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1/517. Integration of preoperative and intraoperative functional brain mapping in a frameless stereotactic environment for lesions near eloquent cortex. Technical note.

    The authors present a method of incorporating preoperative noninvasive functional brain mapping data into the frameless stereotactic magnetic resonance (MR) imaging dataset used for image-guided resection of brain lesions located near eloquent cortex. They report the use of functional (f)MR imaging and magnetic source (MS) imaging for preoperative mapping of eloquent cortex in difficult cases of brain tumor resection such as those in which there are large expansive masses or in which reoperations are required and the anatomy is distorted from prior treatments. To correlate methods of preoperative and intraoperative mapping localization directly, the authors have developed techniques of importing preoperative MS and fMR imaging data into an image-guided frameless stereotactic computer workstation. The data appear as a seamless overlay on the same preoperative volumetric MR imaging dataset used for stereotactic guidance during the operation. Intraoperatively identified functional locations mapped by cortical stimulation are recorded as digitally registered points. This approach should prove useful in assessing the accuracy and reliability of various preoperative functional brain mapping techniques.
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2/517. 18Fluoro-2-deoxyglucose (18FDG) PET scan of the brain in type IV 3-methylglutaconic aciduria: clinical and MRI correlations.

    The clinical, 18fluorodeoxyglucose positron emission tomography (18FDG PET) and the magnetic resonance imaging (MRI) brain scan characteristics of four patients diagnosed to have 3-methylglutaconic aciduria were reviewed retrospectively. The disease has a characteristic clinical pattern. The initial presentations were developmental delay, hypotonia, and severe failure to thrive. Later, progressive encephalopathy with rigidity and quadriparesis were observed, followed by severe dystonia and choreoathetosis. Finally, the patients became severely demented and bedridden. The 18FDG PET scans showed progressive disease, explaining the neurological status. It could be classified into three stages. Stage I: absent 18FDG uptake in the heads of the caudate, mild decreased thalamic and cerebellar metabolism. Stage II: absent uptake in the anterior half and posterior quarter of the putamina, mild-moderate decreased uptake in the cerebral cortex more prominently in the parieto-temporal lobes. Progressive decreased thalamic and cerebellar uptake. Stage III: absent uptake in the putamina and severe decreased cortical uptake consistent with brain atrophy and further decrease uptake in the cerebellum. The presence of both structural and functional changes in the brain, demonstrated by the combined use of MRI and 18FDG PET scan, with good clinical correlation, make the two techniques complementary in the imaging evaluation of 3-methylglutaconic aciduria.
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3/517. 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.
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ranking = 0.028624578695592
keywords = visual
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4/517. 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.
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keywords = visual
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5/517. 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.
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6/517. Treatment of seizures in subcortical laminar heterotopia with corpus callosotomy and lamotrigine.

    Focal and generalized cortical dysgeneses are sometimes seen on the magnetic resonance images (MRI) of patients with epilepsy. Subcortical laminar heterotopia are bilateral collections of gray matter in the centrum semiovale that resemble a band or "double cortex" on MRI. We studied one male and two female patients with subcortical laminar heterotopia who had moderate to severe developmental delay, early-onset epilepsy, and medically refractory seizures. Atonic, atypical absence, tonic, myoclonic, complex partial, and generalized tonic-clonic seizures were recorded. Interictal and ictal electroencephalographic patterns were generalized and, less commonly, multifocal. Two years after corpus callosotomy, one patient was free of generalized tonic-clonic and atonic seizures, but the other patient who had undergone callosotomy had no significant reduction in seizure frequency. With lamotrigine treatment, the patient who had not had surgery had complete cessation of monthly episodes of status epilepticus and a dramatic reduction of generalized tonic-clonic seizures, and the other patient who received lamotrigine had a 50% reduction of her atonic seizures. In patients with subcortical laminar heterotopia, atonic and generalized tonic-clonic seizures can be substantially reduced or eliminated by corpus callosotomy or treatment with lamotrigine.
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keywords = cortex
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7/517. Functional imaging in periventricular nodular heterotopia with the use of FDG-PET and HMPAO-SPECT.

    We analyzed the interictal [18F]fluoro-2-deoxy-D-glucose positron emission tomography (FGD-PET) and single photon emission computed tomography with technetium-99m-hexamethyl-propyleneamine oxime (HMPAO-SPECT) in two epileptic patients with periventricular nodular heterotopia (PNH). In both cases, we found both the glucose metabolism and the perfusion of PNH to be almost identical to those of the normal cerebral cortex. The metabolic activity and perfusion in the heterotopic gray matter in a subependymal white matter area probably represent the glucose metabolism and perfusion of the abnormally located gray matter rather than a subclinical ictal phenomenon. FDG-PET and HMPAO-SPECT were thus found to be a useful complement to magnetic resonance imaging in the evaluation of PNH.
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ranking = 0.16666666666667
keywords = cortex
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8/517. consciousness in congenitally decorticate children: developmental vegetative state as self-fulfilling prophecy.

    According to traditional neurophysiological theory, consciousness requires neocortical functioning, and children born without cerebral hemispheres necessarily remain indefinitely in a developmental vegetative state. Four children between 5 and 17 years old are reported with congenital brain malformations involving total or near-total absence of cerebral cortex but who, nevertheless, possessed discriminative awareness: for example, distinguishing familiar from unfamiliar people and environments, social interaction, functional vision, orienting, musical preferences, appropriate affective responses, and associative learning. These abilities may reflect 'vertical' plasticity of brainstem and diencephalic structures. The relative rarity of manifest consciousness in congenitally decorticate children could be due largely to an inherent tendency of the label 'developmental vegetative state' to become a self-fulfilling prophecy.
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ranking = 0.16666666666667
keywords = cortex
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9/517. Basal forebrain amnesia: does the nucleus accumbens contribute to human memory?

    OBJECTIVE: To analyse amnesia caused by basal forebrain lesions. methods: A single case study of a patient with amnesia after bleeding into the anterior portion of the left basal ganglia. Neuropsychological examination included tests of attention, executive function, working memory, recall, and recognition of verbal and non-verbal material, and recall from remote semantic and autobiographical memory. The patient's MRI and those of other published cases of basal forebrain amnesia were reviewed to specify which structures within the basal forebrain are crucial for amnesia. RESULTS: attention and executive function were largely intact. There was anterograde amnesia for verbal material which affected free recall and recognition. With both modes of testing the patient produced many false positive responses and intrusions when lists of unrelated words had been memorised. However, he confabulated neither on story recall nor in day to day memory, nor in recall from remote memory. The lesion affected mainly the nucleus accumbens, but encroached on the inferior limb of the capsula interna and the most ventral portion of the nucleus caudatus and globus pallidus, and there was evidence of some atrophy of the head of the caudate nucleus. The lesion spared the nucleus basalis Meynert, the diagnonal band, and the septum, which are the sites of cholinergic cell concentrations. CONCLUSIONS: It seems unlikely that false positive responses were caused by insufficient strategic control of memory retrieval. This speaks against a major role of the capsular lesion which might disconnect the prefrontal cortex from the thalamus. It is proposed that the lesion of the nucleus accumbens caused amnesia.
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keywords = cortex
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10/517. 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.
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ranking = 0.057249157391185
keywords = visual
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