Strange feeling like heavy impact in the head when waking, and at times while clenching teeth.

Dear Ask The Doctor: Not exactly a headache but I don't know where else to ask this. Periodically I will wake up feeling like I got punched in the head. No pain or anything or confusion, I just get the weird kind of zing feeling like getting punched in the head. Also sometimes if I clench my teeth the same thing happens. This has been going on for years. I have been diagnosed with a 'temporal lobe malfunction' that may or may not be related to an arachnoid cyst but my GP doesn't seem to think the cyst is related. Thank you.

Dear Trevor: If the cyst is very small most likely the symptoms that you described are not associated to it. Arachnoid cysts are fluid-filled sacs that develop between the brain or spinal cord and a membrane called: Arachnoid, which is one of the three membranes that cover the brain and spinal cord. The symptoms may vary depending on the size and location of the cyst. If the cyst grows large enough may put pressure on surrounding parts of the brain and may produce: headaches, nausea, vomiting, seizures, behavioural changes, hearing or vision problems, vertigo, balance problems while walking or standing, weakness or paralysis in one side of the body.