The classification of all headaches, including migraines, is organized by the International Headache Society, and published in the International Classification of Headache Disorders (ICHD). The current version, the ICHD-3 beta, was published in 2013.^[1]

The first category within the ICHD is Migraine. Migraines in general are considered to be a neurological syndrome. It is estimated that 11% (303 million) of the global population,^[2][3][4] including 43 million Europeans^[5] and 28 million Americans,^[6] experience migraines.

Organization of migraine subtypes

The ICHD-3 beta classification includes 6 main subtypes of migraine (ICHD-1: 7 main subtypes, ICHD-2: 6 main subtypes), most of which are further subdivided. Overall ICHD-3 beta distinguishes 29 migraine subtypes. The following table outlines the main subtypes and their ICHD-1, -2, -3 beta and ICD-10 codes.

Migraine without aura

Migraine without aura, classified as common migraine, represents a recurrent headache disorder characterized by moderate to severe throbbing pain, typically unilateral, and devoid of preceding visual or sensory disturbances known as auras. This neurological condition, affecting a significant portion of the population, manifests with a range of symptoms, including nausea, vomiting, and heightened sensitivity to light and sound.

The etiology of migraines without aura remains multifactorial, involving genetic predispositions, environmental triggers, and complex neurobiological mechanisms. While the exact pathophysiology is not fully elucidated, a cascade of events involving neurotransmitters, vascular changes, and cortical spreading depression is believed to contribute to the onset of migraine headaches.

Clinical management of migraines without aura encompasses a comprehensive approach, emphasizing both preventive strategies and acute treatments. Lifestyle modifications, such as maintaining a consistent sleep schedule, stress management, and hydration, play a pivotal role in reducing the frequency and intensity of episodes. Additionally, identifying and avoiding individual trigger factors forms an integral part of personalized management plans.

In cases of recurrent or severe migraines, healthcare providers may recommend preventive medications tailored to the patient's specific needs. These medications aim to modulate neurochemical imbalances and minimize the frequency of migraine attacks. Acute treatments, on the other hand, focus on providing relief during active episodes and may include analgesics, anti-nausea medications, and, in some cases, triptans.

Patient engagement in their care is paramount, often involving the maintenance of a headache diary to track triggers, symptom patterns, and treatment efficacy. Collaborative efforts between healthcare professionals and patients facilitate the development of individualized care plans, optimizing outcomes and enhancing the quality of life for those affected by migraines without aura.

If there is a suspicion of migraines without aura, seeking consultation with a healthcare professional is essential for accurate diagnosis, appropriate treatment initiation, and ongoing management. A tailored and holistic approach ensures the effective mitigation of symptoms and empowers individuals to navigate the challenges posed by this chronic neurological condition.^[7]

Migraine with aura

Migraine with aura represents a distinct neurological disorder characterized by recurrent headaches preceded or accompanied by sensory disturbances, commonly referred to as auras. These transient symptoms, typically manifesting as visual abnormalities like flashing lights or zigzag lines, serve as distinctive precursors to the ensuing headache. Other sensory experiences, including tingling, numbness, difficulty speaking, or temporary alterations in hearing or smell, may also occur during the aura phase.

The pathophysiology of migraines with aura is multifaceted, involving a complex interplay of genetic predispositions, environmental influences, and intricate neurobiological mechanisms. While the precise etiology remains elusive, the condition significantly impacts affected individuals, necessitating a comprehensive and tailored approach to its management.

Clinical management strategies for migraines with aura encompass both preventive measures and acute treatments. Lifestyle modifications, such as adherence to regular sleep patterns, effective stress management, and identification of trigger factors, constitute integral components of a holistic therapeutic approach. Preventive medications may be prescribed for those experiencing recurrent or severe episodes, while acute treatments, often involving analgesics and specific migraine medications like triptans, aim to alleviate symptoms during active migraine episodes.

Collaboration between healthcare professionals and individuals affected by migraines with aura is imperative for the development of personalized treatment plans. Maintaining a meticulous migraine diary facilitates the tracking of symptom patterns, identification of triggers, and evaluation of intervention efficacy. Early recognition of prodromal symptoms further enables timely and targeted interventions, potentially mitigating the severity of ensuing headaches.

Migraine with brainstem aura

Migraine with brainstem aura (abbreviated MBA) (previously used terms: basilar artery migraine; basilar migraine; basilar-type migraine) is a subtype of migraine with aura in which symptoms clearly originate from the brainstem, but no motor weakness. When motor symptoms are present, the subtype is coded as 1.2.3 Hemiplegic migraine. Originally the terms basilar artery migraine or basilar migraine were used but, since involvement of the basilar artery is unlikely, the term migraine with brainstem aura is preferred in ICHD-3 beta. There are typical aura symptoms in addition to the brainstem symptoms during most attacks. Many patients who have attacks with brainstem aura also report other attacks with typical aura and should be coded for both 1.2.1 Migraine with typical aura and 1.2.2 Migraine with brainstem aura. Many of the symptoms like dysarthria, vertigo, tinnitus, hypacusis, diplopia, ataxia and decreased level of consciousness may occur with anxiety and hyperventilation, and therefore are subject to misinterpretation. Serious episodes of migraine with brainstem aura can lead to stroke, coma, and death. Using triptans and other vasoconstrictors as abortive treatments for migraine with brainstem aura is contraindicated. Abortive treatments for migraine with brainstem aura address vasodilation and restoration of normal blood flow to the vertebrobasilar territory to restore normal brainstem function.

Familial and sporadic hemiplegic migraine

Familial hemiplegic migraine (FHM) is migraine with a possible polygenetic cause—in fact, FHM can only be diagnosed when at least one close relative has it too.^[7] The patient experiences typical migraine with aura headache either preceded or accompanied with one-sided, reversible limb weakness and/or sensory difficulties and/or speech difficulties. FHM is associated with ion channel mutations.

There also exists the "sporadic hemiplegic migraine" (SHM), which is the same as FHM but with no close family members showing the symptoms.

Effecting a differential diagnosis between basilar migraine and hemiplegic migraine is difficult. Often, the decisive symptom is either motor weakness or unilateral paralysis, which occur in FHM and SHM. Basilar migraine can present tingling and numbness, but true motor weakness and paralysis occur only in hemiplegic migraine.

Menstrual migraines

It is well documented that migraine occurs nearly three times as often in women than in men,^[6][7] and is one of the top five most common disabling conditions in women.^[2][10] In over half these women, their headaches are strictly related to their menstrual cycle.^[7]

A clinical epidemiological study of women with migraine without aura in Parma and Pavia, Italy, revealed that 60% of those women experienced their attacks almost exclusively while menstruating, that 10.7% of their migraines first began at menarche (their very first "period", at puberty), and that 67% of them no longer had migraines while pregnant (and thus not menstruating).^[11]

This relationship was noted by the IHS in both versions of the ICHD, and particularly that this disorder fell under "migraine without aura". The ICHD-1 referred to this as menstrual migraine, noting that there were no strict guidelines for this diagnosis, but that at least 90% of a woman's attacks should occur within two days of the beginning or end of menstruation. When the ICHD-2 was published, explicit guidelines for a diagnosis of two distinct types of menstruation-related migraine were released, and appear to the right. However, because the nature of the relationship is still unclear, and because the IHS was still uncertain as to whether these were a subset of migraine without aura or a distinct class of migraine, the criteria were delegated to an appendix, while anticipating that they would appear within the main text in the next revision.^[7]

The ICHD-2 specifies two different forms of the previously dubbed "menstrual migraine": pure menstrual migraine without aura and menstrually-related migraine without aura. The sole difference between these diagnoses is the occurrence of headache attacks outside of the 5-day period described in the diagnostic criteria. If a woman experiences no attacks outside of this 5-day period, she may be diagnosed with pure menstrual migraine with aura; if she does experience other attacks, however, she may develop menstrually-related migraine without aura. This distinction is made solely for treatment purposes; a woman who only experiences migraines in that 5-day period is likely to benefit more from hormone therapy than a traditional migraine medication such as a triptan.^[7]

One defining characteristic of these menstrual migraines is that the woman does not experience an aura. Clinical research has shown migraine with aura to be unrelated to the menstrual cycle, and, in women who have headaches sometimes with aura and sometimes without, the presence or absence of aura does not appear to be related to the menstrual cycle.^[7]

As well as being split into two classes, menstrual migraines may have two different pathophysiologies, based on whether or not a woman is taking any oral contraceptives or another form of cyclical hormone replacement therapy. When these medications are being used, the regular hormonal changes that take place and result in ovulation and other events in the menstrual cycle are suppressed, and menstruation is instead the result of withdrawal from abnormal progestogen concentrations.^[7]

Menstrual migraines may also be linked to oestrogen withdrawal. Under the category of headache attributed to a substance or its withdrawal, the ICHD specifies the diagnostic criteria for oestrogen-withdrawal headache (8.4.3, G44.83 and Y42.4), and suggests that both that diagnosis and one of the menstrual migraine diagnoses be used in case of migraines related to oestrogen withdrawal occurring mainly at menstruation.^[7]

Abdominal migraine

Abdominal migraine is a recurrent disorder of unknown origin, principally affecting children. Sometimes early on, it can be misdiagnosed in an ER setting as appendicitis. Episodes feature nausea, vomiting, and moderate-to-severe central, abdominal pain. The child is well between episodes. The International Classification of Headache Disorders definition is:

Diagnostic criteria:

A. At least 5 attacks fulfilling criteria B-D.

B. Attacks of abdominal pain lasting 1-72 hours (untreated or unsuccessfully treated)

C. Abdominal pain has all of the following characteristics:

1. midline location, periumbilical or poorly localized

2. dull or "just sore" quality

3. moderate or severe intensity

D. During abdominal pain at least 2 of the following:

1. anorexia

2. nausea

3. vomiting

4. pallor

E. Not attributed to another disorder

— International Classification of Headache Disorders^[7]

Most children with abdominal migraines will develop migraine headache in adult life; the two propensities might co-exist during the child's adolescence.

Treating an abdominal migraine can often be difficult;^[12] medications used to treat other forms of migraines are usually employed.^[13] These include Elavil,^[14] Wellbutrin SR,^[15] and Topamax.^[16]

In some cases, the abdominal migraine is a symptom linked to cyclic vomiting syndrome (CVS).^[17] There may be a history of migraines in the family of the patient.^[18]

Retinal migraine

Retinal migraines are a subclass of optical migraines. Those affected will experience a scotoma—a patch of vision loss in one eye surrounded by normal vision—for less than one hour before vision returns to normal. Retinal migraines may be accompanied by a throbbing unilateral headache, nausea, or photophobia.

Not classified in the ICHD-2 under migraine

Acephalgic migraine

Acephalgic migraine is a neurological syndrome. It is a variant of migraine in which the patient may experience aura symptoms such as scintillating scotoma, nausea, photophobia, hemiparesis and other migraine symptoms but does not experience headache. Acephalgic migraine is also referred to as amigrainous migraine, ocular migraine, ophthalmic migraine or optical migraine, the last three of which are misnomers.

People with acephalgic migraine are more likely than the general population to develop classical migraine with headache.

The prevention and treatment of acephalgic migraine is broadly the same as for classical migraine. However, because of the absence of "headache", diagnosis of acephalic migraine is apt to be significantly delayed and the risk of misdiagnosis significantly increased.

Visual snow might be a form of acephalgic migraine.^{[citation needed]}

If symptoms are primarily visual, it may be necessary to consult an optometrist or ophthalmologist to rule out potential eye disease before considering this diagnosis.