CHANGES OF CIRCADIAN BLOOD-PRESSURE PATTERNS AND CARDIOVASCULAR PARAMETERS INDICATE LATERALIZATION OF SYMPATHETIC ACTIVATION FOLLOWING HEMISPHERIC BRAIN INFARCTION

The effects of left- and right-sided hemispheric brain infarction on v ariability in circadian blood pressure and cardiovascular measures wer e investigated in 35 patients to test for asymmetry of the sympathetic consequences of stroke. No significant differences regarding age, siz e of infarction or extent and frequency of damage to the insular corte x could be detected between the two groups. Patients with right-sided infarction showed a significantly reduced circadian blood pressure var iability [diastolic: -1% (95% CI -4 to 1) vs -6% (-9 to -2); P < 0.05] and a higher frequency of nocturnal blood pressure increase (47% vs 3 5%; P < 0.05) as compared with patients with left-sided infarction. Ri ght-sided infarction was also associated with higher serum noradrenali ne concentrations [546 pg/ml (95% CI 415-677) vs 405 pg/ml (266-544); P < 0.05], and ECG more frequently showed QT prolongation (53% vs 35%; P < 0.05) and cardiac arrhythmias (67% vs 20%; P < 0.005). However, i rrespective of the hemisphere damaged, patients with insular infarctio n showed the most pronounced changes of these parameters. In addition, two patients with right-sided strokes (13%) involving the insula, but none with a left-sided infarction, developed myocardial infarction. T hese findings suggest lateralization of sympathetic activation with ri ght-sided dominance for sympathetic effects following hemispheric stro ke.