| Transient global amnesia is an unusual neurologic phenomenon that occasionally occurs after angiography, usually of the cerebral vessels. It represents a benign event, and normal function is ultimately restored, but the amnesia may be frightening for both the patient and the physician until its nature is recognized. The authors describe two cases of transient global amnesia occurring after cerebral angiography with iohexol, outline the criteria for the diagnosis and discuss the proposed mechanism of the phenomenon. ( info) |
392/510. Cholinergic treatment of an amnestic man with a basal forebrain lesion: theoretical implications. Cholinergic deficient states, such as in Alzheimer's disease, are associated with amnesia. Therapeutic trials with cholinergic augmentation in Alzheimer's disease have had only equivocal results, but mechanisms other than cholinergic deficiency may contribute to the memory deficit. Normally the diagonal band of broca provides much of the hippocampal cholinergic input. To learn if amnesia secondary to cholinergic deficiency can be ameliorated by cholinergic augmentation, we treated an amnestic man who had a lesion located primarily in the right diagonal band of Broca with physostigmine and lecithin. During the initial best-dose-finding phase, he demonstrated an inverted U-shaped curve for immediate recall of word lists, with peak performances at 3.0 and 3.5 mg of physostigmine. Single photon emission tomography showed decreased blood flow in the medial temporal region ipsilateral to the lesion at baseline, with a reversal of the asymmetry on 3.5 mg of physostigmine. A follow-up double-blind, placebo-controlled study on 3.5 mg of physostigmine, however, failed to demonstrate that cholinergic treatment improved memory. ( info) |
393/510. Mnestic performance profile of a bilateral diencephalic infarct patient with preserved intelligence and severe amnesic disturbances. The case of a patient with above-average intelligence and educational background, high motivation, and an approximate IQ-MQ difference of 40 points is documented. The patient has been examined repeatedly for nearly a decade. Extensive neuroradiological material of his focal bilateral brain damage in the dorsal diencephalon is available. A widespread range of cognitive tests was used to investigate his actual performance on all relevant aspects of intelligence, attention, subjective memory, immediate retention, learning, skill and problem solving abilities, concept formation, cognitive flexibility, priming, constructional ability, retrograde memory, and long-term retention. The total of more than 50 tests included German-language forms of the revised Wechsler Memory Scale and of the Rivermead Behavioural Memory Test. The patient's short-term memory and attention were, in spite of his advanced years, average or well above average. He gave a number of examples of still intact skills and implicit memory abilities, though there was no uniformity in his performance on implicit memory tests (e.g., with respect to stored vs. new implicit information). He had no awareness of his severe anterograde and retrograde amnesia, documented over a large range of verbal and figural tests. Taken together, the results from our patient confirm the principal dichotomy between declarative and nondeclarative mnestic functions, but give evidence for some restrictions as well. They furthermore demonstrate that focal diencephalic damage may result in profound anterograde and selective retrograde amnesia, especially with respect to data-based material, and that disconnecting portions of the medial and basolateral limbic circuits has devastating consequences on memory. ( info) |
| A 58-year-old woman with relapsing acute guillain-barre syndrome separated by long asymptomatic intervals presented clinical symptoms resembling those of brain death. She remained in this situation for 15 days and recovered with amnesia for this period. The amnesia was not explained either by metabolic encephalopathy or by sedative drugs. This case stresses the importance of the precise etiologic diagnosis of severe brain disease and the isoelectric EEG in brain death. ( info) |
395/510. The clinical management of hiv-related dementia and other memory disorders in the residential drug treatment environment. Human immunodeficiency virus (hiv)-related dementia and other memory and attention disorders are described in terms of etiology, incidence, and symptoms. Assessment for cognitive impairment includes basic screening (examples are given), or a thorough neuropsychological evaluation. Implications for treatment within the residential drug treatment environment include: (a) providing accurate information to staff and residents; (b) identifying residents' anticipatory anxiety; (c) supportive counseling of residents; (d) coaching residents in the use of coping strategies; (e) creating environmental support; and (f) frequent reassessment of treatment goals, including the appropriateness of independent living. Helpful concrete suggestions are listed. ( info) |
396/510. Unilateral amnesic stroke. Six new cases and a review of the literature. BACKGROUND AND PURPOSE: Although persistent amnesia due to bilateral limbic system infarction is well described, reports of amnesic syndromes due to unilateral stroke have appeared infrequently and unsystematically. We report six new cases and review previously published reports to expand and consolidate knowledge regarding amnesic stroke. CASE DESCRIPTIONS: Six patients developed acute amnesia associated with unilateral stroke. Brain computed tomography or magnetic resonance imaging revealed lesions in limbic structures, which accounted for the memory deficit. Based on these as well as similar cases in the literature, we delineate three distinct syndromes of unilateral amnesic stroke involving the territories of the posterior cerebral, anterior choroidal, and thalamic penetrating arteries. Eighty-five percent of reported cases have involved the left hemisphere. CONCLUSIONS: Persistent as well as transient amnesia may be the sole or primary manifestation of unilateral hemispheric stroke. The vascular mechanisms of amnesic stroke are diverse. patients presenting with acute amnesia possibly related to cerebral ischemia should be classified by documented or presumed lesion site as well as the involved vascular territory. Left amygdalohippocampal or diencephalic dysfunction may produce a particular vulnerability to global amnesia. ( info) |
397/510. Posterior ischemia during an attack of transient global amnesia. BACKGROUND: The popular concept that cerebral ischemia causes transient global amnesia has been difficult to prove by cerebral blood flow studies during attacks because the transient global amnesia attacks are so short. CASE DESCRIPTION: We performed single-photon emission computed tomography (SPECT) of the brain and neuropsychological assessment in a 37-year-old woman during a 10-hour attack and twice thereafter. A neuropsychological evaluation 3 hours after the onset of transient global amnesia revealed severe impairment of recent memory and verbal fluency, both of which returned to normal 2 and 28 days later, respectively. A 99mTc-labeled hexamethylpropyleneamine oxime SPECT of the brain performed 6 hours after the onset showed multiple perfusion defects in both occipital lobes, the medial left temporal lobe, and the left thalamus. A second brain SPECT performed 3 days later showed perfusion defects in only the occipital regions. A third brain SPECT performed 28 days later was normal. The patient's brain computed tomographic scan, electroencephalogram, duplex ultrasound of the carotid artery, and echocardiogram were normal. CONCLUSIONS: The perfusion defects revealed by the brain SPECT during the transient global amnesia attack indicated ischemia in the territory of the posterior cerebral arteries, which partially resolved in 3 days and completely resolved by 28 days. ( info) |
398/510. Amnesic syndrome caused by neurosarcoidosis. A 20-year-old woman presented with subacute amnesia, which turned out to have been caused by neurosarcoidosis. The patient showed several remarkable features: isolated bilateral temporal hydrocephalus, caused by ventriculitis/arachnoiditis; spinal arachnoiditis as demonstrated by myelography, which was not noticed on MR scan. Diagnostic difficulties that are sometimes encountered when neurosarcoidosis is suspected (particularly the differentiation from neurotuberculosis if insufficient evidence of systemic sarcoidosis is found) are discussed. ( info) |
| A case of intraoperative recall and awareness in a patient with sickle cell disease who had received midazolam, 10 mg at induction of anesthesia, is reported. The patient was on opioids which may also have caused tolerance. Although the use of midazolam may have been judged to provide adequate amnesia, this was clearly not the case. Upon analysis of the reasons for recall, we predicted from a two-compartment model that the estimated blood level was 88 ng/mL-1; this level would have provided no amnesia. This case illustrates that recall can occur with the use of midazolam, especially if levels become subtherapeutic, and other measures should be taken to provide adequate anesthesia and amnesia. ( info) |
400/510. Impaired temporal context memory on anterograde but not retrograde tests in the absence of frontal pathology. This study examined the memory performance of patient RK who developed substantial memory impairments due to a hypothalamic glioma but in the absence of any evidence of frontal disturbance. RK was evaluated on both tests of anterograde and retrograde memory for temporal context. In the first experiment he exhibited marked deficits on a list discrimination task even when recognition performance was well within control range. Experiment 2 confirmed this disproportionate impairment of temporal order memory and showed that RK's list discrimination deficit was as severe as that found in alcoholic Wernicke-korsakoff syndrome patients. Experiment 3 showed that RK's temporal discrimination deficit was not a general deficit in discrimination because he performed normally on a spatial discrimination test of comparable difficulty to the temporal task. Experiment 4 examined RK's memory for deceased famous people and his ability to indicate the half decade in which they died. RK's performance was indistinguishable from controls whereas WKS patients were extremely impaired. This study adds to the view that frontal damage is not a necessary condition for impairment on anterograde measures of temporal context memory. However, further evidence from this study indicates that temporal judgments about pre-existing memories may depend on intact frontal lobe functioning. ( info) |