Weathering the storm: Predictors and resource burden of paroxysmal sympathetic hyperactivity after severe traumatic brain injury

BACKGROUND: Reported incidence of paroxysmal sympathetic hyperactivity (PSH) after severe traumatic brain injury (TBI) approaches one-third, largely from cohorts that excluded early deaths. Predictors and resource consequences remain unclear. We identified predictors of PSH development and associations between diagnosis, PSH Assessment Measure (PSH-AM) subscores [clinical features scale (CFS) and diagnosis likelihood tool (DLT)], and resource utilization. METHODS: We conducted a retrospective cohort study of adults with severe TBI admitted to a tertiary care center intensive care unit (ICU) (October 2020–September 2025), stratified by PSH diagnosis. Two reviewers assigned PSH-AM scores. PSH cannot be diagnosed until the syndrome declares itself over days, so exposure is conditioned on survival; mortality is reported descriptively. Multivariable logistic regression identified predictors of PSH diagnosis. Log-transformed linear regressions estimated associations of PSH diagnosis and subscores with hospital length of stay (LOS), ICU LOS, and ventilator days. Thirty-day composite outcomes, inverse probability of treatment weighting (IPTW), and landmark analysis evaluated robustness. RESULTS: Of 509 patients with severe TBI, 86 (17%) developed PSH. Younger age [odds ratio (OR): 0.97 (95% CI: 0.96–0.98); P <0.001) and higher ISS [1.05 (1.02–1.07); P <0.001] independently predicted PSH. PSH was associated with longer hospital LOS (372.9%), ICU LOS (278.3%), and more ventilator days (266.4%; all P <0.001). Mortality was 11.6% (PSH) versus 35.9% (non-PSH). IPTW demonstrated PSH had fewer days alive and out of hospital (−46.8%; P <0.001) and landmark analysis highlighted fewer ventilator-free days (−40.2%; P =0.0097) and ICU-free days (−46.9%; P <0.001). Higher DLT subscores were associated with longer hospital (36.3%; P =0.001) and ICU (23.3%; P =0.005) stays, whereas the CFS subscore showed no associations. CONCLUSIONS: The PSH diagnosis is contingent on survival. Younger patients with severe TBI who survive their initial injuries are more likely to develop PSH and occupy hospital beds meaningfully longer. The diagnosis likelihood tool, not the clinical features scale, tracks with that burden. LEVEL OF EVIDENCE: Level III, prognostic/epidemiological.