alone. And that's pretty much what everyone in my AA groups say also. Mine have definitely been confirmed. I will look back in my mychart and send you my diagnosis on them and you can see what it says.