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Timothy Soeken, Al Alonso, Aaron Grant, Eusebia Calvillo, Jonathan Clark, Dorit Donoviel, Eric Bershad; Evaluation of Quantitative Pupillometry for Detection of Intracranial Pressure Changes in Healthy and Idiopathic Intracranial Hypertension Subjects. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5094.
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There is a need to develop non-invasive methods to monitor the intracranial pressure (ICP) in space and on earth. It is unknown whether pupillary reactivity will decrease when ICP is elevated but without brain injury or cerebral edema, such as in patients with idiopathic intracranial hypertension, or healthy subjects undergoing physiological maneuvers to transiently elevate the ICP. We sought to determine the pupillary reactivity related to maneuvers that elevate ICP including head down tilt, breath holding and Valsalva maneuver in healthy subjects and patients with idiopathic intracranial hypertension.
Healthy subjects underwent eight different test scenarios including Valsalva maneuver, breath holding or resting in three different body positions (upright, supine or 45 degree head down tilt (HDT)) in randomized order. Idiopathic intracranial hypertension subjects underwent five different test scenarios including resting in five different body positions (upright, supine, 15 HDT, 30 HDT, 45 HDT). The pupillary dynamics were automatically calculated by the pupillometer and additionally converted to a composite measure of pupillary reactivity known as the neurological pupillary index “NPI”.
Forty-one subjects were enrolled in the study; 30 healthy subjects, and 11 IIH. The mean age of our population was 32 years with 66% females. In the healthy subjects, the NPI, MAX and MIN were observed to change with position. In this same population, there was also a small but statistically significant decrease in NPI observed in the upright position after breath holding. The results for the IIH test subjects are currently under review.
We observed a statistically significant change in the healthy test subjects and IIH test subjects based on changes in position and task. There was also a statistically significant difference between the healthy subjects and the IIH subjects. This is consistent with our hypothesis that elevated ICP may result in decreased pupillary reactivity even in the absence of brain edema. However, the magnitude of change was small, and variable between subjects so it is unlikely that based on this initial data that this method could be used clinically without individual subject calibration.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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