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To the Editor:

I wish to take advantage of the report by Drs. Milligan and Bromfield (1) on migralepsy to emphasize the following:

  • 1
    Occipital seizures are frequently misdiagnosed as migraine, although they are distinctly different.
  • 2
    Important clinical criteria are used in differentiating between elementary visual hallucinations of occipital seizures and migraine.
  • 3
    “Occipital epilepsy–migraine” is far more common than the traditional view of a “migraine–epilepsy” (migralepsy) sequence.

The authors present a woman with visual symptoms of left-sided, brief “2- to 3-min” episodes of “fluorescent-colored flashing lights, black spots, and squiggly lines” alone or followed by bifrontal headaches and nausea. These “scintillations” and headaches, diagnosed as migraine, were sometimes followed by focal seizures and generalized convulsions; hence the diagnosis of “migralepsy” is made. The discussion on “migralepsy” is based on traditional views (1). Evidence that “migralepsy” is often an erroneous diagnosis (2–4) are not considered, as indeed happens in most related publications.

  • 1
    Misdiagnosis of visual seizures as migraine with visual aura is frequent and costly. The major contributory factor to error is that the description of visual hallucinations is often abbreviated in terms such as scintillations, fortification spectrum, teichopsia, phosphenes, and their variations. Elementary visual hallucinations of occipital seizures are fundamentally different from the visual aura of migraine (Fig. 1).
  • 2
    In occipital seizures, elementary visual hallucinations are usually the first and often the only ictal symptom and may progress to other occipital and extraoccipital manifestations and convulsions (2–4). Ictal elementary visual hallucinations are defined by color, shape, size, location, movement, speed of appearance and duration, frequency, and associated symptoms of progression. Elementary visual hallucinations are mainly colored and circular, develop rapidly within seconds, and are brief in duration (2–3 min). They often appear in the periphery of a temporal visual hemifield, becoming larger and multiplying in the course of the seizure, and frequently moving horizontally toward the other side. Significantly, postictal headache often indistinguishable from migraine, occurs in more than half of patients, even after brief visual seizures (2,3). Postictal headache frequently occurs 3–15 min after the seizure ends, a situation known in migraine as the “asymptomatic interval” (end of migraine aura to the onset of headache). Thus occipital seizures often generate migraine-like attacks, “epilepsy–migraine sequence” (2–4). In migraine, the visual aura usually starts as a flickering, uncolored, zigzag line in the center of the visual field and affects the central vision. It gradually progresses over >4 min, usually lasting <30 min, toward the periphery of one hemifield, often leaving a scotoma (5). The total duration of visual auras is 60 min. Acute onset of visual aura is very rare (5). Furthermore, migraine visual aura rarely has daily frequency, nonvisual ictal occipital symptoms, such as eye and head deviation and repetitive eyelid closures, do not occur; it is probably exceptional to progress to nonvisual epileptic seizures. Less typical features of migraine visual aura, such as spots, circles, and beads, with or without colors, may be experienced during the migraine visual aura, but usually they are not dominant. Clustering of other symptoms, as above, betray their migraine nature.
  • 3
    No reason exists that epileptic seizures, which are so vulnerable to precipitating factors, could not be susceptible to cortical changes induced by migraine. However, by probability of prevalence, these cases should have symptoms of a typical visual aura (>90% in comparison with atypical cases) followed by epileptic seizures. Contrary to this are the findings in my review of reported cases of “migralepsy,” in which the majority of them had symptoms of visual seizures as defined earlier, which were interpreted as migraine aura (3). Thus it is probable that these were genuine occipital seizures imitating migraine (epilepsy–migraine sequence). Some cases had symptoms of atypical presentations or bizarre symptoms that could be diagnosed as either migraine or epilepsy.
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Figure 1. Schematic presentation of typical elementary visual hallucinations in occipital seizures (left) and migraine visual aura (right) at their peak. In their clinical differentiation, considerations should be made in regard to their different onsets, speed and location of development, duration, frequency, and associated and following symptoms (see also other illustrations of elementary visual hallucinations in occipital seizures in references 2–4. Tables of differential diagnosis are detailed in references 3 and 4).

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More important, in clinical practice, occipital seizures of visual symptoms associated with headache are often erroneously identified as migraine with significant diagnostic and therapeutic adverse effects (3,4). The differentiation of migraine from epilepsy should not be difficult if clinical data are properly examined and synthesized (2–4).

REFERENCES

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  2. REFERENCES
  • 1
    Milligan TA, Bromfield E. A case of “migralepsy.” Epilepsia 2005;46(suppl 10):26.
  • 2
    Panayiotopoulos CP. Elementary visual hallucinations, blindness, and headache in idiopathic occipital epilepsy: differentiation from migraine. J Neurol Neurosurg Psychiatry 1999;66: 536540.
  • 3
    Panayiotopoulos CP. Visual phenomena and headache in occipital epilepsy: a review, a systematic study and differentiation from migraine. Epileptic Disord 1999;1: 205216.
  • 4
    Panayiotopoulos CP. Occipital lobe epilepsies. In: PanayiotopoulosCP, ed. The Epilepsies: Seizures, Syndromes and Management. Oxford : Bladon Medical Publishing, 2005: 416429.
  • 5
    Russell MB, Olesen J. A nosographic analysis of the migraine aura in a general population. Brain 1996;119: 355361.