ABSTRACT
Previous studies have shown a peak occurrence of ischemic stroke in the morning but no consistent finding has been attributed to this. Focused on lacunar strokes we performed a prospective study with a detailed diagnostic protocol including parameters of recent infection, indicators of sleep apnea and cerebral vasoreactivity (CVR), aimed at defining differences in risk profiles between diurnal and nocturnal strokes. Consecutively we included 33 nocturnal and 54 diurnal strokes. Baseline characteristics, known risk factors, stroke severity and topology were not different between groups. The mean low-density lipoprotein (LDL) cholesterol level was significantly higher amongst patients with nocturnal strokes (133.3 +/- 35.2 mg/dl vs. 115.5 +/- 39.8 mg/dl; P = 0.04), as well as the proportion of patients with any dyslipidemia (94% vs. 77.8%; P = 0.047). Twenty-four-hour blood pressure recordings showed a reduced nocturnal decrease of blood pressure in subjects with strokes that occurred between 10 pm and 6 am in comparison with those whose strokes occurred between 6 am and 2 pm (5.0 +/- 7.3% vs. 11.0 +/- 6.7%; P = 0.049). No significant differences were found for parameters of recent infection (including seroreactivity against Chlamydia pneumoniae and cytomegalovirus), CVR, indicators of sleep apnea and the degree of white matter disease assessed by magnetic resonance tomography. Dyslipidemia, especially elevated LDL cholesterol is more prevalent in nocturnal lacunar strokes especially when combined with a reduced nocturnal dipping of blood pressure. This risk factor profile can be regarded as an additional target for stroke prevention.
