Consecutive Eyeball Pressure Tests Reflect Clinically Relevant Vagal Dysfunction and Recovery in a Patient With Guillain-Barré-Syndrome With Tenacious Cardiac Dysautonomia.

Cardiac dysautonomia is a potentially life-threatening complication of Guillain-Barré syndrome (GBS). Proper and prompt recognition of patients at risk and subsequent intensive care unit (ICU) monitoring are mandatory to prevent fatal outcome. Eyeball pressure testing (EP) has been suggested as an easy applicable bedside test for vagal overreactivity in GBS and thus identifying patients at risk. Yet, there is only sparse follow-up data concerning the course of EP findings in GBS. We report a 25 years-old male patient with GBS who underwent consecutive EP (n = 11) during his ICU stay over a period of 11 weeks. The series of tests performed in this patient (and corresponding clinical events) show that EP data might represent an approximation of vagal dysfunction and vagal recovery in GBS. Interestingly, we observed a much longer duration of pathological EP compared to a previous report. The tenacious cardiac dysautonomia in this patient necessitated long-term application of a transvenous temporary pacemaker.

Eyeball pressure stimulation induces subtle sympathetic activation in patients with a history of moderate or severe traumatic brain injury.

OBJECTIVE: After traumatic brain injury (TBI), there may be persistent central-autonomic-network (CAN) dysfunction causing cardiovascular-autonomic dysregulation. Eyeball-pressure-stimulation (EPS) normally induces cardiovagal activation. In patients with a history of moderate or severe TBI (post-moderate-severe-TBI), we determined whether EPS unveils cardiovascular-autonomic dysregulation. METHODS: In 51 post-moderate-severe-TBI patients (32.7 ±â€¯10.5 years old, 43.1 ±â€¯33.4 months post-injury), and 30 controls (29.1 ±â€¯9.8 years), we recorded respiration, RR-intervals (RRI), systolic and diastolic blood-pressure (BPsys, BPdia), before and during EPS (120 sec; 30 mmHg), using an ocular-pressure-device (Okulopressor®). We calculated spectral-powers of mainly sympathetic low (LF: 0.04-0.15 Hz) and parasympathetic high (HF: 0.15-0.5 Hz) frequency RRI-fluctuations, sympathetically mediated LF-powers of BPsys, and calculated normalized (nu) LF- and HF-powers of RRI. We compared parameters between groups before and during EPS by repeated-measurement-analysis-of-variance with post-hoc analysis (significance: p < 0.05). RESULTS: At rest, sympathetically mediated LF-BPsys-powers were significantly lower in the patients than the controls. During EPS, only controls significantly increased RRIs and parasympathetically mediated HFnu-RRI-powers, but decreased LF-RRI-powers, LFnu-RRI-powers, and LF-BPsys-powers; in contrast, the patients slightly though significantly increased BPsys upon EPS, without changing any other parameter. CONCLUSIONS: In post-moderate-severe-TBI patients, autonomic BP-modulation was already compromised at rest. During EPS, our patients failed to activate cardiovagal modulation but slightly increased BPsys, indicating persistent CAN dysregulation. SIGNIFICANCE: Our findings unveil persistence of subtle cardiovascular-autonomic dysregulation even years after TBI.

Eyeball Pressure Stimulation Unveils Subtle Autonomic Cardiovascular Dysfunction in Persons with a History of Mild Traumatic Brain Injury.

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 ± 12 years; 5-86 months post-injury) and 27 controls (30 ± 11 years), we monitored respiration, electrocardiographic RR intervals (RRI), systolic and diastolic blood pressure (BPsys, BPdia) before and during 2 min of 30 mm Hg EP, applied by an ophthalmologic ocular pressure device (Okulopressor(®)). We calculated spectral powers of RRI in the mainly sympathetic low frequency (LF; 0.04-0.15 Hz) and parasympathetic high frequency (HF; 0.15-0.5 Hz) 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 with post hoc analysis (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.

EFFECT ON DECLINE IN HEART RATE INDUCED BY OCULAR COMPRESSION AND APNEA AFTER EXERCISE / 体力科学

<b>Object </b>: The purpose of this study was to test the response of the decline in heart rate (HR) induced by compression on the eyeball (eyeball pressure : EP) and voluntary non breath (VNB) after pedaling exercise. <b>Methods </b>: EP ; Nine male subjects performed exercise for 3 min in a supine position using a bicycle ergometer. Immediately after the exercise all subjects received EP for 10 seconds. After that, subjects undertook the same protocol without EP (CON-E). VNB ; Four male and two female subjects performed exercise for 5 minutes using a bicycle ergometer. Immediately after the exercise subjects received VNB for 7 seconds. After that subjects undertook the same protocol without VNB (CON-V). <b>Results </b>: The slope of the decline in HR recovery (HR_DS) after exercise in EP increased significantly more than that in CON-E (p<0.05). However, time constant (HR_TC) in CON-E declined faster than that in EP. Thereby, the relationship between HR_DS in EP and HR_TC in CON-E correlated (r=-0.562). The HR_DS of VNB was greater than that of EP and CON-V. However the relationship between HR_DS in VNB and HR_TC in CON-V did not correlate. <b>Conclusion </b>: We suggest that EP affects vagal nervous activity and VNB affects strength of baroreflex sensitivity. Therefore HR_DS of EP might evaluate vagal nervous activity.