Use of the Photo-Electromyogram to Objectively Diagnose and Monitor Treatment of Post-TBI Light Sensitivity
Abstract
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 3): 1) based on Facial Action Coding System (FACS) metrics extracted from video recordings, we have shown that videography and image analysis -- for tracking changes in eyelid position and eye brow shape -- can be used as a substitute method for "measuring" EMG activity unobtrusively, 2) in contrast to earlier results, we have observed an overall decrease in EMG activity after CGRP administration, especially for hRAMP1 transgenic mice. 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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 2014
- Accession Number
- ADA621310
Entities
People
- Andrew F Russo
- Pieter Poolman
- Randy H. Kardon
Organizations
- University of Iowa