Transtemporal Ultrasound (US) Assessment of Third Ventricle Diameter (TVD): Comparison of US and MRI TVD in Pediatric Patients.

INTRODUCTION: In a retrospective magnetic resonance imaging (MRI)-based study, we showed that changes of the third ventricle diameter (TVD) are a reliable mirror of changes of the entire ventricular system. The third ventricle is easily accessible in more than 90% of children and adults using ultrasound (US) via the transtemporal bone-window; thus it can be assessed quickly and free of radiation. In order to use transtemporal US determination of TVD instead of MRI/CT in clinical practice, it is important to know if there is a correlation and bias between both methods, which is addressed in this study. MATERIALS AND METHOD: This prospective study investigates 122 children (newborn-18 years). Diagnoses encompassed hydrocephalus (50%), tumors (14.8%), and other intracranial pathologies (35.2%). US-based TVD was measured via the transtemporal bone-window using a phased array 1 to 4MHz transducer. Results were compared with TVD measured on simultaneously acquired axial T1-weighted axial MRI or computed tomography (CT) scans. RESULTS: Overall mean values for TVD were 6.56 ± 5.84 and 6.47 ± 5.64 mm for US and MRI, respectively. There was an outstanding correlation between TVD measured by MRI and US (r = 0.991, p < 0.01). Bland-Altman analysis showed a mean bias of 0.096 mm with limits of agreement of -0.99 and 1.18 mm. CONCLUSION: US- and MRI-based TVD measurements correlate excellently and measure almost identical TVD values. US-based TVD is in mean ∼0.096 mm larger than MRI-based TVD due to a more angulated measurement plane. US is equal to the gold-standard MRI, a fact, opening new avenues for US-based TVD as a first-line assessment tool of ventricular width.

Noninvasive Intracranial Pressure Assessment in Acute Liver Failure.

BACKGROUND: Elevated intracranial pressure (ICP) is an important cause of death following acute liver failure (ALF). While invasive ICP monitoring (IICPM) is most accurate, the presence of coagulopathy increases bleeding risk in ALF. Our objective was to evaluate the accuracy of three noninvasive ultrasound-based measures for the detection of concurrent ICP elevation in ALF-optic nerve sheath diameter (ONSD) using optic nerve ultrasound (ONUS); middle cerebral artery pulsatility index (PI) on transcranial Doppler (TCD); and ICP calculated from TCD flow velocities (ICPtcd) using the estimated cerebral perfusion pressure (CPPe) technique. METHODS: In this retrospective study, consecutive ALF patients admitted over a 6-year period who underwent IICPM as well as measurement of ONSD, TCD-PI or ICPtcd were included. ONSD was measured offline by a blinded investigator from deidentified videos. The ability of highest ONSD, TCD-PI, and ICPtcd to detect concurrent invasive ICP > 20 mmHg was assessed using receiver operating characteristic (ROC) curves. The ROC area under the curve (AUC) was calculated with 95% confidence interval (95% CI) and evaluated against the null hypothesis of AUC = 0.5. Noninvasive measures were also evaluated as predictors of in-hospital death. RESULTS: Forty-one ALF patients were admitted during the study period. In total, 27 (66%) underwent IICPM, of these, 23 underwent ONUS and 21 underwent TCD. Eleven out of 23 (48%) patients died (two from intracranial hypertension). Results of ROC analysis for detection of concurrent ICP > 20 mmHg were as follows: ONSD AUC = 0.59 (95% CI 0.37-0.79, p = 0.54); TCD-PI AUC = 0.55 (95% CI 0.34-0.75, p = 0.70); and ICPtcd AUC = 0.90 (0.72-0.98, p < 0.0001). None of the noninvasive measures were significant predictors of death. CONCLUSIONS: In patients with ALF, neither ONSD nor TCD-PI reliably detected concurrent ICP elevation on invasive monitoring. Estimation of ICP (ICPtcd) using the TCD CPPe technique was associated with concurrent ICP elevation. Additional studies of TCD CPPe in larger numbers of ALF patients may prove worthwhile.

Prospective Study on Noninvasive Assessment of Intracranial Pressure in Traumatic Brain-Injured Patients: Comparison of Four Methods.

Elevation of intracranial pressure (ICP) may occur in many diseases, and therefore the ability to measure it noninvasively would be useful. Flow velocity signals from transcranial Doppler (TCD) have been used to estimate ICP; however, the relative accuracy of these methods is unclear. This study aimed to compare four previously described TCD-based methods with directly measured ICP in a prospective cohort of traumatic brain-injured patients. Noninvasive ICP (nICP) was obtained using the following methods: 1) a mathematical "black-box" model based on interaction between TCD and arterial blood pressure (nICP_BB); 2) based on diastolic flow velocity (nICP_FVd); 3) based on critical closing pressure (nICP_CrCP); and 4) based on TCD-derived pulsatility index (nICP_PI). In time domain, for recordings including spontaneous changes in ICP greater than 7 mm Hg, nICP_PI showed the best correlation with measured ICP (R = 0.61). Considering every TCD recording as an independent event, nICP_BB generally showed to be the best estimator of measured ICP (R = 0.39; p < 0.05; 95% confidence interval [CI] = 9.94 mm Hg; area under the curve [AUC] = 0.66; p < 0.05). For nICP_FVd, although it presented similar correlation coefficient to nICP_BB and marginally better AUC (0.70; p < 0.05), it demonstrated a greater 95% CI for prediction of ICP (14.62 mm Hg). nICP_CrCP presented a moderate correlation coefficient (R = 0.35; p < 0.05) and similar 95% CI to nICP_BB (9.19 mm Hg), but failed to distinguish between normal and raised ICP (AUC = 0.64; p > 0.05). nICP_PI was not related to measured ICP using any of the above statistical indicators. We also introduced a new estimator (nICP_Av) based on the average of three methods (nICP_BB, nICP_FVd, and nICP_CrCP), which overall presented improved statistical indicators (R = 0.47; p < 0.05; 95% CI = 9.17 mm Hg; AUC = 0.73; p < 0.05). nICP_PI appeared to reflect changes in ICP in time most accurately. nICP_BB was the best estimator for ICP "as a number." nICP_Av demonstrated to improve the accuracy of measured ICP estimation.

Noninvasive measurement of intracranial pressure via the pulsatility index on transcranial Doppler sonography: Is improvement possible?

PURPOSE: We hypothesized that using hemodynamic variables could improve the prediction of intracranial pressure (ICP) from the middle cerebral artery pulsatility index (PI) measured with transcranial Doppler sonography. METHODS: In this prospective study, 39 patients with traumatic brain injury were routinely examined with transcranial Doppler sonography, and the middle cerebral artery PI was calculated. A multivariate model including hematocrit, mean arterial blood pressure, heart rate, and arterial CO2 pressure (PaCO2 ) was evaluated. RESULTS: Thirty-nine comatose patients (16 women and 23 men; age range 18-73 years; median 44 years) were included, and 234 data pairs (consisting of ICP and corresponding PI values) were analyzed. ICP ranged from -3 mmHg to +52 mmHg, and PI from 0.6 to 2.85. We found a significant but weak correlation between PI and the square root of ICP (R(2) between 0.29 and 0.34, p < 0.0001). A slightly stronger correlation was detected when hemodynamic variables were incorporated (R(2) between 0.37 and 0.43). Of these variables, mean arterial blood pressure had the most significant influence. CONCLUSIONS: In this study, PI was not a sufficiently strong predictor of ICP to be used in clinical practice. Its reliability did not improve even when hemodynamic variables were considered. Therefore, we recommend abandoning the use of PI for the noninvasive measurement of ICP in clinical practice.

Assessment of brain midline shift using sonography in neurosurgical ICU patients.

INTRODUCTION: Brain midline shift (MLS) is a life-threatening condition that requires urgent diagnosis and treatment. We aimed to validate bedside assessment of MLS with Transcranial Sonography (TCS) in neurosurgical ICU patients by comparing it to CT. METHODS: In this prospective single centre study, patients who underwent a head CT were included and a concomitant TCS performed. TCS MLS was determined by measuring the difference between the distance from skull to the third ventricle on both sides, using a 2 to 4 MHz probe through the temporal window. CT MLS was measured as the difference between the ideal midline and the septum pellucidum. A significant MLS was defined on head CT as > 0.5 cm. RESULTS: A total of 52 neurosurgical ICU patients were included. The MLS (mean ± SD) was 0.32 ± 0.36 cm using TCS and 0.47 ± 0.67 cm using CT. The Pearson's correlation coefficient (r(2)) between TCS and CT scan was 0.65 (P < 0.001). The bias was 0.09 cm and the limits of agreements were 1.10 and -0.92 cm. The area under the ROC curve for detecting a significant MLS with TCS was 0.86 (95% CI = 0.74 to 0.94), and, using 0.35 cm as a cut-off, the sensitivity was 84.2%, the specificity 84.8% and the positive likelihood ratio was 5.56. CONCLUSIONS: This study suggests that TCS could detect MLS with reasonable accuracy in neurosurgical ICU patients and that it could serve as a bedside tool to facilitate early diagnosis and treatment for patients with a significant intracranial mass effect.

Assessment of middle cerebral artery diameter during hypocapnia and hypercapnia in humans using ultra-high-field MRI.

In the evaluation of cerebrovascular CO2 reactivity measurements, it is often assumed that the diameter of the large intracranial arteries insonated by transcranial Doppler remains unaffected by changes in arterial CO2 partial pressure. However, the strong cerebral vasodilatory capacity of CO2 challenges this assumption, suggesting that there should be some changes in diameter, even if very small. Data from previous studies on effects of CO2 on cerebral artery diameter [middle cerebral artery (MCA)] have been inconsistent. In this study, we examined 10 healthy subjects (5 women, 5 men, age 21-30 yr). High-resolution (0.2 mm in-plane) MRI scans at 7 Tesla were used for direct observation of the MCA diameter during hypocapnia, -1 kPa (-7.5 mmHg), normocapnia, 0 kPa (0 mmHg), and two levels of hypercapnia, +1 and +2 kPa (7.5 and 15 mmHg), with respect to baseline. The vessel lumen was manually delineated by two independent observers. The results showed that the MCA diameter increased by 6.8 ± 2.9% in response to 2 kPa end-tidal P(CO2) (PET(CO2)) above baseline. However, no significant changes in diameter were observed at the -1 kPa (-1.2 ± 2.4%), and +1 kPa (+1.4 ± 3.2%) levels relative to normocapnia. The nonlinear response of the MCA diameter to CO2 was fitted as a continuous calibration curve. Cerebral blood flow changes measured by transcranial Doppler could be corrected by this calibration curve using concomitant PET(CO2) measurements. In conclusion, the MCA diameter remains constant during small deviations of the PET(CO2) from normocapnia, but increases at higher PET(CO2) values.

Multimodal assessment of optokinetic visual stimulation response in migraine with aura.

OBJECTIVE: This study aimed to assess activation patterns and the hemodynamic response to optokinetic stimulation in migraine with aura patients compared with controls. BACKGROUND: It has been proposed that altered visual motion processing in striate and extrastriate visual areas is present in migraine patients and might play a role in the pathophysiology of the disease. Besides activating a large visual network, optokinetic stimulation in particular has been shown to provoke symptoms associated with migraine. METHODS: In this study, we examined the response to visual stimulation in 18 migraine with aura patients compared with 18 healthy controls by using functional magnetic resonance imaging and functional transcranial Doppler, thereby assessing the activation pattern of the visual areas (V1-V5) as well as the vasomotor reactivity of the posterior cerebral artery. For stimulation, we used a vertically rotating optokinetic drum with complex colored figures. RESULTS: Group analysis of migraineurs with aura vs controls revealed different activation patterns in functional magnetic resonance imaging: attenuation of the physiological right lateralization with a significantly increased activation in the left V5 complex, the left area V3, and the right V5 complex. Analysis of the visually evoked flow response of the cerebral blood flow velocity in the posterior cerebral artery showed a larger side-difference of the offset latency (P < .05) and a reduced steepness of the decreasing slope on the left side (P < .05). CONCLUSION: Combining examinations with a good structural (functional magnetic resonance imaging) and temporal (functional transcranial Doppler) resolution is a novel approach to migraine pathophysiology. Our findings of an altered pattern of activation by optokinetic visual stimulation with hyperresponsiveness in visual areas activated by motion perception (V5 and V3) further strengthen the concept of an interictal motion-processing deficit in migraine. This is complemented by the slower restitution of the visually evoked flow response after stimulus offset in migraine with aura patients.

Consensus recommendations for transcranial color-coded duplex sonography for the assessment of intracranial arteries in clinical trials on acute stroke.

BACKGROUND AND PURPOSE: Transcranial color-coded duplex sonography has become a standard diagnostic technique to assess the intracranial arterial status in acute stroke. It is increasingly used for the evaluation of prognosis and the success of revascularization in multicenter trials. The aim of this international consensus procedure was to develop recommendations on the methodology and documentation to be used for assessment of intracranial occlusion and for monitoring of recanalization. METHODS: Thirty-five experts participated in the consensus process. The presented recommendations were approved during a meeting of the consensus group in October 2008 in Giessen, Germany. The project was an initiative of the German Competence Network Stroke and performed under the auspices of the Neurosonology Research Group of the World Federation of Neurology. RESULTS: Recommendations are given on how examinations should be performed in the time-limited situation of acute stroke, including criteria to assess the quality of the acoustic bone window, the use of echo contrast agents, and the evaluation of intracranial vessel status. The important issues of the examiners' training and experience, the documentation, and analysis of study results are addressed. One central aspect was the development of standardized criteria for diagnosis of arterial occlusion. A transcranial color-coded duplex sonography recanalization score based on objective hemodynamic criteria is introduced (consensus on grading intracranial flow obstruction [COGIF] score). CONCLUSIONS: This work presents consensus statements in an attempt to standardize the application of transcranial color-coded duplex sonography in the setting of acute stroke research, aiming to improve the reliability and reproducibility of the results of future stroke studies.

Assessment of incomplete clipping of aneurysms intraoperatively by a near-infrared indocyanine green-video angiography (Niicg-Va) integrated microscope.

OBJECTIVE: The objective of this article was to assess the clinical use and the completeness of clipping with total occlusion of the aneurysmal lumen, real-time assessment of vascular patency in the parent, branching and perforating vessels, intraoperative assessment of blood flow, image quality, spatial resolution and clinical value in difficult aneurysms using near infrared indocyanine green video angiography integrated on to an operative Pentero neurosurgical microscope (Carl Zeiss, Oberkochen Germany). MATERIALS AND METHODS: Thirteen patients with aneurysms were operated upon. An infrared camera with near infrared technology was adapted on to the OPMI Pentero microscope with a special filter and infrared excitation light to illuminate the operating field which was designed to allow passage of the near infrared light required for excitation of indocyanine green (ICG) which was used as the intravascular marker. The intravascular fluorescence was imaged with a video camera attached to the microscope. ICG fluorescence (700-850 nm) from a modified microscope light source on to the surgical field and passage of ICG fluorescence (780-950 nm) from the surgical field, back into the optical path of the microscope was used to detect the completeness of aneurysmal clipping RESULTS: Incomplete clipping in three patients (1 female and 2 males) with unruptured complicated aneurysms was detected using indocyanine green video angiography. There were no adverse effects after injection of indocyanine green. The completeness of clipping was inadequately detected by Doppler ultrasound miniprobe and rigid endoscopy and was thus complemented by indocyanine green video angiography. CONCLUSION: The operative microscope-integrated ICG video angiography as a new intraoperative method for detecting vascular flow, was found to be quick, reliable, cost-effective and possibly a substitute or adjunct for Doppler ultrasonography or intraoperative DSA, which is presently the gold standard. The simplicity of the method, the speed with which the investigation can be performed, the quality of the images, and the outcome of surgical procedures have all reduced the need for angiography. This technique may be useful during routine aneurysm surgery as an independent form of angiography and/or as an adjunct to intraoperative or postoperative DSA.

Diagnostic efficacy of SonoVue, a second generation contrast agent, in the assessment of extracranial carotid or peripheral arteries using colour and spectral Doppler ultrasound: a multicentre study.

The purpose of this study was to demonstrate the improvement in diagnostic quality and diagnostic accuracy of SonoVue microbubble contrast-enhanced ultrasound (CE-US) versus unenhanced ultrasound imaging during the investigation of extracranial carotid or peripheral arteries. 82 patients with suspected extracranial carotid or peripheral arterial disease received four SonoVue doses (0.3 ml, 0.6 ml, 1.2 ml and 2.4 ml) with Doppler ultrasound performed before and following each dose. Diagnostic quality of the CE-US examinations was evaluated off-site for duration of clinically useful contrast enhancement, artefact effects and percentage of examinations converted from non-diagnostic to diagnostic. Accuracy, sensitivity and specificity were assessed as agreement of CE-US diagnosis evaluated by an independent panel of experts with reference standard modality. The median duration of clinically useful signal enhancement significantly increased with increasing SonoVue doses (p< or =0.002). At the dose of 2.4 ml of SonoVue, diagnostic quality evaluated as number of inconclusive examinations significantly improved, falling from 40.7% at baseline down to 5.1%. Furthermore, SonoVue significantly (p<0.01) increased the accuracy, sensitivity and specificity of assessment of disease compared with baseline ultrasound. SonoVue increases the diagnostic quality of Doppler images and improves the accuracy of both spectral and colour Doppler examinations of extracranial carotid or peripheral arterial disease.

Assessment: transcranial Doppler ultrasonography: report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology.

OBJECTIVE: To review the use of transcranial Doppler ultrasonography (TCD) and transcranial color-coded sonography (TCCS) for diagnosis. METHODS: The authors searched the literature for evidence of 1) if TCD provides useful information in specific clinical settings; 2) if using this information improves clinical decision making, as reflected by improved patient outcomes; and 3) if TCD is preferable to other diagnostic tests in these clinical situations. RESULTS: TCD is of established value in the screening of children aged 2 to 16 years with sickle cell disease for stroke risk (Type A, Class I) and the detection and monitoring of angiographic vasospasm after spontaneous subarachnoid hemorrhage (Type A, Class I to II). TCD and TCCS provide important information and may have value for detection of intracranial steno-occlusive disease (Type B, Class II to III), vasomotor reactivity testing (Type B, Class II to III), detection of cerebral circulatory arrest/brain death (Type A, Class II), monitoring carotid endarterectomy (Type B, Class II to III), monitoring cerebral thrombolysis (Type B, Class II to III), and monitoring coronary artery bypass graft operations (Type B to C, Class II to III). Contrast-enhanced TCD/TCCS can also provide useful information in right-to-left cardiac/extracardiac shunts (Type A, Class II), intracranial occlusive disease (Type B, Class II to IV), and hemorrhagic cerebrovascular disease (Type B, Class II to IV), although other techniques may be preferable in these settings.

Assessment of transcranial color-coded duplex sonography for the surveillance of intracranial aneurysms treated with Guglielmi detachable coils.

OBJECTIVE: We sought to evaluate the sensitivity and specificity of transcranial color-coded duplex sonography (TCCS) and the effect of an ultrasonographic contrast agent in the long-term surveillance of intracranial aneurysms treated with Guglielmi detachable coils. METHODS: Forty-six studies were obtained in patients with intracranial aneurysms treated with coils. All studies were obtained within 2 months of surveillance digital subtraction angiograms, which was adopted as the standard for observing aneurysm refilling. For 34 of the studies, imaging was performed both before and after infusing an ultrasonographic contrast agent (Levovist). The remaining 12 studies were unenhanced. Aneurysms were described either as being fully occluded or as having residual flow. The degree of residual flow was quantified as minor, moderate, or extensive. The operator was blinded to the results of digital subtraction angiography during TCCS assessment. RESULTS: TCCS correctly identified 19 of 20 aneurysms with complete occlusion (sensitivity, 95%; specificity, 84%). TCCS also identified all 16 of the clinically relevant aneurysms with either moderate or extensive residual flow visualized on digital subtraction angiograms and 5 aneurysms only after contrast enhancement (sensitivity, 100%; specificity, 97%). The overall accuracy of TCCS in identifying clinically relevant aneurysms was 85% without contrast enhancement and 96% with contrast enhancement. CONCLUSION: Contrast-enhanced TCCS shows promise as a noninvasive imaging method for the surveillance of coiled intracranial aneurysms.

Noninvasive cerebrovascular autoregulation assessment in traumatic brain injury: validation and utility.

A moving correlation index (Mx-CPP) of cerebral perfusion pressure (CPP) and mean middle cerebral artery blood flow velocity (CBFV) allows continuous monitoring of dynamic cerebral autoregulation (CA) in patients with severe traumatic brain injury (TBI). In this study we validated Mx-CPP for TBI, examined its prognostic relevance, and assessed its relationship with arterial blood pressure (ABP), CPP, intracranial pressure (ICP), and CBFV. We tested whether using ABP instead of CPP for Mx calculation (Mx-ABP) produces similar results. Mx was calculated for each hemisphere in 37 TBI patients during the first 5 days of treatment. All patients received sedation and analgesia. CPP and bilateral CBFV were recorded, and GOS was estimated at discharge. Both Mx indices were calculated from 10,000 data points sampled at 57.4Hz. Mx-CPP > 0.3 indicates impaired CA; in these patients CPP had a significant positive correlation with CBFV, confirming failure of CA, while in those with Mx < 0.3, CPP was not correlated with CBFV, indicating intact CA. These findings were confirmed for Mx-ABP. We found a significant correlation between impaired CA, indicated by Mx-CPP and Mx-ABP, and poor outcome for TBI patients. ABP, CPP, ICP, and CBFV were not correlated with CA but it must be noted that our average CPP was considerably higher than in other studies. This study confirms the validity of this index to demonstrate CA preservation or failure in TBI. This index is also valid if ABP is used instead of CPP, which eliminates the need for invasive ICP measurements for CA assessment. An unfavorable outcome is associated with early CA failure. Further studies using the Mx-ABP will reveal whether CA improves along with patients' clinical improvement.

Evaluation of a noninvasive transcranial Doppler and blood pressure-based method for the assessment of cerebral perfusion pressure in pregnant women.

OBJECTIVE: We have developed a Doppler method for the estimation of cerebral perfusion pressure (CPP) using noninvasive techniques. Our objective was to evaluate our new method in pregnant women. METHODS AND MATERIALS: Laboring women with a lumbar epidural in situ had transcranial Doppler interrogation of the maternal middle cerebral artery (MCA) to measure systolic, diastolic, and mean velocities. A pressure transducer was connected to the epidural catheter and pressure was recorded. Systolic (SBP), diastolic (DBP), and mean (MAP) blood pressure were taken with a Dinamap monitor. Doppler estimated CPP (mm Hg) = [V(mean)/(V(mean) - V(diastolic)](MAP - DBP) and directly measured CPP = MAP - Epidural pressure data were plotted on a Bland-Altman graph with limits of agreement. The mean difference (the mean of the sum of both positive and negative differences) and absolute difference (the mean of the sum of the absolute differences) were calculated. In addition, linear and polynomial regression analyses were performed. RESULTS: Twenty laboring women were studied. All had normal pregnancies. The mean maternal age was 28 +/- 7 years and the mean gestational age was 39 +/- 2 weeks. The mean maternal MAP was 77 +/- 12 mm Hg. The Bland-Altman plot showed a mean difference of 2.2 mm Hg at a mean CPP of 65 +/- 12 mm Hg; with a standard deviation of 4.8 mm Hg, the absolute difference was 3.9 +/- 3.0 mm Hg at a mean CPP of 65 +/- 12 mm Hg. The regression analysis showed an r = 0.92, r(2) = 0.86, and p < 0.0001. CONCLUSIONS: Our formula allows the estimation of CPP using a simple calculation and noninvasively acquired data. This method may be of use for frequent, easy, and accurate CPP and intracranial pressure estimation and may, as such, have significant research and clinical applications.

Assessment of >/=50% and <50% intracranial stenoses by transcranial color-coded duplex sonography.

BACKGROUND AND PURPOSE: A favorable risk-benefit ratio for warfarin compared with aspirin has been reported for the prevention of major vascular events in symptomatic >/=50% intracranial stenoses. Transcranial color-coded duplex sonography (TCCS) criteria providing an accurate detection of >/=50% and <50% stenoses of the anterior, middle, and posterior cerebral arteries and basilar and vertebral arteries were evaluated retrospectively with angiography used as the standard of reference. METHODS: Prospectively collected TCCS, extracranial color-coded duplex sonography, and intra-arterial digital subtraction angiography data of 310 patients were reviewed. The patients had angiography for confirmation of symptomatic extracranial >/=70% carotid stenoses, symptomatic stenoses (peak systolic velocity higher than the corresponding mean value +2 SDs of 104 normal subjects), and occlusions of the middle cerebral or basilar artery previously assessed by ultrasound. The sonographer was not aware of angiographic findings. RESULTS: TCCS would have detected all 31 of >/=50% intracranial stenoses with 1 false-positive and 35 of 38 <50% stenoses with 3 false-positives. One of 69 stenoses (1%) and 280 of 2741 normal arteries (10%) were missed because of inadequate insonation windows. The corresponding peak systolic velocity cutoffs for >/=50%/<50% stenoses were >/=155/>/=120 cm/s (anterior cerebral artery), >/=220/>/=155 cm/s (middle cerebral artery), >/=145/>/=100 cm/s (posterior cerebral artery), >/=140/>/=100 cm/s (basilar artery), and >/=120/>/=90 cm/s (vertebral artery). CONCLUSIONS: TCCS may reliably assess >/=50% and <50% basal cerebral artery narrowing and prove useful for noninvasive management of patients with symptomatic intracranial stenoses.

Transcranial Doppler assessment of brain death in children.

AIM: To estimate the values of transcranial doppler (TCD) in the determination of brain death in children. METHOD: Fifty-eight comatose children (from 2 days to 13 years, median 28 months) with Glasgow Coma Sores of < or = 7 had TCD examinations. The waveforms and the cerebral blood flow velocities of the middle cerebral arteries (MCAs) were monitored at intervals. Electroencephalogram (EEG) was recorded continuously in 34 patients. Twenty children survived, 38 died, 17 patients met the criteria for determination of brain death by clinical and EEG criteria or by clinical criteria alone. The prevalence of retrograde diastolic flow (RDF) was analysed by using chi-square test. RESULTS: All the brain death patients displayed "special" TCD waveforms including RDF or small systolic forward flow (SFF). RDF appeared in 14, 2 and 3 patients in the brain death, non-brain death and survival group respectively. The occurrence of RDF in the brain death group was significantly higher than in the other two groups (p < 0.01). Persistence of RDF or SSF and direction of flow index < 0.8 in the MCAs for more than 2 hours in serious comatose children, was a reliable indicator to predict or confirm brain death. Using this criteria, no false negative or false positive results were found in this group of patients. CONCLUSION: TCD has a high sensitivity and specificity in the determination of brain death in children.