Early Development of Spinal Cord Herniation in Spontaneous Intracranial Hypotension

Purpose: Spinal cord herniation has been recognized as a very rare, late complication of spontaneous intracranial hypotension (SIH). This study examined the incidence and timing of early spinal cord herniation in SIH and the factors associated with its development.Methods: Data from a prospective cohort of patients with SIH at Seoul National University Hospital (2022–2024) were analyzed retrospectively. Eligible patients presented within 1 year of symptom onset, had a spinal longitudinal epidural collection, and had no spinal cord herniation at baseline. Kaplan–Meier analysis was used to estimate the cumulative incidence of spinal cord herniation, and Cox regression was used to evaluate risk factors.Results: The study included 92 patients with SIH who presented within 1 year of onset (mean age, 40.6 years; 39.1% male). Spinal cord herniation was first detected in eight patients, a mean of 174.1±180.5 days after symptom onset. Its cumulative incidence reached 10.3% by 1 year and 14.2% by 2 years.Conclusion: In patients presenting within 1 year of symptom onset with a type 1 leak, spinal cord herniation may develop earlier than previously recognized, even without neurological symptoms. Careful follow-up is essential to ensure timely, appropriate management. Caution is warranted, however, when generalizing these incidence estimates to the overall SIH population.