Elevated preoptic brain activity in zebrafish glial glycine transporter mutants is linked to lethargy-like behaviors and delayed emergence from anesthesia

Delayed emergence from anesthesia was previously reported in a case study of a child with Glycine Encephalopathy. To investigate the neural basis of this delayed emergence, we developed a zebrafish glial glycine transporter (glyt1 − / −) mutant model. We compared locomotor behaviors; dose–response curves for tricaine, ketamine, and 2,6-diisopropylphenol (propofol); time to emergence from these anesthetics; and time to emergence from propofol after craniotomy in glyt1−/− mutants and their siblings. To identify differentially active brain regions in glyt1−/− mutants, we used pERK immunohistochemistry as a proxy for brain-wide neuronal activity. We show that glyt1−/− mutants initiated normal bouts of movement less frequently indicating lethargy-like behaviors. Despite similar anesthesia dose–response curves, glyt1−/− mutants took over twice as long as their siblings to emerge from ketamine or propofol, mimicking findings from the human case study. Reducing glycine levels rescued timely emergence in glyt1−/− mutants, pointing to a causal role for elevated glycine. Brain-wide pERK staining showed elevated activity in hypnotic brain regions in glyt1−/− mutants under baseline conditions and a delay in sensorimotor integration during emergence from anesthesia. Our study links elevated activity in preoptic brain regions and reduced sensorimotor integration to lethargy-like behaviors and delayed emergence from propofol in glyt1−/− mutants.

Pneumocephalus following Lumbar Spine Surgery: A Rare Cause of Delayed Emergence from Anesthesia

Pneumocephalus is an unusual presentation after lumbar spine surgery. We report the case of a young healthy patient, who had delayed emergence from anesthesia after undergoing an uncomplicated lumbar spine surgery. After shifting to the Intensive Care Unit, the patient had an episode of generalized tonic—clonic seizure. Computed tomography scan revealed the presence of pneumocephalus. The patient was managed conservatively, extubated the following day and discharged with no neurological deficits.