Migraine is a heterogeneous disorder: attacks vary in pain intensity, duration, pattern of associated features, and frequency of occurrence. Some migraineurs have recurrent attacks without remission periods; others experience symptom-free intervals lasting several years; a third group becomes free of attacks for the rest of their life [47
Migraine is the second most common cause of chronic recurrent headache in school children. The prevalence ranges from 3.2 to 14.5% [4
]. Positive family history for headache is commonly reported with a frequency of 60–77.5% [4
Over the last five decades, several definitions of paediatric migraine have been proposed. Vahlquist [50
], followed by Bille [1
], Prensky and Sommer [51
] have been followed by IHS proposing a new set of criteria [52
]. Revising the IHS headache duration criterion, i.e. decreasing minimum headache duration from 2 to 1 h, the utility of the IHS criteria for migraine performed 47–86.6% sensitivity and 92.4–98.6% specificity [53
]. The currently accepted classification system for migraine was published by the International Headache Society in 2004 and is known as the International Classification of Headache Disorders (ICHD-II) [57
Modification of ICHD-II criteria to include bilateral headache, headache duration of 1–72 h, and nausea and/or vomiting plus two of five other associated symptoms (photophobia, phonophobia, difficulty thinking, light-headedness, or fatigue), in addition to the usual description of moderate to severe pain of a throbbing or pulsating nature worsening or limiting physical activity, improved sensitivity of migraine diagnosis to 84.4% [47
] demonstrated that the ICHD-II criteria are poorly applicable to children under the age of 6 years. Therefore, the development of alternative criteria might be useful [59
]. Further changes in ICHD-II criteria for paediatric migraine could stem from researches comparing the occurrence of headache in the family members and the prevalence of osmophobia in large samples of migraine and TTH patients. Both osmophobia and positive family history could thus become useful in better differentiating migraine and TTH. The prevalence of osmophobia during migraine attacks was 18.5%, and was higher in migraine patients (25.1%) than in those with TTH (8.3%). Osmophobia showed more specificity than phonophobia or photophobia in the differential diagnosis between migraine and TTH [25
Most migraine symptoms included in ICHD-II are not specific for the paediatric age groups. Among various migraine characteristics and associated disorders only type of migraine, migraine frequency, vomiting and dizziness were related to age [62
]. Vomiting may help the diagnosis of migraine in young children with a familial history of migraine and dizziness is more common in children >11 years old and may aid the diagnostic process in this age group [62
A bidirectional relationship between migraine and depression suggests a neurobiological link. Adverse experiences particularly childhood maltreatment, may alter neurobiological systems, and predispose to a multiplicity of adult chronic disorders. The majority of the studies with clinical populations show slightly higher scores on at least one of the anxiety or depression scales in the migraine group as compared to the control group. However, in all eleven studies, the average score on the anxiety and depression scales obtained by children with migraine did not reach a pathological level, according to the norms established by the validated scales. Findings point to above average levels of anxiety or depression, rather than diagnosed psychopathologies. Therefore, certain authors use the term “sub-clinical”. None of the three studies carried out in the general population revealed differences between the anxiety and depression scores in children with migraine as opposed to children in the control group. The difference in results from studies in the general population and clinical populations can most likely be explained by a recruitment bias. Studies conducted with clinical populations recruit subjects from specialised medical consultations for children and adolescents with migraine, who are probably not representative of the general population. These results contradict those found in the adult population. More studies are needed to better clarify the links between anxiety, depression, and migraine in children, adolescents and adults. The association of childhood sexual abuse with migraine and depression is amplified if abuse also occurs at a later age [20
To ensure the validity of future studies, the following remarks should be taken into account.
- The distinction between headache and migraine is not always clear, even when ICHD criteria are used.
- The children considered to have migraines often have a variety of diagnoses.
- Studies should only use the ICHD second edition criteria.
- Children suffering from migraine are usually recruited from specialised headache centres in hospitals. This is a very specific population and probably not representative of children with migraine in the general population.
- In contrast, studies including patients from specialised centres are relevant too, since they are reflecting the situation in those patients actually seen by physicians.
Familial hemiplegic migraine (FHM)
FHM is an uncommon and genetically heterogeneous autosomal dominant subtype of migraine with aura in which the aura consists of hemiparesis. Three subtypes of FHM have been described: FHM1, FHM2 and FHM3. Mutations in the genes CACNA1A12 and SCNA1A13, encoding the pore-forming alpha-1 subunits of the neuronal voltage-gated Ca2+
channels and Na+
channels, are responsible for FHM1 and FHM3, respectively. Mutations in ATP1A2,14 encoding the alpha-2 subunit of the Na+
ATPase, are responsible for FHM2. The gene mutations for FHM are associated with phenotypes that show an overlap between migraine and other paroxysmal disorders [i.e. CACNA1A and episodic ataxia; SCNA1A and generalised epilepsy with febrile seizures plus (GEFS+)]. These findings provide compelling evidence for ion channels as key targets for preventive migraine treatment [66
Basilar-type migraine is a migraine variant that is classified as part of the spectrum of migraine with aura in the ICHD-II classification. The diagnostic criteria comprise vertigo, visual disturbances in both hemifields, bilateral sensory symptoms and ataxia. The sudden appearance of diplopia, vertigo and vomiting must prompt consideration of disorders within the posterior fossa such as arteriovenous malformations, cavernous angiomas, tumours or congenital malformations [70
Ophthalmoplegic migraine (OM) is one of the most clinically challenging migraine variants and, fortunately, one of the least common (annual incidence of 0.7 per million). It has been classified by the Headache Classification Committee of the International Headache Society (IHS) in 2004 under the heading of ‘Cranial neuralgias and central causes of facial pain’ [11
]. OM is defined as consisting of at least two episodes of headache accompanied or followed within 4 days of its onset by paresis of one or more of the third, fourth and/or sixth cranial nerves, with investigations having ruled out parasellar, orbital fissure and posterior fossa lesions. Contrast-enhanced magnetic resonance imaging performed during symptomatic and postsymptomatic periods in patients with ophthalmoplegic migraine may hold great value in identifying the pathophysiological features of oculomotor nerve palsies. Of cases demonstrating abnormal magnetic resonance imaging, a majority show improved but persistent changes on repeat imaging [73
Retinal migraine is extremely uncommon in children and usually seen in young adults. Unlike the descending curtain-like onset of amaurosis fugax, retinal migraine causes patients to experience brief (seconds to <60 min), sudden, monocular blackouts or “grayouts” or bright, blind episodes of visual disturbance before, after or during headache attacks [71
“Alice in Wonderland” syndrome
Originated from Lewis Carol’s novel and characterised by bizarre visual illusions and spatial distortions which precede headaches. The children may describe bizarre or vivid visual illusions such as micropsia, macropsia, metamorphopsia and teleopsia [71
Acute confusional migraine (ACM)
This rare type of migraine described as acute confusional states, lasting 4–24 h, associated with agitation and aphasia commonly seen in juvenile migraineurs. ACM may be a presenting feature and important clue, enabling CADASIL to be recognised. Therefore, a brain MRI and/or testing for Notch3 mutations should be considered in adult patients with ACM [77
Migraine equivalents of infancy, childhood, and adolescence are recognised periodic, paroxysmal syndromes without associated headache that are thought to be migrainous in aetiology. Following equivalents are presently recognised.
- Cyclical vomiting (ICHD-II 1.3.1)
- Abdominal migraine (ICHD-II 1.3.2)
- Benign paroxysmal vertigo (ICHD-II 1.3.3)
- Benign paroxysmal torticollis (ICHD-II A1.3.5)
Analgesic overuse may cause a worsening of non-cephalic pain in patients with extra-cephalic variants of migraine [57
Diagnosis of migraine
The diagnosis of migraine rests mainly on clinical criteria, thus a correct evaluation begins with a thorough medical history followed by a complete physical and neurological examination including examination of the optic fundus. Recently, a practice parameter that outlined guidelines for the clinical and laboratory evaluation of children and adolescents with recurrent headaches [71
] stated that the routine use of any diagnostic studies is not indicated when the clinical history has no associated risk factors and the child’s examination is normal.