The association between acute paroxysmal sympathetic hyperactivity and hydrocephalus or shunt complications in severe acquired brain injury: a retrospective cohort study

Abstract Background Paroxysmal sympathetic hyperactivity (PSH) and hydrocephalus frequently coexist after severe acquired brain injury (sABI) but are generally regarded as independent complications. Reports of PSH resolving after correction of hydrocephalus or shunt complications suggest these conditions may be more closely related. This study examined how frequently hydrocephalus and shunt complications are present in sABI patients with acute PSH, and whether their correction is followed by improvement in PSH. Methods Prompted by an index case, our department implemented a standardized protocol in 2019 whereby acute PSH onset prompts cranial CT within 72 h to screen for hydrocephalus and shunt complications, followed by targeted interventions to correct identified abnormalities and an active medication-tapering trial. We retrospectively reviewed patients with sABI who developed acute PSH during inpatient rehabilitation between 2019 and 2025. Extracted data included baseline characteristics, PSH-related radiographic findings, interventions, and post-intervention outcomes (changes in PSH-related medications within 14 days, and neurological, functional, and radiographic status at 1 month). Results Of 694 patients with sABI admitted for rehabilitation between 2019 and 2025, 94 developed acute PSH, of whom 67 met the inclusion criteria and were analyzed. Cranial CT identified hydrocephalus ( n = 25, 37.3%) or shunt complications ( n = 22, 32.8%) in 47 patients (70.1%). Forty-four underwent targeted interventions, including shunt-pressure adjustment, shunting (alone or with cranioplasty), cranioplasty alone, shunt replacement or removal with endoscopic third ventriculostomy, and dural arteriovenous fistula embolization. Among the 40 who completed 2-week follow-up, PSH-related medications were discontinued in 70.0% and reduced in 22.5%; among the 40 who completed 1-month follow-up, consciousness improved in 65.0% and functional status in 45.0%. Radiographic improvement was observed in 79.4% of those with follow-up imaging ( n = 34). Conclusion Hydrocephalus and shunt complications were frequently identified in sABI patients with acute PSH, and their correction was followed by PSH-related medication reduction and neurological improvement in most patients. These findings suggest PSH may serve as a clinical clue to an underlying, potentially reversible CSF dynamic disturbance, which warrants early neuroimaging evaluation.