Abstract
The prevalence of migraine with aura in adults is 3–5% (1). It is defined as attacks of focal neurological deficits that develop gradually, mostly within 5–20 min, and usually affect the visual system, sensation or language and are often followed by headache within 1 h. The focal deficits normally resolve in 1 h. Except for aphasia, cognitive dysfunction is not considered to be a regular migraine aura phenomenon. We present a case with global cognitive dysfunction accompanied by modest hypoperfusion of the left hemisphere, attributed to a migraine aura.
Case report
A 28-year-old junior research physician was referred to our first-aid department with acute dysphasia that had started 1 h previously. Neurological examination revealed mild dysphasia. She was right-handed. She could not reproduce her home address and complex tasks were not understood. No focal deficits on examination of cranial nerves and extremities were found. She started vomiting and developed a headache. The initial differential diagnosis included cerebral ischaemia, cerebral venous thrombosis and migraine with aura. A computed tomography (CT) scan of the head, 2 h after symptom onset, showed no signs of early ischaemia or thrombosis. The perfusion CT scan showed subtle perfusion abnormalities in all flow territories of the left hemisphere 2 h after symptom onset (Figure 1). After the scan her speech improved. Her boyfriend arrived and it now became clear that in the last 5 years she had had three previous episodes with headache and vomiting that had resolved within 24 h. In one of these episodes there had been a similar language problem, but there had been no apparent additional signs of cognitive problems. There was no other medical history, she did not smoke and used no medication except for an oral contraceptive. Her mother suffered from migraine, apparently without aura.
The computed tomography-perfusion scan shows abnormalities. The penumbra-infarction (PI) map (a) is generated based on the mean transit time (MTT; d) and cerebral blood volume (CBV; b). Cerebral blood flow (CBF) is shown in panel c. The green area on the PI map indicates a prolonged MTT (> 145% compared with the contralateral hemisphere) with a CBV in normal range (> 2 ml/100 g). This combination suggests reversible ischaemia (9). Red areas on the PI map generally represent irreversible ischaemia, but small punctuate red areas (a) may represent artefacts.
Approximately 3 h after the first examination the dysphasia had largely resolved. Although she had no naming difficulties at this stage and her speech had become fluent, she still could not explain what kind of work she did. She could reproduce the months of the year forwards, but not backwards and had difficulty calculating. Additionally, she could not draw a clock or a cube (Figure 2). She lacked insight into these cognitive problems. After using analgesics the headache disappeared. Nine hours after onset the cognitive dysfunction had completely resolved.
Attempt of patient to draw a clock (a) and a cube (b).
Discussion
Our patient presented with mild global aphasia, impaired attention, visuospatial dysfunction, dyscalculia and probably also dysfunction of planning and regulation (executive functions), followed by headache and vomiting. The global nature of the cognitive disturbances in our patient became clear only when she was tested after her dysphasia had resolved. The frequency of cognitive disturbances in relation to an aura may therefore easily be underestimated.
The diagnosis of probable migraine with aura was made (2). A transient ischaemic attack was considered unlikely because of the nature and evolution of the clinical symptoms (i.e. global cognitive deficits and lack of focal motor signs), the medical past with three attacks that were probably also migraine attacks and the global distribution of the hypoperfusion that was not restricted to one vascular territory. Because there had been only three previous episodes of headache and the non-motor aura signs persisted for > 1 h, the diagnosis ‘definite migraine’ could not be made at this stage.
There are relatively few studies on cerebral perfusion during migraine aura. These studies mostly involved patients with a prolonged aura (3–5). Both normal, hypo- and hyperperfusion were reported, but perfusion measurements were not always performed in the acute stage of the aura. Most perfusion abnormalities concerned the occipital cortex. Hypoperfusion of a part of the left parietal lobe has been demonstrated in a patient with aphasic aura (6). More generalized unilateral perfusion abnormalities have been described in hemiplegic migraine, involving hyperperfusion of an entire hemisphere 6 h to days after the onset of the aura 3,7,8). The present case report demonstrates that global modest hypoperfusion of one entire hemisphere can occur in the hyperacute stage of a migraine aura. In conclusion, cognitive disturbances, accompanied by global unilateral cerebral perfusion deficits, may be a manifestation of migraine aura.