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

Ruihao Wang, Katharina M. Hösl, Fabian Ammon, Jörg Markus, Julia Koehn, Sankanika Roy, Mao Liu, Carmen de Rojas Leal, Dafin Muresanu, Steven R. Flanagan, Max J. Hilz

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


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 ± 10.5 years old, 43.1 ± 33.4 months post-injury), and 30 controls (29.1 ± 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.

Original languageEnglish
Pages (from-to)1161-1169
Number of pages9
JournalClinical Neurophysiology
Issue number6
StatePublished - Jun 2018


  • Central autonomic dysfunction
  • Eyeball pressure stimulation
  • Oculocardiac reflex
  • Traumatic brain injury


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