Is Brain Scan Necessary To Diagnose Severe Headaches?

my partner gets really bad severe headaches that start as a tooth ache then travels to the head neck down the right side of his body his vein throbs really bad on his right side of his head hes takjing all the precriptions drugs you can think of and it doesnt seem to relieve it. a doctor has asked to do a brain scan is this procedure nessessary???