BACKGROUND: Hyperbaric oxygen (HBO) therapy increases blood oxygen content, changes cerebral blood flow (CBF) and cerebral metabolism. Its therapeutic effects on cerebrovascular disease have been fully confirmed, but the occasion for HBO therapy is still unclear. OBJECTIVE: To observe the therapeutic effects of HBO therapy at different time on CBF and electroencephalogram (EEG) in patients with acute cerebral infarction (CI). DESIGN: Randomized controlled trial. SETTING: Department of Neurology, Shidong Hospital, Yangpu District of Shanghai. PARTICIPANTS: Ninety-six inpatients with acute CI, admitted to Department of Neurology, Shidong Hospital, Yangpu District of Shanghai from January 2001 to December 2006, were involved in this experiment. The involved participants met the diagnosis criteria of acute CI and confirmed by skull CT or MRI. They all were patients with moderate CI (16–30 points) according to neurologic deficit score formulated by Chinese Medical Association. Informed consents of detected items and therapeutic regimen were obtained from all the involved participants. They were randomized into two groups with 48 in each: early-stage treatment group and advanced-stage treatment group. Among the 48 patients in the early-stage treatment group, 21 male and 27 female, aged 53–68 years, 22 patients were found with basal ganglia infarction, 10 with brain lobe infarction, 16 with multiple infarction, 27 accompanied with hypertension and 2 accompanied with diabetes mellitus. Among the 48 patients in the advanced-stage treatment group, 23 male and 25 female, aged 52–71 years, 25 patients were found with basal ganglia infarction, 10 with brain lobe infarction, 12 with multiple infarction, 1 with brain stem infarction, 28 accompanied with hypertension and 1 accompanied with diabetes mellitus. METHODS: After admission, patients of two groups received routine drug treatment. ① Patients in the early-stage treatment group and advanced-stage treatment group began to receive HBO therapy within one week of CI and 4 weeks after CI, respectively. The total course of treatment both was 2 weeks. EEG examination was carried out before and after therapy, and CBF was determined with 133Xe inhalation. ② Assessment criteria of curative effects: Basically cured: neurologic symptoms and body signs disappeared, could work and do housework; Markedly effective: score of neurologic deficit was decreased by over 21 points, could manage himself/herself partially; Effective: score of neurologic deficit was decreased by 8 to 12 points; Non-effective: Score was increased or decreased less than 8 points, neurologic deficit was worsened, even died. Total effective rate = (number of cured+number of markedly effective+number of effective)/ number of total cases×100%. ③ t test and Chi-square test were used for comparing the difference of measurement data and enumeration data respectively, and Ridit analysis was used for comparing the difference of clinical curative effects. MAIN OUTCOME MEASURES: ① Comparison of EEG and CBF of patients from two groups before and after treatment. ② Comparison of post-treatment neurologic deficit of patients between two groups. RESULTS: All the involved 96 patients with CI participated in the final analysis. ① Clinical symptoms of patients from two groups after therapy were significantly improved as compared with those before therapy, and curative effects of early treatment group were better than those of advanced treatment group (U =1.99, P < 0.05). ②After treatment, CBF in each region of brains, except for that in parietal lobe of patients in the advanced-stage treatment group, was significantly improved (P < 0.05–0.01); The improvement of CBF of patients in the early-stage treatment group was more obvious than that in the early-stage treatment group (P < 0.05–0.01). ③ The abnormal rate of EEF of patients from early-stage treatment group and advanced-stagetreatment group before treatment was 94% and 96%, respectively. After treatment, improvement rate of EEG of patients in the early-stage treatment group was 95%, which was significantly different from that in the advanced-stage treatment group (82%,χ2 =4.32,P < 0.05) CONCLUSION: HBO therapy both at early and advanced stages of CI (within 1 week and 4 weeks after CI attack) can improve CBF and EEG of patients with early CI, especially. BACKGROUND: Hyperbaric oxygen (HBO) therapy increases blood oxygen content, changes cerebral blood flow (CBF) and cerebral metabolism. Its therapeutic effects on cerebrovascular disease have been fully confirmed, but the occasion for HBO therapy is still unclear. OBJECTIVE: To observe the therapeutic effects of HBO therapy at different time on CBF and electroencephalogram (EEG) in patients with acute cerebral infarction (CI). DESIGN: Randomized controlled trial. SETTING: Department of Neurology, Shidong Hospital, Yangpu District of Shanghai. PARTICIPANTS: Ninety-six inpatients with acute CI, admitted to Department of Neurology, Shidong Hospital, Yangpu District of Shanghai from January 2001 to December 2006, were involved in this experiment. The involved participants met the diagnosis criteria of acute CI and confirmed by skull CT or MRI. all of patients with moderate CI (16-30 points) according to neurologic deficit score formulated by Chinese Medical Association. Informed co nsents of detected items and therapeutic regimen were obtained from all the involved participants. They were randomized into two groups with 48 in each: early-stage treatment group and advanced-stage treatment group. Among the 48 patients in the early- 21 the male and 27 female, aged 53-68 years, 22 patients were found with basal ganglia infarction, 10 with brain lobe infarction, 16 with multiple infarction, 27 accompanied with hypertension and 2 accompanied with diabetes mellitus. Among the 48 patients in the advanced -stage treatment group, 23 male and 25 female, aged 52-71 years, 25 patients were found with basal ganglia infarction, 10 with brain lobe infarction, 12 with multiple infarction, 1 with brain stem infarction, 28 accompanied with hypertension and 1 accompanied METHODS: After admission, patients of two groups received routine drug treatment. ① Patients in the early-stage treatment group and advanced-stage treatment group began to receive HBO therapy within one week of CI and 4 weeks after CI, respectively. The total course of treatment both was 2 weeks. EEG examination was carried out before and after therapy, and CBF was determined with 133Xe inhalation. ② Assessment criteria of curative effects : Basically cured: neurologic symptoms and body signs disappeared, could work and do housework; Markedly effective: score of neurologic deficit was decreased by 21 points, could manage himself / herself partially; Effective: score of neurologic deficit was decreased by 8 to 12 Total effective rate = (number of cured + number of markedly effective + number of effective) / number of total cases × 100% . ③ t test and Chi-square test were used for comparing the difference of measurement data and enumeration data respectively, and Ridit analysis was used for comparing the difference of clinical curative effects . MAIN OUTCOME MEASURES: ① Comparison of EEG and CBF of patients from two groups before and after treatment. ② Comparison of post-treatment neurologic deficit of patients between two groups. RESULTS: All involved in 96 patients with CI participated in the final analysis. ① Clinical symptoms of patients from two groups after therapy were significantly improved as compared with those before treatment, and curative effects of early treatment group were better than those of advanced treatment group (U = 1.99, P <0.05). ②After treatment, CBF in each region of brains, except for that in parietal lobe of patients in the advanced-stage treatment group, was significantly improved (P <0.05-0.01); The improvement of CBF of patients in the early-stage treatment group was more obvious than that that in the early-stage treatment group (P <0.05-0.01). ③ The abnormal rate of EEF of patients from early-stage treatment group and advanced-stage treatment group before treatment was 94% and 96%, r espectively. Aftertreatment, improvement rate of EEG of patients in the early-stage treatment group was 95%, which was significantly different from that in the advanced-stage treatment group (82%, χ2 = 4.32, P <0.05) CONCLUSION: HBO therapy both at early and advanced stages of CI (within 1 week and 4 weeks after CI attack) can improve CBF and EEG of patients with early CI, especially.