1/28. Transient amnesia triggered by acute marijuana intoxication. We report an unusual case of sudden isolated transient amnesia triggered by acute marijuana use. The memory disorder, apart from the long duration, had the characteristics of a transient global amnesia-like episode. Acute marijuana intoxication can affect memory more globally and severely than previously reported. ( info) |
| A variety of transient focal neurological signs presenting at high altitude have been described without associated acute mountain sickness or other concurrent illness. We report a case series of transient global amnesia at high altitude. The term high-altitude global amnesia (HAGA) is introduced to indicate this condition, and the pathophysiology is discussed. We hypothesize that because of the highly variable ventilatory response to hypoxia and to individual cerebral vasomotor reactivity, individuals with a marked hyperventilatory response could experience significant hypocapnic cerebral vasoconstriction that in turn could cause local hypoxia or ischemia to particular regions of the brain and resulting transient focal neurological impairment. ( info) |
3/28. Transient global amnesia and amaurosis fugax in a patient with common carotid artery occlusion--a case report. The etiology of transient global amnesia (TGA) is debatable. The hypothesis of a thromboembolic cause of TGA has been questioned by recent case control studies. Occlusion of the common carotid artery (CCA) is rare. Although amaurosis fugax (AF) is a hallmark of ipsilateral internal carotid artery disease, its occurrence in CCA occlusion is less known. association of these three conditions in a patient may imply pathophysiologic significance. Here, the authors report a 76-year-old man who suffered from a spell of TGA and then several attacks of AF of the right eye. Progressive occlusion of the right CCA was documented by repeat carotid duplex scans and was finally confirmed by cerebral angiography. In this patient, the occurrence of CCA occlusion and AF implicates a vascular etiology for the event of TGA. A noninvasive carotid ultrasonographic screen may, therefore, be worthwhile for patients with TGA. ( info) |
| This case report describes an episode of transient global amnesia that occurred during a migraine attack, which had been treated with vasoconstrictors. Magnetic resonance imaging showed a small lesion with an ischemic appearance in the right thalamus. ( info) |
5/28. A SPECT study of the anatomy of transient global amnesia. This report describes single photon emission tomography (SPECT) evidence of transient, relative hypoperfusion of the right basal ganglia and left temporal lobe in a 60-year-old man studied during the acute phase of classical transient global amnesia (TGA). The findings are interpreted in the light of previous reports indicating that involvement of the right hemisphere or both cerebral hemispheres consistently predicts severe retrograde amnesia, in addition to the typical loss of anterograde memory observed during TGA. These deficits involving the right hemisphere and left temporal lobe may reflect disruption of circuits mediating episodic memory retrieval and memory encoding, respectively. ( info) |
6/28. Quantitative single photon emission tomography analysis for the diagnosis of transient global amnesia: adaptation of statistical parametric mapping. We report two cases of transient global amnesia (TGA) diagnosed using a clinical criteria and single photon emission tomography (SPECT) with the aid of Statistical Parametric Mapping (SPM). Both patients underwent an initial SPECT study about 20 h after the disappearance of the amnesic episode, and a second study 3 weeks after the episode. We conducted quantitative cerebral blood flow (CBF) analyses using SPM on Matlab. This revealed regions with abnormal CBF in the first studies but not in the second. This method appears to be useful for diagnosis of TGA, especially in patients with suspected TGA in whom the amnesic episode disappears within a few days. ( info) |
7/28. Evolution of temporal lobe hypoperfusion in transient global amnesia: a serial single photon emission computed tomography study. Previous functional neuroimaging studies performed during transient global amnesia (TGA) have not answered the central question regarding the etiology of TGA, namely: whether the observed hypoperfusion in the mesial temporal lobe structures reflects a primarily ischemic process or whether it represents a secondary phenomenon resulting from locally decreased metabolism. The authors performed Tc 99-m-bicisate brain single photon-emission computed tomography (SPECT) scanning in a 66-year-old man during an episode of TGA, 24 hours after the episode and 3 months after the episode. To the authors' knowledge, this is the only reported study in which a follow-up SPECT scan was performed within 24 hours. The initial study showed bilateral mesial temporal lobe hypoperfusion that partially resolved after 24 hours and returned to normal at 3 months. Resolution of the SPECT scan abnormalities correlated well with resolution of the memory loss. These findings agree with previously reported SPECT, positron-emission tomography (PET), and diffusion magnetic resonance imaging (MRI) studies that indicate the mesial temporal lobe structures as the major site of pathology in TGA. The authors suggest that a process causing decreased local metabolism, such as cortical spreading depression, constitutes the primary pathophysiologic mechanism in this case. ( info) |
| We describe a case of transient global amnesia related to symptomatic renal stones. Transient global amnesia has been related to intense emotional or painful experiences, such as sexual intercourse, cold water bathing and trigeminal stimulation. Renal stones may be at the origin of a painful experience and thus may induce transient global amnesia. ( info) |
9/28. Unilateral temporal lobe stroke causing ischemic transient global amnesia: role for diffusion-weighted imaging in the initial evaluation. ischemia has been proposed as a cause of transient global amnesia (TGA), but proof has been lacking. The authors performed magnetic resonance imaging on a 77-year-old woman with classic TGA at 4 hours and at 6 days after the onset of symptoms. Her initial diffusion-weighted imaging (DWI) and apparent diffusion coefficient imaging suggested an acute infarct in the left mesial temporal lobe. Follow-up T2-weighted imaging at 6 days confirmed the lesion as an ischemic infarct, despite resolution of her symptoms. DWI permits early detection of small ischemic lesions and may identify patients with ischemic TGA who should be evaluated for potential sources of emboli. ( info) |
10/28. Transient global amnesia (TGA) in an MEG study. A patient who had experienced an attack of transient global amnesia (TGA) was examined using neurophysiological methods. magnetoencephalography (MEG) was performed and the Wechsler memory Scale-Revised (WMS-R) test was administered at 5 days and at more than a month after the TGA episode. MEG data on neuronal activity obtained while the patient was undertaking a working memory task and during rest were analyzed using the wavelet-crosscorrelation method, which reveals time-lag and information flow between related sites in the brain. The WMS-R memory scores showed dramatic improvement when the test was administered a month following the attack, although no significant changes were observed in EEG, MRI and SPECT data. The MEG study revealed that under a working memory load how the neuron works functionally and the information propagates assembly within the right hemisphere, and that these brain functions were not performed adequately shortly after the TGA attack. ( info) |