Zopiclone Intoxication: Value of Electroencephalography in the Emergency Room

Standard urine toxicological immunoassays for benzodiazepines, barbiturates, cannabinoids, opiates, methadone, cocaine, buprenorphine, propoxyphene, LSD and amphetamines were negative; serum ethanol level was undetectable. There were no abnormal findings on brain CT with perfusion and venous angiography. EEG on admission showed essentially normal-structured sleep stage II, with symmetrical spindles and K complexes; following nociceptive stimulation, a poorly sustained -rhythm appeared; during the whole recording, abundant, diffuse superimposed (fast)-activity was noted ( fig. 1 a). A flumazenil test was not performed to avoid provoked seizures. Stupor recovered spontaneously within 24 h, and a second EEG 6 days later was normal, with minimal superimposed fast activity ( fig. 1 b). Considering these EEG findings, we performed a serum gas chromatography/mass spectrometry and liquid chromatography UV on the serum sample drawn on admission; this revealed a toxic level of zopiclone (250 g/l; norm