A prospective study on fetal posterior cranial fossa assessment for early detection of open spina bifida at 11-13 weeks.

The objective of this study was to test three measurements: brain stem (BS), intracranial translucency (IT) and brain stem to occipital bone distance (BSOB), as well as one landmark: cisterna magna (CM) visibility, for early diagnosis of open spina bifida (OSB) in a low risk population. A prospective observational study was undertaken in a university hospital. A sample of 1479 women consented to participate between 20 September 2013 and 30 June 2015. Measurements were performed from the mid-sagittal view, as is routinely used for nuchal thickness assessment. CM visibility was assessed qualitatively as the third anechoic band in the posterior cranial fossa (PCF). All pregnancies were screened with a combination of maternal serum alpha-fetoprotein and second trimester anomaly scan and followed until delivery. Predictive values were calculated for each marker. We were able to diagnose two OSB cases and highly suspect one Dandy-Walker malformation case at the first trimester scan by the observation of PCF. PCF characteristics of OSB cases were increased BS diameter, increased BS-BSOB ratio and non-visualization of the CM. All the markers demonstrated high sensitivity and specificity but CM visibility reached the highest positive predictive value. Due to relatively high false positive rates, PCF measurements could not reach a satisfactory performance to validate their clinical use as a single marker. CM visibility has the advantage of being a qualitative marker and reduces the need for sophisticated and time-consuming measurements. Intracranial translucency and BS-BSOB ratio measurements should be used when the CM visibility is absent or in doubt.

Assessment of the posterior brain at 11-14 weeks for the prediction of open neural tube defects.

OBJECTIVE: To evaluate the routine midsagittal view of the posterior brain at the 11-13 weeks' ultrasound examination, for predicting open neural tube defects. METHODS: Posterior brain was examined midsagittally for normality of the four-line view (upper and lower border of the brain stem, the choroid plexus of the fourth ventricle and the occipital bone). Intracranial translucency and cisterna magna (CM) were measured. RESULTS: The posterior brain was assessed in 1330 cases. The four-line view was normal in all but one case. In the two cases of open spina bifida contained in the study population, intracranial translucency was within normal range. The CM and the four-line view were normal in the first case, whereas in the second case, the four-line view was abnormal, and CM was obliterated and impossible to measure. No other cases of abnormal four-line view were observed in the study population. CONCLUSION: Obliteration of the CM appears to be the most consistent early sign of open neural tube defects. Attention should focus on either measuring the cisterna magna or simply observing the presence of four lines in the midsagittal view of the posterior brain. However, these early signs of brain herniation are not present in all abnormal cases.

The fetal cerebellar vermis: assessment for abnormal development by ultrasonography and magnetic resonance imaging.

Fetal magnetic resonance provides a new tool in the imaging of the posterior fossa and is proving useful in cases that are difficult to assess sonographically by allowing further assessment of the fourth ventricle, cisterna magna, and vermian growth and development. We describe various criteria with which to evaluate vermian growth, including vermian biometry and the relationship between the superior and inferior lobes. We demonstrate 2 markers of normal vermian development: the primary fissure and fastigial point. We illustrate the tegmento-vermian angle, "closure" of the fourth ventricle, and communication of the fourth ventricle with the basal cisterns during development and in several disorders. We correlate those features with the expected embryological course of development and illustrate identification of these features and associated abnormalities of the posterior fossa, brain stem, and central nervous system in mid-trimester scans of fetuses with abnormal development. Correlation with contemporaneous ultrasound examinations is demonstrated.

MRI and multiplanar 3D ultrasound compared in the prenatal assessment of enlarged posterior fossa.

Our aim was to compare the diagnostic capabilities of the multiplanar mode of 3D ultrasound (3D US) and MRI in the assessment of a fetal enlarged cisterna magna. Two fetuses showing an enlarged posterior fossa by conventional two-dimensional ultrasound at 24 and 29 weeks of pregnancy were assessed using both diagnostic methods. One fetus was found to have Dandy-Walker syndrome malformation. In the other, the syndrome was ruled out using both methods. Our results suggest that multiplanar 3D US is able to achieve similar results as does MRI when observing the fetal brain.

[Assessment of neurovascular compression in patients with trigeminal neuralgia with a boundary fusion three-dimensional magnetic resonance cisternogram/angiogram].

Precise assessment of the complex nerve-vessel relationship at the root entry zone (REZ) the trigeminal nerve is useful for the planning of the microvascular decompression (MVD) in patients with trigeminal neuralgia. We have applied a boundary imaging of fusion three-dimensional (3D) magnetic resonance (MR) cisternogram/angiogram. The boundary imaging allows virtual assessment of the spatial relationship of the neurovascular compression at the REZ of the trigeminal nerve. The boundary images depicted complex anatomical relationship of the offending vessels to the trigeminal nerve REZ. The presence of offending vessels, compressive site, and degree of neurovascular compression were assessed from various viewpoints in thl cistern and virtually through the brainstem and trigeminal nerve per se. The 3D visualization of the nerve-vessel relationship with fusion images was consistent with the intraoperative findings. The boundary fusion 3D MR cisternogram/angiogram may prove a useful adjunct for the diag nosis and decision-making process to execute the MVD in patients with trigeminal neuralgia.

Endoscopic microneurosurgery: usefulness and cost-effectiveness in the consecutive experience of 210 patients.

OBJECTIVE: Indications, usefulness, and cost-effectiveness of the endoscope in routine microneurosurgery are not clear. To delineate such aspects, we assessed our experience of endoscopic application and additional cost to use an endoscope. METHODS: Endoscopes were used in 210 patients with cranial base and cisternal pathological features in the previous 7 years. Lesions were located in the extradural cranial base in 78 patients and in the cistern in 132 patients. Rigid lens endoscopes 2.7 to 4 mm in width, 11 to 20 cm in length, and 0 to 70 degrees in angle were used. RESULTS: Endoscopes were used for primary or a significant part of the surgery in 64% of the extradural cranial base procedures. Although endoscopes were used only for visual assistance in 82% of cisternal pathological features, significant benefit was noted in 9% and was not different from cranial base lesions. Eleven patients may have had complications if the endoscope had not been used, and 10 procedures would have been impossible without endoscopic use. Therefore, the number of patients need to treat to experience significant benefits by endoscope was 10. Endoscopic equipment costs an additional 326 US dollars per patient and, hence, significant benefit was the equivalent of 3260 US dollars. No permanent complications resulted from the use of the endoscope. CONCLUSION: The endoscope can be applied safely in routine microsurgery with specific equipment and has proven useful in 1 of 10 patients. To perform more effective procedures using endoscopes, we need to develop specially designed instruments usable through a narrow corridor and in an angled field.

Computerized tomography in the assessment of brain shifts in acute subdural hematoma.

Computed tomography (CT) was used to characterize brain shifts in 30 adult patients (mean age 51.9 years) with fatal supratentorial acute subdural hematomes (ASH) who were admitted within 3 hours of the head trauma. The Glasgow Coma Scale (GCS) score, hematoma width, and midline shift were tabulated. The width of the cistern surrounding the brainstem (CSBS) and the distance from the floor of the fourth ventricle to the posterior clinoid process (IVv-PC) were measured. Opening (+) or disappearance (-) of the suprasellar cistern (SC) was determined using axial CT. The data were compared with those in agematched controls (n = 26) using the Wilcoxon and Kruskal-Wallis tests. The hematomas in the SC(-) group (n = 22, mean GCS score: 3.8 +/- 1.0) were wider (p = 0.02) than those in the SC(+) group (n = 8, mean GCS score: 4.7 +/- 1.5). The CSBS in the SC(+) group was significantly smaller than that in the controls (p < 0.01). In the SC(-) group the CSBS was smaller and the IVv-PC was significantly larger than those in the controls (IVv-PC; p < 0.01) and the SC(+) group (IVv-PC; p < 0.05). In the evolution of brainstem shifts in ASH, when the SC is open the predominant vector is in the direction of the skull base, while when the SC is not observed, an axial vector shifts the brainstem.