Primary headache disorders are entities unto themselves and are diagnosed by their symptoms. Secondary headache disorders are due to an underlying condition and are classified by their causes. The two most common primary headache disorders are migraine and tension-type headache. There are multiple other primary headache disorders which are relatively uncommon, and include entities such as cluster headache, trigeminal autonomic cephalalgias, hypnic headache, and hemicranias continua. The single most important thing is to identify the symptoms correctly, including the quality, intensity, frequency, and accompanying signs of the headache complaint. This is most effectively identified by the history given by the patient during the initial visit, thus it is crucial that these things are clearly defined during that appointment. Each disorder may have effective treatments that differ from the others, thus the management is significantly influenced by a correct diagnosis. Due to the interaction and convergence that occurs in the head and neck nervous system the pain patterns may overlap with other entities such as TMD, as well as present concurrently with each other. Treatment is directed at any and all conditions diagnosed thus multi-disciplinary approaches are the most effective involving orofacial pain specialists, neurologists, primary care doctors, pain management doctors, physical therapists, and other medical specialties as required.
Migraine is a complex neurobiological disorder that has been recognized since ancient times. It is not uncommon, and now we understand that the primary driving brain sensitivity is inherited. People who suffer from migraine have different neurobiological response to various stimuli that act as triggers. These can range from light, to types of food, lack of sleep, and stressors. We used to think that migraine was a vascular disorder, but research has not supported that, and now we understand it more clearly as a neurovascular disorder of the brain, involving responses across several aspects that include blood vessels, nerves, and soft tissues in the head and neck. The pain is most commonly in the frontal and ocular aspects of the head, but due to the fact that the trigeminal nerve is intimately related in migraine pathways, and the same nerve serves most of the head and neck in various ways. Migraine is a primary brain disorder most likely involving in an ion channel in the brain stem nuclei, a form of neurovascular headache in which neural events result in dilation of blood vessels aggravating the pain and resulting in further nerve activation. It involves dysfunction of brain-stem pathways that normally modulates sensory input. The key pathway for the pain is the trigeminovascular input from the meningeal vessels.
The two common variants of migraine are with and without aura. The aura is a sensory event that precedes the painful part of the headache sequence. It typically involves visual changes such as wavy lines, but can be other things such as altered speech. The core features of migraine are headache, which is usually throbbing and often unilateral, severe in intensity, and associated features of nausea, sensitivity to light, sound, and exacerbation with head movement. However many patients may not suffer from all these entities, which can sometimes lead to a delay in a proper diagnosis. The headache phase can last from 4-72 hours, and can occur from once in a lifetime to daily.
Tension-type headache is the most common headache pain, and most people will experience one in their lifetime. It is most commonly bilateral, non-pulsating but a pressing/tightening quality, mild-moderate in intensity, no nausea, not aggravated by movement, but light or sound sensitivity may occur. There is an episodic form that occurs infrequently, and a chronic form that occurs frequently (more than 15 days per month). Some patients with a chronic form may, over time, develop some nausea with the headache, but typically this is not associated with the disorder.
The cause of tension-type headache is not completely understood, but it is clear that it involves sensitivity of the peripheral and central nervous system involving the trigeminal nerve distribution. It classically involves the temple region of the head, but can involve the cervical region as well as the frontal/ocular region. It does seem to occur in patients with TMD signs and symptoms, and treatment of TMD has demonstrated improvement in pain levels for patients with tension-type headache. This is likely due to the interaction between the muscles of the jaw and neck with the trigeminal nerve. We cannot definitely link that TMD causes tension-type headache or vice versa. Both demonstrate lowered pain thresholds and increased sensitivity to pain-producing stimuli. As with TMD, a multidisciplinary approach to treatment is often the most effective in eliminating and managing symptoms.