Immediate retrograde amnesia induced by midazolam: A prospective, non‐randomised cohort study

BACKGROUND: Midazolam, a short-acting benzodiazepine, has sedative, anxiolytic, amnestic, and anticonvulsant effect. Given its advantages of rapid onset, short duration, and low toxicity, midazolam is optimal for any procedural sedation. Midazolam is known to cause anterograde amnesia; however, the possibility of retrograde amnesia has also been raised. This prospective cohort, nonrandomized study evaluated the presence and extent of retrograde amnesia induced by midazolam during cesarean delivery. METHODS: One-hundred parturients scheduled for elective cesarean delivery under spinal anesthesia were enrolled. As soon as giving birth, 6 picture cards were shown to the patients in one min intervals, and then midazolam (0.1 mg/kg) was given or not according to the patients' preference. This overall retrograde recall rate of six cards was the primary outcome of our study, which was asked by a blinded investigator. RESULTS: The overall retrograde card recall rate was lower in the midazolam group compared to the control group (77.0 ± 13.4 vs. 87.7 ± 3.9%, p <0.001), especially at one min before midazolam administration (58 vs. 88%, p <0.001). Decreased memory trend was observed as time progressed toward midazolam administration in the midazolam group (p = 0.035). More patients answered 'yes' to the factitious event in the midazolam group than in the control group (26% vs. 4%, p = 0.004). CONCLUSION: Intravenous midazolam could cause a brief-period retrograde amnesia in visual and event memory. Moreover, there were more spurious reports of intraoperative factitious events in the midazolam group, implying that episodic memories were also affected by midazolam.