Acute Cerebrovascular Disease in the Young

Background and Purpose—

Strokes have especially devastating implications if they occur early in life; however, only limited information exists on the characteristics of acute cerebrovascular disease in young adults. Although risk factors and manifestation of atherosclerosis are commonly associated with stroke in the elderly, recent data suggests different causes for stroke in the young. We initiated the prospective, multinational European study Stroke in Young Fabry Patients (sifap) to characterize a cohort of young stroke patients.

Methods—

Overall, 5023 patients aged 18 to 55 years with the diagnosis of ischemic stroke (3396), hemorrhagic stroke (271), transient ischemic attack (1071) were enrolled in 15 European countries and 47 centers between April 2007 and January 2010 undergoing a detailed, standardized, clinical, laboratory, and radiological protocol.

Results—

Median age in the overall cohort was 46 years. Definite Fabry disease was diagnosed in 0.5% (95% confidence interval, 0.4%–0.8%; n=27) of all patients; and probable Fabry disease in additional 18 patients. Males dominated the study population (2962/59%) whereas females outnumbered men (65.3%) among the youngest patients (18–24 years). About 80.5% of the patients had a first stroke. Silent infarcts on magnetic resonance imaging were seen in 20% of patients with a first-ever stroke, and in 11.4% of patients with transient ischemic attack and no history of a previous cerebrovascular event. The most common causes of ischemic stroke were large artery atherosclerosis (18.6%) and dissection (9.9%).

Conclusions—

Definite Fabry disease occurs in 0.5% and probable Fabry disease in further 0.4% of young stroke patients. Silent infarcts, white matter intensities, and classical risk factors were highly prevalent, emphasizing the need for new early preventive strategies.

Clinical Trial Registration Information—

URL: http://www.clinicaltrials.gov .Unique identifier: NCT00414583

Impact of instrumentation on DaTSCAN imaging: how feasible is the concept of cross-systems correction factor?

AIM

The aim of this investigation was to study the impact of applying different camera emission computed tomography (ECT) systems on semi-quantitative analysis of the novel dopamine transporter (DaT) radioligand [123I]-ioflupane (DaTSCAN) and whether applying a system-dependent correction factor is feasible to allow a migration of a ''normal'' reference data set between systems.

METHODS

Two triple-head systems, PrismXP-3000 equipped with high resolution Fan-Beam (PRISM) and Irix (Philips Medical Systems, Europe) equipped with high resolution parallel whole collimators (IRIX), were compared in phantom and patient studies. Acquisition and quantification parameters were standardized. The anthropometric striatal calibration phantom (RSD Inc., CA, USA) at rising striatum: background ratios between 2-11 was studied. Fifty-one consecutive patients (25 females, age 64.5+/-11.9 years, and 26 males, age 60.6+/-12.7 years) were randomized to both cameras for acquisition time typically beginning 3.5 to 4.5 h after i.v. injection of 123I-Joflupane at 2.06+/-0.47 MBq/kg. Striatal uptake of the radioligand was categorized as normal or abnormal, and abnormal images were further subdivided into 3 severity levels. Striatum: cerebellum ratio (SCr) was determined by applying a fixed circular or rectangular striatal and fuzzy cerebellar regions. The effect of introducing scatter compensation (Sc) on quantification and on SCr was investigated.

RESULTS

The regression coefficient (Rc) of SCr computed for both systems was close to identity (IRIX=0.999x (PRISM)+0.48 and 1.01x(PRISM)+0.86 for right and left striatum). Rc of SCr values in the phantom studies was closer to identity when Sc was added (IRIX=0.982x [PRISM]+0.724 with Sc vs 1.22x[PRISM]-0.32 without Sc). SCr values were higher for IRIX by 5-10%. Including Sc increased the percent recovery and the linear dynamic range for both systems; however, fan beam recovery decreased at low SCr values. The delineation of the striatal boundaries improved after applying Sc. Identifying the cerebellar region was easier with PRISM owing to significantly higher count statistics. Both systems performed equally well with respect to image quality. Visual scoring by 2 observers correlated significantly on the k-test (K: 0.883, T: 10, P<0.0001).

CONCLUSION

A simple linear correction is applicable to ''normal'' reference data set to migrate from one system to another; however, data acquisition and quantification parameters need to be standardized. Higher recovery values are dependent on system resolution. The spatial distribution and image quality of DaTSCAN on different high-resolution systems applying standardized acquisition and reconstruction protocols is less operator dependent and does not affect visual rating of striatal DaT loss.

Rehabilitation approaches to stroke

This article describes the state of the science in stroke rehabilitation dealing with three main topics: (1) General approach to stroke rehabilitation (stroke services and stroke units), (2) Neurophysiological and pharmacological interventions (facilitation of brain repair mechanisms) and (3) Experimental approaches (neuronal transplantation). Stroke rehabilitation is an active process beginning during acute hospitalisation, progressing to a systematic program of rehabilitation services and continuing after the individual returns to the community. There is world-wide consensus that stroke patients should be treated at specialised stroke unit with specially trained medical and nursing staff, co-ordinated multidisciplinary rehabilitation and education programs for patients and their families. Stroke Unit has been shown to be associated with a long-term reduction of death and of the combined poor outcomes of death and dependency, independent of patients age, sex, or variations in stroke unit organisations. No study has clearly shown to what extent the beneficial effect is due to specific rehabilitation strategies. New imaging studies in stroke patients indicate altered post stroke activation patterns, which suggest some functional reorganisation. Reorganisation may be the principle process responsible for recovery after stroke. It is assumed that different post ischaemic interventions like physiotherapy, occupational therapy, speech therapy, electrical stimulation, etc. facilitates such changes. Scientific evidence demonstrating the values of specific rehabilitation interventions after stroke is limited. Comparisons between different methods in current use have so far mostly failed to show that any particular physiotherapy, occupational therapy, speech therapy or stroke rehabilitation strategy is superior to another. Clinical data are strongly in favour of early mobilisation and training. Pharmacological interventions in animals revealed that norepinephrine, amphetamine and other alpha-adrenergic stimulating drugs can enhance motor performance after unilateral ablation of the sensory motor cortex. The clinical data in humans are rather contradictory. Neural grafting and neurogenesis are new potential modes of stroke therapy. Neural grafting enhanced functional outcome and reduced thalamic atrophy in rats only when combined with housing in enriched environments. Recent studies have shown that stem cells can differentiate to neurons in the adult human dentate gyrus in vivo.

To do or not to do? Magnetic resonance imaging in mild traumatic brain injury

Clinical quantification of mild traumatic brain injury (MTBI) patients should be based on Glasgow coma scale (GCS) score, duration of loss of consciousness (LOC) and post-traumatic amnesia (PTA). In addition, a short practicable neuropsychological test might be useful in detecting minor memory and attentional deficits. MRI appears to be the most sensitive imaging method for assessing MTBI so far, but information regarding a visualized lesion is not usually utilized in the classification of MTBI. Magnetic resonance imaging (MRI) should, therefore, play a major role in any MTBI classification scheme. An appropriate MRI protocol has to be chosen using at least T1 weighted, T2 weighted, proton density and gradient-echo (GRE) sequence images, all in at least two planes, in order to detect and classify all lesions precisely. Owing to the fact that acute lesions may be missed, it is advisable to perform MRI in the first 2 weeks following trauma. Further research is necessary to clarify the relationship between chronic symptoms after MTBI and MRI abnormalities. It may, thus, be possible to provide optimal strategies for emergency department management, to define a group of patients with a need for acute and rehabilitative intervention after MTBI, and to predict their outcome.

Three-dimensional computer assisted magnetic resonance imaging for neurosurgical planning in parasagittal and parafalcine central region tumors

Usually, conventional magnetic resonance spin echo images (MRI) are sufficient to establish the diagnosis of intracranial pathology. Planning and executing a neurosurgical procedure requires the ability of the neurosurgeon to transform these two-dimensional MRI into a three-dimensional (3-D) virtual image of the pathology and the surrounding neuronal anatomy. Such mentally performed transformations after sequential observation of the individual two-dimensional slices (i.e., MRI and angiography) may be virtual tasks that are very difficult or sometimes impossible to achieve. Using 3-D MRI data sets and a semiautomatic computer assisted segmentation technique, we tried to simulate intraoperative situs-based 3-D MRI reconstructions of parasagittal and parafalcine central region tumors. The MRI reconstructions were integrated into the neurosurgical planning procedure as an additional tool. They proved to be an important adjunct in determining the distinct anatomy of the intracranial pathology in its relation to the surrounding and overlying brain and vascular (especially venous) anatomy. With 10 patients with central region parasagittal and parafalcine tumors, we found that the 3-D MRI reconstructions revealed additional information compared to conventional cross-sectional images and had an influence on neurosurgical planning and strategy, improving neurosurgical performance and patient outcome.

Magnetic resonance spectroscopy (MRS) in five patients with treated propionic acidemia

Propionic acidemia is an inherited disorder caused by a defect of propionyl CoA carboxylase. Untreated, propionic acidemia leads to metabolic decompensation and toxic encephalopathy. We report on the magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) findings in five children who were properly treated by protein restriction and carnitine supplementation, during a phase of clinically and metabolically stable conditions. The examinations were performed on a whole-body 1.5 T scanner. During the observation period, from 1992 to 1996 we employed long echo time single-voxel spectroscopy and chemical shift imaging in addition to a conventional MRI protocol. The two children with the longest delay before onset of therapy showed cerebral atrophy. MRS yielded elevated lactate peaks in four of the children. These results indicate that MRS can detect metabolic alterations in the brains of children with propionic acidemia during metabolically stable conditions. The presence of lactate could be caused by hampered aerobic oxidation within the citrate cycle due to intracellular elevated propionic metabolites.

Effects of hyperoxia and hypocapnia on regional venous oxygen saturation in the primary visual cortex in conscious humans

Hyperoxia can improve oxygen delivery in patients exposed to hypocapnia for neurosurgical procedures but this effect may be modified by regional differences in the degree of hypocapnic vasoconstriction. Using functional magnet resonance imaging (fMRI), we have investigated the influence of hyperoxia on blood flow and blood oxygenation in the primary visual cortex in hypocapnic volunteers. Consecutive fMRI measurements were performed in 10 awake, male volunteers during hypocapnia (mean PE'CO2 3.3 (SD 0.1) kPa) and normocapnia (PE'CO2 5.3 (0.1) kPa) at FIO2 values of 0.21 and 1.0, respectively. Hypocapnia significantly reduced the pixel count in the primary visual cortex (median 169 (quartiles 34-246) vs 21 (0-40) pixels at an FIO2 of 0.21). Additional hyperoxia had no influence on this reduction in pixel count (16 (0-28) pixels at FIO2 1.0 vs 21 (0-40) pixels at FIO2 0.21). Hyperoxia did not influence hypocapnic vasoconstriction in the primary visual cortex. These data suggest that in the primary visual cortex, administration of oxygen alone may not be sufficient to improve oxygen delivery under hypocapnic conditions.

[Development and application of dynamic MR imaging in the evaluation of perfusion changes in rectal carcinoma during radiotherapy in clinical routine. Preliminary results]

PURPOSE

This study was aimed at measuring microcirculatory parameters and contrast medium accumulation within the rectal carcinoma during fractionated radiotherapy in the clinical setting.

MATERIAL AND METHODS

Perfusion data were observed in patients with rectal carcinoma (n = 8) who underwent a pre-operative combined chemo/radiotherapy. To acquire perfusion data, an ultrafast T1 mapping sequence was carried out on a 1.5-Tesla whole body imager to obtain T1 maps at intervals of 14 or 120 seconds. The overall measurement time was 40 minutes. The transaxial slice thickness (5 mm) was chosen in such a way that both arterial vessels and the tumor could be clearly identified. The gadolinium-DTPA (Gd-DTPA) concentration time curve was evaluated for arterial blood and tumor after intravenous constant rate infusion. The method allows a spatial resolution of 2 x 2 x 5 mm and a temporal resolution of 14 seconds. Patients underwent MR imaging before and at constant intervals during fractionated radiotherapy.

RESULTS

Spatial and temporal resolution of dynamic T1 mapping was sufficient to reveal varying CM accumulation levels within the tumor and to identify the great arteries in the pelvis. In 6 patients Gd-DTPA concentration-time-curves were evaluated within the tumor during radiation. Pi index of Gd-DTPA versus radiation dose showed a significant increase in the first or second week of treatment, then either returned slowly to pretreatment level or a renewed increase was observed. The average Pi-value at the beginning was 0.16 (+/- 0.049), reaching highest level of 0.23 (+/- 0.058). In all groups the rise from the Pi-value to the Pi-maximum was statistically significant. The relative increase in perfusion ranged between 20 to 83%.

CONCLUSION

The results show, that the ultrafast MR-technique described above provide a suitable tool for monitoring tumor microcirculation during therapeutic interventions and offers the potential for an individualized optimization of therapeutic procedures.

Neuropsychological, MRI and EEG findings after very mild traumatic brain injury

Neuropsychological performance, magnetic resonance imaging (MRI) and electroencephalography (EEG) were investigated in 12 consecutive patients with very mild traumatic brain injury (MTBI) (Glasgow coma score 15) within 24 hours and 6 weeks after injury. The data were compared to 14 control subjects. There was a significant impairment in neuropsychological performance (verbal memory, arithmetic abilities and psychomotor reaction time) at onset and after 6 weeks, whereas verbal fluency and non-verbal memory test revealed no significant differences matching the control values. In MRI scans, three patients showed traumatic lesions (slight epidural haematoma, haemorrhagic contusions and white matter lesions indicating diffuse axonal injury). In the EEG recordings, no generalized slowing or focal changes were found. Structural and functional impairment can be identified using neuroimaging and neuropsychological examination, even in very MTBI patients.

[Transcranial Doppler ultrasonography: stereotactically guided examinations using magnetic resonance angiography]

The accurate localization of specific intracranial blood vessels is a major difficulty with transcranial Doppler sonography (TCD). It was the purpose of this study to develop a system enabling stereotactic navigation during a TCD examination on the basis of high-resolution three-dimensional magnetic resonance angiographic (MRA) data. During TCD, the examiner is provided--on a computer screen--with a projected view of the respective intracranial vessel anatomy. With the aid of an optoelectronic localization system, the spatial orientation and localization of the US probe is determined in real time, and correlated with the patient's MRA data using a dedicated stereotactic mask. Subsequently, the US beam and the points of insonation are displayed on the screen overlaid on the vessel anatomy. In this way the examiner gains real time control of the localization of the respective intracranial vessel insonated. Points of insonation can be stored and recalled for follow-up examinations. In addition to the successful verification of the system, it was shown that, in comparison with conventional TCD, stereotactic navigation distinctly improves the reproducibility of repeat TCD examinations.

Functional magnetic resonance imaging of the human motor cortex before and after whole-hand afferent electrical stimulation

Electrical stimulation of the whole hand using a mesh-glove has been shown to improve volitional movement of the hand and arm, and decrease muscle hypertonia after hemispherical stroke in patients who have reached a recovery plateau. The goal of this study was to investigate the effect of stimulation of the nerve afferents of the hand on brain cortical activity elicited by whole-hand subthreshold stimulation for sensation in humans with intact nervous systems. Brain cortical activity in 6 healthy subjects (30-45 years) was studied using blood oxygenation level-dependent functional Magnetic Resonance Imaging during a test motor task, finger-to-thumb tapping and after 20 minutes of mesh-glove stimulation of the resting hand prior to performance of an identical motor task, to test the changes in the conditioned motor task established after 20 minutes of mesh-glove stimulation. Fifteen contiguous echo-planar sequences parallel to the bicommissural plane were acquired for functional magnetic resonance. Post-processing of image data included correction of motion artefacts and calculation of correlation coefficients between the signal intensity of pixels during rest and finger tapping and a rectangular reference wave function. The functional Magnetic Resonance Imaging examinations revealed a signal increase in the primary and secondary motor and somatosensory areas when comparing the number of activated pixels during test and conditioned motor tasks. Our preliminary study indicated that change occurred in a definite pattern in the region of the regional cerebral blood flow of the brain cortex after mesh-glove whole-hand stimulation at the subthreshold level for sensation. We assumed that this increase in regional cerebral blood flow also reflected augmented neuronal activity.

Phase-contrast MRI measurement of systolic cerebrospinal fluid peak velocity (CSFV(peak)) in the aqueduct of Sylvius: a noninvasive tool for measurement of cerebral capacity

BACKGROUND

Cerebrospinal fluid (CSF) outflow to intra- and extracranial subarachnoid spaces caused by arterial inflow to the brain predominantly compensates systolic increases in cerebral blood volume. Phase-contrast magnetic resonance imaging is a new tool for noninvasive assessment of CSF displacement by measuring CSF peak velocity (CSFV(Peak)). The authors tested this new tool in an experimental human model of increased intracranial pressure and reduced cerebral capacity by means of continuous positive airway pressure (CPAP) breathing.

METHODS

The authors investigated systolic CSFV(Peak) in the aqueduct of Sylvius in 11 awake, normocapnic (end-tidal carbon dioxide [ET(CO2)] = 40 mmHg) volunteers without CPAP and at two different CPAP levels (6 and 12 cm H2O) by means of electroencephalography-gated phase-contrast magnetic resonance imaging.

RESULTS

Administration of 6 cm H2O CPAP did not change systolic CSFV(Peak) (-4.9+/-2.8 cm/s vs. control: -5.1+/-2.7 cm/s), whereas 12 cm H2O CPAP significantly reduced systolic CSFV(Peak) (-4.0+/-1.8 cm/s vs. control: -5.1+/-2.7 cm/s; P < 0.05).

CONCLUSIONS

These findings in awake volunteers show that monitoring CSFV(Peak) in the aqueduct of Sylvius is a sensitive method for detecting even minor impairment of cerebral capacity caused by experimentally induced increases in intracranial pressure.

Transcranial Doppler sonography guided by magnetic resonance angiography for improved monitoring of intracranial arteries

Transcranial Doppler (TCD) sonography combines the advantages of real-time hemodynamic information, cost-effectiveness, and bedside application. However, measurements can be difficult to reproduce because the spatial resolution and the determination of insonation angles are limited. The purpose of this study was to use the high anatomic resolution of three-dimensional (3D) magnetic resonance angiography (MRA) images for the stereotactic guidance of TCD in order to improve the accuracy and reproducibility of TCD examinations. The MRA examinations were performed on a 1.5 T scanner using a 3D flow compensated gradient-echo sequence. A noninvasive stereotactic mask was used for image registration. The MRA data were then transferred to a personal computer. An infrared tracking system registered the position of the head and the ultrasound probe during TCD. This enabled the authors to superimpose a virtual ultrasound beam onto the MRA projections of the intracranial arteries displayed on the monitor of the personal computer. This allows the examiner to easily identify the insonated intracranial artery and displays the insonation angle. In volunteer examinations (n = 10), the accuracy and reproducibility for the localization of specific vessel segments was 2.48 mm for the middle cerebral artery and 2.81 mm for all insonated intracranial arteries (middle cerebral artery, anterior cerebral artery, internal carotid artery, and posterior cerebral artery). Without navigation the reproducibility of vessel segment insonation dropped to 4.7 mm for the middle cerebral artery and to 4.84 mm for all vessels. The authors conclude that 3D MRA, acquired as an initial procedure in patients with intracranial vascular disorders, can be used to provide stereotactic guidance for repeated TCD examinations. This facilitates the reproducible insonation of specific vessel segments.

MRI findings in cerebral fat embolism

The purpose of this retrospective study was to demonstrate the MRI features of cerebral manifestations in patients with fat embolism syndromes in comparison with cerebral CT (CCT). Magnetic resonance imaging was performed according to standard protocols revealing multiple small non-confluent hyperintense intracerebral lesions larger than 2 mm on proton-density and T2-weighted images to various extents in three of four patients with clinically suspected cerebral fat embolism. Cerebral CT was negative in all patients. Our findings confirm that MRI can detect cerebral fat embolism with a higher sensitivity than CCT. Thus, MRI should be the first choice for imaging of cerebral fat embolism.

Heparin treatment in acute cerebral sinus venous thrombosis: a retrospective clinical and MR analysis of 42 cases

The only randomized data on heparin treatment in acute cerebral sinus venous thrombosis (CSVT) are derived from a small number of patients. The rate of intracranial hemorrhages as a complication of high-dose heparin treatment is still unknown. This retrospective study evaluates the clinical features, neuroimaging monitoring and outcome of 42 patients with proven CSVT. Diagnosis was established by DSA, CT, MR tomography and MR angiography. All patients received heparin intravenously guided by doubling the aPTT value for 3 weeks, followed by oral anticoagulation. Partial or complete recanalization was found in 36 cases. 40 patients improved clinically, in 26 of them complete recovery was observed. One patient deteriorated and developed an apallic syndrome, one further patient died of septic multiorgan failure. Only in one patient was hemorrhagic transformation of infarcted brain tissue observed but without clinical deterioration.

Prediction of recovery from post-traumatic vegetative state with cerebral magnetic-resonance imaging

BACKGROUND

The early post-traumatic vegetative state (VS) is compatible with recovery. Various clinical and laboratory tests have failed to predict recovery so we assessed the value of cerebral magnetic-resonance imaging (MRI) in prediction of recovery.

METHODS

80 adult patients in post-traumatic VS had cerebral MRI between 6 weeks and 8 weeks after injury. MRIs were reviewed by three neuroradiologists for the number, sizes, and location of brain lesions. Three neurologists assessed the patients at the time of MRI and at 2 months, 3 months, 6 months, 9 months, and 12 months after injury using the Glasgow Outcome Scale.

FINDINGS

At 12 months, 38 patients had recovered while 42 patients remained in the VS. The demographic characteristics and causes and severity of injury were similar in patients in persistent VS (PVS) and those who recovered (NPVS). An average of 6.1 different brain areas were injured in patients in PVS compared with 4.6 areas in patients who had NPVS. Patients in PVS revealed a significantly higher frequency of corpus callosum, corona radiata, and dorsolateral brainstem injuries than did patients who recovered. Logistic regression analysis showed that corpus callosum and dorsolateral brainstem injuries were predictive of non-recovery. The adjusted odds ratios for non-recovery of patients with a corpus callosum lesion and dorsolateral brainstem injury were 213.8 (95% CI 14.2-3213.3), and 6.9 (11-42.9), respectively. In contrast, clinical characteristics, such as initial score on the Glasgow Coma Scale, age, and pupillary abnormalities failed to predict recovery.

INTERPRETATION

Cerebral MRI findings in the subacute stage after head injury can predict the outcome of the post-traumatic VS. Corpus callosum and dorsolateral brainstem lesions are highly significant in predicting non-recovery.

Hippocampal volume reduction in male schizophrenic patients

Using magnetic resonance imaging of the brain, we examined volumetric measurements of total brain, hemispheres, lateral ventricles and the hippocampus/amygdala complex in male subjects (41 first-episode schizophrenics, 30 chronic schizophrenic patients and 32 healthy controls). We found significantly smaller total brain size in the chronic schizophrenic group, significantly larger lateral ventricles in both patient groups and hippocampal volume reduction bilaterally in first-episode patients (-13.2% left, -12.05% right) and chronic patients (-10.6% left, -10.5% right) compared to controls--irrespective of diagnostic subtype, family history for psychiatric diseases, psychopathology, duration of illness or age at onset.

The persistent vegetative state after closed head injury: clinical and magnetic resonance imaging findings in 42 patients

OBJECT

In this retrospective study, the authors analyzed the frequency, anatomical distribution, and appearance of traumatic brain lesions in 42 patients in a posttraumatic persistent vegetative state.

METHODS

Cerebral magnetic resonance (MR) imaging was used to detect the number of lesions, which ranged from as few as five to as many as 19, with a mean of 11 lesions. In all 42 cases there was evidence on MR imaging of diffuse axonal injury, and injury to the corpus callosum was detected in all patients. The second most common area of diffuse axonal injury involved the dorsolateral aspect of the rostral brainstem (74% of patients). In addition, 65% of these patients exhibited white matter injury in the corona radiata and the frontal and temporal lobes. Lesions to the basal ganglia or thalamus were seen in 52% and 40% of patients, respectively. Magnetic resonance imaging showed some evidence of cortical contusion in 48% of patients in this study; the frontal and temporal lobes were most frequently involved. Injury to the parahippocampal gyrus was detected in 45% of patients; in this subgroup there was an 80% incidence of contralateral peduncular lesions in the midbrain. The most common pattern of injury (74% in this series) was the combination of focal lesions of the corpus callosum and the dorsolateral brainstem. In patients with no evidence of diffuse axonal injury in the upper brainstem (26% in this series), callosal lesions were most often associated with basal ganglia lesions. Lesions of the corona radiata and lobar white matter were equally distributed in patients with or without dorsolateral brainstem injury. Moreover, cortical contusions and thalamic, parahippocampal, and cerebral peduncular lesions were also similarly distributed in both groups.

CONCLUSIONS

The data indicate that diffuse axonal injury may be the major form of primary brain damage in the posttraumatic persistent vegetative state. In addition, the authors demonstrated in this study that MR imaging, in conjunction with a precise clinical correlation, may provide useful supportive information for the accurate diagnosis of a persistent vegetative state after traumatic brain injury.

Prevention of local scar formation after operative discectomy for lumbar disc herniation

This was a prospective study. The study evaluated the use of Preclude Spinal Membrane to inhibit peridural fibrosis and reduce fibroses-related problems after first-time lumbar discectomy. Peridural scarring causes tethering of dura and nerve roots. Following discectomy Preclude Spinal Membrane was applied to patients of first group (10 patients). The second group (10 patients) was operated on without Preclude Spinal Membrane. Outcome was evaluated with MRI, 3 and 6 month after operation for all patients. No peridural or epidural scar tissue could be found in patients with Preclude Spinal Membrane, in the control group who were operated on without the preclude Spinal Membrane scar tissue of varying degree with complete enclosure of the nerve roots and dura was found.

Magnetic resonance angiographic and clinical features of extracranial vertebral artery dissection

OBJECTIVES

Clinical data and neuroradiological findings of 19 patients with 20 vertebral artery dissections were analysed to describe the features of time of flight magnetic resonance angiography (MRA) for the diagnosis and follow up of this vascular disorder.

METHODS

All patients underwent a combined MRI and MRA protocol with 1.5 T scanners, using a three dimensional flow compensated gradient echo sequence for MRA. Duplex sonography was performed on all patients and selective angiography was available from 17 vertebral artery dissections.

RESULTS

MRI showed ischaemic lesions of the brain in 18 of 19 patients (95%). In the acute and subacute stage, MRA detected signal abnormalities within the dissected vertebral artery in 94% (16/17) and MRI was specific for a dissection in 29% (5/17). Sensitivity of selective angiography was 100% and specificity was 35% (6/17). Combination of the results of both methods increased the specificity to 50%. Duplex sonography was sensitive in 79% (15/19), but lacked specific results. Follow up magnetic resonance in 16 patients showed recanalisation of the dissected vessel in 10 (63%), persistent occlusion in five (31%), and a dissecting aneurysm in one (6%) patient.

CONCLUSIONS

Magnetic resonance improves the triage for selective angiography and discloses complementary information for the diagnosis of vertebral artery dissection. If magnetic resonance identifies a double lumen or a mural haematoma with a stenosis or aneurysmal dilatation, invasive procedures can be omitted.

The prognostic significance of coma-rating, duration of anoxia and cardiopulmonary resuscitation in out-of-hospital cardiac arrest

Early determination of outcome after successful prehospital cardiopulmonary resuscitation (CPR) is a common problem with great ethical, economic, social, and legal consequences. We prospectively investigated 112 adult patients who had been resuscitated after out-of-hospital cardiac arrest (CA). The aim of our study was to determine whether coma rating by the mobile intensive care unit (MICU) is a useful tool for outcome prediction. For neurological assessment the Innsbruck Coma Scale (ICS) was used initially and after return of spontaneous circulation (ROSC) or 20-30 min after the start of CPR, before any sedating drugs were given. The duration of anoxia and CPR were determined with the automatically recorded emergency call protocol of the dispatch centre and the protocol of the MICU. For estimation of cerebral outcome at the time of discharge from hospital we used the Glasgow-Pittsburgh Cerebral Performance Categories (CPC). Restoration of spontaneous circulation was achieved in 42 patients (37%), and 15 (13%) were discharged from hospital. The first coma rating performed immediately at the time of arrival on scene had no significant prognostic value for prediction of neurological outcome (P = 0.204) and survival (P = 0.103). The second coma rating (performed after ROSC or 20-30 min after the start of CPR), however, demonstrated a significant correlation with neurological outcome (P = 0.0000) and survival (P = 0.0000), a correlation which was comparable to both duration of anoxia and duration of CPR. In patients with out-of-hospital cardiac arrest prognostic information could be obtained with the ICS as early as 20-30 min after the start of cardiopulmonary resuscitation.

Image registration of MR and CT images using a frameless fiducial marker system

A new system of fiducial stereotactic markers that can easily be adapted to various imaging modalities without losing image registration was developed and tested. Utilizing MR and CT imaging the accuracy of the new system was evaluated with phantom studies and preliminary patient studies. The markers are clearly visible without artifacts on both imaging modalities. The clear delineation of the marker dots on the images enables an accurate automated marker detection. Using the marker system, image registration was found to yield an accuracy of up to 1 mm, depending on the imaging modality and the employed marker arrangement. The presented marker system shall improve patient comfort in comparison to conventional fixed stereotactic frames if repeated, highly accurate registrations are necessary over longer periods.

The prognostication of cerebral hypoxia after out-of-hospital cardiac arrest in adults

Early determination of outcome after out-of-hospital cardiopulmonary resuscitation is a common problem with great ethical, economic, social and legal consequences. Although there has been a fulminant development of emergency medicine during the last three decades, severe cerebral damage sometimes cannot be avoided. For neurological outcome prediction after cardiac arrest clinical neurological signs, electrophysiological examinations, neuroimaging tests, and laboratory parameters in serum and cerebrospinal fluid are used today, nevertheless, there still remains a considerable degree of uncertainty. However, although prognostic criteria which enable the clinician to stop treatment cannot be given at the present time, useful applications of early prognostication after cardiac arrest range from counseling of families, triage decisions, and do-not-resuscitate decisions to future clinical investigations of brain resuscitative measures.

[Magnetic resonance angiography and magnetic resonance tomography in dissection of the vertebral artery]

Vertebral artery dissection (VAD) is an important cause of posterior circulation stroke in young adults. Initial symptoms are often non-specific and diagnostic arteriography is not performed until neurological deficits are obvious. Since magnetic resonance tomography (MRT) is superior in the diagnosis of vertebrobasilar ischemia, we retrospectively analyzed the role of MRT and MR angiography (MRA) in the detection of dissections of the vertebral artery. Between 1989 and 1995 we identified 24 patients with a vertebral artery dissection and 1 patient with a basilar artery dissection (8 females and 17 males, 23-60 years of age, mean 41.2 years). The diagnosis of VAD (14 left VAD, 9 right VAD, 1 bilateral VAD, 1 basilar artery dissection) was established by specific arteriographical findings (DSA) or clinical and neuroradiological course. All patients underwent a combined MRT/MRA examination protocol at 1.5T that consisted of spin-echo imaging and time of flight MRA of the intra- and extracranial arteries using 2D Flash and 3D Fisp sequences. The MRT/MRA findings were correlated to DSA and ultrasound results. During the acute and subacute stage, MRT/MRA revealed abnormal findings in 21 of 22 dissected vessels (95.5%). There was one false-negative MRT/MRA in a patient with a V1 dissection (intimal flap without peripheral flow disturbances). In 7/22 VAD the MRT/MRA findings were rated specific (double lumen n = 1, mural hematoma n = 4, pseudoaneurysm n = 2). DAS was sensitive in 100% and ultrasound in 77.3%. Specific results were obtained by DSA in 8/ 22 VAD (36.4%) and in 7/22 VAD (30.4%) by MRT/MRA. When MRT/MRA and DSA results were combined, the specific findings increased to 43.5%. Follow-up examinations revealed recanalization in 52% of initially stenosed or occluded vertebral arteries; four patients developed a pseudoaneurysm, and two of them underwent ligation of the VAD. With this retrospective approach, we were able to show a high sensitivity of MRT/ MRA for the presence of disturbed flow in the dissected vertebral artery. The MRA projections tended to overestimate stenosis and were inferior to DSA in the appreciation of irregularities of the vessel wall. Identification of high-grade stenosis, especially in the presence of distal occlusion, was improved on the MRA source images. During the acute and subacute stage, the diagnosis of luminal thrombus can be difficult, because signal ambiguities exist between hemoglobin breakdown products and flow effects and adjacent fat tissues. The differentiation between luminal thrombus and mural hematoma requires interpretation of MRA source images, together with flow compensated spin-echo images. Additional fat suppressed images and flow presaturation may be required at the appropriate levels. The identification of mural hematoma is important, because this finding is considered specific and cannot be obtained with DSA. There is a complementary role of MRT/MRA and DSA for an improved overall specificity for vertebral artery dissection. A negative MRT/MRA result in a patient with appropriate symptoms, however, cannot exclude a dissection and should prompt DSA. On the other hand, a suggestive MRT/MRA result in the appropriate clinical context can replace DSA. The advantage of MRT/MRA is that the method offers a simultaneous diagnosis of posterior fossa ischemia and vertebral artery abnormalities. Therefore, MRT/MRA should be recommended in patients with suspected VAD and especially in those who have no definite neurological deficit. These patients will benefit greatly from early diagnosis and therapy. The fact that all our patients were diagnosed after neurological symptoms and that 64% of them have residual deficits gives an ethical and economical rationale for advocating early MRT/MRA in these patients.

MR-imaging of non-Alzheimer's dementia

Up to now, computerized tomography (CT) and MR-imaging have been used for the morphological assessment of dementia patients, while MRI has become the structure imaging modality of choice. With the advent of fast and ultrafast sequences provided by higher gradient field strengths, functional MR studies like diffusion, perfusion and activation studies become available. The greatest advantage of MR is its versatility including MR-imaging, 3D postprocessing, MR-volumetry, MR-spectroscopy, MR-angiography, MR-perfusion and diffusion imaging as well as functional MRI activation studies. The application of the multimodal MR-technology in dementia disorders has already began and has to be validated in clinical practice. The multimodality of MR represents a diagnostic challenge for the future with the hope, that the diagnostic efficacy, which has to be proven, is also followed by an improvement of patients care and prognosis.

Magnetic resonance volumetry of the cerebellum in epileptic patients after phenytoin overdosages

The aim of this study was to evaluate the relationship between phenytoin medication and cerebellar atrophy in patients who had experienced clinical intoxication. Five females and 6 males, 21-59 years of age, were examined with a 1.5-T whole-body system using a circular polarized head coil. Conventional spin echo images were acquired in the sagittal and transverse orientation. In addition, we performed a high-resolution 3D gradient echo, T1-weighted sequences at a 1-mm slice thickness. The images were subsequently processed to obtain volumetric data for the cerebellum. Cerebellar volume for the patient group ranged between 67.66 and 131.08 ml (mean 108.9 ml). In addition 3D gradient echo data sets from 10 healthy male and 10 healthy female age-matched volunteers were used to compare cerebellar volumes. Using linear regression we found that no correlation exists between seizure duration, elevation of phenytoin serum levels and cerebellar volume. However, multiple regression for the daily dosage, duration of phenytoin treatment and cerebellar volume revealed a correlation of these parameters. We conclude that phenytoin overdosage does not necessarily result in cerebellar atrophy and it is unlikely that phenytoin medication was the only cause of cerebellar atrophy in the remaining patients. Quantitative morphometric studies of the cerebellum provide valuable insights into the pathogenesis of cerebellar disorders.

[Magnetic resonance angiography of intracranial aneurysms after subarachnoid hemorrhage]

Magnetic resonance angiography is now commercially available for a variety of scanners and is being increasingly applied in the diagnosis of cerebrovascular disorders. Considering the clinical consequences, especially in intracranial aneurysms, studies to determine the sensitivity and specificity of the method are essential. Here we report our experience with a 3D-FISH time-of-flight magnetic resonance angiography protocol in 52 patients who have suffered an acute subarachnoid hemorrhage. In 26 of the 52 patients, conventional angiography identified 31 aneurysms (3-20 mm) that were confirmed during surgery or autopsy. Magnetic resonance angiography correctly identified 28 of the 31 aneurysms (sensitivity 90.3%) and missed one ruptured (3 mm) and two incidental aneurysms (3 mm) in patients with multiple aneurysms. The sensitivity for a ruptured aneurysm was 96%. The 26 patients who suffered subarachnoid hemorrhage without evidence of an intracranial aneurysm on repeated angiography served as a control group. Magnetic resonance angiography revealed no false-positive findings, resulting in a specificity of 100%. In correlation with the literature, we conclude that magnetic resonance angiography is not sensitive enough for the management of acute subarachnoid hemorrhage. However, the method provides important complementary information for definition of the bleeding site in patients with multiple aneurysms. In addition, the calculation of projections not possible with conventional angiography can aid surgical planning. Since only very small aneurysms were missed by magnetic resonance angiography, the sensitivity seems appropriate to screen asymptomatic patients who are at risk for intracranial aneurysms.

Management of spontaneous extramedullary spinal haematomas: results in eight patients after MRI diagnosis and surgical decompression

Spinal cord compression due to extradural and subdural haemorrhage is a neurosurgical emergency. Differences in clinical presentation in relation to localisation of the haematoma, value of MRI as a diagnostic tool, surgical treatment, and prognosis were investigated in a retrospective case series of eight patients with extradural (n = four) and subdural (n = four) haematomas. Results of MRI were compared with operative findings and proved to be of high sensitivity in defining the type of bleeding and delineating craniocaudal extension and ventrodorsal location. Surgical treatment by decompressive laminectomy, haematoma evacuation, and postoperative high dose corticosteroids resulted in resolution of symptoms in five patients and improvement in the clinical situation in two patients. One patient with a chronic subdural haematoma had a second operation because of arachnoidal adhesions. One patient presented with a complete cord transection syndrome due to an acute subdural haematoma and remained paraplegic. It is concluded that prompt, reliable, and non-invasive diagnosis by MRI leads to efficient surgical treatment and a favourable outcome in this rare condition.

Syndrome of the anterior spinal artery as the primary manifestation of aspergillosis

Aspergillosis of the central nervous system (CNS) is an uncommon infection, mainly occurring in immunocompromised patients. Beside cerebral involvement spinal cord lesions are extremely rare. To our knowledge, aspergillosis initially presenting with acute paraplegia due to mycotic thrombosis of the anterior spinal artery in a formerly healthy patient has, so far, not been reported. Neither a primary focus nor an underlying disease had been detected.