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Biomedical subjects

C Ozdoba

Publications and source records attributed to C Ozdoba.

At least 37 records · Page 2Linked to original sources
PubMed1998

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↗
PubMed1998

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↗
PubMed1998

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↗
PubMed1998

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↗
PubMed1997

Accuracy of computer-assisted pedicle screw placement. An in vivo computed tomography analysis.

STUDY DESIGN: A computer-assisted planning and visualization system (the Orthopaedic Surgery Planning System) was tested for pedicle screw insertion in vivo. OBJECTIVES: To evaluate the system's applicability for regular intraoperative use and its accuracy for pedicle screw placement in vivo. SUMMARY OF BACKGROUND DATA: Pedicle screw placement poses considerable anatomic and biomechanical risks. The reported rates of screw misplacement with conventional insertion techniques are unacceptably high. It previously has been shown in vitro that computer assistance offers the potential to decrease the number of screws perforating the pedicular cortex. METHODS: The accuracy of 162 pedicle screws inserted with the Orthopaedic Surgery Planning System was assessed by means of postoperative computed tomography evaluation. Reconstructions of the horizontal, frontal, and sagittal planes were analyzed. Cortex perforations were graded in steps of 2 mm. RESULTS: The cortex was perforated in 2.7% of pedicles. Complete preoperative computed tomography scanning of the levels to be operated on is essential to allow for a precise image reconstruction. Initial difficulties in applying the system contribute to the malplacements. A learning curve for general handling of the Orthopaedic Surgery Planning System was observed. CONCLUSIONS: The system provides a safe and reproducible technique for pedicle screw insertion. Other applications in the field of spine surgery are under evaluation.

Bone Screws↗
PubMed1997

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↗
PubMed1997

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↗
PubMed1997

Retardation of myelination due to dietary vitamin B12 deficiency: cranial MRI findings.

Vitamin B12 deficiency is known to be associated with signs of demyelination, usually in the spinal cord. Lack of vitamin B12 in the maternal diet during pregnancy has been shown to cause severe retardation of myelination in the nervous system. We report the case of a 14(1)/2-month-old child of strictly vegetarian parents who presented with severe psychomotor retardation. This severely hypotonic child had anemia due to insufficient maternal intake of vitamin B12 with associated megaloblastic anemia. MRI of the brain revealed severe brain atrophy with signs of retarded myelination, the frontal and temporal lobes being most severely affected. It was concluded that this myelination retardation was due to insufficient intake of vitamin B12 and vitamin B12 therapy was instituted. The patient responded well with improvement of clinical and imaging abnormalities. We stress the importance of MRI in the diagnosis and follow-up of patients with suspected diseases of myelination.

Anemia, Megaloblastic↗
PubMed1997

Perinatal ultrasonography and magnetic resonance imaging findings in congenital hydrocephalus associated with fetal intraventricular hemorrhage.

OBJECTIVE: We present the case histories of three premature infants with congenital posthemorrhagic hydrocephalus. STUDY DESIGN: The timing of the lesion was monitored in utero in two of the three cases. Magnetic resonance imaging studies (prenatal in one case, within 24 hours of birth in all three cases) established the duration of the lesions and thereby added to the ultrasonographic findings. RESULTS: All three patients demonstrated a similar pattern of lesions, consisting of (1) unilateral germinal matrix hemorrhage with cystic resorption, (2) residual blood in the cerebrospinal fluid with a "granular" ependymal reaction, (3) asymmetric ventriculomegaly predominating on the side of the hemorrhage with mild atrophy and periventricular cysts, and (4) partial hypoplasia of the ipsilateral thalamus. On the basis of two cases in which information about the pregnancy was available and in which fetal oligohydramnios without ruptured membranes was detected, we assume that this pattern of lesions may have resulted from a hypoxic-ischemic episode followed by intraventricular hemorrhage. CONCLUSIONS: Because these three infants with congenital hydrocephalus were born during a period of only 18 months in a perinatal center serving a region with 16,000 live births per year, we speculate that a posthemorrhagic cause for congenital hydrocephalus underestimated.

Adult↗
PubMed1997

Nontraumatic spinal epidural hematomas. MR features.

PURPOSE: Spinal epidural hematoma (SEH) is a rare clinical entity with a bleak outcome. The aim of our study was to establish the value of MR findings in the diagnosis of nontraumatic SEH. MATERIAL AND METHODS: Seven patients with nontraumatic SEH were examined by MR at 1.5 T. Two patients were under anticoagulation therapy with heparin, and 2 others were taking salicylic acid. One patient had lupus erythematodes with a marked thrombocytopenia. One patient had a spinal arteriovenous malformation. RESULTS: MR imaging permitted the accurate localization of extradural intraspinal expansive lesions which exhibited the characteristic signal intensities of blood. Five patients underwent laminectomy and evacuation of the hematoma. In the acute phase, the hematomas appeared isointense when compared with the spinal cord on T1-weighted images and hyperintense on T2-weighted images. Later the hematomas were hyperintense on T1-weighted images and showed signals identical to those of cerebrospinal fluid (CSF) on T2-weighted images. CONCLUSION: MR imaging established the exact diagnosis and localization of SEH in all cases. MR also can provide useful information about the age of the hematomas.

Acute Disease↗
PubMed1997

Dural puncture and activated protein C resistance: risk factors for cerebral venous sinus thrombosis.

OBJECTIVES: Dural puncture is regarded a safe procedure when contraindications are carefully excluded and has so far not been recognised as a risk factor for cerebral venous sinus thrombosis (CVST). Five patients are described with CVST after dural puncture in the presence of additional risk factors. METHODS: In four out of five patients complete investigations for thrombophilia were performed at least one month after withdrawal of oral anticoagulation. RESULTS: In three out of four patients tested, activated protein C (APC) resistance due to heterozygous coagulation factor V R506Q mutation (factor V Leiden) was found. One patient was using oral contraceptives as a circumstantial risk factor and three had had spinal anaesthesia for surgical procedures. Family history of venous thromboembolism was negative in all patients. Retrospective evaluation of 66 patients with CVST disclosed that dural puncture was the fourth most common risk factor (8%) possibly contributing to thrombosis. CONCLUSION: Dural puncture may constitute an additional risk factor for CVST especially in patients with APC resistance or surgery. In such patients a thrombophilia screen is indicated.

Adult↗
PubMed1997

Human cortical plasticity: functional recovery with mirror movements.

Cortical plasticity of the human brain permits functional recovery after brain injury even in the absence of neuronal recovery. We report the combined evaluation, including electrophysiology and functional magnetic resonance imaging, of the pattern of cortical and cerebellar reorganization, in a patient with mirror movements as a sequel of perinatal unilateral brain injury. Recovery resulted in motor control by the healthy hemisphere using direct ipsilateral corticospinal projections and the contralateral cerebellum.

Adolescent↗
PubMed1997

Planning and insertion of pedicle screws with computer assistance.

Transpedicular screw fixation relies on thorough knowledge of the pedicular anatomy and a reliable intraoperative technique. To enhance the safety and accuracy of screw insertion, computer-assisted systems have been introduced. Our in vitro study investigated the potential benefits of such a system for the preoperative planning and the intraoperative visualization. In part 1, the potentially possible range of screw paths (trajectories) through lumbar pedicles was analyzed. In part 2, the accuracy of actual pedicle-hole preparation with and without preoperative planning was assessed. It was shown that, especially in the lower lumbar regions, the possible range of trajectories is considerable, with inclinations of < or = 40 degrees in the transverse plane and a range of angulation in the sagittal plane of > 20 degrees. The computer assistance in preparation of 100 pedicle holes resulted in cortex perforation in only one case. Computer assistance therefore may be used as a valuable tool to minimize the risks of transpedicular screw insertion. It furthermore may assist in determining the desired screw orientation and length and transform this planning into the intraoperative pedicle-hole preparation.

Bone Screws↗
PubMed1996

Recordings of eye movements for stimulus control during fMRI by means of electro-oculographic methods.

A method for monitoring eye movements in humans during functional MRI is presented. It is based on the acquisition of electro-oculographic (EOG) signals near one eye. EOG potentials were amplified and converted into an optical signal just outside the head coil. An optical fiber was used for signal transmission from inside the magnet bore to the control room. The EOG sensor was tested during EPI sequences at 1.5 Tesla without contamination of the MR signal. Some flow related artifacts on the EOG were observed inside the magnet, but no additional interactions from the MR sequence. An analysis of the latency, direction, and amplitude of the saccadic eye movements was possible.

Electrooculography↗
PubMed1996

Internal carotid artery dissection: MR imaging features and clinical-radiologic correlation.

PURPOSE: To analyze the usefulness of magnetic resonance (MR) imaging techniques and diagnostic sensitivity in internal and carotid artery dissection (ICAD) and to correlate these findings with those of other imaging modalities and with clinical signs. MATERIALS AND METHODS: Thirty-one patients with ICAD underwent MR imaging within 2-40 days (mean, 13 days) after onset of clinical symptoms. All patients initially underwent Doppler sonography; 15 patients underwent additional angiographic studies. RESULTS: T1-weighted fat-suppressed MR images most accurately demonstrated intramural hematoma in the internal carotid artery (ICA) in all patients. Kinking or coiling of the ICA was found in nine (29%) patients. Hyperintense signal was seen on T1- and T2-weighted images in the carotid canal or in the cavernous sinus in two-thirds of the patients. Findings characteristic of ICAD were seen on 13 of 16 angiograms. CONCLUSION: MR imaging most accurately demonstrated ICAD. The high rate of kinking and coiling in the carotid artery suggests that these anatomic conditions may be predisposing factors.

Adult↗
PubMed1995

[Diagnostic tomodensitometry of acute basilar thrombosis].

Basilar artery thrombosis is a potentially treatable neurologic disease whose initial symptoms are sometimes difficult to recognize. The basilar artery is hyperdense on computed tomography in cases with basilar artery thrombosis. We have studied computed tomography attenuation values before and after contrast administration in a total population of 117 patients, 12 of whom were diagnosed angiographically as having basilar artery thrombosis. While it is not always possible to detect basilar artery thrombosis simply by evaluation of the tomodensitometric values before or after contrast, the differential values obtained by subtracting them (after contrast/before), or by an attenuation ratio corresponding to the differential value divided by the value before contrast, are more helpful. Indeed, the differential values and attenuation ratios in the normal population have a mean value of 51.1 and 1.37 compared with 14.47 and 0.33 in patients with basilar artery thrombosis.

Aged↗
PubMed1995

Cardiac myxomas: a long term study.

From 1980 to 1992 we followed 12 patients with cardiac myxomas for an average of 4.4 years (8 months-11 years). Presenting symptoms were neurological in four patients (hemiparesis, aphasia, visual field deficits, progressive dementia or vertigo), progressive dyspnoea in six, pulmonary embolism in one, and peripheral arterial or renal emboli in three. The diagnosis was suspected clinically in 11 patients. It was confirmed by echocardiography in ten and by thoracic CT in one. All these patients had cardiac surgery. One diagnosis was made at autopsy; the patient died unexpectedly during surgery for emboli to the leg arteries. At follow-up, two additional patients had died, one from myocardial infarction and one from rhabdomyosarcoma. Only one of the nine surviving patients had recurrent symptoms after cardiac surgery. His dementia continued to progress. The patients without new symptoms after cardiac surgery had normal MRI of the brain or residual ischaemic lesions. MRI of the patient with progressive dementia showed multiple cerebral lesions with a bright centre and a dark rim on T1- and T2-weighted spin-echo images. On CT there were many calcified lesions. CT, MR angiography and contrast angiography revealed multiple fusiform aneurysms. The rare occurrence of progressive neurological symptoms after myxoma resection with multiple cerebral lesions and aneurysms should suggest myxoma metastases to the brain.

Adult↗