1/556. Visual loss with Langerhans cell histiocytosis: multifocal central nervous system involvement.A 42-year-old woman with a 6-year history of diabetes insipidus and progressive hypersomnolence presented with visual loss. neuroimaging showed infiltration in the hypothalamus, the optic nerve, and the chiasm, as well as multiple lesions in other areas of the brain parenchyma. biopsy showed Langerhans cell histiocytosis. This is an unusual presentation of Langerhans cell histiocytosis, involving the visual pathways without manifestations outside of the central nervous system. The differential diagnosis and the magnetic resonance imaging findings will be discussed.- - - - - - - - - - ranking = 1keywords = visual (Clic here for more details about this article) |
2/556. role of diffusion-weighted echo-planar MRI in distinguishing between brain brain abscess and tumour: a preliminary report.Our purpose was to evaluate diffusion-weighted (DW) echo-planar MRI in differentiating between brain abscess and tumour. We examined two patients with surgically confirmed pyogenic brain abscess and 18 with metastatic brain tumours or high-grade glioma, using a 1.5 T system. The apparent diffusion coefficient (ADC) of each necrotic or solid contrast-enhancing lesion was measured with two different b values (20 and 1200 s/mm2). All capsule-stage brain abscesses (4 lesions) and zones of cerebritis (2 lesions) were identified on high-b-value DWI as markedly high-signal areas of decreased ADC (range, 0.58-0.70 [(10-3 mm2/s; mean, 0.63)]). All cystic or necrotic portions of brain tumours (14 lesions) were identified on high-b-value DWI as low-signal areas of increased ADC (range, 2.20-3.20 [(10-3 mm2/s; mean, 2.70)]). Solid, contrast-enhancing portions of brain tumours (19 lesions) were identified on high-b-value DWI as high-signal areas of sightly decreased or increased ADC (range, 0.77-1.29 [(10-3 mm2/s; mean, 0.94)]). Our preliminary results indicate that DW echo-planar MRI be used for distinguishing between brain abscess and tumour.- - - - - - - - - - ranking = 1.0156766674977keywords = contrast (Clic here for more details about this article) |
3/556. Contrast agent neurotoxicity presenting as subarachnoid hemorrhage.A patient developed signs, symptoms, and radiologic findings compatible with acute subarachnoid hemorrhage after receiving a large dose of heparin and intravascular contrast medium for coronary angiography and stent placement. Subsequent CT indicated the subarachnoid enhancement was due to contrast. Neurotoxicity from contrast agents is well-known, however this is an unusual report of toxicity mimicking subarachnoid hemorrhage clinically and radiologically.- - - - - - - - - - ranking = 1.5235150012466keywords = contrast (Clic here for more details about this article) |
4/556. The measurement of spatial contrast sensitivity in cases of blurred vision associated with cerebral lesions.Thirty-five patients with known cerebral lesions complained of recently acquired blurred vision. None of them had evident oculomotor or pupillary abnormalities, and each had intact central fields and normal visual acuity by conventional standards. Examination of spatial contrast sensitivity was carried out with sinusoidal grating patterns, by determining the minimum contrast between alternate light and dark bars required to distinguish the pattern from a homogeneous field. This was done at each of several spatial frequencies which were established by varying the width of the bars and hence the coarseness of the pattern. The contrast sensitivities were plotted as "visuograms" which, by analogy to audiograms, record the sensitivities in comparison to normal standards. Of the 35 patients, most showed significant losses, amounting to greater than 50 per cent elevation of contrast thresholds. Eighteen showed high frequency losses; 11 had uniform reductions over the entire visible spatial frequency range and 6 had selective frequency losses in the intermediate frequency ranges. These defects in spatial contrast sensitivity, which were not predictable from standard acuity scores, indicate that the visual symptoms in our patients may have been caused by damage to frequency-selective neural elements in the central visual systems. The method may be used to advantage in clinical investigations as well as in physiological investigations of the functional pathways subserving central vision.- - - - - - - - - - ranking = 7.6015670175884keywords = contrast, visual, sensitivity (Clic here for more details about this article) |
5/556. multimodal imaging of residual function and compensatory resource allocation in cortical atrophy: a case study of parietal lobe function in a patient with Huntington's disease.In a case of Huntington's disease (HD) with dementia and pronounced parieto-frontal atrophy, the functional state of the affected regions was investigated using functional magnetic resonance imaging (fMRI) and fluorodeoxyglucose-positron emission tomography (FDG-PET). It was observed that although parietal areas showed extensive atrophy and reduced resting glucose metabolism, the patient performed with similar accuracy but with longer response time in a visuospatial task compared with healthy control subjects. At the same time, the blood oxygen level-dependent (BOLD) fMRI signal in these areas, which are involved in visuospatial processing, showed a similar task-dependent modulation as in control subjects. The signal amplitude (signal percent change) of the task-dependent activation was even higher for the HD patient than in the control group. This residual functionality of parietal areas involved in visuospatial processing could account for the patient's performance in the task concerned, which contrasted with his poor performance in other cognitive tasks. The increased percent-signal change suggests that a higher neuronal effort was necessary to reach a similar degree of accuracy as in control subjects, fitting well with the longer reaction time. We propose that fMRI should be considered as a tool for the assessment of functionality of morphologically abnormal cortex and for the investigation of compensatory resource allocation in neurodegenerative disorders.- - - - - - - - - - ranking = 0.50783833374886keywords = contrast (Clic here for more details about this article) |
6/556. Sinus histiocytosis with massive lymphadenopathy: a case of multiple dural involvement.An exceptional case of Rosai-Dorfman disease (sinus histiocytosis with massive lymphadenopathy) arising from the meninges in a 60-year-old Japanese man is presented. Computerized tomographic scans and magnetic resonance images demonstrated well-circumscribed tumorous lesions that were homogeneously enhanced with contrast medium. Systemic examination revealed no abnormalities except for a cervical lymphadenopathy and diabetes mellitus. Microscopic examination of the resected specimens showed proliferated histiocytosis and infiltration of plasma cells and lymphocytes. The histology was characterized by the presence of histiocytes demonstrating lymphophagocytosis and immunoreactivity for S-100 protein staining. Immunohistochemical studies and electron microscopy were useful in confirming the diagnosis. The clinical and histopathological features of this disease are discussed.- - - - - - - - - - ranking = 0.50783833374886keywords = contrast (Clic here for more details about this article) |
7/556. blindness from bad bones.Progressive visual loss is the most common neurologic finding in osteopetrosis. Several mechanisms may explain this phenomenon, including compression of the optic nerves caused by bony overgrowth of the optic canals and retinal degeneration. We report a child with osteopetrosis and progressive visual loss, even though patent optic canals were demonstrated by computed tomography and digital holography. This patient's visual loss was caused by increased intracranial pressure secondary, to obstruction of cerebral venous outflow at the jugular foramen. This case points to the importance of a full evaluation of the skull base foramina in the diagnostic workup of visual loss in patients with osteopetrosis.- - - - - - - - - - ranking = 2keywords = visual (Clic here for more details about this article) |
8/556. Endoscopic-guided proximal catheter placement in treatment of posterior fossa cysts.PURPOSE: Treatment of posterior fossa cysts by cystoperitoneal shunting may be complicated by a malpositioned proximal catheter located within the brainstem or cerebellum causing acute shunt malfunction or neurological deficits. We propose that proximal catheter placement from a posterior fossa approach aided by a malleable endoscope may prevent malposition and its complications. methods: We present 4 procedures we performed on 3 patients with posterior fossa cysts using a posterior fossa approach. In each case, the proximal catheter was molded along with a malleable endoscope to place the catheter parallel to the long axis of the fourth ventricle. Direct visualization during catheter placement insured an intracavitary position. RESULTS: Ultimately, the procedure was successful in all 3 patients as judged by intracavitary catheter position and decrease in cyst size on postoperative imaging. In 1 patient, revision using the same technique was required based upon suboptimal catheter position within one of numerous cystic compartments within the posterior fossa. There were no complications related to direct or indirect brainstem injury. CONCLUSIONS: Many posterior fossa cysts can be treated effectively and safely via a posterior fossa approach with the aid of a malleable endoscope. Direct visualization facilitates intracavitary catheter placement and orientation of the catheter in the long axis of the cyst, thereby decreasing the risk of injury to surrounding structures.- - - - - - - - - - ranking = 1keywords = visual (Clic here for more details about this article) |
9/556. The role of corticosteroids in the treatment of cerebral schistosomiasis caused by schistosoma mansoni: case report and discussion.A 26-year-old Brazilian man was admitted to The Toronto Hospital with a headache and visual scintillation. His last travel to brazil was five years previously. A computed tomography (CT) scan of the head showed an occipital mass with surrounding vasogenic edema. Occipital brain biopsy revealed schistosoma mansoni eggs. The patient was treated with two doses of praziquantel (20 mg/kg) and dexamethasone (10 mg). His symptoms and occipital mass resolved. Cerebral schistosomiasis is, in part, caused by the host's inflammatory response to Schistosoma. Modes of treatment have included surgical resection, the antiparasitic drugs oxamniquine or praziquantel, and corticosteroids. Corticosteroids may diminish granulomatous inflammation, thereby preventing further tissue destruction, and there is evidence that they also reduce ova deposition. Our review of the literature supports prompt medical therapy in patients with cerebral schistosomiasis. While the minimally or asymptomatic individual may be treated with praziquantel alone, clinicians should consider adjunctive therapy with corticosteroids for patients with prominent neurologic signs or symptoms or mass lesions with evidence of surrounding edema on a CT scan or by magnetic resonance imaging.- - - - - - - - - - ranking = 0.5keywords = visual (Clic here for more details about this article) |
10/556. MRI of cerebral alveolar echinococcosis.Cerebral alveolar echinococcosis is rare. We report a case with multiple intracranial masses which show cauliflower-like contrast enhancement pattern on MRI. The lesions originated from hepatic involvement with invasion of the inferior vena cava.- - - - - - - - - - ranking = 0.50783833374886keywords = contrast (Clic here for more details about this article) |
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