Much variation occurs in migraine. As already alluded to, the headaches need not be unilateral and the pulsatile aspect may not be prominent. The headache may be exceptionally severe and abrupt in onset (“crash migraine” or “thunderclap headache”), raising the specter of subarachnoid hemorrhage. Careful questioning in these cases sometimes reveals that the headache did not truly attain its peak rapidly but evolved over several minutes. Nonetheless, the distinction of this type of “thunderclap headache” from subarachnoid hemorrhage can be made only by examination of the CSF and imaging of the brain (see further on).
A headache may at times precede or accompany, rather than follow, the neurologic abnormalities of migraine with aura. Although typically hemicranial (the French word migraine is said to be derived from megrim, which, in turn, is from the Latin hemicrania, and its corrupted forms hemigranea and migranea), the pain may be frontal, temporal, or, quite often, generalized. Furthermore, throbbing or pulsating pain is not an inviolate feature.
Any two of the three principal components— neurologic abnormality, headache, and gastrointestinal upset—may be absent. With advancing age, for example, in some instances there is a tendency for the headache and nausea to become less severe, finally leaving only the neurologic abnormality, which itself recurs with decreasing frequency. This is also subject to great variation. One common configuration is a full-blown visual aura without subsequent headache (migraine without headache, or migraine dissocié). Visual and neurologic disturbances differ in detail from patient to patient; numbness and tingling of the lips and the fingers of one hand are probably next in frequency after visual displays, followed by transient dysphasia or thickness of speech and hemiparesis as mentioned earlier. Rarely, there is sudden, transient blindness or hemianopia at the onset of a migraine attack, accompanied by only mild headache.
Furthermore, there are several special forms of migraine that do not conform to the usual patterns discussed above, as listed in the following section.
In addition to variability in the pattern of conventional migraine detailed just above, there are several distinctive syndromes that have been allied with migraine. They are so classified because they have as main features recurrent migrainous headache with reversible neurological deficits or visual displays that are identifiable as aura components of typical migraine. What sets them apart from conventional migraine is paralysis, stupor, ophthalmoplegia, or monocular visual loss. Furthermore, patients or their families may display both typical migraine and one of these variants.
Migraine with Brainstem Aura (Basilar Migraine)
An uncommon form of the migraine syndrome with prominent premonitory brainstem symptoms was described by Bickerstaff. These patients, usually children with a family history of migraine, first develop visual phenomena like those of typical migraine except that they occupy much or the whole of both visual fields (temporary cortical blindness may occur). There may be associated vertigo, staggering, incoordination of the limbs, dysarthria, and tingling in both hands and feet, and sometimes around both sides of the mouth but curiously, rarely is there paralysis. These symptoms last 10 to 30 min and are followed by headache, which is usually occipital. Some patients, at the stage when the headache would have been likely to begin, may faint, and others become confused or stuporous, a state that may persist for several hours or longer. Exceptionally, there is an alarming period of coma or quadriplegia. The symptoms closely resemble those caused by ischemia in the territory of the basilar-posterior cerebral arteries—hence the name basilar, or vertebrobasilar migraine. Subsequent studies have indicated that basilar migraine, although more common in children and adolescents, affects men and women more or less equally over a wide age range, and that the condition is not always benign and transient because of rare instances with residual deficits.