The curative effect comparison of two kinds of therapeutic regimens on decreasing the relative intensity of microembolic signal in CLAIR trial.

BACKGROUND: Microembolic signals (MESs) are direct markers of unstable large artery atherosclerotic plaques. In a previous study, we found that the number of MESs is associated with stroke recurrence and that clopidogrel plus aspirin more effectively reduce the number of MESs than does aspirin alone. Stroke recurrence is associated with not only the number of MESs but also the size of the MES, which can theoretically be estimated by monitoring the MES intensity via transcranial doppler (TCD). Thus, we compared the effects of clopidogrel and aspirin with aspirin alone on MES intensity using TCD. METHODS: We recruited 100 patients who experienced acute ischemic stroke or transient ischemic attack (TIA) within 7days of symptom onset. All patients also had large artery stenosis in the cerebral or carotid arteries and the presence of MES as revealed by TCD. The patients were randomized to receive either aspirin or clopidogrel and aspirin for 7days. MES monitoring was performed on days 2 and 7. RESULTS: Intent-to-treat (ITT) analysis (46 patients in the dual therapy group, 52 patients in the monotherapy group) and per-protocol (PP) analysis (25 patients in the dual therapy group, 31 patients in the monotherapy group) were performed on 98 patients. The primary finding was that the MES intensity was dramatically reduced in the dual therapy group. ITT analysis of the dual therapy group revealed that the MES intensity was 8.04 (0-16) dB before treatment, 0.00 (0-17) dB on day 2, and 0.00 (0-12) dB on day 7 (P=0.000). In the monotherapy group, the MES intensity was 9.00 (0-20) dB before treatment, 8.25 (0-17) dB on day 2, and 7.0 (0-18) dB on day 7 (P=0.577). PP analysis revealed similar results. No severe hemorrhagic complications were detected. The two patients in this study who experienced stroke recurrence were in the monotherapy group. CONCLUSIONS: Clopidogrel and aspirin more effectively decrease the MES intensity than aspirin alone in patients with large artery stenotic minor stroke or TIA.

Long-term follow-up of myasthenia gravis patients with hyperthyroidism.

OBJECTIVE: To access clinical characteristics and treatment outcome of myasthenia gravis (MG) patients with hyperthyroidism (HT). MATERIALS AND METHODS: The clinical characteristics of 51 MG patients with HT were studied. The treatment outcome was analysed in 34 patients, comparing high-dosage prednisolone (HDP) (group IS), HDP and/or immunosuppressants with antithyroid drugs (group IS + antiHThyr), antithyroid drugs (group antiHThyr), and thymectomy. RESULTS: The prevalence of HT in MG was 17.5%. Group IS showed higher remission of both diseases compared with group antiHThyr, but not with group IS + antiHThyr. Remission of HT and relapse of both diseases showed no difference among the three groups. Ten patients who had thymectomies had a lower relapse of MG but not of HT, whilst remission of both diseases was no different to 24 non-thymectomy patients. CONCLUSION: This study showed a high prevalence of HT in Thai MG. HDP alone can induce remission of both diseases without difference in relapse. Thymectomy lowers MG relapse further but has no influence on HT.

Middle cerebral artery flow velocity correlates with common carotid artery volume flow rate after CO2 inhalation.

Cerebral vasoreactivity can be studied with transcranial Doppler (TCD) by monitoring CO2-induced middle cerebral artery (MCA) velocity changes. Expected MCA mean velocity (Vm) changes due to changes in end-expiratory CO2 (EE-CO2) are established, but reactivity of common carotid artery (CCA) volume flow rate (VFR) has not been extensively reported. The authors assess the relationship between MCA Vm, CCA VFR, and EE-CO2. Ten normal individuals without cerebrovascular disease and with CCA diameters of more than 3.0 mm were studied. CCA VFR was obtained by Color Velocity Imaging Quantification and Ipsilateral MCA Vm by standard TCD methods. Each side was studied before, during, and after inhalation of 5% CO2. EE-CO2, blood pressure, and pulse rate were monitored. Four women and 6 men with mean age of 36 years were included. Significant correlations between MCA Vm and EE-CO2, CCA VFR and EE-CO2, and MCA Vm and CCA VFR were found. MCA Vm and CCA VFR increased 5.2% and 4.3% per mm Hg increase in EE-CO2, respectively. MCA Vm increased 0.3 cm/s for each ml/min increase in CCA VFR. In normal individuals, there is a direct correlation between MCA Vm, CCA VFR, and EE-CO2. Measurement of CCA VFR changes during CO2 inhalation may be an alternative method to estimate cerebral vasoreactivity when the MCA velocity cannot be obtained because of inadequate acoustic temporal windows.

A new dynamic method for detection of internal jugular valve incompetence using air contrast ultrasonography.

The internal jugular (IJ) valve is the only valve between the heart and the brain, preventing venous reflux into the IJ vein. Internal jugular valve competence has been tested by IJ venography. Doppler ultrasonography of the IJ vein and M-mode ultrasonography of the IJ valve, and color flow imaging (CFI) of the IJ vein. However, interpretation of venous Doppler and CFI is difficult, and venography is invasive. The purpose of this study was to evaluate the feasibility of a new dynamic method to test IJ valve competency, and to review the literature regarding the potential clinical importance of this pathophysiology. Ten patients had intravenous injection of agitated air and saline during Valsalva maneuver with B-mode monitoring and CFI of the right IJ vein. Contrast bubbles were clearly identified refluxing into the right IJ vein in 50% of patients. Air contrast studies more often showed IJ valve incompetence than CFI. Bubbles appeared in the IJ vein within 19.2 sec and persisted up to 282 sec. Bubble aggregation was also observed. There was no correlation between positive bubbles and the presence of spontaneous echo contrast on baseline B-mode imaging. Air contrast ultrasound venography (ACUV) is a new noninvasive method to assess competency of the IJ valves. This technique is feasible, appears to be more sensitive than CFI, and adds a new dimension to the study of the venous system in cerebrovascular disease. Potential clinical application includes evaluation of patients with increased central venous pressure, those with morning headaches, and those on positive end-expiratory pressure ventilators.

Mirror-image artifact can affect transcranial Doppler interpretation.

Transcranial Doppler ultrasonography (TCD) allows evaluation of blood-flow velocity in intracranial arteries detection and monitoring of vasospasm in patients with subarachnoid hemorrhage. Spectral Doppler artifacts can affect TCD data. A 1-month series of TCD findings showed marked fluctuation in blood-flow velocity values in both the middle and anterior cerebral arteries of a patient with subarachnoid hemorrhage. A mirror-image artifact of the Doppler fast Fourier transform velocity spectrum resulted in erroneous interpretation of higher flow velocity in certain vessels. This artifact may cause misinterpretation of TCD flow-velocity data and lead to improper diagnosis of the condition and treatment of patients.

Single oral loading dose of phenytoin: a pharmacokinetics study.

In order to determine the optimal single oral loading dose of phenytoin in patients with seizures, a two part study of phenytoin pharmacokinetics was conducted. In the first part, 15 mg/kg of phenytoin was given orally as a single dose to 19 normal medical volunteers with informed consent. Serum concentrations of phenytoin reached the therapeutic level (10 micrograms/ml) with an average of 2.62 +/- 1.25 h. The peak concentrations at 7.26 +/- 4.77 h was 11.95 +/- 2.8 micrograms/ml. The oral loading doses, calculated from a model incorporating a first order of absorption and Michaelis-Menten elimination kinetics to yield the target phenytoin serum concentration of 15 micrograms/ml were 18.7 mg/kg in males and 24.8 mg/kg in females. The larger dose for females is probably required due to the higher total apparent volume of distribution in females than in males. In the second part, seven male and seven female patients with seizures with informed consent received these calculated dosage regimens. For these patients, a single oral loading dose of phenytoin rapidly produced therapeutic concentration (10 micrograms/ml) within an average of 2.04 +/- 0.44 h in males and 2.35 +/- 1.6 h in females with minimal side-effects. For males, the peak concentration at 9.71 +/- 5.94 h was 23.89 +/- 5.46 micrograms/ml and that for females was 21.46 +/- 5.08 micrograms/ml at 7.71 +/- 3.73 h, respectively. Oral loading dose of phenytoin is safe, effective and can be considered in patients who need prompt control of seizures within a few hours, particularly in those areas where medical facilities are limited. It may also replace the intravenous route of phenytoin when the intravenous route is contraindicated.