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Migraine variants

Familial Hemiplegic Migraine (FHM)

FHM is an uncommon autosomal dominant form of migraine headache in which the aura

has a “stroke-like” quality producing some degree of hemiparesis. The nosology is somewhat

misleading since there is actually a wide diversity of symptoms and signs which can accompany

this migraine variant beyond motor deficits.

       

The discoveries into the molecular genetics of FHM have

broadened our understanding of the fundamental mechanisms of migraine and demonstrated the

Overlap with other paroxysmal disorders such as acetazolamide-responsive episodic ataxia.

Genetic linkage to chromosome 19p13 has been identified in half of the known FHM pedigrees

and, more recently, a separate pedigree with linkage to chromosome 1q31 has been reported.

The chromosomal 19 defect produces a missence mutation in a neuronal calcium channel gene providing an evidence that FHM represents a channelopathy(83,84).

hemiplegic migraine is characterized by transient (hours to days) episodes of focal neurologic deficits which precede the headache phase by 30-60 minutes, but, occasionally, extend well beyond the headache itself. The headache is often, but notinvariably, contralateral to the focal deficit.

 

The IHS diagnostic criteria for FHM include the following:

1.      The presentation fulfills criteria for migraine with aura.

2.      The aura includes some degree of hemiparesis and may be prolonged.

3.      At least one first-degree relative has identical attacks.(9)

 

 

 

Alternating hemiplegia of childhood

The syndrome has  traditionally been considered a variant of hemiplegic migraine.  

Initial symptoms begin before 18 months of life. Affected children have attacks of

paralysis: hemiparesis, monoparesis, diparesis, ophthalmoparesis, bulbar paralysis which may be

accompanied by variable tone changes (flaccid, spastic, or rigid). A variety of paroxysmal

involunary movements including chorea, athetosis, dystonia, nystagmus and respiratory

irregularities (hyperpnea) can be seen. (85)

Basilar Migraine (BM)

Also known as basilar artery, vertebro-basilar, or Bickerstaff migraine(86), this clinical entity

is the most frequent of complicated migraine variants and is estimated to represent 3-19% of all

migraine. This wide range of frequency relates to the rigorousness of the definition. 

The I.H.S.(9) criteria require 2 or more symptoms and

emphasizes bulbar and bilateral sensorimotor features.

The age of onset of BM tends to be in the younger children with mean age being 7 years,

although the clinical entity probably appears as early as 12-18 months as episodic pallor,

clumsiness, and vomiting .(87)

Affected children will have attacks of intense dizziness, vertigo, visual disturbances,

ataxia and diplopia. These early transient features last minutes to an hour and are then followed

by the headache phase. But unlike the more typical frontal or temporal location, the headache

may be occipital in location. The quality of the pain may be difficult for the child to describe

and the terms such as pulsating or throbbing may not be used. A small subset of children with BM

will have their posterior fossa symptoms after the headache phase is well established.(88)

 

 

 

Ophthalmoplegic Migraine (OM)

 One of the least common migraine variants. the epidemiological data suggest an annual

Incidence of 0.7 per million. The two key features are ophthalmoparesis and headache, though

the headache may be mild or a nondescript retro-orbital discomfort. While verbally sophisticated

school aged children may describe blurred vision or diplopia, young children may simply rub

their eye. Attacks of OM have been reported during infancy, as early as 5-7 months of age.

Ptosis, adduction defects and skew deviations are the common objective findings. 

acute treatment with

steroids and prophylactic treatment must be considered.(89,90)

Retinal Migraine

Also referred to as ocular, ophthalmic or anterior visual pathway migraine, this variant is

extremely uncommon in children and usually seen in young adults. Unlike the descending

curtain-like onset of amauroses fugax, affected patients will report brief (seconds to <60

minutes), sudden, monocular black or gray "outs", or bright, blinding episodes (photopsia) of

visual disturbance before, after, or during the headache. (90)

Benign Paroxysmal Vertigo

      Typically, an affected young child (median 18 months) child will be struck by a sudden

unsteadiness on their feet. They will anxiously grab onto a nearby table, chair or adult for

stability or fall to the ground. Consciousness will not be lost but keen observers may notice

nystagmus. Vomiting may be vigorous. The spells usually last minutes and afterwards the child

will sleep. Upon awakening, the children return to their normal baseline. The spells will occur

in clusters over several days, then subside for weeks or months.

These spells probably represent the early evolution of basilar migraine and the

differential diagnosis would be similar. During a long-term follow-up of 7 cases, Lanzi reported

5 of 7 BPV cases spontaneously resolved and 6 of 7 patients later developed migraine and other

migraine-related symptoms. The authors suggest that BPV can be interpreted as a migraine

precursor(91).

Investigations

 

Headache is a common disorder with many potential causes. The primary headache disorders, which include migraine, cluster, and tension-type headaches, account for the majority of headaches (108), while secondary headaches, which are those with underlying pathology (e.g., tumor, aneurysm, or giant cell arteritis) are far less common. Most patients presenting with headache in the primary care setting do not have serious underlying conditions. The relative rarity of secondary headaches, compared with the large number of patients with primary headache, raises concern about the wisdom of routine neuroimaging studies, either computerized tomography (CT) or magnetic resonance imaging (MRI), to exclude underlying causes of headache(109,110, 111).

In adult patients with recurrent headaches defined as migraine, including those with visual aura, with no recent change in headache pattern, no history of seizures, and no other focal neurologic signs or symptoms, the routine use of neuroimaging is not warranted. (110)

 

Reasons to consider neuroimaging in migraine

 

Unusual, prolonged, or persistent aura

Increasing frequency, severity, or change in clinical features

First or worst migraine

Basilar, confusional migraine

Hemiplegic

Late-life migraine accompaniments

Aura without headache

Headaches always on the same side

Posttraumatic

Patient or family and friends request

 

Meta-analysis of patients with migraine and a normal neurological examination found a rate of significant intracranial lesions of 0.18 % (2/1000); previously reported rates of finding intracranial lesions with CT and MRI ranged from 0.3% to 0.4%. Neuroimaging is thus unlikely to reveal an abnormality on MRI or CT scanning in patients with migraine and a normal neurological examination. MRI appears to be more sensitive in finding white matter lesions and developmental venous anomalies than CT. (110,111)

Blood tests generally are not helpful for the diagnosis of headaches. There are numerous indications, however, such as the following: erythrocyte sedimentation rate (ESR) or C-reactive protein to evaluate for temporal arteritis; ESR, rheumatoid factor, and antinuclear antibody in a patient with headaches and arthralgias to evaluate for collagen vascular disease such as lupus (111)

The electroencephalogram  is not useful in the routine evaluation of patients with headache. This does not exclude the use of EEG to evaluate headache patients with associated symptoms suggesting a seizure disorder such as atypical migrainous aura or episodic loss of consciousness. Assuming head imaging capabilities are readily available, EEG is not recommended to exclude a structural cause for headache. (112)

MR imaging or CT scan is performed before a lumbar puncture for the evaluation of headaches except in some cases in which acute meningitis is suspected and there are no focal findings. Lumbar puncture can be diagnostic for meningitis or encephalitis, meningeal carcinomatosis or lymphomatosis, SAH, and high (e.g., pseudotumor cerebri) or low CSF pressure diseases (111)