Acute mountain sickness is not related to cerebral blood flow: a decompression chamber study.
(17/1182)
To evaluate the pathogenetic role of cerebral blood flow (CBF) changes occurring before and during the development of acute mountain sickness (AMS), peak mean middle cerebral artery flow velocities () were assessed by transcranial Doppler sonography in 10 subjects at 490-m altitude, and during three 12-min periods immediately (SA1), 3 (SA2), and 6 (SA3) h after decompression to a simulated altitude of 4,559 m. AMS cerebral scores increased from 0. 16 +/- 0.14 at baseline to 0.44 +/- 0.31 at SA1, 1.11 +/- 0.88 at SA2 (P < 0.05), and 1.43 +/- 1.03 at SA3 (P < 0.01); correspondingly, three, seven, and eight subjects had AMS. Absolute and relative at simulated altitude, expressed as percentages of low-altitude values (%), did not correlate with AMS cerebral scores. Average % remained unchanged, because % increased in three and remained unchanged or decreased in seven subjects at SA2 and SA3. These results suggest that CBF is not important in the pathogenesis of AMS and shows substantial interindividual differences during the first hours at simulated altitude. (+info)
Assessments of flow by transcranial Doppler ultrasound in the middle cerebral artery during exercise in humans.
(18/1182)
This study examined the consistency between three indexes of cerebral blood flow (CBF) obtained by using transcranial Doppler ultrasound in eight human volunteers. Each subject undertook three sessions of graded exercise, consisting of 6 min of rest, 6 min at 20% of maximal oxygen uptake (VO2 max), 6 min at 40% VO2 max, and 6 min of recovery. Values were obtained every 10 ms for the velocity associated with the maximal frequency of the Doppler shift (VP), the intensity-weighted mean velocity (VIWM), and total signal power (P). Beat-by-beat averages for three indexes (P, IWM, provided significantly different results for the percent changes in CBF with exercise. At 20% of VO2 max, P and IWM showed significant (P < 0.05) increases of 8 and 6%, respectively, whereas showed a nonsignificant increase of 3%. At 40% of VO2 max, P and IWM showed significant (P < 0.05) increases of 14 and 8%, respectively, whereas showed a nonsignificant increase of 4%. Our results suggest that the increase in CBF with exercise that has been reported with transcranial Doppler ultrasound needs to be treated with caution, as much of the response could arise as an artifact from the increase in amplitude and frequency of the arterial pressure waveform. (+info)
Transcranial Doppler pattern after intracarotid papaverine and prostaglandin E1 incorporated in lipid microsphere in patients with vasospasm.
(19/1182)
We studied the effects of intracarotid papaverine and prostaglandin E1 incorporated in lipid microsphere (Lipo-PGE1) in relation with transcranial Doppler parameters such as mean flow velocity (MFV) and pulsatile index (PI) of the proximal segment of the middle cerebral artery. Eighty patients with subarachnoid hemorrhage (SAH) were included in this study. In the case of angiographic vasospasm, papaverine at 7 mg/min with total dose below 300 mg per artery and 10-20 micrograms of Lipo-PGE1 were injected in the supraclinoid portion of the internal carotid artery. Vasospasm was improved in 24 patients (63%), however, it was unchanged in 14 patients (37%). The former patients had more favorable outcomes than the latter patients (p < 0.005). After intracarotid injection therapy, the correlation between MFV and PI was classified into three types: type 1, both MFV and PI decreased; type 2, MFV decreased but PI increased; and type 3, both MFV and PI fluctuated. The Glasgow Outcome Scale 3 months after SAH was as follows: type 1 (n = 15), good in 14 (93%) and moderate disability in one (7%); type 2 (n = 9), good in eight (89%) and vegetative state in one (11%); and type 3 (n = 14), moderate disability in five (36%), severe disability in seven (50%), and death in two (14%). Chi-square analysis showed significant differences between type 1 and type 3 (p < 0.005), and type 2 and type 3 (p < 0.005). In conclusion, intracarotid papaverine combined with Lipo-PGE1 was effective for vasospasm but type 3 patients require a different treatment protocol. (+info)
Transluminal angioplasty for middle cerebral artery stenosis in patients with acute ischemic stroke.
(20/1182)
BACKGROUND AND PURPOSE: Precutaneous transluminal angioplasty (PTA) is currently performed to treat supraaortic atherosclerotic lesions. Our purpose was to evaluate the safety and efficacy of PTA for middle cerebral artery (MCA) stenosis in patients with acute ischemic stroke. METHODS: We performed PTA with the use of a microballoon (2-2.5 mm in diameter and 10-13 mm in length) in 10 consecutive patients (mean age, 48 years) who met the following criteria: high-grade M1 stenosis (> 70%) and mild neurologic deficits (NIH stroke scale < 4) and/or recurrent transient ischemic attacks (TIAs) resistant to anticoagulation, or a large area of hypoperfusion in the MCA territory on brain perfusion SPECT scans. During follow-up, we administered antiplatelet agents and evaluated the status of restenosis by angiography (n = 2), brain perfusion SPECT (n = 4), and/or transcranial Doppler sonography (TCD) (n = 7). RESULTS: Stenotic arteries were successfully dilated in nine of 10 patients. Angioplasty failed in one patient because the balloon could not pass through the tortuous cavernous internal carotid artery. None of the patients experienced either peri- or postangioplasty complications. Residual stenosis was less than 50%, and clinical improvement, including elimination of TIAs in four patients who had suffered resistant TIAs, was observed in all patients; improvement of the cerebral perfusion was also noted in two patients with a large hypoperfusion area in the MCA territory. The average follow-up period was 11 months (range, 2 to 36 months). None experienced recurrent stroke during the follow-up period. TCD revealed decreased flow velocity of the MCA after angioplasty in seven patients. CONCLUSION: PTA of the proximal portion of the MCA seems to be a safe and effective therapeutic technique for the prevention of secondary ischemic stroke. (+info)
Cerebral blood flow velocity during neonatal seizures.
(21/1182)
AIM: To determine if cerebral blood flow velocity increases during all types of neonatal seizure, and whether the effect is due solely to an increase in blood pressure, transmitted to the cerebral circulation when autoregulation is impaired. METHODS: Seizures were diagnosed in 11 high risk neonates using cotside 16 channel video-EEG polygraphy. EEG, cerebral blood flow velocity (CBFV) using transcranial Doppler ultrasound, and arterial blood pressure (ABP) measurements were made. At least two 5-10 minute epochs of simultaneous measurements were performed on each infant. These epochs were then reviewed to eliminate artefacts, and one minute data periods containing a clear seizure onset were created. Each period contained 20 seconds before the seizure. Data periods without seizures from the same infants were also analysed and compared with seizure periods. RESULTS: Four infants had purely electrographic seizures-without clinical manifestations. Six infants had electroclinical seizures. One infant displayed both seizure types. A random effects linear regression analysis was used to determine the effect of seizures on CBFV and ABP. A significant increase was found in mean CBFV in those periods containing seizures. The mean percentage change in velocity for all infants was 15.6%. Three infants showed a significant increase in mean ABP after seizures but the overall increase in ABP for all infants was not significant. CONCLUSION: Electroclinical and electrographic neonatal seizures produce an increase in CBFV. In some infants the increase is not associated with an increase in blood pressure. These preliminary results suggest that electrographic seizures are associated with disturbed cerebral metabolism. Treatment of neonatal seizures until electrographic seizure activity is abolished may improve outcome for these infants. (+info)
Methodological parameters influence the detection of right-to-left shunts by contrast transcranial Doppler ultrasonography.
(22/1182)
BACKGROUND AND PURPOSE: Contrast transcranial Doppler ultrasonography is a new method to detect intracardiac right-to-left shunts, such as the patent foramen ovale. However, the methodology of the procedure varies considerably among investigators. This study was undertaken to assess the influence of methodological parameters on the results of the contrast transcranial Doppler examination in the detection of right-to-left shunts. METHODS: A total of 72 patients (mean age, 58.2+/-14.7 years) had a contrast transcranial Doppler ultrasonography examination. To study the influence of methodological factors, patients with evidence of a right-to-left shunt underwent repeated examinations with modified procedures. Parameters under investigation were the timing of the Valsalva maneuver, the dose of the contrast medium, and the patient's posture during the examination. RESULTS: The median contrast signal count was 58.5 and 48.0 (P<0.001) and the median latency of the first intracranially detected contrast signal was 12.5 and 8.5 seconds (P=0.05) when the Valsalva maneuver was performed 5 and 0 seconds after the start of the injection, respectively. Reducing the contrast medium dose from 10 to 5, 2.5, and 1.2 mL resulted in a decline of the median signal count from 54.5 to 28.5, 20.5, and 12.0 (P<0.01), respectively, while the latency of the first contrast signal increased from 13.3 to 14.0, 14.6, and 15.0 seconds (P<0.05). The sitting position also produced a lower signal count than the supine position (P<0.02). CONCLUSIONS: This study demonstrates that several essential methodological parameters influence the results of the contrast transcranial Doppler ultrasonography examination. Therefore, it is necessary to standardize the procedure to permit comparable quantitative assessments of the shunt volume. The findings of the present study suggest that 10 mL of contrast medium be injected with the patient in the supine position and that the Valsalva maneuver be performed 5 seconds after the start of the injection. (+info)
Cerebrovascular reserve before and after vertebral artery angioplasty.
(23/1182)
The selection of patients with severe vertebrobasilar artery stenosis for angioplasty is based mainly on clinical experience rather than on controlled data. We present a patient with severe vertebral artery stenosis in whom we could document the positive effect of angioplasty on posterior circulation hemodynamics by using transcranial Doppler sonography. (+info)
Multivariate analysis of predictors of cerebral vasospasm occurrence after aneurysmal subarachnoid hemorrhage.
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BACKGROUND AND PURPOSE: The role of type of treatment on cerebral vasospasm occurrence after aneurysmal subarachnoid hemorrhage (SAH) has not been studied. Through multivariate analysis we determined the independent prognostic factors of the occurrence of symptomatic vasospasm following aneurysmal SAH in a study cohort of 244 patients undergoing either surgical or endovascular treatment. The prognostic factors of sequelae after aneurysmal SAH were studied as well. METHODS: Symptomatic vasospasm was defined as the association of deterioration in a patient's neurological condition between 3 and 14 days after SAH with no other explanation and an increase in mean transcranial Doppler velocities of >120 cm/s. The prognostic factors were registered on admission and during the intensive care stay. RESULTS: Symptomatic vasospasm occurred in 22.2% surgical patients compared with 17.2% endovascular treatment patients (P=0.37). Multivariate analysis revealed that the probability of occurrence of symptomatic vasospasm decreased with age >50 years (relative risk [RR], 0.47 [0.25 to 0.88]) and severe World Federation of Neurological Surgeons (WFNS) grade measured on admission (RR, 0.43 [0.20 to 0.90]) and increased with hyperglycemia occurring during the intensive care stay (RR, 1.94 [1.04 to 3.63]). No difference in risk of symptomatic vasospasm could be identified between surgical and endovascular treatment. Symptomatic vasospasm (OR, 4.73 [CI, 1. 77 to 12.6]) as well as WFNS grade of >2 (OR, 8.95 [3.46 to 23.2]), treatment complications (OR, 8.39 [3.16 to 22.3]), and secondary brain insults were associated with an increased risk of 6-month sequelae. CONCLUSIONS: Age <50 years, good neurological grade, and hyperglycemia were all associated with an increased risk of cerebral vasospasm whereas treatment was not. This provides a basis for future clinical prospective randomized trials comparing both treatments. (+info)