The prevalence of having any type of headache is 90%. A 1-year prevalence is 12% for migraine and 38% for tension type headache. Migraine is the third most prevalent disorder worldwide. Approximately 90% of headaches in patients with a normal neurologic examination are primary (such as migraine, tension type, and cluster). The remaining 10% are due to numerous secondary causes.
Actually our brain itself is not pain sensitive. The following are sensitive to pain: cranial nerves, the circle of Willis, meningeal arteries, large veins in the brain and dura, and structures external to the skull (including scalp and neck muscles, cutaneous nerves and skin, the mucosa of paranasal sinuses, external auditory canal and tympanic membrane, orbital structures and eyeballs, salivary glands, teeth, temporomandibular joints, cervical nerves and roots, and the external carotid arteries and branches).
A detailed headache history is essential for establishing the diagnosis. Most patients do not need neuroimaging. Again, 90% of patients have primary headaches with a diagnosis made by a detailed history and normal neurologic examination.
1. The “first or worst” headache
2. Subacute headaches with increasing frequency or severity
3. A progressive or new daily persistent headache, chronic headache
4. Headaches always on the same side
5. If the characteristic of your headache is changed
6. Headaches associated with fever, stiff neck, nausea, and vomiting
7. Headaches associated with focal neurologic symptoms or signs
8. Headaches cooccurring with seizures, a history of cancer or immunosuppression pregnancy or the postpartum period
9. New-onset headache in those over 50 years of age
10. Headaches triggered by cough, exertion, or Valsalva maneuver
11. Headaches not responding to treatment
In this circumstances you need to see a doctor and need neuroimaging
When available, MRI is the preferred study for the evaluation for headaches. CT is preferable in acute situations such as head trauma, subarachnoid hemorrhage, as well as in patients with contraindications to MRI.