History
Variant migraine episodes may be independent of actual head pain. Other symptoms may predominate and be significantly more troublesome.
Hemiplegic migraine
Hemiplegic migraine presents with hemiplegia or hemiparesis, with or without a speech or language disturbance, which clears in minutes to hours. Headache may be less dramatic than the hemiplegia. Other migrainous symptoms (eg, nausea, vomiting, and photophobia) are present to varying degrees. Hemiplegia may precede or accompany the headache.
Hemiplegic migraine is often familial, is dominantly inherited, and is linked to chromosome 19 in some studies. [11, 12] An alternative locus has been described on chromosome 1. [13, 14] A defect in the gene for the calcium channel is documented in some families (affecting the voltage-dependent P/Q-type calcium channel alpha-1A [CACNA1A] subunit). [15, 16] An increased risk of stroke exists in families with this disorder.
Cerebral autosomal dominant arteriopathy and subcortical infarcts and leukoencephalopathy (CADASIL), an autosomal dominant disorder in which multiple subcortical strokes may lead to dementia in early adulthood, sometimes presents in adolescence as atypical hemiplegic migraine. The CADASIL mutation also localizes to chromosome 19.
Additional genetic associations have been found including with mutations in SCN1a, ATP1A2, and PRRT2 genes. All of these mutations include variable phenotypes with epilepsy, paroxysmal dyskinesias, episodic ataxia, and hemiplegic migraine seen in affected families. Families with the same mutation may manifest differing combinations of symptoms, and the same symptoms may be due to different mutations. [7, 9, 10]
The diagnosis cannot be made during the first episode, though it may be suspected in the presence of a positive family history. Exclude more serious causes of headache with hemiplegia or hemiparesis, including intracranial hemorrhage, mass, infection, and stroke. With repeated stereotyped episodes and complete clearing between episodes, the diagnosis can be made with more confidence, particularly in the presence of a positive family history.
The differential diagnosis of repeated episodes includes alternating hemiplegia of childhood, unobserved partial seizures with postictal paralysis, and mitochondrial cytopathies, particularly the mitochondrial encephalomyopathy, lactic acidosis, and stroke syndrome (MELAS). On occasion, hemiplegic migraine may be associated with reversible unilateral cerebral edema on imaging. [17]
Confusional migraine
Although confusional migraine is more common in younger children, it sometimes presents in postpubertal adolescents or adults. Occasionally, a child whose episodes began in the prepubertal years continues to have episodes into adolescence. The child has a period of confusion and disorientation, with or without agitation, followed by vomiting, which is relieved by sleep. Headache may not be prominent or may be elicited only retrospectively.
So-called "Alice-in-Wonderland syndrome" may be a special case of confusional migraine. The patient subjectively experiences the sensation of their own body being either larger or smaller than normal, and objects and people around them appearing larger or smaller, combining both somesthetic and visual perceptual disturbances. The same clinical syndrome can also be associated with a variety of viral illnesses, including influenza and EBV infection, but if it occurs repeatedly may be a migraine aura. [18]
Making the diagnosis during the first episode is difficult; it is possible only after the episode has resolved fully. Acute differential diagnosis of a single episode includes all types of encephalopathy or encephalitis, toxic ingestion, intoxication, and an unobserved seizure with postictal agitation.
Abdominal migraine
A child with abdominal migraine may complain of episodic pain, nausea, and vomiting. The headache may be minimal or absent. An aura may precede the pain but is not frequent. Symptoms are relieved by sleep and antiemetic or antimigraine therapies. The diagnosis is difficult to make during the first episode.
Cyclic vomiting of childhood, which can be associated with a mitochondrial cytopathy, may be a severe variant of abdominal migraine.
Basilar migraine
A patient with basilar migraine may have an aura followed by dizziness, vertigo, syncope, and dysarthria. Headache may be minimal or absent. This variant is observed most frequently in adolescent girls. The differential diagnosis includes cardiogenic or vasovagal syncope, inner ear disease, somatoform disorder, and posterior-fossa tumors.
Migraine aura without headache
Migraineurs of any age may experience an aura with or without the typical headache. In some, the headache may be minimal while neurologic symptoms predominate. Visual symptoms without subsequent headache are fairly frequent. These include scintillating scotomata, formed visual hallucinations (usually stereotyped, in a single visual field), micropsia, and tunnel vision.
The differential diagnosis includes occipital epilepsy, with or without an identifiable lesion. If episodes never are accompanied by headache, the diagnosis is speculative.
Auditory hallucinations as migraine auras are infrequent but can occur. Sensory dysesthesias (usually hemisensory numbness or tingling) similar to a more typical migraine aura may occur without subsequent head pain.
Benign paroxysmal vertigo of childhood
Given the high proportion of children with a family history of migraine, benign paroxysmal vertigo of childhood is sometimes considered a migraine variant. This syndrome is not uncommon and frequently is followed by the development of more typical migraine headaches later in childhood.
The syndrome presents with brief episodes of vertigo. Toddlers may be unable to verbalize the symptoms, but they typically cling to the parent and look frightened. Older children often verbalize that they are “moving.” Headache does not follow the attack.
Ophthalmoplegic migraine
Ophthalmoplegic migraine may begin in childhood. Acute disorders of eye movement, unilateral abnormal pupillary response, or Horner syndrome may precede or accompany the headache.
Physical Examination
As with all vascular headache syndromes, the neurologic examination between episodes typically yields completely normal findings. If persistent neurologic signs (eg, hemiparesis, visual changes, sensory loss) are evident between episodes, strongly consider and investigate alternative diagnoses.
Migraineurs have a higher risk of stroke, and patients with hemiplegic migraine may be at even higher risk. Abdominal migraine (cyclic vomiting syndrome) may cause significant dehydration.
