Definition of Terms

Accompanying symptoms: Symptoms that typically accompany rather than precede or follow headache. In migraine, for example, the most frequent are nausea, vomiting, photophobia and phonophobia; osmophobia, diarrhoea and other symptoms occur more rarely.

Anorexia: Lack of appetite and dislike for food to a mild degree.

Attack of headache (or pain): Headache (or pain) that builds up, remains at a certain level for minutes to 72 hours, then wanes until it is gone completely.

Aura: Early symptoms of an attack of migraine with aura, being the manifestations of focal cerebral dysfunction. The aura typically lasts 20-30 minutes and precedes the headache. See also: Focal symptoms, Prodrome, Premonitory symptoms, Warning symptoms and Neurological symptoms.

Central neuropathic pain: Pain (qv) caused by a lesion or disease of the central somatosensory nervous system (see also Neuropathic pain).

Chronic: In pain terminology, chronic denotes persistence over a period longer than three months. In headache terminology, it retains this meaning for secondary headache disorders. For primary headache disorders that are more usually episodic (qv), chronic is used whenever attacks of headache (qv) occur on more days than not over a period longer than three months. The trigeminal autonomic cephalalgias are the exception: in these disorders, chronic is not used until the disorder has been unremitting for more than one year.

Close temporal relation: This term is used to describe the relation between an organic disorder and headache. Specific temporal relations may be known for disorders of acute onset where causation is likely, but have often not been studied sufficiently. For chronic disorders the temporal relation as well as causation are often very difficult to ascertain.

Cluster headache attack: One episode of continuous pain lasting 15-180 minutes.

Cluster period: The time during which cluster headache attacks occur regularly and at least once every other day.

Cluster remission period: The time during which attacks cease to occur spontaneously and cannot be induced with alcohol or nitroglycerine. To be considered a remission, the attack-free period must exceed one month.

Duration of attack: Time from onset until termination of an attack of headache (or pain) (qv) meeting criteria for a particular headache type or subtype. After migraine or cluster headache, a low-grade non-pulsating headache without accompanying symptoms may persist, but this is not part of the attack and is not included in duration. If the patient falls asleep during an attack and wakes up relieved, duration is until time of awakening. If an attack of migraine is successfully relieved by medication but symptoms recur within 48 hours, these may represent a relapse of the same attack or a new attack. Judgement is required to make the distinction (see also Frequency of attacks).

Episodic: Recurring and remitting in a regular or irregular pattern of attacks of headache (or pain) (qv) of constant or variable duration. Through long usage the term has acquired special meaning in the context of episodic cluster headache, referring to the occurrence of cluster periods separated by cluster remission periods (qv) rather than to attacks. Similar usage has been adopted in paroxysmal hemicrania.

Facial pain: Pain below the orbitomeatal line, above the neck and anterior to the pinnae.

Focal symptoms: Symptoms of focal brain (usually cerebral) disturbance such as occur in migraine aura.

Fortification spectrum: Angulated, arcuate and gradually enlarging visual hallucination typical of migrainous visual aura.

Frequency of attacks: The rate of occurrence of attacks of headache (or pain) (qv) per time period (commonly one month). Successful relief of a migraine attack with medication may be followed by relapse within 48 hours. The IHS Guidelines for Controlled Trials of Drugs in Migraine, 2nd edition, recommended as a practical solution, especially in differentiating attacks recorded as diary entries over the previous month, to count as distinct attacks only those that are separated by an entire day headache-free.

Headache: Pain located above the orbitomeatal line.
Headache days: Number of days during an observed period of time (commonly one month) affected by headache for any part or the whole of the day.

Heterophoria: Latent strabismus.

Heterotropia: Manifest strabismus.

Intensity of pain: Degree of pain usually expressed in terms of its functional consequence and scored on a verbal four-point scale: 0, no pain; 1, mild pain, does not interfere with usual activities; 2, moderate pain, inhibits but does not wholly prevent usual activities; 3, severe pain, prevents all activities. It may also be expressed on a visual analogue scale.
Lancinating: Brief, electric, shock-like along a root or nerve.

Neuralgia: Pain in the distribution of a nerve or nerves. (Common usage, especially in Europe, often implies a paroxysmal or lancinating (qv) quality, but the term neuralgia should not be reserved for paroxysmal pains.)

Neuritis: A special case of neuropathy (qv); the term is now reserved for inflammatory processes affecting nerves.

Neuroimaging: CT, MRI, PET, SPECT or scintigraphy of the brain.

Neuropathic pain: Pain (qv) caused by a lesion or disease of the somatosensory nervous system.

Neuropathy: A disturbance of function or pathological change in a nerve or nerves (in one nerve: mononeuropathy; in several nerves: mononeuropathy multiplex; when diffuse and bilateral: polyneuropathy). The term neuropathy is not intended to cover neurapraxia, neurotmesis, section of a nerve, disturbances of a nerve due to transient impact such as a blow, stretching or epileptic discharge (the term neurogenic applies to pain attributed to such temporary perturbations).

New headache: Any type, subtype or subform of headache from which the patient was not previously suffering.

Not sufficiently validated: Of doubtful validity as a diagnostic entity judged from the experience of the subcommittee and/or controversy in the literature.
Nuchal region: Dorsal (posterior) aspect of upper neck including the region of insertion of neck muscles on the cranium.

Pain: An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage (see also: Neuropathic pain, Central neuropathic pain and Peripheral neuropathic pain).

Pericranial muscles: Neck muscles, muscles of mastication, facial muscles of expression and speech and muscles of the inner ear (tensor tympani, stapedius).

Peripheral neuropathic pain: Pain (qv) caused by a lesion or disease of the peripheral somatosensory nervous system (see also Neuropathic pain).

Phonophobia: Hypersensitivity to sound, usually causing avoidance.

Photophobia: Hypersensitivity to light, usually causing avoidance.

Premonitory symptoms: Symptoms preceding and forewarning of a migraine attack by 2-48 hours, occurring before the aura in migraine with aura and before the onset of pain in migraine without aura. Among the common premonitory symptoms are: fatigue, elation, depression, unusual hunger, craving for certain foods.

Pressing/tightening: Pain of a constant quality often compared to an iron band around the head.

Pressure algometer: Device to measure the detection threshold or tolerance threshold of pressure-induced pain.

Previously used term: A diagnostic term that has been used previously with a similar or identical meaning to the classified term or is subsumed within it. Previously used terms are often ambiguous and/or have been used differently in different countries.

Prodrome: This term has been used with different meanings, most often synonymously with premonitory symptoms. It should be avoided in the future.

Pulsating: Varying with the heart beat; throbbing.

Referred pain: Pain perceived in another area than the one where nociception arises.

Refraction error: Myopia, hypermetropia or astigmatism.

Scintillation: Visual hallucinations that are bright and fluctuate in intensity, often at approximately 8-10 cycles/second. They are typical of migraine aura.

Scotoma: Loss of part(s) of the visual field of one or both eyes. Scotoma may be absolute (no vision) or relative (obscured or reduced vision).

Stab of pain: Sudden pain lasting a minute or less (usually a second or less).

Substance: Organic or inorganic chemical, food or additive, alcoholic beverage, gas or vapour, drug or medication, herbal, animal or other substance given with medicinal intent although not licensed as medicinal products, etc.

Teichopsia: Synonym for fortification spectrum (qv).

Tenderness: A feeling of discomfort or pain caused by pressure that would not normally be sufficient to cause such sensations.

Throbbing: Synonym for pulsating (qv).

Unilateral: On either the right or the left side, not crossing the mid line. Unilateral headache does not necessarily involve all of the right or left side of the head, but may be frontal, temporal or occipital only. When used for sensory or motor disturbances of migraine aura it includes complete or partial hemidistribution.

Vasospasm: Constriction of artery or arterioles to such a degree that tissue perfusion is reduced.

Warning symptoms: Previously used term for either aura or premonitory symptoms and therefore ambiguous. It should not be used.

Zigzag line: Synonym for fortification spectrum.