Date of Award

January 2013

Document Type

Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

David G. Silverman

Subject Area(s)

Medicine

Abstract

The Effect of Mental and Physical Stress on Brain Temperature as Measured Via the Brain Temperature Tunnel

Dionne Rudison, David G Silverman, Marc M Abreu , Saeeda Qadri, Swaboda Haberlund, Nyasha George.

Core temperature measurement via sublingual, esophageal, and ear routes have been shown to differs significantly intracranial temperature. In 1998, it was discovered that the termination point of the superior ophthalmic vein under the skin adjacent to the canthus of the eye provided an accurate and non-invasively means to measure brain temperature (14). This location is called the Brain Temperature Tunnel (BTT) . In this study, we investigated the effect of mental and physical stress exercises on intracranial temperature as measured via BTT.

Methods: After obtaining IRB approval, non-invasive adhesive thermal sensors were placed at the BTT site near the canthus of the eye of 10 volunteers. We simultaneously measured both aural (AU) and sublingual (SL) temperatures. Laser Doppler Finger Plethysmograph was used to determine changes in heart rate during the experiment. Volunteers were subject to three exercises: Mental Effort (ME), Criticism (CR), and immersion of extremity in 4°C water (EW). Increases in temperature and changes in heart rate (HR) were compared to indicate that sympathetic response or stress occurred. Changes in SL, AU, and BTT were compared via paired t-tests with Bonferroni correction.

Results: ME: The mean increase in BTT (°C) was 0.21ᵒ C and mean increase in HR was 35.5%. The correlation coefficients of SL and AU vs. BTT were 0.13 and 0.28 respectively. CR: The mean increase in BTT was 0.11 and mean increase in HR was 29.74%. The correlation coefficients of SL and AU vs. BTT were 0.13 and 0.13 respectively. EW: The mean increase in BTT was 0.09 and mean increase in HR was 19.90%. The correlation coefficients of SL and AU vs. BTT were 0.4 and 0.18 respectively.

Discussion: The results suggest that the mental effort phase was sufficient to trigger a sympathetic or stress response, which in turn resulted in a change in cerebral metabolism and an increase in BTT. The data for the CR and EW phases were equivocal. Further study is needed to more fully assess the effect of stress on brain temperature.

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