Biomedical subjects

W Reith

Publications and source records attributed to W Reith.

At least 19 recordsLinked to original sources

PubMed2006

Simulation of cerebral hemodynamics for preoperative risk assessment.

BACKGROUND: An important part of the medical treatment of many cerebrovascular diseases is the occlusion of brain supplying arteries. Until now, the risk of this intervention can only be estimated by invasive diagnostics including the risk of cerebrovascular accidents. METHODS AND RESULTS: As a supporting tool, a computer model of the circle of Willis was designed. The model is based upon linear differential equations describing electrotechnical circuits extended non-linearly. By these means, time continuous simulations of different states and the online observation of all calculated state variables such as blood pressure and blood flow in every modeled vessel became feasible. For individual simulations, model parameters were determined by MR-angiography and boundary values by simultaneous Duplex-measurements in both carotid and vertebral arteries. State variables generated by the model behaved physiologically and the reaction of individual cerebrovascular systems in critical situations could be investigated by special scenarios. Inaccuracies concerning the determination of model parameters and boundary values of the used differential equations are likely to be resolved in the near future through a more careful and technically improved determination of these values. CONCLUSIONS: Computer models of subjects were created taking in account the individual anatomical and non-linear physical properties of real vascular systems supplying the brain. Thereby information could be obtained concerning the hemodynamic effects of an iatrogenic vascular occlusion.

Brain↗

PubMed2006

Cognitive changes after carotid artery stenting.

INTRODUCTION: We aimed to test changes in cognitive performance after carotid artery stenting (CAS). METHOD: Ten patients were neuropsychologically tested at least 24 h before and 48 h after CAS. To diminish thromboembolic events, we used a proximal protection device. The following neuropsychological tests were selected: The Mini Mental State Examination (MMSE), symbol digit test and subtests of the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) battery (verbal fluency, constructional practice, word list memory and delayed recall). Affective state was determined by the Beck Depression Score (BDS). RESULTS: No patient suffered from depression (BDS <1) or dementia (MMSE 29.9+/-1.5). Nine of the ten patients (P=0.12) showed increased speed in the Number Connection Test (NCT) (corresponding to trail making test). Most patients showed better or similar results concerning delayed recall (P=0.31). No change was observed in the symbol digit test, word list memory, verbal fluency or constructional practice. Better results concerning NCT and delayed recall after carotid stenting might be due to improved brain perfusion. CONCLUSION: After CAS, cognitive and memory performance seem to improve. Further studies with different time intervals and more refined testing, as well as perfusion-weighted imaging, are needed.

Aged↗

PubMed2006

Mutations in the gene encoding peroxisomal sterol carrier protein X (SCPx) cause leukencephalopathy with dystonia and motor neuropathy.

In this report, we describe the first known patient with a deficiency of sterol carrier protein X (SCPx), a peroxisomal enzyme with thiolase activity, which is required for the breakdown of branched-chain fatty acids. The patient presented with torticollis and dystonic head tremor as well as slight cerebellar signs with intention tremor, nystagmus, hyposmia, and azoospermia. Magnetic resonance imaging showed leukencephalopathy and involvement of the thalamus and pons. Metabolite analyses of plasma revealed an accumulation of the branched-chain fatty acid pristanic acid, and abnormal bile alcohol glucuronides were excreted in urine. In cultured skin fibroblasts, the thiolytic activity of SCPx was deficient, and no SCPx protein could be detected by western blotting. Mutation analysis revealed a homozygous 1-nucleotide insertion, 545_546insA, leading to a frameshift and premature stop codon (I184fsX7).

Adult↗

PubMed2006

[Clinical course of a partially thrombosed, symptomatic aneurysm of the basilar artery tip with partial recanalization subsequent to coiling].

A 72-year-old patient was referred to the neuroradiological department for diagnostic angiography. She was suffering from vertigo and double vision. Magnetic resonance imaging performed elsewhere had demonstrated a giant aneurysm of the basilar artery tip 2 cm in diameter. Angiography revealed a large aneurysm with a broad neck that was partially thrombosed, which precluded closure by coiling. Neurosurgical management by clipping also appeared to be unsuitable because of the proximity to the cerebrum. The decision was reached to proceed expectantly by closely monitoring the clinical course. When the aneurysm increased in size in the ensuing weeks, coiling was performed successfully. Angiographic follow-up showed reperfusion of the aneurysm neck and closure was again achieved by repeat coiling. Reperfusion is not a rare complication following coiling and often necessitates renewed intervention.

Aged↗

PubMed2006

[Imaging cervical myelo- and radiculopathy].

PURPOSE: This article gives an overview of the diagnostic possibilities available in the diagnosis of cervical myelo- and radiculopathy. We compared conventional myelography, CTM, and MRI. MATERIAL AND METHODS: Twenty-five patients with clinical evidence of cervical myelo- or radiculopathy were included. Sagittal and transverse T1-weighted (T1w) TSE and T2-weighted (T2w) TSE sequences were compared with myelography and CTM. Statistical analysis was performed using Wilcoxon's -test. RESULTS: Disc herniation could be depicted in CTM as well as in MRI. The extent of herniation did not differ between CTM and T1w. The extent of herniation seemed higher on T2w than on T1w (p <0.001). Foraminal encroachment was easier to diagnose in CTM. When regarding transverse T1w and T2w images simultaneously, a missing root in MRI corresponded to a missing root in CTM and conventional myelography and vice versa. Our data demonstrated the relative inability of MRI to determine whether the compression is by soft tissue or bony structures. CONCLUSION: The present study proposes that MRI, when available, should be the imaging method of first choice in patients with suspected radiculo- and myelopathy.

Adult↗

PubMed2006

[Vascular anomalies of the cerebellopontine angle].

Vascular anomalies of the cerebellopontine angle are rare compared to tumors in this area. Irritation of the trigeminal, facial, or vestibulocochlear nerve may cause trigeminal neuralgia, hemifacial spasm and vertigo, or tinnitus accordingly. Vessel loops in the cerebellopontine cisterns may cause compression at the root entry or exit zone of the cranial nerves V, VII, and VIII, a phenomenon which is called "vascular loop syndrome." Megadolichobasilar artery and aneurysms of the vertebrobasilar system can also lead to dislocation and compression of the cranial nerves and brain stem. Three-dimensional CISS MR imaging and MR angiography are useful in the detection of neurovascular compression. Microvascular decompression is an effective surgical procedure in the management of compression syndromes of the cranial nerves V, VII, and VIII.

Aged↗

PubMed2006

[Anatomy of the cerebellopontine angle].

The cerebellopontine angle (CPA) is an anatomically complex region of the brain. In this article we describe the anatomy of the CPA cisterns, of the internal auditory canal, the topography of the cerebellum and brainstem, and the neurovascular structures of this area.

Brain Stem↗

PubMed2006

[Spondylitis/spondylodiscitis].

Spondylitis is an inflammation of the vertebral body. If the infection is manifested in the vertebral motor segment it is called spondylodiscitis, which can be divided into specific and nonspecific forms. It is clinically impressive that at the beginning of the disease, the patients who are quite often immunosuppressed suffer from localized, especially nocturnally exacerbated backache. The initial diagnostic work-up generally consists of clinical history, examination, laboratory tests, and (especially advanced) imaging findings. Although computed tomography still remains the most frequently used advanced imaging technique, magnetic resonance imaging is the golden standard for the diagnosis of spondylitis and spondylodiscitis.

Back Pain↗

PubMed2006

[Differential diagnosis of back pain].

Back pain is one of the most frequent clinical pictures encountered in a physician's practice. It can pose a great burden on the individual and in addition have a multifactorial origin. It can be caused by intervertebral discs, vertebral joints, nerve roots, ligaments, sacroiliac joints, or a combination of the above. Back pain, as a symptom of a systemic disease, can also be a warning signal of grave disorders such as malignancies or in the event of aortic aneurysm. The well-considered choice of appropriate diagnostic procedures and suitable treatment requires a thorough knowledge of this multifactorial clinical picture.

Back Pain↗

PubMed2006

[Postoperative syndrome after spine surgery].

Postoperative syndrome after spine surgery, i.e., symptoms or syndromes caused by complications or procedure-related consequences, is gaining more and more importance. Due to great improvements concerning imaging and operative techniques (microsurgery, instrumentation) the total number of spinal surgeries as well as their related complications are increasing. Procedure-related postoperative complications including neurological deficit syndromes can occur acutely or at a later date. Concerning imaging techniques for postoperative evaluation after spinal surgery there are several modalities available. Their indications depend on complex factors including initial pathology the surgery was performed for, kind of surgical technique (surgical approach, instrumentation), anatomy of the patient as well as the time between onset of symptoms and surgery. In cases of ambiguous findings, the combination of different imaging techniques can be instrumental.

Back Pain↗

PubMed2006

[Stroke].

Today stroke represents a major medical and political problem in Western industrial nations. High demands need to be placed on the initial diagnostic work-up and therapeutic treatment to ensure that the patients benefit from the recent advancements achieved in diagnostic and therapeutic fields. According to the motto "time is brain" the clinical examination and imaging have to be performed within 60 min ("door to needle time") so that potential patients can be quickly treated with systemic or intra-arterial lysis. However, it should be taken into consideration that the selection of diagnostic imaging facilities depends on several factors such as infrastructure, the time remaining in the diagnostic window, and the severity of the clinical symptoms.

Critical Care↗

PubMed2006

[Imaging of extradural spinal lesions].

There is a wide variety of spinal extradural tumors. In addition to real neoplasms, degenerative diseases, congenital abnormalities and inflammatory disorders can be causes of extradural masses. Due to the bony boundary of the spinal canal, both benign as well as malignant masses can cause progressive neurological deficits including paraplegia. Most of the spinal tumors are benign (hemangioma of the vertebral body, degenerative diseases). In younger patients congenital abnormalities and primary tumors of the spine have to be considered, whereas in adults the list of differential diagnoses should include secondary malignancies such as metastases and lymphomas as well as metabolic disorders such as osteoporotic vertebral compression fracture and Paget's disease. Cross-sectional imaging techniques such as magnetic resonance imaging (MRI) and computed tomography (CT) of the spine often help to make a specific diagnosis of extradural spinal lesions and represent important tools for tumor staging and preoperative evaluation.

Diagnosis, Differential↗

PubMed2006

[Differential diagnosis of non-neoplastic space-occupying lesions of the spinal cord].

This overview addresses the topic of non-neoplastic intraspinal space-occupying lesions. Knowledge of these entities is essential to distinguish them from tumorous processes. A selection of clinically relevant differential diagnoses is presented which pertain to inflammatory, vascular, and degenerative diseases. In addition, special clinical findings, the radiological procedure, and therapeutic possibilities are outlined.

Angiography↗

PubMed2006

[Spinal infections].

Regardless of the compartment involved, imaging of spinal infections and other spinal inflammatory diseases must be performed by magnetic resonance imaging (MRI). This allows early detection of changes in disk space or vertebral bodies. Associated paraspinal and epidural masses are depicted. However, in spinal cord inflammation MRI has a very limited specificity and cannot usually differentiate between the wide array of possible causes of intramedullary lesions. This article covers a spectrum of inflammatory lesions of the spinal cord.

Adult↗

PubMed2006

[Imaging of spinal tumors].

Spinal tumors are often categorized into extradural, intradural extramedullary, or intramedullary. Although this classification represents somewhat of an overgeneralization as a lesion may reside in two compartments, it still helps to characterize spinal tumors. In the intradural, extramedullary space, primary tumors, such as neurofibroma and meningioma, are relatively common. Secondary tumors or leptomeningeal enhancement also occur. In the intramedullary space, primary tumors are far more common than secondary tumors or metastases.

Contrast Media↗

PubMed2006

Filling a cervical spine cage with local autograft: change of bone density and assessment of bony fusion.

To date, it remains debatable whether cervical spine fusion cages should be filled with any kind of bone or bone substitute. Using a bone substitute would produce additional costs, using an autologous bone graft from the iliac crest would make the use of the cage at least questionable. As an alternative, cortical and subcortical bone from the anterior osteophytes of the segment in which the disc has been removed could be used to fill the cage: higher costs and complications at the iliac crest could both be avoided and the cage could be filled. However, the fate of these bone chips made from the anterior osteophytes is unclear as well as whether fusion will occur using this technique. The objective of the current study was to investigate possible changes in the bone density of this local autograft in the cage within the first 12 months after surgery by means of computed tomography. A second objective was to assess segmental bony fusion using this technique. 21 patients, suffering from degenerative disc disease of the cervical spine, were included into this prospective study. They all underwent anterior decompression, cage insertion and plate stabilisation. The cage (Rabea, Signus Medizintechnik, Alzenau, Germany), was filled with bone chips made from the anterior osteophytes of the segment that underwent discectomy. On the third day after surgery as well as three, six and 12 months after surgery, an axial computed tomography scan through the cage was taken and density within the apertures of the cage was measured in a standardised manner. Flexion-extension lateral radiographs were taken to investigate segmental fusion. Statistical significance was assumed to be at a 95 % level of significance. 23 cages were implanted. The mean value of the bone density obtained by computed tomography was 505 (+/- 119) HU on day three, 635 (+/- 156) HU after three months, 769 (+/- 162) HU after six months, and 814 (+/- 198) after 12 months. There was a significant difference when the values after 12 months were compared to those obtained after three days (p < 0.001) and after three months (p = 0.004). Bony fusion was seen in 21 out of 23 segments (91.3 %) after 12 months. It may be concluded that this technique could be an alternative to the current treatment options.

Bone Density↗

PubMed2006

Regulation of MHC class II expression, a unique regulatory system identified by the study of a primary immunodeficiency disease.

Major histocompatibility complex class II (MHC-II) molecules are of central importance for adaptive immunity. Defective MHC-II expression causes a severe immunodeficiency disease called bare lymphocyte syndrome (BLS). Studies of the molecular defects underlying BLS have been pivotal for characterization of the regulatory system controlling the transcription of MHC-II genes. The precisely controlled pattern of MHC-II gene expression is achieved by a very peculiar and highly specialized molecular machinery that involves the interplay between ubiquitous DNA-binding transcription factors and a highly unusual, tightly regulated, non-DNA-binding coactivator called the MHC class II transactivator (CIITA). CIITA single handedly coordinates practically all aspects of MHC-II gene regulation and has therefore been dubbed the master controller of MHC-II expression. Several of the unusual features of the MHC-II regulatory system may be a consequence of the fact that CIITA originated from an ancient family of cytoplasmic proteins involved in inflammation and innate immunity. The function of CIITA in transcriptional regulation of MHC-II genes could thus be a recent acquisition by an ancestral protein having a role in an unrelated system.

Animals↗

PubMed2006

A deficiency in RFX3 causes hydrocephalus associated with abnormal differentiation of ependymal cells.

Ciliated ependymal cells play central functions in the control of cerebrospinal fluid homeostasis in the mammalian brain, and defects in their differentiation or ciliated properties can lead to hydrocephalus. Regulatory factor X (RFX) transcription factors regulate genes required for ciliogenesis in the nematode, drosophila and mammals. We show here that Rfx3-deficient mice suffer from hydrocephalus without stenosis of the aqueduct of Sylvius. RFX3 is expressed strongly in the ciliated ependymal cells of the subcommissural organ (SCO), choroid plexuses (CP) and ventricular walls during embryonic and postnatal development. Ultrastructural analysis revealed that the hydrocephalus is associated with a general defect in CP differentiation and with severe agenesis of the SCO. The specialized ependymal cells of the CP show an altered epithelial organization, and the SCO cells lose their characteristic ultrastructural features and adopt aspects more typical of classical ependymal cells. These differentiation defects are associated with changes in the number of cilia, although no obvious ultrastructural defects of these cilia can be observed in adult mice. Moreover, agenesis of the SCO is associated with downregulation of SCO-spondin expression as early as E14.5 of embryonic development. These results demonstrate that RFX3 is necessary for ciliated ependymal cell differentiation in the mouse.

Animals↗