We applied frequency domain analysis to detect and quantify spontaneous fluctuations in the blood flow velocity of the middle cerebral artery (MCAFV). Instantaneous MCAFV of normal volunteers was detected using transcranial Doppler sonography. Spectral and transfer function analyses of MCAFV and arterial blood pressure (ABP) were performed by fast Fourier transform. We found the fluctuations in MCAFV, like ABP, could be diffracted into three components at specific frequency ranges, designated as high-frequency (HF, 0.15 to 0.4 Hz), low-frequency (LF, 0.04 to 0.15 Hz), and very low-frequency (VLF, 0.016 to 0.04 Hz) components. The HF and LF components of MCAFV exhibited high coherence with those of ABP, indicating great similarity of MCAFV and ABP fluctuations within the two frequency ranges. However, it was not the case for the VLF component. Transfer function analysis revealed that the ABP-MCAFV phase angle was frequency-dependent in the LF range (r = -0.79, P < 0.001) but not in the HF range. The time delay between LF fluctuations of ABP and those of MCAFV was evaluated as 2.1 seconds. We conclude that in addition to traditional B-wave equivalents, there are at least two different mechanisms for MCAFV fluctuations: the HF and LF fluctuations of MCAFV are basically secondary to those of ABP, and cerebral autoregulation may operate efficiently in LF rather than HF range. Frequency domain analysis offers an opportunity to explore the nature and underlying mechanism of dynamic regulation in cerebral circulation.

This study evaluates the validity of the transfer function analysis of spontaneous fluctuations of arterial blood pressure (ABP) and blood flow velocity of the middle cerebral artery (MCAFV) as a simple, convenient method to assess human cerebral autoregulation in patients with carotid stenosis. Eighty-three consecutive patients with various degrees of carotid stenosis and 37 healthy controls were enrolled. The carotid stenosis was graded based on the diagnostic criteria of duplex ultrasound. Instantaneous bilateral MCAFV and ABP of all participants were assessed noninvasively using transcranial Doppler sonography and the servocontrolled infrared finger plethysmography, respectively. Spectral analyses of ABP and MCAFV were performed by fast Fourier transform. The fluctuations in ABP as well as in MCAFV were diffracted into three components at specific frequency ranges designated as high-frequency (HF; 0.15 to 0.4 Hz), low-frequency (LF; 0.04 to 0.15 Hz), and very low-frequency (VLF; 0.016 to 0.04 Hz). Cross-spectral analysis was applied to quantify the coherence, transfer phase, and magnitude in individual HF, LF, and VLF components. Transcranial Doppler CO2 vasomotor reactivity was measured with 5% CO2 inhalation. The LF phase angle (r=-0.53, P<0.001); magnitude of VLF (r=-0.29, P=0.002), LF (r=-0.35, P<0.001), and HF (r=-0.47, P<0.001); and CO2 vasomotor reactivity (r=-0.66, P<0.001) were negatively correlated with the severity of stenosis. Patients with unilateral high-grade (greater than 90% stenosis) carotid stenosis demonstrated significant reduction in LF phase angle (P<0.001) and HF magnitude (P=0.018) on the ipsilateral side of the affected vessel compared with their contralateral side. The study also revealed a high sensitivity, specificity, and accuracy using LF phase angle and HF magnitude to detect a high-grade carotid stenosis. A strong correlation existed between the LF phase angle and the CO2 vasomotor reactivity test (r=0.62, P<0.001), and the correlation between the HF magnitude and the CO2 vasomotor reactivity (r=0.44, P<0.001) was statistically significant as well. We conclude that transfer function analysis of spontaneous fluctuations of MCAFV and ABP could be used to identify hemodynamically significant high-grade carotid stenosis with impaired cerebral autoregulation or vasomotor reserve.

The age-specific incidence rates in this study are higher than those reported from the United Kingdom and the United States. The rates are close to those in a report from Japan and a report from a city in mainland China at the same latitude. Cerebral hemorrhages are more common among people in Taiwan than among Occidental people.

People with severe jugular venous reflux exhibit more severe age-related white matter changes, especially in caudal brain regions. We also demonstrate age-dependent jugular venous reflux effects on the severity of age-related white matter changes. These findings may provide new clues into the pathophysiology of age-related white matter changes.

No abstract

The effectiveness of acupuncture in acute stroke remains largely untested and unproved. A randomized, controlled trial was carried out to study the feasibility of acupuncture in combination with conventional supportive treatment for acute stroke patients. A total of 30 patients, aged 46-74, with the onset of symptoms within 36 h were enrolled into the study after appropriate screening. All patients gave informed consent. Basing on the same supportive treatment, patients were randomly assigned to a treatment with or without acupuncture. The procedure and acupoint selection were discussed and decided through several meetings of a group of senior acupuncture doctors in Taiwan. Acupuncture was applied 3 times/ week for 4 weeks. During the study period, there were no problems in conducting this trial in terms of patient availability and acceptance, and physician cooperation. A significantly better neurologic outcome was observed in the acupuncture group on day 28 and day 90. The improvement in neurologic status was greatest in patients with a poor neurologic score at baseline. There were no important side effects except for one episode of dizziness related to acupuncture treatment. The data and results of this study will be used as a guideline for planning a full-scale clinical trial, e.g. sample size calculation, method of randomization with stratification of prognostic factors, choosing acupuncture points and technique of acupuncture.

ROAF may result from intracranial hemodynamic compromise. Patients with unilateral high-grade cervical carotid stenosis/occlusion in combination with intracranial stenosis appear to be a significant risk factor for poor functional outcome and increased incidence of ROAF.

We investigated the prevalence of stroke in Taiwan in an epidemiologic study of stroke, diabetes, and cardiovascular disease that used a two-phase survey design. The study population was drawn by cluster sampling and consisted of both urban and rural communities from four regions of Taiwan. There were 8,705 people 36 years of age or older interviewed during the period of October 1 to December 31, 1986, and 143 cases of completed stroke were later identified by a neurologist. The point prevalence rate for people aged 36 or older in our study was 1,642/100,000 population (95% confidence interval 1,389-1,942/100,000). Prevalence rates differed significantly among the four study regions and between urban and rural communities; prevalence was greater in northern Taiwan and in urban communities. Percentages of the major types of stroke in 143 stroke survivors were as follows: cerebral infarction 67.1% (96 cases), cerebral hemorrhage 14.0% (20 cases), subarachnoid hemorrhage 4.2% (six cases), and unclassified 14.7% (21 cases). Of the stroke survivors, 67.1% were independent in activities of daily living, and 75.5% were independent in ambulation. Hypertension, heart disease, diabetes mellitus, and a family history of stroke were significantly more common in stroke survivors than in strokefree individuals. {Stroke 1989;20:858-863) C erebrovascular disease ranked as the most common cause of death in Taiwan in the 20 years from 1963 through 1982. It is now the second cause of death, behind cancer.1 Heart disease, diabetes mellitus, and hypertension were fourth, fifth, and eighth, respectively, on the list of leading causes of death in 1984. To date, few epidemiologic studies concerning incidence, prevalence, and risk factors of these diseases have been conducted in Taiwan. 2 -3 In an attempt to conduct an epidemiologic investigation of these diseases, we began a study entitled "Epidemiologic Study of Stroke, Diabetes, and Cardiovascular Disease," and we present our results concerning prevalence, clinical features, and disability of stroke patients. Subjects and MethodsSince stroke, heart disease, and diabetes affect chiefly the elderly, we selected our study population from people 36 years of age or older in both rural and urban communities. The family was used Received October 13, 1988; accepted January 8, 1989. as the study unit and consisted of people born before 1950. On the basis of geographic location, we randomly chose one rural and one urban community from the northern, central, southern, and eastern regions of Taiwan (Figure 1). Thus, a stratified cluster random-sampling method was used and yielded a total sample population of 13,930. Age, sex, and educational level representative of each community were tested before we began the survey. For the stroke survey, we used a two-phase design that included a door-to-door household survey and physical examination. The 88 interviewers consisted of public health nurses and student nurses who were specifically trained to ensure a high level of sensitivity and specifi...