Spinal intramedullary schwannomas—report of a case and extensive review of the literature

Neurosurgical Review - Intramedullary schwannomas (IMS) represent exceptional rare pathologies. They commonly present as solitary lesions; only five cases of multiple IMS have been described so...     

Diffusions-Tensor-Bildgebung (DTI) bei Patienten im apallischen Syndrom

Zusammenfassung Hintergrund und Ziel: Die Diagnostik des apallischen Syndroms beschränkte sich bisher auf die klinische Untersuchung und Zusatzuntersuchungen mittels EEG und evozierter Potentiale. Die Bildgebung spielte bei der Diagnosesicherung keine Rolle. Mit der Diffusions-Tensor-Bildgebung (DTI) sollte versucht werden, den Defektbereich im Hirnstamm zu visualisieren. Patienten und Methodik: Sieben Patienten im apallischen Syndrom nach Schädel-Hirn-Trauma (SHT) wurden in einem 1,5-Tesla-MRT-Gerät (INTERA, Fa. Philips) mit koronaren diffusionsgewichteten Spinechosequenzen untersucht. Es wurden sechs nicht kolineare Gradientenanregungen entlang den kortikospinalen Bahnsystemen verwendet. Die Untersuchung fand im Mittel 6 Monate nach SHT statt. Die Rekonstruktion der Faserbahnen erfolgte mit einem IDL-basierten (Interactive Data Language; Research System Inc.) Fiber-Tracking-Tool. Im Defektbereich wurden des weiteren der ADC (apparent diffusion coefficient) und die FA (fraktionelle Anisotropie) bestimmt und mit einer Kontrollgruppe von 20 gesunden Probanden verglichen. Ergebnisse: Die Faserdarstellung zeigte bei allen Patienten eine Unterbrechung der kortikospinalen Bahnsysteme auf Höhe des Mesencephalons. Die ADC-Werte im Defektbereich waren im Vergleich zur Kontrollgruppe normal bis leicht erhöht. Die FA-Werte waren um fast 40% reduziert als Ausdruck einer Schädigung auf zellulärer Ebene. Patienten mit Kontrollen nach 5 Monaten zeigten atrophische Hirnstammveränderungen in Pons und Mesencephalon als morphologisches Korrelat einer Schädigung auf zellulärer Ebene. Schlussfolgerung: Mit Hilfe der DTI ist es erstmals gelungen, die Unterbrechung kortikospinaler Bahnsysteme bei apallischen Patienten zu visualisieren. Die FA-Werte können als Marker der Schädigung auf zellulärer Ebene angesehen werden und dürften für den Verlauf und die Verlaufsbeurteilung dieser Patientengruppe von Bedeutung sein.     

Anatomy of the cerebral ventricular system for endoscopic neurosurgery: a magnetic resonance study

Summary ?Background. Endoscopy has developed into an integral part of minimally invasive neurosurgery. For further technological innovations, detailed knowledge about the pathological anatomy is essential. The gross anatomy of the cerebral ventricular system has been meticulously investigated with ventriculography and casts. Extensive volumetric measurements based on neuroradiological images have been performed, but only little is known about the surgically relevant linear distances in patients with hydrocephalus. Method. Thirty healthy volunteers and thirty patients suffering from hydrocephalus were scanned with high-resolution 3-D magnetic resonance imaging sequences. The image volumes were sliced identically with the help of Siemens Prominence^? software. Individual anatomical measurements of the ventricular system were carried out, mean values and standard deviations were calculated, and different endoscopic approaches were investigated. Findings. In healthy volunteers the measurements confirmed the results obtained from ventriculography and anatomic casts. In hydrocephalic patients the ventricular system was found to be enlarged asymmetrically. The optimal neuroendoscopic approach showed considerable, interindividual variation. Interpretation. This 3-D magnetic resonance imaging study revealed surgically and clinically relevant aspects of the pathologic anatomy of hydrocephalic patients, in comparison to healthy volunteers. Individualized planning of the endoscopic approach appears to be warranted. Finally, the data provided a sound basis for the further development of neuroendoscopes. Published online June 4, 2003     

A new semiautomated,three-dimensional technique allowing precise quantification of total and regional cerebellar volume using MRI

A new method was developed to measure total and regional cerebellar volumes using MRI. Previously, the volumes of the cerebellum and its substructure had been studied planimetri-cally. The new method uses three-dimensional semiautomated volumetry with focus on reliability and performance. The method consists of a manual presegmentation using landmark-adjusted planes followed by region-growing segmentation and calculation of volume. The cerebellum is partitioned into 11 regions defined by planes, which are adjusted for internal cerebellar landmarks (three radial regions inside the vermis that extend into the medial hemisphere (one-fourth of the transverse diameter of the hemisphere); one region in the lateral hemisphere (remaining three-fourths)). Forty-six healthy volunteers were examined and the effects of age, gender, and symmetry were estimated. Shrinkage in the vermis (especially anterior superior compartment) was marked. Age effects diminished laterally and were not observed in the lateral hemisphere. Age effects on the total cerebellar volume were marginal. Effects of gender and symmetry were nonsignificant. Technique and results are discussed and related to methods and findings of others.     

Risk factors for periprocedural complications in carotid artery stenting without filter protection

Introduction In highgrade stenosis, carotid artery stenting (CAS) may be chosen as an alternative to carotid surgery. Ischemic periprocedural complications may be documented best with diffusion–weighted MRI (DWMRI). In this prospective study serial DW–MRI and color–coded duplex sonography (CCDS) were used to identify carotid stenosis, which is associated with an increased risk of ischemic events due to CAS. Methods High resolution DW–MRI were performed in 74 out of 77 patients before and after CAS. All MRI scans were analyzed in a blinded manner. With CCDS each carotid stenosis was evaluated according to the grade, length, echo properties and plaque surface. Results In 42 out of 74 patients (56.8 %) a total of 188 new procedure– related DWI–lesions could be detected, while in 32 patients MRI–controls remained normal. Of the lesions 79.25 % had a size < 1 cm. In one major and two minor strokes due to CAS (total complication rate 3.9 %) corresponding territorial infarcts could be demonstrated. A highly significant correlation was found between the length of the stenosis and the incidence of new DWI–lesions (p = 0.0141). In contrast, neither the grade of ICA stenosis nor the sonographic plaque morphology or plaque surface correlated with the number of DWI–lesion in postinterventional scans. Conclusions The length—and not the degree—of an ICA stenosis seems to be the most decisive sonographic factor for estimating the periprocedural risk of embolism. DWI–lesions are much more frequent than clinical complications and may represent an important surrogate marker for improving the techniques of carotid artery stenting, especially comparing the benefit of different mechanical protection devices.     

Quality planning for minimally invasive procedures in neurosurgery.

Parallel to the introduction of a minimally invasive method in a department, a documentation system should be introduced for quality management. The first step of quality management of an innovation is quality planning. During the course of patients being treated neuroendoscopically, the pre- and postoperative imaging, the intraoperative video recording, the patient-relevant files and the data of the planning have to be documented. These amounts of data require a multimedial documentation concept.We found the CD-ROM as an optimal documentation media because the discs are both cheap and easily accessible and once stored extremely robust against external influences. Therefore, every neuroendoscopically treated patient is documented with all relevant pictures, files and video sequences on a single CD-ROM.     

New virtual system for planning of neuroendoscopic interventions.

OBJECTIVE: The demands on virtual planning systems are increasing, particularly for technically pretentious surgical interventions such as intracranial endoscopy. In this article, a new virtual system for neuroendoscopy (VIVENDI) is presented. The main purpose of this system is to provide support for planning and training in neuroendoscopic interventions. MATERIALS AND METHODS: The software is applied for virtual endoscopic visualization of three-dimensional magnetic resonance datasets, using a clinical magnetic resonance scanner. Rendering is performed on a Hewlett-Packard UNIX workstation. RESULTS: Virtual endoscopy provides a three-dimensional view of the cerebral ventricles, with good visualization of anatomic details. The rendering system used allows the generation of fly-through sequences for the entire ventricular system in real time. Navigation is controlled by mouse movements, and the visualization of the computer-generated intraventricular spaces is adapted to the characteristics of the optical endoscope. CONCLUSIONS: The presented virtual neuroendoscopy system is a promising tool for planning and training in neuroendoscopic procedures. It enables these procedures to be simulated prior to surgery based on the patient's individual anatomy.     

3D spiral CT imaging of bone anomalies in a case of diastematomyelia.

The case of a 48-year-old woman, suffering from a diastematomyelia, is presented. This case and the diagnostic findings are used to demonstrate the demands on imaging methods with respect to a new classification of split cord malformations (SCMs) recently published. Although MRI is the method of choice for imaging of the spinal cord generally, only X-ray methods and especially conventional computer tomography provide the information necessary for correct classification of SCMs. Additional 3D-reconstructions from suitable CT-data are helpful in visualizing complex anomalies of bony structures found in most cases of SCM.     

Interdisciplinary concept for classification and treatment of vascular anomalies in the head and neck]

PURPOSE: In patients with extended vascular anomalies in the head and neck, therapeutic decisions may pose a challenge to maxillofacial surgeons, dermatologists, and interventional radiologists. We analyzed the value of an interdisciplinary classification and treatment concept. PATIENTS AND METHODS: The classification distinguishes hemangiomas and vascular malformations. Whereas hemangiomas are endothelial proliferations, vascular malformations are considered to be developmental anomalies, which are further classified into high-flow or low-flow lesions and according to the vascular channels into capillary, venous, or lymphatic malformations. Since 2000 we have provided interdisciplinary consultation for patients with vascular anomalies. In patients with hemangiomas and venous malformations, the clinical diagnosis is confirmed by color-coded duplex sonography and magnetic resonance imaging; angiography is performed as part of the treatment planning for patients with arteriovenous malformations. Patients with hemangiomas are treated surgically by cryosurgery or laser surgery or conservatively according to lesion size and behavior. In patients with venous malformations, percutaneous sclerotherapy is combined with surgical reduction; patients with arteriovenous malformations undergo transarterial embolization prior to surgical excision of the nidus. RESULTS:A total of 73 patients attended the interdisciplinary consultation. This group included 53 patients with facial hemangiomas, 7 with venous malformations, 2 with capillary malformations, 5 with lymphatic malformations, and 6 with high-flow arteriovenous malformations. CONCLUSIONS: The interdisciplinary protocol increases diagnostic accuracy and helps to establish individual treatment plans for patients with extended vascular anomalies.