Multimodal event-related potential P3 after transient global amnesia

The putative generators of the event-related P3 component are still a matter of debate. There is reasonable evidence that the mesial temporal lobe structures are crucial in the generation of event-related potentials. Transient global amnesia (TGA) is characterized by anterograde and retrograde amnesia without neurological deficits in which a temporal hypoperfusion is the most likely pathomechanism. The aim of this study is to evaluate a possible delay in the P3 latency in a cohort of patients with TGA (n = 18). We used classic oddball paradigms with visual and auditory stimuli. The P3 latencies were compared to 18 age-matched patients with transient ischaemic attacks (TIAs) in the carotid artery territory and 23 age-matched controls. The mean age of the patients was 60.1 years (SD 14.1), in the TIA group 64.7 (SD 12.1) and 57.7 (SD 10.1) in the controls; the mean time interval between onset of TGA symptoms and performance of P3 investigations was 4.3 days (range 1-7 days); and the mean latencies measured at the vertex (Cz electrode) were 422.9 ms (SD 44.6) for the TGA patients, 436.4 ms (SD 62.1) for the TIA group, and 409.3 ms (SD 48.5) for the controls in the visual paradigm and 371.7 ms (SD 41.7), 399.7 ms (SD 51.2) and 385.3 ms (SD 46.5) in the auditory paradigm for the TGA, the TIA and the control groups. The P-values were not significant. These results suggest different neuronal networks in the generation of scalp P3 from those responsible for the disturbance of episodic memory in TGA.