Background The glymphatic pathway transports cerebrospinal fluid through the brain, thereby facilitating waste removal. A unique aspect of this pathway is that its function depends on the state of consciousness of the brain and is associated with norepinephrine activity. A current view is that all anesthetics will increase glymphatic transport by inducing unconsciousness. This view implies that the effect of anesthetics on glymphatic transport should be independent of their mechanism of action, as long as they induce unconsciousness. We tested this hypothesis by comparing the supplementary effect of dexmedetomidine, which lowers norepinephrine, with isoflurane only, which does not. Methods Female rats were anesthetized with either isoflurane (N = 8) or dexmedetomidine plus low-dose isoflurane (N = 8). Physiologic parameters were recorded continuously. Glymphatic transport was quantified by contrast-enhanced magnetic resonance imaging. Cerebrospinal fluid and gray and white matter volumes were quantified from T1 maps, and blood vessel diameters were extracted from time-of-flight magnetic resonance angiograms. Electroencephalograms were recorded in separate groups of rats. Results Glymphatic transport was enhanced by 32% in rats anesthetized with dexmedetomidine plus low-dose isoflurane when compared with isoflurane. In the hippocampus, glymphatic clearance was sixfold more efficient during dexmedetomidine plus low-dose isoflurane anesthesia when compared with isoflurane. The respiratory and blood gas status was comparable in rats anesthetized with the two different anesthesia regimens. In the dexmedetomidine plus low-dose isoflurane rats, spindle oscillations (9 to 15 Hz) could be observed but not in isoflurane anesthetized rats. Conclusions We propose that anesthetics affect the glymphatic pathway transport not simply by inducing unconsciousness but also by additional mechanisms, one of which is the repression of norepinephrine release.

Purpose Accidental dural puncture and post-dural puncture headache are well-known complications of neuraxial anesthesia in parturients. The primary goal of this study was to identify the rate of post-dural puncture headache and epidural blood patch in all parturients who received a neuraxial anesthetic during a ten-year period at an academic tertiary-care medical centre. A secondary goal was to identify any delay in hospital discharge due to a post-dural puncture headache. Methods We conducted a retrospective analysis of all patients who received a neuraxial anesthetic on the labour and delivery unit at Stony Brook Medical Center from 1 January, 2006 to 31 December, 2015. Standardized neuraxial anesthesia equipment was used throughout this period. Chart reviews were conducted on all patients who received a neuraxial anesthetic and had an accidental