Left dominance of EEG abnormalities in patients with transient global amnesia.

PURPOSE: Transient global amnesia (TGA) is a syndrome of unknown etiology. Electroencephalographic (EEG) abnormalities in TGA have been reported previously. We analyzed the frequency and characteristics of EEG abnormalities in patients with TGA. METHODS: We collected EEGs of patients with a clinical diagnosis of TGA who had visited the emergency room or the outpatient clinic over a period of 8 years and compared clinical and demographic characteristics of the patients with normal EEGs with those with abnormal EEGs. RESULTS: EEG abnormalities were found in 35 (22.9%) out of 153 patients and epileptiform discharges were seen in 26 (74.3%) out of these 35 patients. Spikes or sharp waves were detected on the left side only (48.6%) or on both sides (25.7%), but none of the patients showed spikes or sharp waves on right side only. In six patients the EEG had normalized within three months of presentation, in ten within six months, and in twelve by one year. The EEG remained abnormal in eleven out of the 23 patients one year after presentation. CONCLUSION: In this largest consecutive EEG study at one center, the proportion of patients with TGA in whom epileptiform discharges were demonstrated within days of the episode of TGA was significantly higher than in the previous literature. EEG abnormalities such as spikes or sharp waves spontaneously disappeared in almost half of cases over one-year of follow-up. There was a clear left dominance of EEG abnormalities in patients with TGA.

Clinical experience of modified diffusion-weighted imaging protocol for lesion detection in transient global amnesia: an 8-year large-scale clinical study.

BACKGROUND AND PURPOSE: The detection rate of typical transient global amnesia (TGA) lesions on diffusion-weighted imaging (DWI) can be improved, up to 85% with optimal DWI parameters and imaging time. There is limited evidence that these findings are similar to those observed in large-scale consecutive patients with TGA in clinical practice. METHODS: Patients with clinically diagnosed TGA underwent magnetic resonance imaging studies, consecutively, with three sets of DWI parameters (standard clinical DWI protocols, the TGA DWI protocol I and the TGA DWI protocol II) in which the resolution, slice thickness, and the time interval between symptom onset of DWI were varied over an 8-year period. RESULTS: TGA lesion detection rates were up to 88% with a modified TGA DWI protocol. The lesion detection rate was the highest using TGA DWI protocol I, with b = 3,000 s/mm(2), a slice thickness of 3 mm, and performed on the third day after symptom onset, and TGA DWI protocol II, with b = 2,000 s/mm(2) and a slice thickness of 2 mm. CONCLUSIONS: A modified TGA DWI protocols for detecting TGA lesions are useful in large-scale clinical practice for confirming the diagnosis of TGA patients with clinical findings.