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MIGRAINE WITH
AURA (CLASSIC) The new term for classic migraine, that is, migraine with aura requires at least two attacks with any three of the following four features: [1] One or more fully reversible aura symptoms; [2] aura developing over a course of more than four minutes; or [3] lasting less than sixty minutes; and [4] headache following aura within sixty minutes. This is summarized in Table 3. Table 3. Migraine with aura
Migraine with aura refers to a more well-defined clinical constellation than does migraine without aura. The episodes are characterized by definite prodrome or aura, which is usually a visual sensation; however, sometimes motor or other sensory phenomena precede the headache. The headaches of classic migraine tend to be more compact and intense, rarely lasting more than 12 hours; most often 2 to 3 hours. Many general characteristics are shared by common and classic migraine. Both varieties affect men and women and can occur at any age, often seemingly triggered by a significant event such as puberty, school graduation, or marriage. A family history is usually present both in classic and common migraine and there may be an earlier history of colic as a baby or car sickness as a small child. The full history of a complete migraineur would include migraine with aura in the teens, migraine without aura with nausea and vomiting in the second and third decades, followed by simple periodic headache or isolated migrainous auras in later life. Migraine with aura is subclassified into migraine with typical aura (homonymous visual disturbance, unilateral numbness or weakness, or aphasia); migraine with prolonged aura (or lasting longer than 60 minutes); familial hemiplegic migraine; basilar migraine; migraine without headache and migraine with acute-onset aura. The primary feature of migraine with aura is the visual aura. Extensive reviews of this phenomenon are found throughout the literature.{4,5,24,41-43} While many variations occur, the following description by Richards{44} summarizes the most common type of visual phenomena: The visual disturbance usually precedes the headache...[it] begins near the center of the visual field as a small gray area with indefinite boundaries. If this area first appears during reading, as it often does, then the migraine is first noticed when words are lost in a region of "shaded darkness." During the next few minutes the gray area slowly expands into a horseshoe with bright zigzag lines appearing at the expanding outer edge. These lines are small at first and grow as the blind area expands and moves outward toward the periphery of the visual field. Examples are shown in Figure 2  Figure 2. Successive arcs expand across half of visual field, as shown in two diagrams based on Airy. The spectra may take 20 to 25 minutes to expand from a fuzzy gray area near the fixation point (dot) to the outer limit of the visual field. (Richards W: The fortification illusions of migraines. Sci Am 224:88, 1971) and in Figure 3:  Figure
3. Emerging honeycomb pattern form plotting data derived from visual
phenomena in migraine subjects. Honeycomb and tendency for inner angle
between lines to approximate 60 suggests a hexagonal organization of
occipital cortical cells. (Richards W: The fortification illusions of
migraine. Sci Am 224:88, 1971)One important aspect of the visual disturbance just described, is that it expands slowly, over a period of 10 to 20 minutes. The initial region of visual abnormality is most often near fixation and then, as described by Lashley,{39} with increase in size the disturbed area moves or "drifts" across the visual field so that its central margin withdraws from the macular region as its peripheral margin invades the temporal...the area may be totally blind (negative scotoma), amblyopic or outlined by scintillations. I have depicted this in the following diagram:  The scintillations surrounding the negative scotoma make "fortification" figures or spectrums, so called by the appearance of a "map of the bastions of a fortified town".{39} The walls of the fort are set at angles in order to cover to give "line of sight" ( small dotted lines ) cover of approaching enemies. Thus: 
The scintillations are brilliant, with the intensity of a bright fluorescent bulb flickering at a rate of 5 to 10 cycles/second. Illustrations are portrayed in Fig. 4: 
and in Figure 5: 
Gowers,{45} commenting on the descriptions by the British astronomer, Sir George Airy, and his physician son, Dr. Hubert Airy, (both migraineurs), was particularly impressed with the intensity of the visual sensation. Many migraine sufferers can precisely recall their own vivid visual experiences well enough to precisely describe them or even on occasion to paint them. Further illustration are depicted in Figure 6: 
Not all migraine visual disturbances begin near the fixation point; some patients consistently experience scotomas starting eccentrically in the visual field, and these sensations can appear alternately or simultaneously in both hemifields as depicted in Fig 8:  Figure 8. Radial movement of a visual stellate object that itself remained unchanged throughout the episode. Stellate form appeared near edge of right half of field just below the horizontal and consisted of approximately six pointed leaflike projections alternatively red and blue. It appeared on a small area of darkness, moved slowly toward the left and upward, passing above the fixation point to beyond the middle line. Then it returned to its starting place, retraced this path once or twice, and passed to the right edge of the field, suddenly disappearing at the spot where it began. (Gowers WR: Visual sensations in migraine. In Subjective Sensations of Sight and Sound, Abiotrophy and Other Lectures. London, Churchill, 1907) Other less dramatic visual auras also occur: just the sensation of peripheral brightness or awareness of a rhythmicity or pulsating character in the intensity of the ambient light. The duration of these visual symptoms is measured in minutes rather than the brief few seconds of flashing, bright moving spots, or transient flickering phenomena characteristic of occipital epileptic discharges.{6,45} Additional visual disturbances are categorized by Klee and Willanger,{42} consisting of metamorphopsia, diplopia, polyopia, and apparent movement of stationary objects. Variations in the scotomas of migraine, including their occurrence in patients with acquired blindness, are well described.{41,46} The auras of migraine, although most commonly only visual, have many other associated manifestations, such as hemihypesthesias, perioral anesthesia, vertigo, and transient aphasia. The aura or prodromes of classic migraine may be precipitated by intense stimuli: bright lights, loud noises, head trauma, or the intake of certain foods in susceptible individuals. In the usual sequence of migraine with aura the sensory prodrome precedes the onset of the headache (in accord with the traditional concept of vasoconstriction followed by vasodilatation). The visual disturbance rarely may have a simultaneous onset with headache or, once having disappeared, may recur following the onset of headache. Such unusual patterns, or strict unilaterality for all attacks, should increase suspicion of a mass lesion or vascular malformation. As opposed to definite periodicity with symptom-free intervals and predictable circumstances, as in migraine without aura, migraine with aura may occur "out of the blue" and in multiple attacks over a few days. Migraine with aura attacks tend to diminish in the third and fourth decades. While most migraine patients experience a stereotyped clinical pattern, there is a well-recognized group in which both classic and common migraine attacks are admixed.{47} Some patients with classic migraine may lose the headache component eventually and suffer only isolated auras thereafter. This monosymptomatic pattern stresses the importance of accurate history-taking when confronted by a patient with isolated visual phenomena (migraine dissociée). Hass{48} emphasized the occurrence of 'migraine aura status'. The differential diagnosis should include consideration of vertebro-basilar transient ischemic attacks. Symptomatology that favors migraine has been reviewed by Fisher,{49} and includes: luminous visual images, build-up of images, progression from one aura to another, and benign outcome.
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