Circadian effects on outcome following surgery for intracerebral hemorrhage in humans?

Previous studies indicated that recovery of brain injury involves in circadian system and circadian system also modulates cardiovascular function. The present study was focused on the circadian characteristic of blood pressure (BP) and heart rate (HR) of patients with hypertensive intracerebral hemorrhage (HICH) after neurosurgical operation at the first 24-hour and its relationship to prognosis of HICH. This retrospective study was based on the analysis of circadian rhythm of postoperative patients with HICH who received no anti-hypertensive treatment before operation and during the first 24-hour after operation. Series data of BP and HR after operation were analyzed with cosinor method to determine whether circadian rhythms were present or absent. The patients were divided into two groups, including presence of circadian rhythm group and absence of circadian rhythm group. The basic clinical characteristics of two groups were analyzed with Student's t-test. The percentage of good prognosis in two groups was analyzed with Pearson's Chi-squared test. Statistical results indicated that the percentage of good prognosis was significantly different between the presence and absence group. More cases of good prognosis in presence group of Systolic Blood Pressure (SBP) was discovered than in absence group (p=0.032). The results of Diastolic Blood Pressure (DBP) and HR were similar as SBP was observed in presence group for DBP (p=0.002) and for HR (p=0.001), respectively. We conclude that the presence or absence of circadian rhythm after operation would be an early predictor of the postoperative prognosis from hypertensive intracerebral hemorrhage.