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Color doppler imaging (GDI) is a diagnostic tool that allows non-invasive evaluation of the orbital and intra-cranial structures. It operates by the doppler principle, which is detecting changes in the frequency of sound that is r...
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Color doppler imaging (GDI) is a diagnostic tool that allows non-invasive evaluation of the orbital and intra-cranial structures. It operates by the doppler principle, which is detecting changes in the frequency of sound that is reflected from flowing blood, allowing estimation of flow velocity. GDI has been used in the diagnosis and follow up of ophthalmic conditions such as central retinal artery occlusion, central retinal vein occlusion, arteritic and non-arteritic ischemic optic neuropathy and the ocular ischemic syndrome. In addition, orbital conditions like varices can be evaluated. Transcranial doppler has been used to assess strokes and arteriovascular malformations of the brain. The main limitation of GDI is that it provides information about velocity and not flow. Despite this, it remains a valuable tool to diagnose ocular and intracranial conditions characterized by ischemia or abnormal blood flow.
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This study tested the hypothesis that reduction in cerebral blood flow (CBF) during orthostatic stress after bed rest can be ameliorated with volume loading, exercise, or both. Transcranial Doppler was used to measure changes in C...
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This study tested the hypothesis that reduction in cerebral blood flow (CBF) during orthostatic stress after bed rest can be ameliorated with volume loading, exercise, or both. Transcranial Doppler was used to measure changes in CBF velocity during lower body negative pressure (LBNP) before and after an 18-day bed rest in 33 healthy subjects. Subjects were assigned into four groups with similar age and sex: 1) supine cycling during bed rest (Exercise group; n = 7), 2) volume loading with Dextran infusion after bed rest to restore reduced left ventricular filling pressure (Dextran group; n = 7), 3) exercise combined with volume loading to prevent orthostatic intolerance (Ex-Dex group; n = 7), and 4) a control group (n = 12). LBNP tolerance was measured using a cumulative stress index (CSI). After bed rest, CBF velocity was reduced at a lower level of LBNP in the Control group, and the magnitude of reduction was greater in the Ex-Dex group. However, reduction in orthostatic tolerance was prevented in the Ex-Dex group. Notably, volume loading alone prevented greater reductions in CBF velocity after bed rest, but CSI was reduced still by 25%. Finally, decreases in CBF velocity during LBNP were correlated with reduction in cardiac output under all conditions (r 2 = 0.86; P = < 0.001). Taken together, these findings demonstrate that volume loading alone can ameliorate reductions in CBF during LBNP. However, the lack of associations between changes in CBF velocity and orthostatic tolerance suggests that reductions in CBF during LBNP under steady-state conditions by itself are unlikely to be a primary factor leading to orthostatic intolerance.
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The effect of combined treatment with transcranial direct current stimulation (tDCS) on cerebral blood flow in patients with symptomatic epilepsy was studied. 29 patients with symptomatic epilepsy were examined and received the co...
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The effect of combined treatment with transcranial direct current stimulation (tDCS) on cerebral blood flow in patients with symptomatic epilepsy was studied. 29 patients with symptomatic epilepsy were examined and received the course of treatment. The comparison group was formed from 14 children who received the course of basic medical and rehabilitation procedures. The main group included 15 children who, in addition to the same therapy, received a course of tDCS. A transcranial Doppler ultrasoundexamination of cerebral blood vessels was used to evaluate cerebral hemodynamics in children with symptomatic epilepsy before and after combined treatment with tDCS. After the course of tDCS, the children had a marked improvement in the EEG pattern, andalso tDCS significantly reduced the high mean blood flow rate per cycle in the basilar, middle, and anterior cerebral arteries (20.5, 17.2, and 7.9%, respectively). In the comparison group, no statistically significant positive dynamics was observed. tDCS significantly increased the low mean blood flow rate in the basilar, middle, and anterior cerebral arteries (by 25.1,20.9, and 10.2%, respectively); a statistically significant increase in MVF by 12.7% was observed only in the middle cerebral artery inthe comparison group of patients. Our data indicate that the use of tDCS in the combined treatment of patients with epilepsy improves cerebral hemodynamics in 84% of patients, in contrast to 58% in the comparison group. Including the method of tDCS to the complex treatment of patients with epilepsy improves the effectiveness of treatment and may also positively influence the clinical course of the disease.
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Purpose: There have been some reports on right-to-left shunt as a cause of cryptogenic stroke. Although contrast transcranial Doppler (c-TCD) can detect RLS, an insufficient temporal window has occasionally restricted its applicab...
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Purpose: There have been some reports on right-to-left shunt as a cause of cryptogenic stroke. Although contrast transcranial Doppler (c-TCD) can detect RLS, an insufficient temporal window has occasionally restricted its applicability. Thus, we compared the rates of detecting RLS among temporal windows for the middle cerebral arteries (MCAs) and the orbital window for the internal carotid artery (ICA) on c-TCD. Methods: We used c-TCD to detect RLS in patients with suspected ischemic stroke. We enrolled patients who had both sufficient bilateral temporal windows for MCAs and a right orbital window for ICA and performed c-TCD using all three windows simultaneously. Results: We enrolled 106 consecutive patients and identified microembolic signals (MES) in 30 (28%) of them. Among these 30 patients, 15 had MES from all 3 windows. When these 30 patients were defined as being positive for RLS, the rates of detection were 67%, 73%, and 80% from the right temporal, left temporal, and right orbital windows, respectively (P= .795). Conclusion: The right orbital window as well as the temporal window for c-TCD could detect RLS. Insonation from the orbital window should be useful for patients who lack temporal windows.
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Purpose: There have been some reports on right-to-left shunt as a cause of cryptogenic stroke. Although contrast transcranial Doppler (c-TCD) can detect RLS, an insufficient temporal window has occasionally restricted its applicab...
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Purpose: There have been some reports on right-to-left shunt as a cause of cryptogenic stroke. Although contrast transcranial Doppler (c-TCD) can detect RLS, an insufficient temporal window has occasionally restricted its applicability. Thus, we compared the rates of detecting RLS among temporal windows for the middle cerebral arteries (MCAs) and the orbital window for the internal carotid artery (ICA) on c-TCD. Methods: We used c-TCD to detect RLS in patients with suspected ischemic stroke. We enrolled patients who had both sufficient bilateral temporal windows for MCAs and a right orbital window for ICA and performed c-TCD using all three windows simultaneously. Results: We enrolled 106 consecutive patients and identified microembolic signals (MES) in 30 (28%) of them. Among these 30 patients, 15 had MES from all 3 windows. When these 30 patients were defined as being positive for RLS, the rates of detection were 67%, 73%, and 80% from the right temporal, left temporal, and right orbital windows, respectively (P= .795). Conclusion: The right orbital window as well as the temporal window for c-TCD could detect RLS. Insonation from the orbital window should be useful for patients who lack temporal windows.
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Abstract Background Stroke, the most devastating consequence of sickle cell anemia (SCA), is associated with endothelial damage and intracranial artery stenosis. We aimed to assess transcranial Doppler (TCD) ultrasound accuracy in...
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Abstract Background Stroke, the most devastating consequence of sickle cell anemia (SCA), is associated with endothelial damage and intracranial artery stenosis. We aimed to assess transcranial Doppler (TCD) ultrasound accuracy in detecting intracranial stenosis when compared to magnetic resonance angiography (MRA). Methods Children with SCA and at least one TCD and MRA within 1?month were identified from a retrospectively collected database. Sensitivity and specificity were obtained to assess the overall accuracy of TCD mean flow velocity (mFV) ≥200?cm/s in detecting vessel stenosis of ≥50%. Multivariate analysis identified independent factors associated with MRA stenosis. Results Among 157 patients in the database, 64 had a TCD and MRA within 1?month (age 11.8?±?5.3?years, 56% female, 20% with cerebral infarcts on MRI, 8 or 13% had mFV ≥200?cm/s and 20% or 21%, had intracranial stenosis ≥50% on MRA). TCD mFV ≥200?cm/s had a high specificity (95%) but low sensitivity (29%) to detecting intracranial stenosis. As a continuous variable, TCD mFV of 137.5?cm/s had maximal specificity (77%) and sensitivity (72%). After adjustment for age, hemoglobin level, transfusion status, hydroxyurea treatment, and vessel, for every increase in cm/sec on TCD, there was a 2% increase in the odds of ≥50% stenosis on MRA (p?收起
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ObjectiveTo evaluate the usefulness of the transcranial doppler ultrasound in the brain death patients. Material and Methods: Transcranial doppler ultrasound was performed in 522 patients with the 522 brain death patients by use o...
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ObjectiveTo evaluate the usefulness of the transcranial doppler ultrasound in the brain death patients. Material and Methods: Transcranial doppler ultrasound was performed in 522 patients with the 522 brain death patients by use of the transcranial doppler ultrasound from January, 1996 to September, 2009. In all cases, transcranial doppler ultrasound patterns, velocity, pulsatility index were analysed. ResultsMale to female was 329 : 193, common ages were fifty : 127 cases, fourty : 121 cases, thirty : 112 cases, etc. Causes of the brain death were spontaneous subarachnoid hemorrhage 139 (26.6%), traumatic subdural hematoma 145 (27.8%), etc. The patterns of the brain death were reverberating flow, systolic peak wave, zero flow, velocity of the cerebral arteries was below 10cm/sec. pulsatility index over 2.5. ConclusionTranscranial doppler ultrasound is very useful noninvasive diagnostic method for brain death.
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Primary hypertension is associated with decreased performance on neurocognitive testing and a blunted cerebrovascular reactivity to hypercapnia. Parents of 14 children with hypertension and prehypertension completed the Behavior R...
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Primary hypertension is associated with decreased performance on neurocognitive testing and a blunted cerebrovascular reactivity to hypercapnia. Parents of 14 children with hypertension and prehypertension completed the Behavior Rating Inventory of Executive Functions. Children underwent 24-hour ambulatory blood pressure monitoring and transcranial Doppler with reactivity measurement using time-averaged maximum mean velocity and end-tidal carbon dioxide during hypercapnia-rebreathing test. Comparing the reactivity slope for the patients to historical controls showed a statistically significant difference (t = -5.19, df = 13, P < .001), with lower slopes. Pearson correlations of the Behavior Rating Inventory of Executive Functions scores with the reactivity slopes showed a statistically significant inverse relationship with Behavioral Regulation Index (r = -.60, P = .02), Metacognition Index (r = -.40, P = .05), and the Global Executive Component (r = -.53, P = .05). Children with hypertension have decreased executive function, and this correlates to low transcranial Doppler-reactivity slopes, suggesting that the brain is a target organ in hypertensive children.
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Carotid duplex ultrasound (CDU) is routinely used for detection of extracranial internal carotid artery (EICA) stenosis in stroke patients. Power M-mode transcranial Doppler (PMD-TCD) is a new technology designed for studying intr...
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Carotid duplex ultrasound (CDU) is routinely used for detection of extracranial internal carotid artery (EICA) stenosis in stroke patients. Power M-mode transcranial Doppler (PMD-TCD) is a new technology designed for studying intracranial vessels. This prospective study was performed for validation of CDU versus digital subtraction cerebral angiography (DSA) and PMD-TCD versus CDU in detection of EICA stenosis. Part I: Validation of CDU versus DSA in 50 stroke patients (100 carotids) admitted to Walter Mackenzie Center, Canada in 2003. All of the CDUs were performed by a sonographer with an HP Sono 5500 device (USA) and a 13-MHz linear probe. The degree of EICA stenosis was measured using DSA according to North American symptomatic carotid endarterectomy trial (NASCET) method by another neuroradiologist blinded to CDU results.Part II: Validation of PMD-TCD versus CDU in another group of 50 patients (100 carotids) with stroke. All PMD-TCD studies were performed with a TCDM100 device (Spencer, USA) and a 2-MHz probe by a sonographer blinded to CDU results.Part I: Compared with DSA, CDU had a sensitivity of 96%, specificity of 100%, positive predictive value (PPV) of 100%, and negative predictive value (NPV) of 82% in detecting EICA stenosis of 50% and over. CDU versus DSA confirmed EICA stenosis of 70% and over with a sensitivity of 88%, specificity of 95%, PPV of 96%, and NPV of 87%.Part II: Compared with CDU, PMD-TCD had a sensitivity of 45%, specificity of 94%, PPV of 50%, and NPV of 93% for detection of EICA-stenosis of 50% and over. PMD-TCD, when compared with CDU, confirmed EICA-stenosis of 70% and over with a sensitivity of 43%, specificity of 99%, PPV of 75% and NPV of 96%. In our center, CDU is a highly reliable noninvasive diagnostic tool for detection of EICA stenosis. PMD-TCD of carotid has a moderate sensitivity for detection of EICA stenosis and is not recommended as a screening test for this purpose.
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