11/134. Hyperacute infarction: early CT findings.The aim of our study is to determine how early and reliably ischemic brain infarcts can be detected on CT scanning. We report two cases of an early CT finding of acute ischemic infarcts where CT examination was obtained within the first 3 hours of onset of neurological symptoms. CT examination showed blurred outlines and decreased attenuation of the left lentiform nucleus, loss of the white-gray matter interface in the left insular cortex and left cortical global hypoattenuation with obliteration of left cortical sulci in one patient. In second patient CT showed the following: hyperdense left middle cerebral artery, loss of clear margins of left lentiform nucleus, subtle focal cortical hypodensity in the left fronto-parietal area with signs of mass effect in the form of ventricular compression. CT is still the first choice in the deferential diagnosis of acute stroke. Although older literature positions have suggested that CT was negative during the first 48 hours, modern CT technology can demonstrate positive findings even in the first 3 hours of onset. This is important in patients with acute stroke, as thrombolytic therapy when elected, has to be given within the first 3-6 hours after onset of symptoms. To determine how early and reliably ischemic brain infarcts can be detected on CT scanning, we report two cases of an early CT finding of acute ischemic infarcts where CT examination was obtained within the first 3 hours of onset of neurological symptoms.- - - - - - - - - - ranking = 1keywords = nucleus (Clic here for more details about this article) |
12/134. Thalamic hand dystonia: an MRI anatomoclinical study.Focal dystonia has been attributed to lesions involving the basal ganglia and/or thalamus. hand dystonia was studied in a patient with a unilateral thalamic infarction documented by MRI. A 18-year-old girl presented with severe isolated dystonia of the right hand as a sequel of perinatal infarction. MRI scan revealed infarction affecting part of the dorsomedian, lateral posterior, ventral lateral, ventral posterior lateral nuclei, and centromedian-parafascicular nucleus of the contralateral thalamus. The unique MRI anatomoclinical presentation of this case, taken together with the literature data, could provide evidence that a lesion affecting one or several thalamic nuclei, including the centromedian nucleus, can induce hand dystonia.- - - - - - - - - - ranking = 1keywords = nucleus (Clic here for more details about this article) |
13/134. Bilateral paramedian thalamo-midbrain infarction showing electroencephalographic alpha activity.A 57-year-old man became unresponsive and mute with bilateral ophthalmoplegia and quadriplegia. magnetic resonance imaging (MRI) showed bilateral infarctions at the ventral midbrain and the dorsomedial nucleus of the thalamus. Serial studies with MR and vertebral angiography disclosed hypoperfusion and spontaneous reperfusion of the bilateral posterior cerebral arteries at their origin from the basilar artery. Electroencephalographically, a posteriorly distributed alpha rhythm was clearly recorded and it was reactive in response to external stimuli. The findings seen in the present patient suggest that the ventral midbrain and medial dorsal thalamus are not necessary to produce posterior electroencephalographic alpha activity.- - - - - - - - - - ranking = 0.5keywords = nucleus (Clic here for more details about this article) |
14/134. Right medial thalamic lesion causes isolated retrograde amnesia.Pervasive retrograde amnesia without anterograde memory impairment has rarely been described as a consequence of circumscribed brain damage. We report this phenomenon in a 33 yr-old, right-handed man (JG) in association with the extension in the right thalamus of a previously small, bilateral thalamic lesion. JG presented with a dense amnesia for autobiographical material more than a few years old, with some sparing of recent memories. Furthermore, he was completely unable to recognise famous people or world events. Many other aspects of semantic knowledge were intact and there was no evidence of general intellectual impairment, executive dysfunction or loss of visual imagery. magnetic resonance imaging revealed an acute lesion in the right thalamus and two small, symmetrical, bilateral non-acute thalamic lesions. Follow-up neuropsychological assessment indicated a stable pattern of impaired retrograde and spared anterograde memory over 18 months and psychiatric assessments yielded no evidence of confabulation, malingering or other symptoms to suggest psychogenic amnesia. JG's profile indicates that the division of declarative memory into just two categories - episodic and semantic - is inadequate. Rather, his case adds to the growing body evidence to suggest that world knowledge pertaining to people and events is stored or accessed similarly to autobiographical information and differently from other types of more general factual knowledge. We hypothesize that the right mediodorsal thalamic nucleus and immediately surrounding regions comprise the central processing mechanism referred to by McClelland (Revue Neurologique, 150 (1994) 570) and Markowitsch (brain research review, 21 (1995) 117) as responsible for inducing and co-ordinating the recall of these sorts of cortically stored memory engrams.- - - - - - - - - - ranking = 0.5keywords = nucleus (Clic here for more details about this article) |
15/134. See-saw nystagmus and brainstem infarction: MRI findings.A patient with see-saw nystagmus had a lesion localized by magnetic resonance imaging (MRI) to the paramedian ventral midbrain with involvement of the right interstitial nucleus of Cajal. This the first MRI study of see-saw nystagmus associated with a presumed brainstem vascular event. Our findings support animal and human studies suggesting that dysfunction of the interstitial nucleus of Cajal or its connections is central in this disorder.- - - - - - - - - - ranking = 1keywords = nucleus (Clic here for more details about this article) |
16/134. Convergence retraction nystagmus: a disorder of vergence?The pathological mechanism of convergence retraction nystagmus (CRN) is not known. To determine whether CRN is a disorder of vergence or of the saccadic system, the scleral search coil technique was used to record binocularly the three-dimensional components of CRN in a patient with a left mesencephalic infarction involving the nucleus of the posterior commissure and the rostral interstitial nucleus of the medial longitudinal fascicle. CRN had disconjugate horizontal and torsional components. The horizontal amplitude/velocity relationship of CRN aligned with the main sequence of vergence responses of normal control subjects but not with that of saccades. Vergence responses of the right eye and left eye were not asynchronous. The slow phases of CRN showed an exponential decay with a time constant of 70 milliseconds. Thus, CRN is probably a disorder of vergence rather than of opposing adducting saccades.- - - - - - - - - - ranking = 1keywords = nucleus (Clic here for more details about this article) |
17/134. sinusitis and ischemic stroke.Acute sinusitis is a prevalent and generally uncomplicated infection that is normally resolved by medical therapy. However, severe neurological complications are known, and comprise of cerebral abscess, cavernous sinus thrombosis, meningitis, and epidural or subdural empyema. We report a case about a 10-year-old girl with a severe acute pansinusitis and ischemic stroke in the right lentiform nucleus and the anterior part of the right internal capsule. Possible explanations for this rare combination are discussed.- - - - - - - - - - ranking = 0.5keywords = nucleus (Clic here for more details about this article) |
18/134. Severe personality changes after unilateral left paramedian thalamic infarct.personality changes are not uncommon after paramedian thalamic infarction, but usually bilateral or relatively large lesions, often complicated by other neurological or neuropsychological deficits, are present. 'Pure' cases of unilateral lesions are extremely rare. We report that a right-handed, 48-year-old man, who was hypertensive and diabetic but had no prior psychiatric history, developed severe personality changes and a frontal-like syndrome after recovery from acute-onset impairment of consciousness at the age of 43. Other neurological and neuropsychological disturbances, especially verbal and visual amnesia, were unremarkable. MRI showed a very small infarct in the left paramedian area of the thalamus, mainly involving the dorsomedial nucleus.- - - - - - - - - - ranking = 0.5keywords = nucleus (Clic here for more details about this article) |
19/134. Micrographia secondary to lenticular lesions.Four patients with a stroke developed micrographia. In two patients, the condition was pure and in the two other patients it was associated with signs of writer's cramp. We conclude that infarct of the left lenticular nucleus could either mimic pure micrographia similar to that of Parkinson's disease or micrographia associated with dystonia.- - - - - - - - - - ranking = 0.5keywords = nucleus (Clic here for more details about this article) |
20/134. Deficits of memory, executive functioning and attention following infarction in the thalamus; a study of 22 cases with localised lesions.The thalamus plays a crucial role in memory, executive functioning and attention. It remains, however, unclear whether thalamic structures have specific roles in each of these functions. We tested 22 cases of thalamic infarction, proven with MR imaging, using experimental and established neuropsychological tests. We performed a lesion-overlap study in standardised stereotactic space of patients sharing a certain deficit, corrected for the lesion distribution of patients without such deficits and determined the regions of interest using an atlas of the human thalamus. We checked for additional, non-thalamic, damage and for deficient comprehension and perception that would preclude interpretation of the results. Non-thalamic damage such as white matter lesions, hippocampal atrophy, sulcal widening and infarctions occur significantly more often in patients aged over 60. The patients with additional damage overlapped to a major degree with those who showed loss of orientation, or lack of comprehension of the test requirements. In the 10 patients judged 'clean', we observed a deficit of episodic long-term memory with relative sparing of intellectual capacities and short-term memory when the mammillo-thalamic tract was damaged. Lesions including the medial dorsal nucleus, midline nuclei and/or intralaminar nuclei accompany executive dysfunctioning. Reduced simple processing speed and attention are associated with age, but not with a particular structure in the thalamus. Complex attention deficits follow damage to the intralaminar nuclei.We conclude that the analysis of structure-function relationships must take into account extra-structure damage which may explain cognitive deficits. Separate thalamic structures are involved in memory, executive functioning and attention.- - - - - - - - - - ranking = 0.5keywords = nucleus (Clic here for more details about this article) |
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