The patient had a well-established antecedent history of migraine with aura for more than 20 years. He presented with slowly progressing symptoms as illustrated by his drawing, a combination of positive (flickering edge of the scotoma, tingling in case of sensory aura symptoms) and negative symptoms (scotoma, word finding difficulties in case of language aura symptoms), and temporally related mild headache. The diagnosis was made with taking a detailed history and physical examination. Additional testing was not necessary, especially as the patient had undergone a complete workup some years earlier and symptoms were essentially unchanged. The situation would have been very different in an elderly patient lacking an established history of migraine with aura and presenting with aura symptoms for the first time, in which case a full differential diagnostic work-up, especially for TIA, would have been warranted.

The ICHDIIIbeta 1.2.1 migraine with typical aura criteria were fulfilled, as the patient experienced multiple rather stereotyped episodes consisting of visual, sensory and/or speech/language symptoms, each fully reversible, but no motor, brainstem or retinal symptoms. Moreover, his visual aura symptoms spread gradually over ≥5 min, and, if present, sensory and language symptoms succeeded the visual symptoms, rather than appearing at the same time. Visual aura symptom duration was within the 5–60 min interval put forward in the criteria. Visual symptoms and, if present, sensory symptoms were always unilateral. A mild headache accompanied the aura, or immediately followed the aura symptoms, which is within the 60 min interval allowed in the criteria. The patient fulfils ICHDIIIbeta 1.2.1.1 subtype criteria for typical aura with headache, as the aura symptoms are accompanied or immediately followed by a headache that lost its migraine features over the years.

A typical migraine aura consists of visual and/or sensory and/or speech/language symptoms and is characterized by gradual development, duration of each symptom no longer than 1 h, a mix of positive and negative features and complete reversibility. Visual disturbances are the most common aura symptoms in migraine with aura. Sensory symptoms and speech/language disturbances seldom occur without preceding visual symptoms. Motor, brainstem or retinal symptoms are coded elsewhere in the ICHDIIIbeta under hemiplegic migraine, migraine with brainstem aura and retinal migraine. The average visual aura duration is close to 30 min. Aura symptoms can be differentiated from TIA by their progressive onset, spreading over time and quality, often a combination of both positive and negative symptoms (Table 17.1). The prototype of visual aura is the scintillating scotoma, in which a gradually expanding scotoma is bordered by a flickering edge. A subclassification of migraine with aura is made in the ICHDIIIbeta into typical aura with (1.2.1.1) or without (1.2.1.2) headache. In the former subtype aura is accompanied or followed within 60 min by a headache with or without migraine characteristics.

Late life visual aura symptoms are not rare. Data from the Framingham study suggest visual migraine aura symptoms occur in at least 1 % of the population in mid or late life. These episodes may occur for the first time after age 50 years, in the absence of headache, and a history of recurrent headaches may not be present. They appeared not to be associated with increased risk of stroke in this population. More recent epidemiological studies have shown that certain patients with migraine with aura are at greater risk for stroke, namely, women under the age of 40 years, especially those using an oestrogen-containing contraceptive and smoking.

Cortical spreading depression is a slowly propagating neuronal and glial depolarization that spreads at a characteristic rate of 3–5 mm per minute. It has been studied in mammalian cortices, and closely resembling phenomena have been documented in the human cortex following ischaemic stroke, intracerebral haematoma, subarachnoid haemorrhage and brain trauma, and there is indirect evidence to suggest it is the underlying mechanism of migraine aura. There are however some unresolved questions about the relationship between CSD and aura, and an additional role for astrocytic calcium waves has been suggested.