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M H T Reinges

Publications and source records attributed to M H T Reinges.

15 recordsLinked to original sources
PubMed2006

Silent microemboli related to diagnostic cerebral angiography: a matter of operator's experience and patient's disease.

INTRODUCTION: The aim of the present investigation was to elucidate in a large consecutive patient cohort whether the level of training has an effect on the number of microemboli detected by diffusion-weighted imaging (DWI) and which additional risk factors can be identified. METHODS: A total of 107 consecutive patients in whom a diagnostic cerebral angiography had been performed were prospectively investigated with DWI; 51 angiographies were performed by experienced neuroradiologists, 56 by neuroradiologists in training. RESULTS: In 12 patients (11.1%), a total of 17 new lesions without any clinically overt neurological symptoms were identified. Of these, 12 patients, 11 (91.7%) with 16 lesions were investigated by junior neuroradiologists. In 11 of 12 patients with DWI abnormalities (91.7%), risk factors could be identified (atherosclerotic vessel wall disease, vasculitis, hypercoagulable states). Experienced neuroradiologists performed 21 of 48 angiographies (43.8%) on patients with the above-mentioned risk factors, whereas junior neuroradiologists performed 27 angiographies in this subgroup (46.2%). The rate of diffusion abnormalities in patients with risk factors was 11/48 (22.9%) - considerably higher than in patients without risk factors (1/59; 1.7%). CONCLUSION: The level of experience and the nature of the underlying disease are predictors of the occurrence of cerebral ischemic events following neuroangiography. Alternative diagnostic modalities should be employed in patients who are investigated for diseases with the highest risk of angiographic complications (i.e., vasculitis, and arteriosclerotic vessel wall disease). If diagnostic angiography remains necessary in these patients, the highest level of practitioner training is necessary to ensure good patient outcome.

Adolescent↗
PubMed2006

Diffusion tensor imaging in acquired blind humans.

Retinal implants as a future possible therapy of blindness rely on an intact neural transmission from the retina to the primary visual cortex. By now it remains unknown, in how far the absence of afferent input in blindness affects also the organization of the optic radiation. Using diffusion tensor imaging (DTI), the non-invasive evaluation of large fiber tracts including the optic radiation has become possible. This method is sensitive to changes of the axonal state such as wallerian degeneration. We have compared DTI data from 6 acquired blind patients with those of a group of 11 healthy control subjects. Neither the relative anisotropy quotient of the visual fiber tract and the pyramidal tract showed a statistically significant difference between the blind patients and the control group nor did the absolute values of the relative anisotropy in the pyramidal tract and the visual fiber tract. There was no axonal degeneration of the optic radiation in late onset acquired blindness. With the optic pathways remaining intact, transmitting electric signals of retinal implants to the visual regions of the human brain seems to be possible even after decades of acquired blindness.

Adult↗
PubMed2005

Primary lymphoma of the skull base.

This case demonstrates the rare finding of a primary malignant lymphoma of the frontobasis and ethmoidal cells in a patient presenting with progressive loss of vision. Computed tomography and MRI demonstrated a homogenously enhancing tumour with extensive bony destructions of the skull base. After transsphenoidal biopsy, histology revealed a highly malignant primary B-cell lymphoma. The patient was further treated with immunochemotherapy. Tissue diagnosis is, therefore, crucial before a definitive therapy is instituted.

Biopsy↗
PubMed2005

Image-guided microneurosurgical management of small cerebral arteriovenous malformations: the value of navigated computed tomographic angiography.

In small arteriovenous malformations (AVM) with large hematomas, surgery remains the main therapeutic option. However, intraoperative identification of the AVM, feeders, and draining veins could be difficult in the environment of substantial intracerebral blood. In those selected cases, we use navigated computed tomographic angiography (CTA) for the microneurosurgical management. It is our objective to report our initial experiences. Prior to operation a conventional CTA with superficial skin fiducials placed on a patient's head was acquired for diagnostic and neuronavigation purposes. Image data were transferred to a neuronavigation device with integrated volume rendering capacities which allows a three-dimensional reconstruction of the vascular tree and the AVM to be created. In all patients the AVM was removed successfully after having been localized with CTA-based neuronavigation. Navigated CTA is helpful for the operative management of small AVMs with large hematomas. The technique allows feeding arteries to be distinguished from draining veins thereby allowing the nidus of the AVM to be identified despite the presence of substantial intracerebral blood. CTA can be easily implemented into commercial neuronavigation systems.

Adult↗
PubMed2004

Spontaneous regression of two supraophthalmic internal cerebral artery aneurysms following flow pattern alteration.

We report on a patient with fibromuscular dysplasia who presented with a right-sided giant calcified cavernous internal carotid artery (ICA) aneurysm and two additional supraophthalmic ICA aneurysms. Endovascular closure of the right ICA using detachable balloons was performed with collateralisation of the right hemisphere via the right-sided posterior communicating and the anterior communicating arteries. Repeat angiography after 6 months demonstrated spontaneous complete regression of the two supraophthalmic aneurysms, although the parent vessel was still perfused. In comparison to the former angiography, the flow within the parent vessel was reversed due to the proximal ICA balloon occlusion. MRI demonstrated that the aneurysms were not obliterated by thrombosis alone, but showed a real regression in size. This case report demonstrates that changes in cerebral hemodynamics potentially lead to plastic changes in the vessel architecture in adults and that aneurysms can be flow-related, even if not associated with high flow fistulas or arteriovenous malformations, especially in cases with an arterial wall disease.

Aged↗
PubMed2004

Double spinal dural arteriovenous fistulas: case report and review of the literature.

Spinal dural arteriovenous fistula (SDAVF) is the most common spinal vascular malformation. It mainly affects men after the fifth decade and is usually an acquired lesion with an unknown etiology. We report on a patient with the unusual finding of two separate SDAVFs at the level of L1 on the right and L2 on the left side. Initial selective spinal digital subtraction angiography (DSA) was terminated with demonstration of a SDAVF at the level of L1 but incomplete demonstration of all segmental arteries. Due to a recurrent deterioration of the patient's neurological status, and persistent pathological vessels seen on MRI, a second spinal DSA was performed 6 years later, demonstrating the second fistula at the level of L2 on the left side with a separate venous drainage pattern. A retrospective analysis of the angiographic films suggested that both fistulas had already been present 6 years previously. This conclusion is justified because of a transient and faint opacification of the left L2 fistula demonstrated on the films after injection of the right L2 segmental artery. We conclude that in the case of incomplete angiography and persistent clinical and MR findings not only reopening of the treated SDAVF has to be taken into account but also the existence of a second fistula. Since this is the first case of a double fistula in our series of 129 SDAVFs, and given the few reported cases of double SDAVFs, we do not think that completion of selective spinal DSA has to be postulated routinely after a fistula has been found. However, repeat angiography should be performed in patients who continue to deteriorate, fail to improve with persisting MRI pathologies, or demonstrate delayed deterioration after a period of improvement.

Angiography, Digital Subtraction↗
PubMed2004

Course of brain shift during microsurgical resection of supratentorial cerebral lesions: limits of conventional neuronavigation.

BACKGROUND: The authors have conducted a prospective study to evaluate the amount and course of brain shift during microsurgical removal of supratentorial cerebral lesions, and to assess factors which potentially influence these shifts. METHOD: In 61 patients the displacement of 2-3 cortical landmarks on the cerebral surface was dynamically quantified during surgery, i.e. during dissection of the tumour at the estimated half-time of surgery, and at the end of microsurgical removal of the cerebral lesion using the neuronavigation system EasyGuide Neuro. In 14 of these patients the displacement of a subcortical landmark was additionally analysed. Age of the patients, preoperative midline shift, location of the lesion, lesion volume, depth of the lesion below the cortical surface, presence or absence of oedema, and size of the craniotomy were analysed for potential influence on the amount of brain shift. Correlations were analysed for all patients together and for the subgroups of vault meningiomas (n=10), gliomas (n=30), and nonglial intra-axial lesions (n=21). FINDINGS: The mean displacement of the cortical landmarks ranged between 0.8 and 14.3 mm (mean: 6.1 mm, standard deviation: 3.4 mm) during surgery (10-210 minutes [mean: 50.7 minutes, standard deviation: 34.5 minutes] after dura opening) and between 2.4 and 15.2 mm (mean: 6.6 mm, standard deviation: 3.2 mm) at the end of microsurgical removal of the tumourous cerebral lesions (20-375 minutes [mean: 107.2 minutes, standard deviation: 65.6 minutes] after dura opening). Significant correlations (p<0.01) for the entire patient group were found between brain shift and tumour volume, midline shift, and size of the craniotomy, respectively. For the subgroup of vault meningiomas a significant correlation (p<0.01) between brain shift and patient age was found. For the subgroup of gliomas a significant correlation (p<0.01) between brain shift and tumour volume, midline shift and size of the craniotomy, respectively, was found. For the subgroup of nonglial intra-axial lesions a significant correlation (p<0.01) between brain shift and midline shift and between brain shift and size of the craniotomy was found. The quantity of shared common variance ranged between 10-50%. Performing a discriminant analysis, lesion volume was the only certain factor influencing brain shift intra-operatively as well as at the end of lesion removal. 58.5% of the extent of brain shift could be correctly classified by the tumour volume as the only discriminating variable during dissection of the tumour and at the end of surgery. Comparing superficial with subcortical brain shift over the same time period, a mean superficial shift of 4.6 mm (1.6-10.8 mm, standard deviation: 2.8 mm) and a mean subcortical shift of 3.5 mm (1.0-7.7 mm, standard deviation: 2.3 mm) was found. A highly significant Spearman correlation (Rho:.97, p<0.001) between superficial and subcortical brain shift emerged. Shifting of superficial landmarks exceeded shifting of subcortical structures in all patients. CONCLUSIONS: The data demonstrate the dynamics of brain shift and the limits of conventional neuronavigation and add additional support for the unavoidable inaccuracy of contemporary neuronavigational systems once the cranium is opened. Brain shift leads to a significant loss of reliability of neuronavigation systems during microsurgical removal of intracranial lesions and there are differences of the course and the amount of brain shift in relation to special subgroups of supratentorial cerebral lesions. However, because of the heterogeneous nature of lesions neurosurgeons have to remove, the modest quantity of shared common variance, and the differences between superficial and subcortical brain shift, it seems unlikely that the amount and course of brain shift become exactly predictable pre-operatively. Only an intra-operative update of image data should have the capacity to overcome this fundamental problem of modern neuronavigation.

Adolescent↗
PubMed2004

Functional and diffusion-weighted magnetic resonance imaging for visualization of the postthalamic visual fiber tracts and the visual cortex.

Diffusion-weighted magnetic resonance imaging (MRI) offers the possibility to study the course of the cerebral white matter tracts whereas functional MRI (fMRI) provides information about the specific functions of cortical areas. We evaluated the combination of fMRI and diffusion-weighted MRI to detect cortical visual areas with their corresponding visual fiber tracts in 15 healthy controls (age: 23 - 53 years, male : female = 8 : 7). We demonstrated activation within the primary visual cortex and white matter bundles connecting the lateral geniculate body and the striate cortex in all subjects investigated. Additional activation could be appreciated in some subjects within the lateral geniculate bodies (n = 2) and the motion-sensitive area V5 (n = 3). The combination of diffusion-weighted and functional imaging allows visualization of the origin, direction and functionality of large white matter tracts. This will prove helpful for imaging structural connectivity within the brain during functional imaging. Moreover, this technique might provide important information for neurosurgical patients presenting with space-occupying lesions close to the cortical and subcortical visual system since this technique can -- in contrast to diffusion tensor imaging -- easily be adopted into a neuronavigation system and can be performed on all MR scanners capable of diffusion-weighted imaging without specific post-processing programs.

Adult↗
PubMed2003

MRI and intraoperative findings in cavernous haemangiomas of the spinal cord.

More sensitive imaging techniques, such as MRI, have led to an increase in the number of reported cases of spinal cord cavernous haemangioma (SCCH). Complete surgical resection has been performed with good outcomes. However, operative findings do not always confirm preoperative MRI as to the size and site (superficial or deep) of the lesion. We evaluated whether MRI can be used to predict whether or not SCCH reach the surface of the spinal cord, since this has an impact on surgical strategy. We reviewed the preoperative MRI, case-notes and video recordings of 12 patients who underwent surgery, at which five superficial and seven deep-seated lesions were identified. T1-weighted images correctly indicated the site of the lesion in ten, T2-weighted images in only eight. One deep lesion was thought to be superficial on both T1- and T2-weighted images. Intravenous contrast medium was not helpful in diagnosis or localisation. In no case was a surgically proven superficial lesion interpreted as deep in the spinal cord.

Adult↗
PubMed2002

Factors related to the magnitude of T2* MR signal changes during functional imaging.

Our aim was to determine whether age, sex, the degree of weakness, anticonvulsants, the histology of the underlying lesion(s), the presence of oedema or the distance of the lesion from the motor region have an impact on the blood oxygenation level-dependent (BOLD) signal strength and therefore on the validity of functional MRI (fMRI). We studied 98 patients with masses near the central region imaged for surgical planning at 1.5 tesla, employing a BOLD sequence during a motor task. We calculated percentage signal change in the primary motor cortex between rest and activation and carried out multiple linear regression to examine the impact of the above factors on signal strength. Using a stepwise analysis strategy, the distance of the lesion from the motor region had the strongest influence (r=0.653, P<0.001). The factor with largest uncorrelated additional impact on signal change was the presence of oedema. Both predictors together formed a highly significant multiple r=0.739 ( P<0.001). No other predictive factor was identified (all P>0.20). Disturbances of cerebral blood flow and metabolism induced by the tumour were presumed to be the causes of a decrease in signal in the adjacent cortex.

Adolescent↗
PubMed2002

Activation in primary and secondary motor areas in patients with CNS neoplasms and weakness.

OBJECTIVE: To demonstrate whether cortical activation within different cortical motor regions in neurosurgical patients varies with the degree of paresis induced by mass lesions near the central region. METHODS: A total of 110 patients with brain tumors infiltrating the central region and with varying degrees of paresis were investigated employing fMRI during the performance of hand motor tasks. The percent signal change between rest and activation was calculated for four cortical regions: primary motor cortex (M1), supplementary motor area, premotor area, and superior parietal lobule. RESULTS: Significant decreases in activation with increasing degrees of paresis were found in M1, whereas significant increases in activation were noted in secondary motor areas that were not affected by the tumor. CONCLUSIONS: The signal loss in areas adjacent to tumor tissue may relate either to tumor-induced changes in cerebral hemodynamics or to a direct loss of cortical neurons resulting in a lesser degree of hemodynamic changes after motor activation. The increase in activation within secondary motor areas with increasing degrees of paresis supports the growing evidence of a practice- and lesion-dependent reorganization of the cortical motor system and the ability of the brain to modulate its excitatory output according to external demands.

Adult↗
PubMed2002

Functional MRI and 18F FDG-positron emission tomography for presurgical planning: comparison with electrical cortical stimulation.

BACKGROUND: In patients with mass lesions near "eloquent" cortical areas different preoperative mapping techniques can be used. Two of the most widely used approaches include positron emission tomography (PET) and functional MRI (fMRI). We employed both methods in the same patients undergoing presurgical evaluation and compared the results to those obtained by direct electrical cortical stimulation (DECS). METHOD: 22 patients with tumours of different aetiology near the central region were investigated. FMRI was performed using a T2(*)-weighted gradient-echo BOLD sequence at 1.5 T, PET was performed after injection of 122-301 MBq (18)F-Fluorodeoxyglucose (18-FDG) under rest and activation conditions. DECS was performed in all patients with recordings of muscles primarily involved in the investigated tasks. FINDINGS: In 19 patients all three modalities could be compared, 1 patient demonstrated discordance between fMRI and PET with DECS speaking in favour of fMRI, 6 patients had neighbouring results of PET and fMRI (between 1-2 cm distance), 12 patients had overlapping results. INTERPRETATION: The high incidence of neighbouring results is presumably related to fMRI specific artefacts. Advantages of fMRI are: Higher spatial and temporal resolution, more and different functional runs, shorter examination time, wider availability, longitudinal examinations, non-invasiveness and cost-effectiveness, easy registration to anatomical images. Advantages of PET are: higher signal-to-noise ratio, lesser susceptibility to artefacts (motion, draining veins), evaluation of tumour metabolism. It is our opinion that the neurosurgeon has to decide on a case-by-case basis which study suits his specific needs in the presurgical evaluation of his patient.

Adult↗
PubMed2002

Movement artefacts and MR BOLD signal increase during different paradigms for mapping the sensorimotor cortex.

BACKGROUND: The authors evaluated the impact of motion artefacts on presurgical mapping of the sensorimotor cortex with functional magnetic resonance imaging (fMRI). Different mapping paradigms were compared with regard to the frequency of motion artefacts and the resulting signal increase. METHOD: 94 surgical candidates with mass lesions near the central region were investigated using BOLD(1)-contrast T2(*) weighted multislice multi-echo EPI gradient echo sequences on a 1,5 T Philips Gyroscan. Three functional paradigms were performed: a) repetitive self-paced clenching of the hand to a fist (68 runs); b) repetitive finger-to-thumb opposition (46 runs); c) sensory stimulation by repetitive brushing of the palm (15 runs). Task-related haemodynamic changes were identified by statistical analysis with the Kolmogorov-Smirnov-test. MR signal increase in percent was calculated for each of the paradigms. Motion artefacts were rated on a scale from 1 to 3. FINDINGS: Severe motion artefacts occurred in 8 hand clenching runs and in 2 finger opposition runs. Artefacts were more pronounced in hand clenching than in finger opposition. There were no motion artefacts in any of the sensory stimulation runs. Concerning the percent MR signal change there was no significant difference between hand clenching and finger opposition (T-test: p>0,5) but a highly significant difference (p<0,0001) between both motor tasks and the sensory paradigm (hand clenching: 2.68+/-0.75; finger opposition: 2.76+/-0.79; sensory stimulation: 1.72+/-0.65). INTERPRETATION: Sensory stimulation causes by far less artefacts than motor paradigms but it also has to be considered less sensitive as it produces a smaller MR signal increase. Therefore in presurgical evaluation sensory stimulation should be kept in reserve for cases in whom motion artefacts are very likely to occur, i.e. patients with severe forms of paresis.

Adolescent↗
PubMed2002

Error analysis in cranial neuronavigation.

Neuronavigation systems are now an important component of many modern neurosurgical treatment strategies. Their support facilities intraoperative orientation and makes neurosurgical operations more precise and less traumatic. Computer-aided neurosurgery is definitively not a temporary fashionable phenomenon, the concept of neuronavigation is here to stay. This report summarizes a ten-years-long experience and presents an error analysis of 108 failures (12.4 %) in a total of 874 image-guided cranial neurosurgical procedures with an arm-linked (mechanical) system and two different infrared-light emitting (optical) systems. The application of neuronavigation incurs multiple reasons for pitfalls because of the complex man-machine interface. Principally, we have to differentiate two types of errors: "machine made errors" due to soft- or hardware failure and "man made errors" generally, due to inadequate handling of the navigation system. The error analysis demonstrated that the so-called human interface plays the main role causing a high error rate.

Bias↗