Jeffrey P. Okeson
The complaint of headache is very commonly reported in the general population and is also a challenge in the differential diagnosis of orofacial pains (see chapter 17). Some individuals are only occasionally troubled by headaches, while others are regularly debilitated. It is very rare to find an individual who has never had a headache. Headache means different things to different people. Many people think of headache as pain felt in the temple or forehead. Others report headache in the back of their head. On occasion, a patient will report pain in the midfacial area. When this location is reported, the patient will often relate the headache to the structure where the pain is felt, such as the sinus, the jaw, or even a tooth. In this instance, the patient will often report to the dental practitioner for assistance. It is therefore important for the dentist to understand and appreciate the most common types of headaches that are encountered in practice. Failure to recognize these types of headaches may lead to a misdiagnosis and misdirected treatment (see also chapters 17 and 20).
Most headaches are expressed as a heterotopic pain, meaning that the location of the pain felt by the patient is not the actual origin of the nociceptive input producing the pain. Therefore, when the patient is examined, the location of the headache fails to reveal any reason for the pain. In order for the headache to be successfully managed, therapy needs to be directed to the origin of the pain, which may be elusive and often arises from central mechanisms. This concept is quite different from the typical dental pains that clinicians treat (see chapter 20).
The understanding of headache classification for differential diagnosis is very complicated. The classification from the leading organization in the field, the International Headache Society (IHS), describes more than 230 types and subtypes of headaches.1 The IHS classification attempts to separate all headaches according to etiology and involved structures. Within this classification (Box 25-1), the four primary headache types plus two of the secondary types (see nos. 11 and 13 of Box 25-1 for those dealing with facial and intraoral pain conditions) are more relevant in the differential diagnosis. The clinician also needs to consider that there are many overlapping symptoms between temporomandibular disorders (TMDs) and orofacial pain, making differential diagnosis even more difficult.3 Therefore, this chapter will review some of the more common headaches that may be felt in the masticatory structures but are not associated with TMDs: migraine, tension-type headache, temporal arteritis, and headache attributed to head and neck trauma. For a more thorough review of all headaches, the reader is encouraged to refer to texts specifically addressing headaches.4,5
|Box 25-1 Categories of headache2|
|Part one: The primary headaches|
|1.1 Migraine without aura|
|1.2 Migraine with aura|
|2. Tension-type headache|
|3. Cluster headache and other trigeminal autonomic cephalalgias|
|4. Other primary headaches|
|Part two: The secondary headaches|
|5. Headache attributed to head and/or neck trauma|
|6. Headache attributed to cranial or cervical vascular disorder|
|7. Headache attributed to nonvascular intracranial disorder|
|8. Headache attributed to a substance or its withdrawal|
|9. Headache attributed to infection|
|10. Headache attributed to disorder of homoeostasis|
|11. Headache or facial pain attributed to disorder of cranium, neck, eyes, ears, nose, sinuses, teeth, mouth or other facial or cranial structures|
|12. Headache attributed to psychiatric disorder|
|Part three: Cranial neuralgia, central and primary facial pain, and other headaches|
|13. Cranial neuralgias, central causes of facial pain|
|14. Other headaches, cranial neuralgias, central and primary facial pain|
Migraine is characterized by throbbing, often debilitating pain of moderate to severe intensity (Table 25-1). The headache is unilateral 60% of the time; it is often reported in the temple or behind the eye. Migraine can be felt in the maxillary arch, a condition referred to as midface migraine. This can be a diagnostic problem for the dental clinician because the pain can be felt in the teeth. The patient will often report photophobia, phonophobia, and osmophobia, and will seek a dark, quiet room. The pain is aggravated by routine physical activity and sometimes even by simple head movements.
Migraine affects approximately 16% of the population, with women affected more than men at a ratio of 3:1; about 25% of the female population is affected during their lifetime.6 Migraine most often appears in the first 3 decades of life. When the onset is in the teenage years, it is important for the clinician to recognize this condition so that it is not mistreated. The pain episodes may occur at any time of day or night but are most frequent on arising in the morning. The pain episode commonly lasts 4 to 72 hours in adults and 2 to 4 hours in children.7 The pain can vary greatly from mild to very intense.8 Scalp tenderness occurs in two-thirds of patients during or after the headache.
Some migraine patients report a complex of focal neurologic symptoms that immediately precedes the headache.8 This aura usually develops in 5 to 20 minutes and lasts less than 1 hour. The IHS has 2 designations for migraine: migraine with aura and migraine without aura. The former is sometimes referred to as classic migraine, the latter as common migraine. When present, the aura is commonly characterized by visual, sensory, or motor phenomena, and may even include language and brain stem disturbances. The visual symptoms are the most common symptoms and are characterized by sensations of unformed flashes of light before the eyes (photopsia), the partial loss of sight (scotoma), or a zigzag, flashing colored phenomenon that migrates across the visual field (teichopsia). Sensory symptoms such as paresthesia can occur.9
Studies suggest that migraine patients have a genetic susceptibility to this pain condition: 50% to 60% of migraine patients have parents who also experience migraines.10 Migraine is considered a neurovascular phenomenon since both neural and vascular structures are involved in its pathophysiology. The neural innervation of the intracranial vessels is called the trigeminovascular system, and current evidence suggests that there is a neurologic trigger in the brain stem that initiates a cascade of events resulting in neurogenic inflammation of the intracranial vessels that produces the headache.