Use of the Photo-Electromyogram to Objectively Diagnose and Monitor Treatment of Post-TBI Light Sensitivity.

摘要

Purpose: to test the whether photosensitivity (photophobia) after traumatic brain injury (TBI) is due to increased sensitivity of the brainstem trigeminal sensory nucleus, as revealed objectively by an exaggerated photoblink reflex (photo-electromyogram). This will be tested in humans and in a mouse strain genetically engineered to be hypersensitive to calcitonin gene related peptide (CGRP), the neurotransmitter modulating trigeminal nerve function. Scope: objective methods to quantify photo-sensitivity include 1) light evoked potentials (electromyogram) from the blinking and squinting muscles of the forehead 2) the pupil light reflex 3) light evoked changes in sympathetic nerve activity, measured by changes in skin conductance and heart rate. Major Findings (Year 4): 1) we have designed and assembled a multi-camera platform that will allow us to transition from EMG recording with surface skin electrodes to an electrode-free system that will take advantage of facial feature changes in response to light and pain which is anticipated to be useful in remote settings and home testing, utilizing smart phone devices, 2) we have configured the recording and analysis software to apply Componica's software library to multiple camera video streams simultaneously in order to analyze minute changes in facial features in real time, and 3) we have tested additional normal subjects to better match age and sex of those subjects already tested with photosensitivity in order to define the normative range of values for light induced EMG. Significance: objective testing of photosensitivity in humans and mice will provide new approaches to finding the underlying mechanisms, classification of photosensitivity, diagnosis and monitoring of new treatments.