1/3. Contributions of the left intralaminar and medial thalamic nuclei to memory. Comparisons and report of a case.A patient complained of memory disturbance after a small left thalamic infarction. Neuropsychological testing revealed her memory to be normal provided that she was allowed to rehearse or use semantic encoding strategies. When these strategies were prevented, her performance was impaired. Mapping of the lesion demonstrated involvement of the caudal intralaminar nuclei (centre median and parafascicular nuclei), and portions of the medial nuclei (medioventral [reuniens], centromedial, and the most inferior aspect of the mediodorsal nucleus). The majority of mediodorsal nucleus, the mammillary bodies, the mammillothalamic tract, and the anterior thalamic nuclei, were spared. A comparison among our patient's performances and those of alcoholic Korsakoff patients, patient NA, and amnestic patients with circumscribed diencephalic lesions suggests that there are two distinct behavioral and anatomic types of memory impairment associated with diencephalic lesions. The severe amnesia associated with damage to the mammillary bodies, midline nuclei, mammillothalamic tract, and/or dorsomedial nucleus of the thalamus (eg, Korsakoff and NA) is characterized by encoding deficits that never approximate normal performance. The memory disturbance associated with damage to the intralaminar and medial nuclei of the thalamus is milder and is characterized by severe distractibility.- - - - - - - - - - ranking = 1keywords = amnestic (Clic here for more details about this article) |
2/3. adult post-infectious thalamic encephalitis: acute onset and benign course.We report on two young patients with an encephalitic syndrome and bilateral thalamic lesions following a presumably viral or mycoplasma respiratory tract infection with the main clinical symptoms of organic psychosis in the first and a prolonged amnestic syndrome and ataxia in the second case. Four months later the patients had recovered clinically and the thalamic lesions had resolved on magnetic resonance imaging in one case and almost completely in the other. We interpret the patients' illness as rare cases of a post-infectious acute thalamic encephalitis in adults. The cases and their relationship to possible post-infectious autoimmune inflammatory or toxic pathophysiological mechanisms are discussed and a review of the literature is provided.- - - - - - - - - - ranking = 1keywords = amnestic (Clic here for more details about this article) |
3/3. amnesia following thalamic hemorrhage. Another stroke syndrome.The clinical manifestations of thalamic hemorrhage frequently comprise hemiparesis, hemianesthesia, and oculomotor abnormalities. Since the advent of computed tomography, an amnestic syndrome following thalamic hemorrhage has been recognized, but the thalamic structures involved and the mechanism of amnesia have remained uncertain. We report a patient with sudden memory dysfunction following hemorrhage into the anterior nucleus of the left thalamus that was shown neuropathologically to disrupt the mamillothalamic fasciculus, one of the principal components of the limbic system. It is considered that the amnestic syndrome following thalamic (anterior nucleus) hemorrhage is due to interruption of the mamillothalamic fasciculus.- - - - - - - - - - ranking = 2keywords = amnestic (Clic here for more details about this article) |