General anaesthesia is a drug-induced, reversible condition that includes specific behavioral and physiological components of unconsciousness, analgesia, and akinesia with concomitant stability of the autonomic, cardiovascular, respiratory, and thermoregulatory systems. 

Administration of a small dose of a hypnotic drug such like propofol, which acts on 

γ-aminobutyric acid type A (GABA_A) receptors, induces a state of sedation in which the patient is calm and easily arousable, with the eyes closed. 

Arousal and maintenance of organized behavior during wakefulness is regulated by the central thalamus area of the ascending pathways from the brainstem and basal forebrain and descending pathways from the cortex. Studies have shown that the hippocampus too is a pivotal associated structure in the arousal pathway, and events that are seen post-operatively like delayed emergence, amnesia, post-operative delirium and post-operative cognitive decline can be attributed to the volume changes seen in hippocampus.
Delayed recovery /emergence from anaesthesia is the abnormally slow pace of regaining consciousness after general anaesthesia which is characterised by persistent somnolence. Delayed recovery remains one of the biggest challenges that anaesthesiologists are concerned with, as it requires additional time to analyse and use of extra resources. The delay in recovery of the patients from sedation leads to increased duration of stay in the post-procedure room, increases the need for additional monitoring and care and duration of hospital stay. 

Hippocampal electrical activity is shown to have direct correlation with sleep, wakefulness and arousal after anaesthesia. Several molecular and electrophysiological studies have shown that various factors ( sevoflurane/etomidate anaesthesia, temporal lobe resection leading to hippocampal atrophy in epilepsy patients ) affecting hippocampal cells or electrical activity causes delay in recovery from anaesthesia. Having established that, a recent study suggests that hippocampal volume correlates with the type of emergence from anaesthesia. As we are conducting a study which is exploratory in nature, based on the findings of the above mentioned studies studies, we hypothesised that delayed recovery after propofol sedation may be seen in patients with decreased hippocampal volumes.

The aim of our study is to correlate the hippocampal volumes and the duration of recovery and discharge after propofol sedation in the patients undergoing magnetic resonance imaging (MRI) from the post procedure observation room.