Valsalva Maneuver Identifies Subtle Sympathetic Cardiac Dysfunction in Patients with Mild Traumatic Brain Injury (P05.200)

Abstract

Objective: To determine whether sympathetic and parasympathetic challenge by means of the Valsalva maneuver (VM) identifies autonomic dysregulation in post-mTBI-patients without overt autonomic failure. Background After mild traumatic brain injury (mTBI), patients have increased long-term mortality rates (McMillan et al., J Neurol Neurosurg Psychiatry 2011;82:931-5). TBI-induced autonomic dysregulation may contribute to fatalities (Hilz et al., J Neurotrauma 2011;28:1727-38). Design/Methods: In 29 healthy persons (31.3±12.2 years; 9 women) and 25 post-mTBI-patients (35.0±13.2 years, GCS scores 13-15 assessed 30 minutes post-injury; 7 women, 4-98 months post-injury), we recorded respiratory frequency, RR-intervals (RRI) and systolic blood pressure (BP) at rest and during three VMs (40mmHg expiratory pressure for 15 seconds). At rest, we assessed parameters of total autonomic modulation [RRI-coefficient of variation (CV), RRI-standard deviation (SD)], of sympathetic [RRI-low-frequency-powers (LF)] and parasympathetic modulation [square root of mean squared differences of successive RRIs (RMSSD), RRI-high-frequency-powers (HF)]. We calculated the Valsalva-ratio (VR) and the time from the lowest to the highest RRIs after strain (VR-time) as indices of parasympathetic activation, and the intervals from the highest BP-values after strain to the time when BP had fallen by 60% respectively 90% of the differences between peak-phase-IV-BP and baseline-BP, as indices of sympathetic withdrawal (60%-BP-recovery-time, 90%-BP-recovery-time).We compared patient- and control-values before and during VM (ANOVA; post-hoc analysis; significance: p Results: At rest, RRI-CVs, RRI-SDs, RRI-LF-powers, RRI-RMSSDs, RRI-HF-powers were lower in patients than controls. During VMs, both groups had similar RRIs, BPs, VR, and VR-times while 60%-BP-recovery-time (9.0±3.8s vs. 7.2±2.1s; P=0.03) and 90%-BP-recovery-time (16.9±7.1s vs. 12.6±4,9s; P=0.01) were longer in patients than controls. Conclusions: Mild-TBI-patients had reduced autonomic modulation at rest, normal VR-times suggesting normal parasympathetic activation, but prolonged 60%- and 90%-BP-recovery-times indicating impaired sympathetic withdrawal after VMs. Altered sympathetic modulation may contribute to cardiovascular complications after mTBI. Supported by: The study was funded by the International Brain Research Foundation, Secaucus, NJ, USA. Disclosure: Dr. Hilz has received personal compensation for activities with Genzyme Corporation and International Brain Research Foundation, Inc. as a speaker and/or consultant.Dr. Hilz has received research support from Genzyme Corporation and International Brain Research Foundation, Inc. Dr. Moeller has nothing to disclose. Dr. Ammon has nothing to disclose. Dr. Markus has nothing to disclose. Dr. Flanagan has received personal compensation for activities with NDI Medical as a consultant. Dr. De Fina has received personal compensation for activities with Comprehensive Neuroscience Center as a consultant. Dr. Schwab has nothing to disclose. Dr. Koehn has nothing to disclose.