Objective To analyze the correlation between the duration of hyperbaric oxygen (HBO) therapy and oral medication clonazepam reduction in patients with paroxysmal sympathetic hyperactivity (PSH).

Methods Clinical data of patients with secondary PSH after severe brain injury at Capital Medical University Affiliated Fuxing Hospital from September 2017 to July 2023 were retrospectively included, covering general information, etiology, lesion location, comorbidities, vital signs at admission, PSH attack characteristics, HBO treatment frequency, PSH treatment drugs and dosage. According to the number of HBO treatments, PSHpatients were divided into HBO short course group (10 treatments) and HBO long course group (>10 treatments). Multiple logistic regression and rank correlation analysis were used to investigate the correlation between the duration/frequency of HBO treatment and the reduction of clonazepam.

Results A total of 75 PSH patients who met the inclusion and exclusion criteria were selected, including 38 cases (50.7%) who received reduced doses of clonazepam. There were 32 cases (42.7%) in the HBO short course group and 43 cases (52.3%) in the HBO long course group. The reduction rate of clonazepam in the HBO short course group was lower than that in the HBO long course group31.3% (10/32) vs.65.1% (28/43), crude OR=4.11 (95% CI: 1.55-10.90), P=0.004. After adjusting for confounding variables, a multivariate Logistic regression model showed a significant correlation between HBO long course and clonazepam reduction (OR= 3.76, 95% CI: 1.23-11.55, P=0.021). Rank correlation analysis showed a positive correlation between HBO treatment frequency and clonazepam reduction (r_s=0.331, P=0.004).

Conclusions Long course HBO treatment was positively correlated with oral reduction of clonazepam in PSH patients, which may help reduce the side effects caused by clonazepam and become a non- pharmacological treatment option for PSH.