Physiology of the fetal circulation

Our understanding of fetal circulatory physiology is based on experimental animal data, and this continues to be an important source of new insight into developmental mechanisms. A growing number of human studies have investigated the human physiology, with results that are similar but not identical to those from animal studies. It is time to appreciate these differences and base more of our clinical approach on human physiology. Accordingly, the present review focuses on distributional patterns and adaptational mechanisms that were mainly discovered by human studies. These include cardiac output, pulmonary and placental circulation, fetal brain and liver, venous return to the heart, and the fetal shunts (ductus venosus, foramen ovale and ductus arteriosus). Placental compromise induces a set of adaptational and compensational mechanisms reflecting the plasticity of the developing circulation, with both short- and long-term implications. Some of these aspects have become part of the clinical physiology of today with consequences for surveillance and treatment.     

Offenes Foramen ovale, Vorhofseptumaneurysma und Hirninfarkt

Zusammenfassung Die Frage der Kausalität eines offenen Foramen ovale bei ischämischem Schlaganfall sowie der optimalen Sekundärprävention dieser Patienten wird derzeit kontrovers diskutiert. Die beste verfügbare Evidenz stammt aus Fall-Kontroll-Studien, die in ihrer Gesamtheit auf einen Zusammenhang hindeuten, diesen aber letztlich nicht beweisen können. Neben paradoxen Embolien sind andere Pathomechanismen denkbar, deren genauer Nachweis in der Praxis jedoch nur selten gelingt. Bei niedrigem Rezidivrisiko zumindest für jüngere Patienten kann bei der momentanen Studienlage keine evidenzbasierte Empfehlung zur Sekundärprävention gegeben werden. Mehrere derzeit laufende randomisierte Studien sollen hier in einigen Jahren Klärung bringen. Primäres und sekundäres Risiko erscheinen jedoch deutlich erhöht bei begleitendem Vorhofseptumaneurysma. Zur weiteren Risikostratifizierung sollte der Einfluss begleitender Faktoren wie Shuntgröße und Gerinnungsstörungen weiter untersucht werden.     

Magnitude of right-to-left shunt as the only determinant of stroke in a pair of identical twins

Abstract. Right-to-left shunt due to patent foramen ovale is a well-established risk factor for stroke in the young. The magnitude of shunt seems to be correlated to the risk of stroke in individuals. We report the cases of two 51-year-old identical twins, with similar risk factors for ischemic stroke, in which the sibling with a large and permanent shunt suffered a left hemispheric stroke and the other, with a small and latent shunt, was asymptomatic. In a three-year follow-up, the siblings were both asymptomatic, and the dimensions of shunts were unchanged. Our cases stress the importance of quantifying right-to-left shunt in order to stratify the risk of stroke in individuals, and suggest a role of heredity in patency of foramen ovale.     

Der juvenile ischämische Insult

Zusammenfassung Der juvenile ischämische Insult (Alter bis 45 Jahre) stellt eine diagnostische und therapeutische Herausforderung unter den Schlaganfallsyndromen dar. Ätiologisch kommen eine Vielzahl von z. T. seltenen Krankheiten in Betracht. Vor allem müssen nichtatherosklerotische Arteriopathien — mit der Gefäßdissektion als Hauptvertreter —, paradoxe Embolien und Thrombophilien berücksichtigt werden. Bei flüchtigen Insulten ohne Nachweis struktureller Läsionen kann eine Abgrenzung zu nichtvaskulären Krankheiten (sog. Pseudoinsulten) v. a. einer Migräneaura, einem epileptischen Anfall und einer dissoziativen Störung schwierig sein. Daher führen juvenile Insulte zu einem erheblichen diagnostischen Mehraufwand, der die evidenzbasierten Mindestanforderungen weit übersteigt. Zahlreiche Therapiestrategien beruhen nicht auf großen randomisierten Studien und müssen auf individueller Basis gestaltet werden. Trotz guter Patientencompliance beträgt das jährliche Risiko für Reinsulte etwa 2–3% und für Myokardinfarkte etwa 1%.     

Foramen magnum meningiomas: detailed surgical approaches and technical aspects at Lariboisière Hospital and review of the literature

Foramen magnum meningiomas are challenging tumors, requiring special considerations because of the vicinity of the medulla oblongata, the lower cranial nerves, and the vertebral artery. After detailing the relevant anatomy of the foramen magnum area, we will explain our classification system based on the compartment of development, the dural insertion, and the relation to the vertebral artery. The compartment of development is most of the time intradural and less frequently extradural or both intraextradural. Intradurally, foramen magnum meningiomas are classified posterior, lateral, and anterior if their insertion is, respectively, posterior to the dentate ligament, anterior to the dentate ligament, and anterior to the dentate ligament with extension over the midline. This classification system helps to define the best surgical approach and the lateral extent of drilling needed and anticipate the relation with the lower cranial nerves. In our department, three basic surgical approaches were used: the posterior midline, the postero-lateral, and the antero-lateral approaches. We will explain in detail our surgical technique. Finally, a review of the literature is provided to allow comparison with the treatment options advocated by other skull base surgeons.     

Posterior fossa morphometry in symptomatic pediatric and adult Chiari I malformation

The linear dimensions and volume of the posterior fossa, and the length of the supra-occiput and the clivus in children with Chiari I malformations (CMI) were studied. A statistical relationship between patient demographics, radiological features, posterior fossa and occipital bone morphometry in the study and control groups was investigated. The results of 21 pediatric patients was compared to those of a matched control group. The posterior fossa volume (PFV) of an adult CMI group was also studied. Linear measurements were used to calculate the length of the occipital bone, spherical PFV and intracranial volume (ICV) using pre-operative MRI and CT scans. A PFV to ICV ratio was obtained to standardize the comparison. The volumetric measurement in the pediatric study group was also compared to the adult CMI group.The antero-posterior dimension, width, and volume of the posterior fossa and the PFV to ICV ratio in pediatric CMI patients was significantly lower than in the control group (p < 0.05). There was no statistical difference in the length of the clivus and the supra-occiput between the two pediatric groups. The difference in the PFV to ICV ratio between pediatric and adult CMI patients was not statistically significant. Thus, the authors provide a simple, yet accurate, and reproducible method of comparison of posterior fossa volume in patients with CMI in different age groups, based on linear measurements. There is no significant difference between the length of the occipital bone at the base of the skull in pediatric CMI patients and the normal pediatric population. Development of the clivus due to late fusion of the sphenoid and occipital synchondroses in the second decade could result in manifestation of the disease in adulthood in CMI patients who were asymptomatic as children.     

Jugular foramen schwannoma in a child treated with complete surgical excision

INTRODUCTION: A rare case of a large jugular foramen tumour presenting as a posterior fossa mass is described. MATERIALS AND METHODS: The patient, a 13-year-old boy presented with symptoms of raised intracranial pressure and on MRI imaging demonstrated the tumour origin within the jugular foramen, with appearances suggestive of schwannoma. He underwent a complete excision as a single-stage procedure thorough a lateral suboccipital craniotomy with minimal morbidity. Histology confirmed the diagnosis of schwannoma (WHO I). Jugular foramen schwannoma is virtually unheard of in the paediatric population. CONCLUSION: The differential diagnosis of a jugular foramen tumour includes tumours of the glomus jugulare, meningiomas, schwannomas, myxomas and chondrosarcomas. The imaging characteristics are important when considering this differential diagnosis.     

X线和神经刺激器双引导经卵圆孔半月神经节周围注射阿霉素治疗三叉神经痛的效果

目的 探讨X线和神经刺激器双引导经卵圆孔半月神经节周围注射阿霉素治疗三叉神经痛的效果.方法 原发性三叉神经痛患者78例,年龄29～89岁,病程6月～30年.在C型臂X线和神经刺激器双引导下经卵圆孔半月神经节周围注射0.5%阿霉素0.5 ml,于治疗前及治疗后当日、7 d、1、6、12、24月时评估疼痛缓解程度,计算有效率、优良率、完全缓解率和复发率,观察并发症的发生情况.结果 所有患者均顺利完成卵圆孔穿刺和治疗.治疗后当日、7 d、1、6、12、24月完全缓解率分别为21%、18%、51%、45%、43%、39%;优良率分别为42%、41%、68%、65%、62%、54%;有效率分别为76%、82%、92%、91%、78%、70%;治疗后6、12、24月复发率分别为3%、20%、35%.眩晕、恶心、呕吐的发生率12%,复视发生率1%,面部肿胀、血肿的发生率6%,面部感觉减退发生率22%,患侧咀嚼无力发生率5%,均可自行恢复或对症治疗后恢复.结论 X线和神经刺激器双引导下,经卵圆孔半月神经节周围注射0.5%阿霉素0.5 ml治疗三叉神经痛具有一定的的疗效,且安全性较高.     

Surgical management of foramen magnum meningiomas

The objective of the study is to describe our experience in the surgical management of foramen magnum meningiomas with regard to the clinical-radiological findings, the surgical approach and the outcomes after mid-term follow up. Over a 5-year period, 15 patients presenting with meningiomas of the foramen magnum underwent surgical treatment. The medical records were reviewed in order to analyze the clinical-radiological aspects, as well as the surgical approach and the outcomes. Based on the preoperative magnetic resonance imaging exams, the tumors were classified as anterior or anterolateral in the axial slices and clivospinal or spinoclival in the sagittal slices. The lateral approach was used in all cases. However, the extent of bone removal and the management of the vertebral artery were tailored to each patient. Fourteen patients were females, and one was male, ranging in age from 42 to 74 years (mean 55,9 years). The occipital condyle was partially removed in eight patients, and in seven patients, removal was not necessary. Total removal of the tumor was achieved in 12 patients, subtotal in two, and partial resection in one patient. Postoperative complications occurred in two patients. Follow-up ranged from 6 to 56 months (mean 23.6 months).There was no surgical mortality in this series. The extent of the surgical approach to foramen magnum meningiomas must be based on the main point of dural attachment and tailored individually case-by-case. The differentiation between the clivospinal and spinoclival types, as well as anterior and anterolateral types, is crucial for the neurosurgical planning of foramen magnum meningiomas.     

Endoscopic biopsy of foramen of Monro and third ventricle lesions guided by frameless neuronavigation: Usefulness and limitations

Objectives

To describe our institution experience regarding the usefulness and limitations of frameless neuronavigation in the endoscopic biopsy of foramen of Monro and third ventricle lesions.

Methods

We report our experience with 22 patients harbouring intraventricular lesions located in the region of the foramen of Monro or the third ventricle who underwent endoscopic biopsy guided by the neuronavigation system. Nine lesions were located on the posterior aspect of the third ventricle or at the pineal region, and thirteen lesions were located at the foramen of Monro or anterior third ventricle region. The endoscopes were introduced via an operating sheath, which had previously been inserted with a trocar under neuronavigational control. After approaching the foramen of Monro from the planned angle, surgery was continued under direct visualisation until the lesion was reached, if it was located on the third ventricle. In cases where the lesion was located at the foramen of Monro, an excellent view of the lesion was obtained and neuronavigation was used to determine the location of critical areas.

Results

Histological examination of biopsy specimens obtained endoscopically was diagnostic in all cases. Open surgery following endoscopic biopsy was only needed in 1 patient out of 22.

Conclusion

In our experience, image-guided neuroendoscopy can improve the accuracy of the endoscopic approach, minimising brain trauma. It can be particularly helpful when performing a brain biopsy in the absence of clear intraventricular landmarks or in the event of adverse visual conditions such as intraventricular bleeding.