Page 80 - Migraine, the heart and the brain

Chapter 4
immediately after TCD-c, migraine attacks were present in 8% of 159 participants; all of them had a permanent RLS. Sorensen et al. [27] prospectively questioned 445 individuals for the occurrence of different symptoms, including visual aura, after TCD-c in different patient groups (transient ischemic attack, cryptogenic stroke, migraine). TCD-associated symptoms such as migraine headache or ischemic symptoms were noted in 21% of participants. Occurrence of visual forti cation aura occurred in 8% of migraine patients (n = 214) and in 0.4% of 231 nonmigraineurs (nonsigni cant difference). Note that it was not reported whether the individuals experiencing speci c symptoms had a RLS; generally it was concluded that any neurological symptom after TCD was more frequent in the RLS group (27%), compared with the non-RLS group (11%) (P < 0.001). Contrary to these studies [26,27], provoked migraine aura after aircontrast study seldom seems to occur in daily neurological practice. The relatively frequent occurrence of symptoms in these studies can also be explained by chance or other precipitating factors such as stress or the tight head frames used for TCD investigation. The nocebo effect, in which participants are (probably as a result of speci c questioning) more likely to report side-effects, is also likely to play a role, especially when individuals can hear noise when emboli are detected by TCD.
Emboli after sclerotherapy
A second type of exogenous venous emboli occurs in sclerotherapy with the use of foam or liquids to treat varicose veins. Emboli in the middle cerebral artery (presumably after crossing a RLS) have been observed with TCD in the absence of neurological complications in up to 42% of patients undergoing foam sclerotherapy [28]. The composition of the emboli (e.g. gas, platelets or other compounds) is not known. A study using polidocanol (thought to cause smaller emboli) reported emboli during the sclerotherapy in as many as 89% of 61 participants with a RLS, but no neurological signs or symptoms [29]. A systematic review of cohort studies and randomized trials including 10 801 persons who underwent sclerotherapy reported the occurrence of visual disturbances (not considered to be a transient ischemic attack or stroke) in 84 persons (0.8%) [30]. Migraine (not further speci ed) occurred in 29 persons (0.3%) [30]. In these studies, percentages of individuals with a history of migraine were not reported and only in few of the included studies the RLS status in those experiencing migraine symptoms was known.
An alternative explanation for the occurrence of migraine attacks after sclerotherapy could be an increase of endothelin-1 following sclerotherapy, which has been shown in rats [31*]. Endothelin-1 is able to induce CSD in rats, linking endothelial
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