Bubble at tip of the stent delivery system of the Palmaz-Schatz stent improves trackability to the target site.
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Catheterization↗
Biomedical subjects
G Schroth
Publications and source records attributed to G Schroth.
[Diffusion-weighted imaging in acute stroke].
Magnetic resonance imaging represents today the most important tool in neuroradiology for both clinical practice and research. MRI allows imaging of the human body in 2 or 3 dimensions with variable tissue contrast. The natural diffusion of tissue protons can now be used as a supplementary contrast mechanism. Different MRI techniques can be used to obtain clinically useful diffusion-weighted images. These techniques all require the use of strong gradient pulses in order to obtain the diffusion contrast. In the current article, the most important physical principles of diffusion measurement are presented. After a short introduction into the basic physical principles, we will present the prerequisites and limitations of clinically relevant applications today. Finally a few select examples of clinical use of these techniques in the acute diagnosis of stroke will be presented.
Acute Disease↗
MRI in a patient with congenital agammaglobulinaemia.
MRI in a 17-year-old boy with known congenital agammaglobulinaemia (CA) demonstrated signs of chronic leptomeningeal inflammation with thickened, enhancing meninges. Furthermore, high signal was found symmetrically on T2-weighted images in the frontal and parietal white matter. The patient presented with severe general brain dysfunction and recent cerebellar ataxia. Extensive investigation did not reveal a causal agent. This case shows that MRI can be helpful in establishing the presence of pathological changes in cases where laboratory results are negative.
Adolescent↗
Pure methotrexate encephalopathy presenting with seizures: CT and MRI features.
With the advent of chemotherapy, mortality rates in acute lymphoblastic leukaemia (ALL) have decreased, but complications in the central nervous system have appeared. These include direct involvement of the brain itself and the development of chemotherapy-related encephalopathy as a delayed reaction. In most reported cases, this encephalopathy is believed to be due to necrotising angiitis arising from the combination of chemotherapy with adjuvant radiotherapy. We report the cases of four children with ALL who had been treated with high-dose intravenous and intrathecal chemotherapy but no radiation therapy, and who were admitted to hospital because of seizures. CT of the brain revealed the presence of diffuse periventricular white matter hypodensities in all cases and subcortical hyperdense foci in three cases. MRI showed diffuse hyperintense white matter lesions on T2-weighted images in all four patients; hypointense changes were observed on susceptibility-sensitive FLASH sequences in the hyperdense foci seen on CT as well as changes that were hyperintense on T1-weighted images. It was, therefore, concluded that the lesions corresponded to a leukoencephalopathy with calcific deposits. These findings are of a pure form of methotrexate encephalopathy causing seizures.
Antineoplastic Agents↗
Middle cerebral artery occlusion AND ocular fat embolism after autologous fat injection in the face.
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Adipose Tissue↗
Pulsatile tinnitus--a review of 84 patients.
Pulsatile tinnitus can be annoying for a patient and can also be the only clue to a potentially devastating and life-threatening disease. In order to understand its clinical spectrum and management better we analysed the files of 84 patients seen at our institution over a 10-year period. Noninvasive techniques (ultrasound, computed tomography, magnetic resonance imaging) and angiography were employed as investigations tailored to the individual patient. A vascular disorder [i.e. arteriovenous fistula, dissection of the internal carotid artery (ICA), fibromuscular dysplasia, aneurysm of the ICA and sinus thrombosis] was found in 36 patients (42%), most commonly a dural arteriovenous fistula or a carotid-cavernous sinus fistula. In 26 patients with a vascular abnormality, pulsatile tinnitus was the presenting symptom. In 12 patients (14%), nonvascular disorders such as glomus tumour or intracranial hypertension with a variety of causes explained the tinnitus. We conclude that patients with pulsatile tinnitus should be investigated with noninvasive techniques. If these are negative or to clarify abnormal findings of noninvasive techniques selective angiography is needed for diagnosis and to guide treatment.
Adolescent↗
Functional organisation of saccades and antisaccades in the frontal lobe in humans: a study with echo planar functional magnetic resonance imaging.
The cortical activation pattern of saccades and antisaccades (versus rest) in the frontal lobe was analysed using an echo planar imaging (EPI) technique in 10 healthy subjects. Statistical analysis of activity in the dorsolateral prefrontal cortex disclosed a significantly greater activation during antisaccades in this region than during saccades. On the other hand, activity in the frontal eye fields was not statistically different in both tasks. These results confirm the important role of the dorsolateral prefrontal cortex for the correct performance of antisaccades obtained by studies in humans with isolated lesions of the dorsolateral prefrontal cortex.
Adult↗
Carotid artery stenosis, occlusion, and pseudo-occlusion: first-pass, gadolinium-enhanced, three-dimensional MR angiography--preliminary study.
PURPOSE: To determine the accuracy of gadolinium-enhanced three-dimensional magnetic resonance (MR) angiography in the evaluation of carotid artery stenosis. MATERIALS AND METHODS: A prospective blinded comparison of first-pass MR angiography with conventional digital subtraction angiography (DSA) was performed in 21 patients suspected of having carotid artery stenosis. MR angiography was performed on a 1.5-T magnet with gradient overdrive equipment, with a coronal radio-frequency-spoiled, three-dimensional, fast low-angle shot sequence after intravenous injection of contrast material. The guidelines of the North America Symptomatic Carotid Endarterectomy Trial for measuring stenosis of the internal carotid artery were applied on maximum intensity projection images and conventional angiograms. RESULTS: Grading of stenoses at MR angiography agreed with that at DSA in 92% of the 44 carotid arteries. In the 18 carotid arteries with severe stenosis (70%-99%), agreement was 94%. All internal carotid occlusions (n = 7) or pseudo-occlusions (n = 3) were accurately detected with MR angiography. CONCLUSION: The accuracy of gadolinium-enhanced MR angiography in characterizing the degree of carotid stenosis was high. Findings with MR angiography were accurate for differentiating between occlusion and pseudo-occlusion.
Aged↗
Selective intra-arterial fibrinolysis of acute central retinal artery occlusion.
BACKGROUND AND PURPOSE: Occlusion of the central retinal artery (CRAO) causes a sudden decrease of monocular vision. Because early restoration of blood flow may improve outcome, we attempted to treat CRAO with selective intra-arterial fibrinolysis. METHODS: Intra-arterial fibrinolysis was performed within 6 hours after symptom onset in 17 patients with thromboembolic CRAO. Symptoms were painless, acute and severe decrease of vision. Urokinase (100 000 to 900 000 IU) was given through a microcatheter into the ophthalmic artery over 10 to 90 minutes. For comparison, the history and visual outcome of 15 control patients who did not receive fibrinolytics were evaluated. In both groups some of the patients underwent paracentesis and/or received carboanhydrase inhibitors. RESULTS: Patients who underwent fibrinolysis fared better than control patients (P=0.01). Three patients (17.6%) recovered completely after fibrinolysis and regained visual acuity of 20/20 (n=2) to 25/20 (n=1). Two additional patients (11.8%) showed a marked improvement to a visual acuity of 20/30. In 6 patients (35. 3%) vision improved slightly. They were able to count fingers, detect hand movements, or perceive light. In 6 patients (35.3%), fibrinolytic treatment was without effect. Among control patients, 1 patient (6.7%) showed partial, 4 patients (26.7%) minimal, and 10 (66.7%) no improvement of vision. CONCLUSIONS: A complete or marked improvement of visual acuity was achieved in one third of intra-arterial fibrinolysis patients but in none of the control patients. Intra-arterial fibrinolysis seems to have the potential to "lighten" the spontaneously poor outcome of CRAO.
Acute Disease↗
Local intra-arterial thrombolysis in acute ischemic stroke.
BACKGROUND AND PURPOSE: We performed a retrospective analysis of the prognostic factors in patients treated with local intra-arterial thrombolysis (LIT). The purpose of this study was to evaluate the safety and efficacy of LIT using urokinase in patients with acute ischemic stroke of the anterior or posterior circulation and to determine the influence of clinical and radiological parameters on outcome. METHODS: Forty-three patients were treated with LIT using urokinase (median dose, 0.75x10(6) IU). The median National Institutes of Health Stroke Scale (NIHSS) score at hospital admission was 18 (range, 9 to 36). Nine patients had occlusions of the internal carotid artery (ICA), 23 of the middle cerebral artery (MCA), 1 of the anterior cerebral artery, and 10 of the basilar artery (BA). Outcome was assessed after 3 months and classified as good for Rankin Scale (RS) scores of 0 to 3 and poor for RS scores of 4 or 5 and death. RESULTS: Nine patients (21%) recovered to RS scores 0 or 1, 17 (40%) to scores of 2 or 3, and 7 (16%) to scores of 4 or 5. Ten patients (23%) died. Outcome was good in 17 patients (80%) with MCA occlusions, in 3 patients (33%) with ICA, and in 5 patients (50%) with BA occlusions. Good outcome was associated with an initial NIHSS score of <20 (P<0.001), improvement by 4 or more points on NIHSS score within 24 hours (P=0.001), and vessel recanalization (P=0.02). Recanalization was more likely if LIT was started within 4 hours (P=0.01). Symptomatic cerebral hemorrhage occurred in 2 patients (4.7%). CONCLUSIONS: LIT was most efficacious in patients with MCA and BA occlusions when the initial NIHSS score was less than 20 and when treated within 4 hours. It is of limited value in patients with distal ICA occlusions.
Acute Disease↗
Neurosyphilis mimicking Miller-Fisher syndrome: a case report and MRI findings.
A 36-year-old man presented with rapidly progressive unsteadiness of gait and diplopia. He had horizontal nystagmus, left sixth nerve palsy, severe ataxia, and areflexia. CSF protein content was 2.4 g/L. Despite a pleocytosis, Miller-Fisher syndrome was diagnosed. Two years later, reevaluation revealed active neurosyphilis in the freshly drawn and stored serum and CSF samples. Clinical findings were consistent with tabes dorsalis. MRI showed lesions confined to the posterior columns of the spinal cord.
Adult↗
MR angiography with ultrashort echo time in cerebral aneurysms treated with Guglielmi detachable coils.
We evaluated a time-of-flight three-dimensional MR angiographic sequence with an ultrashort echo time for its ability to characterize the perfusional state of cerebral aneurysms that had been treated with Guglielmi detachable coils and to depict adjacent cerebral arteries. The results were compared with findings at conventional MR angiography and digital subtraction angiography. Adjacent vessels were seen better in 36% of patients imaged with the new technique. Both MR angiographic methods detected residual cerebral aneurysmal perfusion with a tendency to overestimate the patent portion of the aneurysm.
Adult↗
[Computer-assisted surgical navigation with a dynamic mobile framework for the nasal fossae, sinuses and base of the skull].
Surgery of the skull base and of the paranasal sinuses is often difficult because of the complex anatomy and the delicate structures; serious complications (loss of vision, cerebral lesion) have been reported. To improve the safety of such operations, computer-assisted navigation surgery is increasingly being put to use. We introduce the system which was developed in Berne. Our computer-assisted system is based on an intraoperative pursuit of the head and instruments which are equipped with infrared diodes and registered by an opto-electronic system-camera. The CT-acquisition of the head is accomplished framelessly without a head-holding device. This allows free movement of the head during surgery. Between March and November 1997, 35 navigation operations were performed for various pathologies at the anterior and lateral skull base. The majority of the cases were endonasal operations. No surgical complications occurred inspite of the complexity of the operations. The measured accuracy of the system between the CT and the actual instrument location in the patient was 0.5-2 mm (mean : < 1 mm) for the anterior skull base and 1-2.5 mm (mean < 1.5 mm) for the lateral skull base. The intraoperative navigation system allows identification of essential anatomical structures and permits safe and efficient surgery without additional loss of time. In addition, such a system allows minimal invasive approaches, and new operations may become possible.
Adult↗
Outcome of survivors of accidental deep hypothermia and circulatory arrest treated with extracorporeal blood warming.
BACKGROUND: Cardiopulmonary bypass has been used to rewarm victims of accidental deep hypothermia. Unlike other rewarming techniques, it restores organ perfusion immediately in patients with inadequate circulation. This study evaluated the long-term outcome of survivors of accidental deep hypothermia with circulatory arrest who had been rewarmed with cardiopulmonary bypass. METHODS: Deep hypothermia (core temperature, <28 degrees C) with circulatory arrest was found in 46 of 234 patients with accidental hypothermia. In 32 of the 46 patients, rewarming with cardiopulmonary bypass was attempted, resulting in 15 long-term survivors. In most of these patients, deep hypothermia developed after mountaineering accidents or suicide at tempts. After an average (+/-SD) of 6.7+/-4.0 years of follow-up, we obtained the patients' medical histories and performed neurologic and neuropsychological examinations, neurovascular ultrasound studies, electroencephalography, and magnetic resonance imaging of the brain. RESULTS: The average age of the patients was 25.2+/-9.9 years; seven were female and eight were male. The mean interval from discovery of the patient to rewarming with cardiopulmonary bypass was 141+/-50 minutes (range, 30 to 240). At follow-up there were no hypothermia-related sequelae that impaired quality of life. Neurologic and neuropsychological deficits observed in the early period after rewarming had fully or almost completely disappeared. One patent had cerebellar atrophy on magnetic resonance imaging with mild clinical signs, a condition that may have been caused by hypothermia. Other clinical abnormalities were either preexisting or due to injuries not related to hypothermia CONCLUSIONS: This clinical experience demonstrates that young, otherwise healthy people can survive accidental deep hypothermia with no or minimal cerebral impairment, even with prolonged circulatory arrest. Cardiopulmonary bypass appears to be an efficacious rewarming technique.
Accidents↗
[Ocular myositis].
We report a young woman presenting with "painful diplopia" caused by inflammation of external eye muscles affecting both eyes sequentially. Orbital MRI disclosed swelling, signal hyperintensity and enhancement of isolated eye muscles. Corticosteroid treatment led to a complete remission within a few days. The compiled data of a literature review enclosing 52 sufficiently documented patients diagnosed as orbital myositis is reported with respect to clinical features, laboratory findings, associated disease, value of imaging procedures (CT,MRI). Therapeutic aspects and differential diagnosis are reviewed.
Adult↗
Initial and follow-up MRI in a case of early diagnosed Reye's syndrome.
Early MRI in a case of clinically established Reye's syndrome confirmed CT findings of compressed ventricles and additionally demonstrated signal alterations in the thalamus, mesencephalon and pons. On follow-up MRI the pontine lesion had vanished by 1 week later, while the thalamic lesion persisted for more than 2 months. The patient, however, recovered without neurological sequelae.
Adolescent↗
MRI of paramedian thalamic stroke with sleep disturbance.
The paramedian thalamus is believed to play an important role in the regulation of sleep, and disturbances of sleep regulation are known to occur in paramedian thalamic stroke (PTS). We examined 12 consecutive patients with PTS and sleep disturbance by MRI. Two distinct groups of patients could be defined: six presenting with severe hypersomnia (group 1) and six with slight sleepiness (group 2). On MRI, all patients had ischaemic lesions involving the paramedian thalamic nuclei, the centre of the lesions being the dorsomedial and centromedial thalamic nuclei. In group 1 the lesions were bilateral, butterfly-shaped infarcts involving the paramedian nuclei (three cases); or unilateral with an extension into the subthalamic nuclei. In group 2 the lesions were unilateral and limited to the paramedian nuclei, mainly the dorsomedial nucleus. Bilateral lesions can be attributed to a common origin in some cases for both paramedian thalamic arteries and the mesencephalic arteries.
Adolescent↗
High-resolution echo-planar imaging of the brain: is it suitable for routine clinical imaging?
To assess the value of echo-planar imaging (EPI) for ultra-fast routine clinical diagnostic MRI, we compared four different EPI sequences with conventional T2-weighted spin-echo images on a commercial clinical imager. We examined 25 randomly selected patients who posed different clinical questions. The images were interpreted by two experienced neuroradiologists blinded as to the sequence used. Image quality and diagnostic certainty were evaluated and the main diagnosis established from the EPI study was compared to that obtained from the T2-weighted images. Finally, EPI- and T2-based diagnoses were compared with the diagnosis resulting from a complete MRI examination. Apart from one sequence that was generally rated low as regards both diagnostic certainty and image quality, the EPI sequences were comparable to each other, but inferior to the T2-weighted images. However, two EPI sequences gave better diagnostic results than T2-weighted images compared to the full MRI examination. Gradient-echo EPI was particularly sensitive to haemorrhagic lesions. All normal cases were correctly identified on EPI studies. Only two pathological cases were missed; both had isolated cranial nerve lesions. The absence of false-positive results and the high sensitivity to ischaemic and mass lesions mean that EPI can be used for ultra-fast screening. However, from these initial studies, EPI seems unsuitable for neuroradiological investigation of patients who may have subtle lesions whose detection requires either special sequences or administration of contrast medium. EPI can nevertheless be used in addition to high-resolution T1-weighted images and may replace T2-weighted spin-echo sequences for special indications.
Adolescent↗