Since the first public demonstration of ether anaesthesia in 1846, there has been concern about anaesthetic-induced neurotoxicity. Shortly after observing this demonstration, Henry Jacob Bigelow, a Professor of Surgery at Massachusetts General Hospital, began characterizing the post-etherized state of these particular patients. ‘The character of the lethargic state, which follows this inhalation, is peculiar’, he initially remarked. He later provided the following vivid description of a patient: narcotism was complete during more than twenty minutes, the insensibility approached to coma’. More than a century later, Bedford suggested in 1955 that minor dementias and even catastrophic mental impairment sometimes occur in the aftermath of general anaesthesia. He went on to recommend, operations on elderly people should be confined to unequivocally necessary cases [1]. In 1961, Eckenhoff and colleagues characterized the phenomenon of ‘post-anaesthetic excitement’, which occurred with disproportionate frequency in paediatric patients. Today, the question of whether anaesthetic agents at clinically relevant concentrations are neurotoxic represents a major clinical and scientific controversy in the field.