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PubMed2006

Sonographic developmental milestones of the fetal cerebral cortex: a longitudinal study.

OBJECTIVE: To identify sonographic landmarks of normal fetal cortical development. METHODS: Serial ultrasound examinations were performed every 2 weeks from 18 weeks of gestation until term. In each session a detailed examination of the fetal brain was performed and the appearance of the main sulci and gyri was recorded. RESULTS: Twenty-two pregnant women volunteered to participate in the study. The fetal cortex followed an orderly pattern of development. By the time of the first ultrasound examination, at 18 weeks, the major fissures were present. The first sulci could be demonstrated as early as 18 weeks. Main landmarks, represented by the parieto-occipital fissure and the cingulate and calcarine sulci, were present between 22-24 weeks. The central sulcus was present in all cases by 28 weeks. By 30-32 weeks most of the main sulci could be demonstrated. CONCLUSIONS: Prenatal sonographic examinations can accurately demonstrate structures of the fetal cortex. Comparison of our results with those of both magnetic resonance imaging and other sonographic studies shows similarities in the order of appearance of the sulci and gyri, with only minor differences in the exact gestational age at which they are detected. Accurate knowledge of the ultrasound appearance of the fetal cortex at different stages of gestation is important in order to be able to diagnose in-utero malformations of cortical development.

Cerebral Cortex↗
PubMed2006

Rotation of the vermis as a cause of enlarged cisterna magna on prenatal imaging.

OBJECTIVES: Dandy-Walker complex is a continuum of developmental anomalies of the posterior fossa which includes vermian rotation. However, vermian rotation alone may be benign. The aim of this study was to describe our experience with sagittal-plane prenatal ultrasound in the diagnosis of rotation of the vermis in cases of suspected enlarged cisterna magna on routine antenatal imaging, and to describe the follow-up of these patients. METHODS: Seven women, who were referred to our ultrasound unit for evaluation of an enlarged fetal cisterna magna and suspected agenesis of the vermis on axial-plane imaging, underwent further multiplanar studies of the posterior fossa and measurements of the vermis. RESULTS: The mean maternal age was 27 (range, 20-33) years and the mean gestational age at diagnosis was 19.5 (range, 18-31) weeks. The standard axial plane image showed a 'direct communication' between the cisterna magna and the fourth ventricle. In the mid-sagittal plane, the vermis was clearly delineated, with posterosuperior rotation. Vermis size was within normal limits for gestational age in all cases. Findings were confirmed by prenatal magnetic resonance imaging (MRI) in two cases and postnatal MRI and/or sonography in five. During a mean follow-up of 4.5 (range, 1-7.5) years, all children developed normally, with no neurological complications. CONCLUSION: The finding of an enlarged cisterna magna on standard- (axial-)plane ultrasound should be evaluated further in the sagittal plane to determine whether the cause is rotation of a normal vermis. This may spare patients unnecessary tests, anxiety and, in some cases, pregnancy termination.

Adult↗
PubMed2006

Characteristics, associations and outcome of partial agenesis of the corpus callosum in the fetus.

OBJECTIVES: To report, in a population of fetuses diagnosed with partial agenesis of the corpus callosum (PACC), the sonographic characterization, incidence of cerebral, extracerebral and chromosomal anomalies, and outcome. In addition, in some of our cases a comparison was made between findings on ultrasound and fetal magnetic resonance imaging (MRI). METHODS: This was a retrospective study of all cases of PACC seen at two referral centers for prenatal diagnosis of congenital anomalies over a 10-year period. The following variables were assessed: indication for referral, additional cerebral and extracerebral malformations, chromosomal abnormalities, and pregnancy and fetal/neonatal outcome. RESULTS: Among 54 cases of fetal agenesis of the corpus callosum detected in the referral centers during the observation period, PACC was diagnosed at prenatal sonography in 20 cases and confirmed at pre/postnatal MRI and necropsy examinations in 19 cases (35%). These 19 constituted the study group. The diagnosis was made in the sagittal planes and in 12 cases it was made prior to 24 weeks. In most cases the indication for referral was the presence of indirect signs of callosal anomalies, such as colpocephaly. In 10 cases PACC occurred in association with other anomalies and in nine it was isolated. MRI was particularly useful for demonstrating some additional cerebral anomalies such as late sulcation, migrational pathological conditions and heterotopia. Regarding pregnancy outcome, of those diagnosed before 24 weeks which had associated anomalies, all except two were terminated. Of the nine cases with isolated PACC, all were liveborn. Follow-up was available in eight, and two of these (25%) showed evidence of significant developmental delay. In our series the outcome of isolated PACC was not better than that of complete agenesis of the corpus callosum reported in other series. CONCLUSIONS: PACC can be diagnosed reliably and characterized in prenatal life. The sonographic sign present in most cases is colpocephaly. Prenatal MRI can be performed to confirm the diagnosis. It is particularly useful to demonstrate some additional cerebral anomalies such as late sulcation, migrational pathological conditions and heterotopia. The relatively poor survival rate is due to the high rate of terminations and associated major anomalies.

Abnormalities, Multiple↗
PubMed2003

Maternal transcranial Doppler in pre-eclampsia and eclampsia.

Pre-eclampsia affects 3-7% of women and is associated with significant maternal and perinatal morbidity and mortality. Transcranial Doppler (TCD) has been used in pre-eclampsia/eclampsia to evaluate non-invasively the cerebrovascular hemodynamics in the maternal middle cerebral artery. TCD has demonstrated in pre-eclamptic women maternal cerebral vasospasm, which does not correlate with mean arterial pressure assessed simultaneously. Estimated cerebral perfusion pressure, assessed using a modified formula, has been shown to be increased in women with severe and non-severe pre-eclampsia. However, in severe pre-eclampsia, elevated cerebral perfusion pressure is counterbalanced by increases in cerebrovascular resistance and cerebral blood flow is unaffected. In eclampsia a significant fall in cerebral vascular resistance occurs which, in the presence of increases in cerebral perfusion pressure, leads to hyperperfusion. Cerebral vascular changes to date have not been sensitive enough to predict the development of pre-eclampsia or eclampsia. Longitudinal studies with the aim of predicting the onset of pre-eclampsia and to assess the effects of various drugs on the maternal cerebral circulation need to be designed.

Blood Flow Velocity↗
PubMed2003

Oscillations of cerebrovascular resistance throughout the menstrual cycle in healthy women.

OBJECTIVES: Increased concentration of endogenous estrogen during a typical menstrual cycle has been shown to correlate with augmentation of blood flow through the internal carotid arteries (ICAs), which may be related to changes in vascular resistance within the brain. In this study we investigated the effects of endogenous estrogen and progesterone on cerebrovascular impedance in young healthy women. METHODS: The blood flow in the ICA and the common (CCA) and external (ECA) carotid arteries was studied with duplex Doppler sonography. The resistance index (RI) was determined and correlated with plasma 17beta-estradiol concentration in 14 young healthy women throughout their menstrual cycle. RESULTS: The concentration of 17beta-estradiol increased in the follicular phase of the cycle and reached a peak on day 14, whereas concentration of progesterone remained low. Along with an increase in estrogen concentration, the ICA RI had decreased from its initial level on average by 9.2% on day 13 and by 6.7% on day 14 (P < 0.05). In contrast, the trend of the ECA RI was to increase during the peak of estrogen concentration. There were no significant changes in the CCA RI or in the systolic blood pressure, heart rate, hematocrit and hemoglobin concentration through the menstrual cycle. CONCLUSIONS: Estrogen-related augmentation of blood flow through the ICA is caused mainly by decreased cerebrovascular impedance, as shown by a decrease in the ICA RI. These changes in RI suggest that estrogen influences cerebral impedance mainly by altering the resistance of cerebral microvasculature.

Adult↗
PubMed2003

Late onset microcephaly: failure of prenatal diagnosis.

We present a case of recurrent primary developmental microcephaly of late onset, the prenatal diagnosis of which could not be achieved despite performing targeted serial ultrasound scans that revealed no obvious fetal abnormality. Serial scans for head measurements and detailed examination of the brain anatomy by both transabdominal and transvaginal sonography including color and power Doppler assessment revealed no obvious brain abnormality. Frontal lobe distance and thalamic frontal lobe distance at 36 weeks were on the 30th and 50th centiles, respectively. Growth velocity remained on the 50th centile up to 36 weeks; between 36 and 38 weeks measurements were between the 35th and 40th centiles. The infant was delivered by Cesarean section at 38 weeks on parental request. On examination after birth the head circumference was on the 9th centile, but the facies was that of a microcephalic child with a sloping forehead and neurologically he was severely abnormal. The adequacy of the normal reference ranges used is reviewed: the use of sex-specific growth charts at 38 weeks would have demonstrated the biparietal diameter and the head circumference to be on the 20th and 15th centiles, respectively, rather than just below the 40th centile. However, even sex-specific charts may not allow the recognition of a substantial number of affected fetuses.

Brain↗
PubMed1996

Specific cognitive abilities in 2-year-old children with subependymal and mild intraventricular hemorrhage.

Subependymal and mild intraventricular hemorrhages (S/IVH) are likely to affect the subcortical and frontal cortex regions of the brain in premature infants. Damage to the subcortical and frontal areas has been associated with poorer performance in certain abilities, including visual attention, memory for location, and ability to change response set. This study investigated whether S/IVH, occurring at birth, affect these abilities in young children. Two-year-old premature children with S/ IVH, premature children with normal neonatal head ultrasound scans, and full term children with normal births were evaluated on a series of tasks. These tasks were a habituation/novelty preference task (visual attention), Piaget's invisible displacement task (memory for location), an object discrimination reversal task (ability to change response set), and the Bayley Scales of Infant Development (traditional infant test). Premature children with hemorrhage performed significantly less well on the task of ability to remember the last location of a hidden object and on the task of ability to reverse response set. Both groups of premature children performed.

Cerebral Hemorrhage↗
PubMed1996

Cerebral lateralization in random letter task in the visual modality: a transcranial Doppler study.

Seven right handed volunteers were studied to determine cerebral lateralization patterns for a visually presented random letter task. The subjects participated in three conditions, which included resting baseline, passive fixation (nonlinguistic), and random letter (linguistic) tasks. Mean blood flow velocity (MBFV) was recorded using bilateral simultaneous transcranial Doppler measurements in the posterior cerebral arteries in these conditions. The experimental conditions produced an increase in MBFV during both tasks but the linguistic task showed a greater change. There was a tendency toward right lateralization with the linguistic compared to the nonlinguistic tasks. There is a physiological correlate of right hemisphere participation in the processing of the random letter task.

Adolescent↗
PubMed2002

Perspectives of B-mode transcranial ultrasound.

Transcranial color coded sonography has proved valuable in the diagnostic work-up of cerebrovascular disorders in adults. More recently, evidences have converged that transcranial sonography is also useful in the diagnosis of brain parenchymal disorders. Here, a new field of application is the visualization of signal intensity shift in specific brain areas in some neurodegenerative disorders (Parkinson's disease, idiopathic dystonia, and depression). Findings obtained by transcranial ultrasound complement information from other neuroimaging data in these disorders and have led to the generation of new pathophysiological concepts. In this review we summarize the application fields of transcranial sonography with special emphasis on recent findings in neurodegenerative disorders and their implications for future research. As new application and processing techniques are being developed transcranial color coded sonography will gain increasing impact on both diagnosis and research of neurological disorders.

Adult↗
PubMed2005

The intracranial B-waves' amplitude as prognostication criterion of neurological complications in neuroendovascular interventions.

The purpose of this study was to evaluate dynamics of B-waves' amplitudes (BWA) of blood flow velocity (BFV) in patients with cerebrovascular diseases during endovascular operations. We examined 12 patients with neurovascular pathology during neuroendovascular interventions. Patients were divided into two groups: 1st group (6 cases)--without intraoperative neurological complications, 2nd group (6 cases)--with complications. Bilateral monitoring of BFV in middle cerebral arteries was carried out applying Multi Dop X. To estimate BWA Fourier analysis was used. In the 1st group preoperative BWA on the affected side was 3.9 +/- 0.6 cm/s. Intraoperative (during an access to pathologic formation and its embolisation) BWA increased up to 7.7 +/- 1.1 cm/s (p < 0.05). Postoperative BWA decreased to 4.2 +/- 0.8 cm/s. In the 2nd group the preoperative BWA on the affected side was 9.6 +/- 1.1 cm/s (p < 0.05), thus higher than in the 1st group. Intraoperatively we observed further increase of BWA up to 12.1 +/- 2.6 cm/s, accompanied by occurrence or increase of neurological symptoms. Postoperative BWA decreased to 10.4 +/- 2.9 cm/s, whereas we didn't observe regression of neurological symptoms.

Adult↗
PubMed2005

Clinical study of continuous non-invasive cerebrovascular autoregulation monitoring in neurosurgical ICU.

Ultrasonic "time-of-flight" monitor (Vittamed) was used for continuous monitoring of intracranial blood volume (IBV) pulse, respiratory, slow waves and cerebrovascular autoregulation (CA). The objectives are to compare of invasively and non-invasively monitored slow intracranial waves and CA of ICU patients and to evaluate the phase shift between ABP and IBV respiratory waves as a possible estimator of CA. CA monitoring has been performed in 13 patients with severe TBI (age mean/range 30.5/(18-64)). Data were collected from 87 one-hour sessions of simultaneous invasive and non-invasive wave monitoring and from 53 one-hour sessions of invasive and non-invasive CA monitoring. High correlation (R > 0.9) has been obtained between invasively and non-invasively recorded intracranial slow waves. Bland Altman difference between invasively and non-invasively recorded intracranial slow waves is clinically not significant (mean =-0.07, SD = 0.089, alpha = 0.05). Agreement has been confirmed between invasive and non-invasive CA monitoring data in a wide range of R = [-0.85; +0.96]. Hypothesis of the coincidence of invasive and non-invasive CA assessment is accepted (p < 0.05). Phase shift monitoring of permanent respiratory ABP waves and IBV waves permit continuous non-invasive CA estimation without unnatural physical or pharmacological stimulations of CA system.

Blood Pressure↗
PubMed2003

Measurement of tissue oxygenation index during the first three days in premature born infants.

No normal values of tissue oxygenation index (TOI) of the brain are known regarding premature born infants. We measured TOI, a measure for the cerebral hemoglobin oxygen saturation, on the head of 15 preterm infants with a median postmenstrual age of 28 weeks (interquartile range (IQR) between 26-29 weeks) with spatially resolved spectroscopy (NIRO 300, Hamamatsu) during the first three days of life. Infants with intra-ventricular hemorrhage or periventricular leucomalacia before the first measurement, as shown by ultrasound, were excluded. The first measurement was done within the first 6 hours of life, the second and third measurement at, respectively, 24 and 48 hours after this first measurement. The mean TOI was calculated if saturation did not change by more than 5% for at least 30 minutes. Other parameters measured were PaO2, PCO2, pH, mean arterial blood pressure, heart rate, hemoglobin, glycemia and peripheral oxygen saturation. There was a significant increase of TOI after 24 (p < 0.05) and 48 (p < 0.001) hours. The median TOI on the first day was 57% (95% CI: 54-65.7), 66.1% on the second day (95%CI: 61.9-82.3%) and 76.1% on the third day (95%CI 67.8-80.1%). No correlation was found between TOI and peripheral oxygen saturation, blood pressure, PaO2, PaCO2 and hemoglobin concentration after multiple regression analysis. TOI increases in the first three days in premature born babies. The increase of TOI is not due to an increase of oxygenation or mean arterial blood pressure. In our opinion, it reflects the increase in cerebral blood flow during the first three days.

Adult↗
PubMed2003

Intraoperative ultrasound imaging: practical applicability as a real-time navigation system.

Experience with the use of Intaoperative Ultrasound (US) imaging as real time navigation system in neurosurgery is presented and discussed. Since 1987 we have performed US routinely in a wide variety of intracerebral and intramedullar pathologies. In this analysis we define useful intraoperative applications. Accurate definition of deep-seated lesions and their delineation from surrounding anatomical structures is possible with an US frequency of 5 MHz. Small subcortically located lesions can clearly be visualized with a high frequency probe. Differentiation between solid tumor, cyst and necrosis can be delineated. Identification of residual tumor is difficult. Dural sinuses and eventual invading tumor can be visualized by a 10 MHz probe. US guidance can be helpful for puncturing with a catheter, needle or endoscope. Postoperative percutaneous US imaging through a burr hole did not prove to be useful. The intraoperative use of US imaging is a reliable method for determining the size, shape and localization of lesions. It can be used as a practicable, cost effective and timesaving real time navigation system.

Brain Diseases↗
PubMed2003

Intraoperative ultrasound imaging: comparison of pathomorphological findings in US versus CT, MRI and intraoperative findings.

Since 1987, Ultrasound (US) is performed routinely as real time navigation system in our neurosurgical practice. In 374 cases with different pathologies the preoperative CT and MRI images were compared with the intraoperative US images and the operative findings. In all instances, the lesion could be localized and described in detail. US findings correlated with the findings an CT/MRI, concerning size and shape of lesions. US allowed the differentiation of more structural details within tissue compartments. The demarcation of gliomas was not as well defined in US as compared to CT/MRI, which correlated with the intraoperative situation. As for CT/MRI imaging, a correlation between US findings and histopathology of the lesion was not possible. In our opinion. intraoperative US imaging is an excellent tool for localization of cerebral and medullar lesions and for detailed description of their interior. This indicates a widespread applicability of this method in neurosurgery as an anatomical link between preoperative imaging and the reality of the operative field.

Brain↗
PubMed2003

Intraoperative imaging in a comprehensive neuronavigation environment for minimally invasive brain tumour surgery.

BACKGROUND: Development of an image-guided operation theatre offering multimodal information for mini-invasive neurosurgical brain tumour operations. METHODS: A multi-purpose resistive low-field MR scanner with on-off capability, was installed in a radio frequency-shielded operating room with in-room control panel and display. Intraoperative ultrasound imaging with Doppler mode as needed is used to provide check-up image data between intraoperative MR-imaging sessions. Cortical stimulation and registration are performed during awake craniotomies. The neuronavigation systems are customised arm-based and passive optical. The navigation systems show the positions of the ultrasound probe, cortical stimulation electrode, biopsy needles, endoscope and other instruments on the intraoperative MR-images. FINDINGS: Since 1999, 70 patients (mean age 47, range 3-88 years) have been operated with intraoperative MR-guidance (including 10 tumour biopsies, 56 resections). Twenty-one patients (mean age 46, range 16-67 years) underwent awake craniotomy and tumour resection secured with cortical stimulation and usually preoperative fMR-imaging. The present operating environment offered useful multimodal information for surgery of brain tumours in critical locations. Surgical mortality was 0%, morbidity included 3 (4.3%) infections and 2 (2.9%) permanent hemiparesis. Further removal of tumour was continued in 17 cases (57%) out of the 30 cases where intraoperative MR imaging was used for controlling completeness of the resection.

Adolescent↗