Abstract Details

Title Near Infrared Spectroscopy-measured Glymphatic Activity is Disrupted Several Years after Concussion

Topic Neuro Trauma and Critical Care

Presentation(s) S34 - Neuro Trauma and Sports Neurology (11:39 AM-11:51 AM)

Poster/Presentation
Number 003

Objective To measure water flux during sleep in TBI and Healthy Controls using Near Infrared Spectroscopy.

Background The glymphatic system has been shown in animal studies to be impaired in traumatic brain injury (mTBI) and may contribute to neurodegeneration, but human studies are lacking. This study examines sleep-related fluctuations in oxyhemoglobin (HbO) and water, using functional near-infrared spectroscopy (fNIRS) and Electroencephalography (EEG) to characterize glymphatic activity in mTBI and healthy control participants.

Design/Methods We used near-infrared spectroscopy (fNIRS) to track HbO and water concentration changes during sleep in mTBI (N=9) and healthy (N=18) controls, alongside electroencephalography (EEG) recordings. After removing movement artifacts, we applied the Modified Beer-Lambert Law (MBLL) to compute HbO and water fluctuations. We then analyzed their spectra in respiratory and cardiac frequency ranges, isolating the periodic component by removing aperiodic power.

Results .In healthy controls, water and oxyhemoglobin signals dynamically adjusted amplitude across sleep stages, particularly between NREM and Wake (H2O: d = 1.7, ***p < 0.001; OxyHb: d = 1.05, ***p < 0.001), reflecting normal physiological fluid and vascular adaptations during sleep. For the mTBI group, these adaptive shifts were absent (H2O: d = 0.04, ns; OxyHb: d = 0.18, ns). Additionally, healthy participants demonstrated dynamic shifts in the peak frequency of low-frequency oscillations (LFOs) of water and HbO across sleep stages, particularly between NREM and Wake (*d = 1.67, p < 0.001). In mTBI participants, these shifts were blunted or entirely absent (Water LFOs: ns; OxyHb LFOs: ns).

Conclusions This suggests mTBI disrupts water flux, which we hypothesize includes glymphatic function, particularly in deep sleep. Additionally, in REM sleep, TBI subjects show reduced cardiac frequency range bandpower, indicating impaired autonomic regulation. These findings warrant further investigation in hemodynamics and water flux / glymphatic exchange in the mTBI population, raising the possibility for potential therapeutic targeting in future work.

Authors/Disclosures
J. Kent Werner, Jr., MD, PhD (Uniformed Services University) PRESENTER	Dr. Werner has received personal compensation for serving as an employee of Cogentis Therapeutics. Dr. Werner has stock in Cogentis Therapeutics. Dr. Werner has received intellectual property interests from a discovery or technology relating to health care. Dr. Werner has received intellectual property interests from a discovery or technology relating to health care. Dr. Werner has received personal compensation in the range of $100,000-$499,999 for serving as a Neurologist with United States Navy. Dr. Werner has received personal compensation in the range of $50,000-$99,999 for serving as a CEO / CoFounder with Cogentis Therapeutics.
Sujasha Gupta, PhD	Dr. Gupta has nothing to disclose.
Franck G. Amyot, PhD (HJF)	Dr. Amyot has nothing to disclose.
Angeliki Pollatou	Dr. Pollatou has received research support from The Geneva Foundation.
William G. Coon, PhD	Dr. Coon has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Arena Labs.
Elizabeth Metzger	Ms. Metzger has received personal compensation for serving as an employee of The Geneva Foundation. Ms. Metzger has received research support from University of Michigan .
Clara Scholl (JHU Applied Physics Laboratory)	No disclosure on file
Angelica M. Lee, DO (Uniformed Services University of the Health Sciences)	Dr. Lee has nothing to disclose.

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