ABSTRACT
The International Headache Society (IHS) has classified the secondary headaches into eight distinct categories based upon their causes (Figure 2.1). Secondary headaches can often have the same characteristics as primary headache disorders such as migraine and tension-type headache. Some of the secondary headaches can have serious and at times life-threatening causes. Fortunately, the vast majority of headache complaints are due to primary headache disorders such as migraine or tensiontype headache. Many different diseases may present with the symptom of headache, and physicians must determine which cases need to be investigated further for possible secondary causes.
