Transient global amnesia after breathing hyperoxic mixtures in otherwise regular dives

The diagnosis of decompression sickness may be difficult, particularly when patients present with atypical clinical manifestations after dives going on uneventfully and with full adherence to safety parameters. The case reports involve two divers who presented with transient global amnesia (TGA) immediately after surfacing from otherwise regular dives during which they had been breathing hyperoxic mixtures (Nitrox). A wide spectrum of symptoms of neural dysfunction following hyperoxic mixtures have been reported, including cases of memory impairment related to previous generalized convulsions. After a review of the literature, however, we found no previous reports of TGA, which is very unlikely to result from an epileptic mechanism, as an adverse effect of breathing hyperoxic mixtures.