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PubMed1995

Cavernous malformations of the optic chiasma.

Two cases of cavernous malformation of the optic chiasm are reported, and 12 previously reported cases are reviewed. The first patient presented with gradually progressive and the second patient with a subacute chiasmal syndrome. Total excision was performed in both cases. Visual function improved slightly after surgery in the first patient while the other showed marked improvement. Although cavernous malformations are angiographically occult, pre-operative diagnosis has become possible based on the characteristic features such as repeated haemorrhages in multiple sinusoidal structures as revealed by magnetic resonance imaging (MRI). A gliotic interspace between the malformation and normal neural tissue provides a plane of cleavage for dissection which permits total excision without causing new deficits. Review of previously reported cases revealed that chiasmal cavernous malformations haemorrhage more frequently than those in the brain. Early diagnosis with total excision is the treatment of choice for cavernous malformations of the optic chiasma.

Adolescent↗
PubMed1992

Computer assisted localizer for planning of surgery and intra-operative orientation.

There is discrepancy between the exact representation of anatomical structures and tumours in the CT or MRI scan and the more or less accurate intra-operative localisation methods based mostly upon landmarks of the skull and extracerebral space and visible abnormalities of the cerebral surface. To overcome these problems of exact intra-operative localisation a Computer Assisted Localizer (CAL) is presented which allows precise intra-operative orientation without these aids. It consists of a mechanically articulated arm with six degrees of freedom with a high precision digital incremental and an image processor for 3 D data of the head. MRI and/or CT investigation is done pre-operatively with four reference markers fixed on the patient's head. They are visible on the CT or MRI slices and are used as reference points during surgery for adjustment of the device. The co-ordinates of the digitalizer arm tip are projected into the corresponding axial, sagittal and coronal CT slices so that the system simultaneously presents three orthogonal multiplanar CT reconstructions with a reticule indicating the position of the tip of the arm. As the surgeon directs the arm to the region of interest the corresponding CT slices are displayed on the monitor at a rate of 20 slices/sec determined by the motion of the arm. The accuracy of measurement of the device itself lies within 1 mm. The accuracy is somewhat reduced however by the thickness of CT or MRI slices (routinely 2 mm slices were taken) and by deviations of the reference markers on the skin surface which amount up to 3 mm.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Dysplastic gangliocytoma of cerebellum in a newborn. Diagnosis by ultrasonography and MRI.

A cerebellar lesion was detected by ultrasonography (US) in a symptomatic newborn. Magnetic Resonance Imaging (MRI) demonstrated this lesion as a gyriform structure. Therefore a rare dysplastic gangliocytoma was suspected, which was compatible with histopathology. Immunohistochemical studies (monoclonal antibody Ki-67) showed signs of progression.

Cerebellar Neoplasms↗
PubMed1998

Sex differences in morphology of the brain stem and cerebellum with normal ageing.

The cerebral hemispheres become atrophic with age. The sex of the individual may affect this process. There are few studies of the effects of age and sex on the brain stem and cerebellum. We used MRI morphometry to study changes in these structures in 152 normal subjects over 40 years of age. In the linear measurements, men showed significant age-associated atrophy in the tegmentum and pretectum of the midbrain and the base of the pons. In women, only the pretectum of the midbrain showed significant ageing effects after the age of 50 years, and thereafter remained rather constant. Only men had significant age-associated reduction in area of the cerebellar vermis area after the age of 70 years. Both men and women showed supratentorial brain atrophy that progressed by decades. There were significant correlations between supratentorial brain atrophy and the diameter of the ventral midbrain, pretectum, and base of the pons in men, and between brain atrophy and the diameter of the fourth ventricle in women.

Adult↗
PubMed2005

Congenital diseases of the thoracic aorta. Role of MRI and MRA.

Aortic malformations may be associated with other congenital heart abnormalities or may present independently, as incidental findings in asymptomatic patients. For more than 30 years, conventional imaging techniques for detection and assessment of congenital anomalies of the aorta have been chest X-ray, echocardiography and angiography. In recent times, considerable interest in congenital aortic diseases has been shown, due to technical progresses of noninvasive imaging modalities. Among them, magnetic resonance imaging (MRI) almost certainly offers the greatest advantages, especially in young patients in which a radiation exposure must be avoided as much as possible. MRI provides an excellent visualization of vascular structures with a wide field of view, well suited for evaluation of the thoracic aorta malformations. With the implementation of magnetic resonance angiography (MRA) it is also possible to depict any relationship with supra-aortic or mediastinal vessels. Phase contrast technique allows identification of the hemodynamic significance of the aortic alteration. Some technical considerations, which include fast spin-echo, gradient-echo and, especially, MRA techniques with phase-contrast and contrast enhanced methods, are discussed and applied in the evaluation of congenital thoracic aorta diseases.

Aorta, Thoracic↗
PubMed2005

Acquired diseases of the thoracic aorta: role of MRI and MRA.

Diseases of the thoracic aorta can present with a broad clinical spectrum of symptoms and signs. Their prevalence appears to be increasing in western populations, most likely corresponding to aging and heightened clinical awareness but also influenced by the progress of high-resolution, noninvasive imaging modalities. Among them, MRI provides an excellent visualization of vascular structures and is well suited for evaluation of thoracic aorta disease. Currently, in many centers, noninvasive imaging modalities are the first choice in the cardiovascular system evaluation and diagnosis, reserving conventional angiography for use only before therapeutic intervention. Understanding the principle MRA techniques is essential for acquiring consistent diagnostic images. Basic technical considerations, which include fast spin-echo, fast gradient-echo, and MRA techniques with phase contrast and contrast-enhanced methods, are discussed and applied in the evaluation of acquired thoracic aorta diseases.

Aorta, Thoracic↗
PubMed2003

[Treatment of ankylosing spondylitis and undifferentiated spondyloarthritis with TNF alpha-antagonists].

The spondyloarthritides (SpA) are common inflammatory rheumatic diseases with an overall prevalence of 0.6-1.9%. Ankylosing spondylitis (AS) and undifferentiated spondyloarthritis (uSpA) are the most common subsets of SpA. Women are almost as frequently affected as men, but the total burden of disease may be similar. At least one third of AS patients are severely affected with impaired function and a poor quality of life similar to patients with rheumatoid arthritis. However, AS starts 20-30 years earlier in life. Thus, AS has a relevant socioeconomic impact on society. After decades of no progress concerning treatment options in SpA, there is now accumulating evidence that the new anti-TNF alpha agents do not only reduce signs and symptoms of AS caused by inflammation but they may also diminish structural damage. Very recent magnetic resonance imaging (MRI) data of a follow-up study support this assumption. The following paper reviews the currently available literature on anti-TNF alpha therapy in AS and uSpA. Efficacy, side effects and experiences with different doses are discussed. In expectation of the approval of infliximab and etanercept for the treatment of active AS international guidelines for initiation, monitoring and discontinuation of these agents have been recently proposed.

Antirheumatic Agents↗
PubMed2003

Cognitive impairment in patients with carotid artery occlusion and ipsilateral transient ischemic attacks.

Although transient ischemic attacks (TIAs) by definition do not cause lasting neurological deficits, cognitive impairment has been suggested in patients with carotid artery disease who have suffered from a TIA. The purpose of our study was to assess whether patients with carotid artery disease and TIAs are cognitively impaired, to describe the frequency, nature and severity of this impairment, and to search for associated patient characteristics.Thirty-nine consecutive patients with carotid occlusion and ipsilateral cerebral or retinal TIAs, and 46 healthy controls underwent extensive neuropsychological assessment. Performances were compared group-wise with analysis of variance. In addition, the presence of cognitive impairment in the individual patient was determined. Associations between illness characteristics and cognitive impairment were explored with regression analysis.Fifty-four percent of patients were cognitively impaired. Cognitive deficits were non-specific in nature and mild in severity. Impairment occurred also in patients with isolated retinal symptoms and in those without visible ischemic brain lesions on MRI. Neither the presence of any vascular risk factor, the side of the symptomatic carotid occlusion, the uni- or bilaterality of carotid occlusion, nor the number of cerebral ischemic lesions were predictors of cognitive impairment. We conclude that about half of the patients with carotid artery occlusion and ipsilateral TIAs are cognitively impaired. The presence of cognitive deficits in patients with isolated retinal symptoms and in those without cerebral ischemic lesions on MRI argues against an exclusive role for structural brain damage in the pathogenesis of these deficits.

Adult↗
PubMed2005

Iatrogenic fractures in ankylosing spondylitis--a report of two cases.

STUDY DESIGN: Two cases of intraoperative, iatrogenic cervical spine fractures in patients with ankylosing spondylitis are reported. OBJECTIVE: To describe the uncommon complication of iatrogenic cervical spine fractures occurring during spine surgery in patients with ankylosing spondylitis. SUMMARY OF BACKGROUND DATA: To our knowledge, this is the first report on this rare complication. METHODS: A 39-year-old patient (1) with ankylosing spondylitis was operated on for cervical stenosis due to C1/2 anterolisthesis. Fifteen hours postoperatively, he developed acute quadriplegia. MRI revealed a fracture/dislocation of C6 on C7 and compression of the spinal cord at this level. Revision was performed with decompression and instrumentation from the occiput to T3. A 55-year-old patient (2) with ankylosing spondylitis and thoracic hyperkyphosis underwent a correction procedure consisting of costotransversectomy, anterior cage implantation at T8/9, and posterior instrumentation from T4 to L1. Halo traction was temporarily applied for correction. At the end of the operation, with the patient still under anesthesia, increased mobility of the cervical spine was noticed. Emergent MRI revealed a fracture of the anterior structures of C6/7. Posterior instrumentation from C5 to T1 was then performed. RESULTS: Quadriplegia persisted in patient 1 until his death secondary to further complications. Patient 2 was mobilized without any neurologic deficits. The fracture healed in good alignment. CONCLUSIONS: Iatrogenic fractures of the cervical spine during surgery in ankylosing spondylitis patients are a rare but potentially severe complication. Early diagnosis and therapy are necessary before dislocation, cord compression, and subsequent neurologic impairment occur.

Adult↗
PubMed2003

2D-RF-pulse-encoded curved-slice imaging.

A new approach to curved-slice imaging is described in which spatial resolution is achieved using 2D-RF-pulse- and conventional-frequency encoding. This approach offers the opportunity to image curved anatomical structures directly using curved single-slice MRI. A set of 2D-RF pulses is employed to excite transverse magnetization in an arbitrarily shaped curved-slice profile in three-dimensional space. Spatial resolution along the curved-slice direction is achieved by encoding the different volume elements of the slice using a set of specially designed RF pulses and an appropriate encoding scheme. The remaining spatial direction is measured using conventional-frequency encoding. Phantom and in vivo experiments were carried out to illustrate the basic feasibility and the limitations of this approach.

Anatomy, Cross-Sectional↗
PubMed2006

Imaging osteoarthritis: magnetic resonance imaging versus x-ray.

Until recently, imaging evaluation of osteoarthritis has relied primarily on conventional radiography. Using radiography in clinical practice or clinical research, however, has been fraught with difficulty. Techniques for reproducibly acquiring serial radiographs of joints have improved considerably over the past several years. However, the greatest promise for advancing knowledge about osteoarthritis and its treatment lies in MRI and its unique ability to examine the joint as a whole organ. In contrast to conventional radiography, MRI can directly visualize the articular cartilage, synovium, menisci, and other intra-articular structures important to the functional integrity of joints. There have been considerable advances in MRI of articular cartilage in particular over the past several years. However, much of this has come from small cross-sectional studies. Larger, longitudinal studies are ongoing, and publications are just emerging. This paper reviews the current status of x-ray and MRI in osteoarthritis and points to where changes might be anticipated in the future.

Arthrography↗
PubMed1991

Cytochrome c oxidase-associated Leigh syndrome: phenotypic features and pathogenetic speculations.

Fourteen new cases of cytochrome oxidase (COX)-associated Leigh syndrome (LS) are combined with 20 reported cases to describe the clinical, laboratory, and radiological features of this devastating metabolic condition. Three clinical stages are identified. Most patients have normal neurological development during the first 8-12 months (stage I). Somatic complaints are common, including chronic diarrhea, recurrent vomiting, anorexia, and decelerating body and head growth. The second stage evolves during late infancy and early childhood when motor regression becomes evident. Eye signs, altered breathing patterns, pyramidal, extrapyramidal, and cerebellar signs emerge and sudden clinical deterioration occurs during intercurrent infectious or metabolic stress. The last stage may extend from 2 to 10 years and is manifested by extreme hypotonia, swallowing difficulties and undernutrition. Feeding assistance is necessary and seizures may occur. The CSF lactate concentration is consistently elevated and MRI abnormalities are seen in the subcortical structures. COX deficiency affects most tissues, but is not always generalized. For example, 3 patients with a cardiomyopathy had normal COX activity in cultured skin fibroblasts. Nearly normal amounts of cross-reacting material are present by ELISA and immunoblot analyses. Parental consanguinity has been found in several families, the hereditary pattern is recessive and males are affected more commonly (2:1). The biomolecular abnormality causing COX deficiency in LS is unknown, but the available evidence implicates a nuclear-encoded protein that affects the structure or the stability of the holoenzyme complex.

Adolescent↗
PubMed1991

The role of SPECT brain imaging in assessing psychopathology in the medically ill.

Cerebral single photon emission computed tomography (SPECT), a method of functional brain imaging, measures cerebral blood flow and metabolism. This paper describes the imaging procedure and several cases where cerebral SPECT was of use in the differential diagnosis of medically ill patients who also presented with psychopathology. SPECT patterns in cerebrovascular disease, dementia, focal epilepsy, and AIDS are at present the best described and seem to be the most specific. Often changes in regional cerebral blood flow are seen before structural changes become apparent on CT or MRI. Cerebral SPECT can add valuable diagnostic information in assessing psychopathology in the medically ill and can often lead to changes in treatment.

AIDS Dementia Complex↗
PubMedDate not supplied

Magnetic resonance imaging of retained surgical sponges. Case report.

The magnetic resonance imaging (MRI) features of sponges retained postsurgically in three patients are described. MRI depicted these as well-defined round masses, which were of low signal intensity on T1-weighted images and very high signal intensity on T2-weighted images. We scrutinized these masses on T2-weighted images. MRI revealed the low-signal-intensity structures to have wavy, striped, and/or spotted appearances, which raised the suspicion that they might be retained surgical sponges within mass lesions.

Aged↗
PubMed1992

Hot-water epilepsy in an adult: ictal EEG, MRI and SPECT features.

Reflex epilepsy constitutes a rare form of epileptic seizures. We observed a 20-year-old man who presented with seizures induced by immersion in hot water. The trigger stimulus was specific. Contrast CT scan and MRI were all normal, not revealing any structural lesion. Ictal EEG recorded during a hot bath showed focal epileptic discharges in the left temporo-occipital area. Interictal SPECT showed a hypometabolism in the same cerebral region. Neuroimaging studies were rarely performed in this uncommon type of epilepsy. Nevertheless, in our case the result of the SPECT suggests a localized functional disturbance in the emergence of the disorder.

Adult↗
PubMed2006

Conscious awareness of flicker in humans involves frontal and parietal cortex.

Even when confined to the same spatial location, flickering and steady light evoke very different conscious experiences because of their distinct temporal patterns. The neural basis of such differences in subjective experience remains uncertain . Here, we used functional MRI in humans to examine the neural structures involved in awareness of flicker. Participants viewed a single point source of light that flickered at the critical flicker fusion (CFF) threshold, where the same stimulus is sometimes perceived as flickering and sometimes as steady (fused) . We were thus able to compare brain activity for conscious percepts that differed qualitatively (flickering or fused) but were evoked by identical physical stimuli. Greater brain activation was observed on flicker (versus fused) trials in regions of frontal and parietal cortex previously associated with visual awareness in tasks that did not require detection of temporal patterns . In contrast, greater activation was observed on fused (versus flicker) trials in occipital extrastriate cortex. Our findings indicate that activity of higher-level cortical areas is important for awareness of temporally distinct visual events in the context of a nonspatial task, and they thus suggest that frontal and parietal regions may play a general role in visual awareness.

Adult↗
PubMed2006

Analysis of radiological features relative to histopathology in 42 skull-base chordomas and chondrosarcomas.

Chordomas and chondrosarcomas are malignant tumors that are reported to have similar clinical presentations and radiological features but different behaviors and outcomes. The aim of this retrospective study was to determine whether specific radiological features of skull-base chordomas or chondrosarcomas are correlated with histopathology, and thus allow preoperative diagnosis. The study involved 32 classic chordomas, 6 chondroid chordomas and 4 chondrosarcomas (42 tumors total). For each case, tumor size and extent, the detailed anatomy involved, and magnetic resonance imaging and computed tomography findings were analyzed. Tumor extent was assessed using a novel method that assessed presence/absence in 18 defined skull-base zones. The chondrosarcomas presented significantly earlier in life than the chordomas (means, 20.5 years versus 36 years, respectively). At time of diagnosis, the median tumor volume was 23 cm(3) (range, 1.2-78.8 cm(3)) and the mean tumor extent was 6.7+/-2.9 zones. There were no differences between chordomas and chondrosarcomas, or between the two chordoma subgroups, with respect to lesion volume or extent. Comparison of other imaging findings revealed no features that were diagnostic for either chordoma or chondrosarcoma. The data support previous claims that chondrosarcomas present earlier in life than chordomas, but this finding is not diagnostic. There is wide variation in the extent of skull-base chordomas and chondrosarcomas, and in the specific anatomical structures these tumors involve. None of the MRI or CT features of these tumors appear to be useful for differentiating chordomas from chondrosarcomas preoperatively. For surgical planning, specific, area-oriented definition of tumor extent might provide more useful information than tumor-type classification schemes.

Adolescent↗
PubMed2004

Functional localization of brain sources using EEG and/or MEG data: volume conductor and source models.

In this overview we examine the basic principles of properties of electroencephalogram and magnetoencephalogram and the corresponding models of sources and of the volume conductor. In particular we show how the dipolar model is anchored in neurophysiological findings and how the different conductivities of the brain and the tissue surrounding it can be estimated. Using these basic models as tools we show how the functional localization of the neural sources of rhythmic activities (alpha and mu rhythms and sleep spindles) and of epileptiform activities can be estimated and integrated with structural data of the brain obtained with MRI.

Brain↗