Faculty Bibliography

BACKGROUND: Patients with a history of mild TBI (post-mTBI-patients) have an unexplained increase in long-term mortality which might be related to central autonomic dysregulation (CAD). We investigated whether standardized baroreflex-loading, induced by a Valsalva maneuver (VM), unveils CAD in otherwise healthy post-mTBI-patients. METHODS: In 29 healthy persons (31.3 +/- 12.2 years; 9 women) and 25 post-mTBI-patients (35.0 +/- 13.2 years, 7 women, 4-98 months post-injury), we monitored respiration (RESP), RR-intervals (RRI) and systolic blood pressure (BP) at rest and during three VMs. At rest, we calculated parameters of total autonomic modulation [RRI-coefficient-of-variation (CV), RRI-standard-deviation (RRI-SD), RRI-total-powers], of sympathetic [RRI-low-frequency-powers (LF), BP-LF-powers] and parasympathetic modulation [square-root-of-mean-squared-differences-of-successive-RRIs (RMSSD), RRI-high-frequency-powers (HF)], the index of sympatho-vagal balance (RRI LF/HF-ratios), and baroreflex sensitivity (BRS). We calculated Valsalva-ratios (VR) and times from lowest to highest RRIs after strain (VR-time) as indices of parasympathetic activation, intervals from highest systolic BP-values after strain-release to the time when systolic BP had fallen by 90 % of the differences between peak-phase-IV-BP and baseline-BP (90 %-BP-normalization-times), and velocities of BP-normalization (90 %-BP-normalization-velocities) as indices of sympathetic withdrawal. We compared patient- and control-parameters before and during VM (Mann-Whitney-U-tests or t-tests; significance: P < 0.05). RESULTS: At rest, RRI-CVs, RRI-SDs, RRI-total-powers, RRI-LF-powers, BP-LF-powers, RRI-RMSSDs, RRI-HF-powers, and BRS were lower in patients than controls. During VMs, 90 %-BP-normalization-times were longer, and 90 %-BP-normalization-velocities were lower in patients than controls (P < 0.05). CONCLUSIONS: Reduced autonomic modulation at rest and delayed BP-decrease after VM-induced baroreflex-loading indicate subtle CAD with altered baroreflex adjustment to challenge. More severe autonomic challenge might trigger more prominent cardiovascular dysregulation and thus contribute to increased mortality risk in post-mTBI-patients.

After mild traumatic-brain-injury (mTBI), patients have increased long-term-mortality-rates, persisting even beyond 13 years. Pathophysiology is unclear. Yet, central-autonomic-network dysfunction may contribute to cardiovascular dysregulation and increased mortality. Purely parasympathetic cardiovascular challenge by eyeball-pressure-stimulation (EP), might unveil subtle autonomic-dysfunction in post-mTBI-patients. We investigated whether mild EP shows autonomic-cardiovascular-dysregulation in post-mTBI-patients. In 24 patients (34+/-12years; 5-86 months post-injury) and 27 controls (30+/-11years), we monitored respiration, electrocardiographic RR-intervals (RRI), systolic- and diastolic-blood-pressure (BPsys, BPdia) before and during 2 minutes of 30mmHg EP, applied by an ophthalmologic ocular-pressure-device (Okulopressor(R)). We calculated spectral-powers of RRI in the mainly sympathetic low (LF: 0.04-0.15Hz) and parasympathetic high (HF: 0.15-0.5Hz) frequency-ranges, and of BP in the sympathetic LF-range, the RRI-LF/HF-ratio as index of the sympathetic-parasympathetic-balance, normalized (nu) RRI-LF- and HF-powers, and LF- and HF-powers after natural-logarithmic-transformation (ln). Parameters before and during EP in post-mTBI-patients and controls were compared by repeated measurement analysis of variance (ANOVA) with post-hoc analysis (significance: p<0.05). During EP, BPsys and BPdia increased in post-mTBI-patients. Only in controls but not in post-mTBI-patients, EP increased RRI-HFnu-powers and decreased RRI-LF-powers, RRI-LFnu-powers, BPsys-LF-powers, BPsys-lnLF-powers and BPdia-lnLF-powers. RRI-LF/HF-ratios slightly increased in post-mTBI-patients but slightly decreased in controls upon EP. Even with only mild EP, our controls showed normal EP-responses and shifted sympathetic-parasympathetic-balance towards parasympathetic predominance. In contrast, our post-mTBI-patients could not increase parasympathetic heart rate modulation but increased BP upon EP, indicating a paradox sympathetic activation. The findings support the hypothesis that central-autonomic-dysfunction might contribute to an increased cardiovascular risk, even years after mTBI.

OBJECTIVE: This study examined components of the Sports Concussion Assessment Tool, 3rd Edition (SCAT3) and a vision-based test of rapid number naming (King-Devick [K-D]) to evaluate sports and non-sports concussion patients in an outpatient, multidisciplinary concussion center. While the Symptom Evaluation, Standardized Assessment of Concussion (SAC), modified Balance Error Scoring System (BESS), and K-D are used typically for sideline assessment, their use in an outpatient clinical setting following concussion has not been widely investigated. METHODS: K-D, BESS, SAC, and SCAT3 Symptom Evaluation scores were analyzed for 206 patients who received concussion care at the Concussion Center at NYU Langone Medical Center. Patient age, gender, referral data, mechanism of injury, time between concussive event and first concussion center appointment, and the first specialty service to evaluate each patient were also analyzed. RESULTS: In this cohort, Symptom Evaluation scores showed a higher severity and a greater number of symptoms to be associated with older age (r=0.31, P=0.002), female gender (P=0.002, t-test), and longer time between the concussion event and first appointment at the concussion center (r=0.34, P=0.008). Performance measures of K-D and BESS also showed associations of worse scores with increasing patient age (r=0.32-0.54, P