Frequency and characteristics of multi-domain autonomic dysfunction in patients with spontaneous intracranial hypotension

We aimed to evaluate multi-domain autonomic function in patients with spontaneous intracranial hypotension (SIH) and investigate its association with clinical and radiological features. SIH often presents with orthostatic symptoms that overlap with autonomic disorders; however, the prevalence and distribution of autonomic dysfunction in SIH remain poorly characterized. In this cross-sectional study conducted at a tertiary care center in Seoul, Republic of Korea, 34 patients with imaging-confirmed SIH underwent a comprehensive autonomic function testing between October 2024 and February 2025. The autonomic function testing battery included heart rate response to deep breathing, Valsalva maneuver, head-up tilt test, and quantitative sudomotor axon reflex test. Hemodynamic responses during head-up tilt were monitored using both intermittent brachial and continuous beat-to-beat blood pressure measurements. Autonomic abnormalities were determined using age- and sex-matched Korean normative data. All enrolled patients presented with extradural fluid collection on spinal magnetic resonance imaging, indicating SIH due to dural tears. Autonomic dysfunction was identified in 18 of 34 (52.9%) of patients in the orthostatic domain, nine of 34 (26.5%) in the cardiovagal domain, and 10 of 34 (29.4%) in the sudomotor domain. Postural orthostatic tachycardia syndrome was the most frequent orthostatic abnormality, observed in 12 of 34 (35.3%) patients, followed by classical orthostatic hypotension in four of 34 (11.8%), syncope in one of 34 (2.9%), and delayed orthostatic hypotension in one of 34 (2.9%). No significant associations were identified between domains of autonomic dysfunction and the clinical or imaging features of SIH in false discovery rate-corrected analyses. In patients with SIH due to dural tears, orthostatic hemodynamic abnormalities were common, with postural orthostatic tachycardia syndrome being the most frequent phenotype.