Effect of History of Mild Traumatic Brain Injury on Optic Nerve Sheath Diameter Changes after Valsalva Maneuver.

Optic nerve sheath diameter (ONSD) measured by transocular ultrasound is a marker of real-time intracranial pressure (ICP). The objective of this study was to evaluate the association between optic nerve sheath (ONS) dilation after a Valsalva maneuver and a prior history of mild to moderate traumatic brain injury (mTBI) in a heterogeneous sample of participants. Participants were excluded if they had had a recent brain injury, were symptomatic from a prior brain injury, had a history consistent with severe TBI and/or had undergone intracranial surgery. Ninety-five participants with and without a history of mTBI were included in the study. Transocular ultrasound of the ONS was performed before and after a Valsalva maneuver. Differences in the ONSD before and after a Valsalva maneuver were analyzed and correlated to the participants' history of mTBI. Baseline ONSD measurements between groups were not statistically significant. Following Valsalva, participants with a history of mTBI had a statistically significant increase in the ONSD compared with participants with no history of mTBI. This significant difference persisted after controlling for age, race, and sex. This study demonstrated an association between a prior history of mTBI and dilation of the ONS after Valsalva maneuver in a sample of asymptomatic participants, which was not seen in participants without a history of mTBI.