Rationale:
Seizures delay REM sleep onset and shorten REM sleep duration. The majority of spot EEGs also do not demonstrate REM sleep, given that spot EEGs can last only 20-30 minutes. If sleep is captured, it is usually non-REM because REM is preceded by non-REM in a typical night of sleep cycling. However, there was an unusual peak of spot EEGs with REM sleep from the Winnipeg Health Sciences Centre emergency department in the summer of 2023. We sought to determine the most pertinent clinical characteristics that may account for this finding.
Methods:
Retrospective case series of patients with REM sleep in their spot EEGs ordered through the emergency department. Charts were reviewed for past medical histories, medications, history of present illnesses, reason for EEG, and severity of EEG findings.
Results:
Four spot EEGs with REM sleep were flagged by recording technologists and confirmed by one EEG reader. EEGs had been ordered to rule out a recent seizure in all four patients, aged 20-77 years and 25% female, presenting with altered mentation. Patient 1 ingested between seven to ten alcoholic beverages daily. His EEG occurred 42 hours after presentation and was within normal limits. Patient 2 had a history of mesial temporal sclerosis and polysubstance use including opioids, cocaine, and methamphetamine. He endorsed methamphetamine use during the two days just prior to the emergency department presentation. His EEG occurred 24 hours after presentation and was within normal limits. Patient 3 used methamphetamine several hours before presenting at the emergency. There was also a documented history of sleep deprivation. His EEG occurred 14 hours after presentation and was normal. Patient 4 had a reported history of focal and absence seizures in the setting of callosal agenesis, and no substance use. EEG only showed asymmetric sleep architecture, often lost over the left hemisphere. None of the four patients had a documented history of narcolepsy.
Conclusions:
Most of our patients with REM sleep on spot EEG in the emergency department were on substances, such as alcohol and methamphetamine, that usually reduce REM sleep. Withdrawal from these substances in the emergency department may have promoted REM sleep rebound. Furthermore, seizures disrupt REM sleep to make finding REM sleep on the spot EEG from an individual who recently seized even less likely. Hence, the presence of REM sleep on spot EEGs in the emergency department may not be just coincidental. Rather, this suggests that REM sleep on a benign spot EEG from the emergency department could be a negative biomarker against seizures, which is worthy of future exploration.
Funding:
N/A