A CAT scan because of a headache...really? An aneurysm....really? I'm no doctor, I guess it could be tumor or something, maybe an aneurysm. However, sometimes a lifter doesn't breathe correctly, or sometimes they might 'drive' their head back while lifting. I see guys pushing off the leg-press with their heads all the time. The combination can create one hell of a headache! It does usually occur while working high rep. stuff, but I've seen and done it myself a time or two going heavy. Of course how much harm could a CAT scan do?