1. 2026;29;E29-E42A Nomogram to Predict of Epidural Blood Patch Treatment Failure in Patients With Spontaneous Intracranial Hypotension and Subdural Hematoma
   Retrospective Study
   Hua Huang, MD, Fei-Fang He, MD, Zhong-Feng Niu, MD, and TIng-Ting Wei, MD.

BACKGROUND: Subdural hematoma (SDH) is a frequent and serious complication of spontaneous intracranial hypotension (SIH), often requiring timely intervention. An epidural blood patch (EBP) is widely recognized as the preferred interventional treatment for SIH and its complications. However, treatment failure remains a concern, and predicting outcomes in patients with SIH and a concurrent SDH post EBP remains a clinical challenge.

OBJECTIVES: Our study aimed to develop and validate a predictive nomogram for treatment failure following an EBP in patients with SIH complicated by an SDH, identifying key clinical and imaging predictors associated with poor prognosis.

STUDY DESIGN: This was a retrospective cohort study conducted over a 7-year period.

SETTING: The study was conducted from January 2017 through December 2023 at a single tertiary care center, using electronic health records and radiologic databases.

METHODS: A total of 233 patients diagnosed with SIH and concurrent SDH and treated with an EBP were retrospectively enrolled. Patients were sequentially assigned to a development cohort (n = 175) and a validation cohort (n = 58) at a 3:1 ratio. Backward stepwise multivariable logistic regression was applied to the development cohort to identify independent treatment failure predictors. A nomogram was constructed based on the final regression model. The model’s performance was assessed through discrimination (C-index), calibration plots, and decision curve analysis to evaluate clinical utility.

RESULTS: Treatment failure occurred in 86 of 233 patients (36.9%), with similar rates between development (36.6%) and validation (37.9%) cohorts (P = 0.977). Four independent predictors were identified: gender, the maximum SDH thickness, SDH density type (based on computed tomography brain imagery), and pontomesencephalic angle. Specifically, men (odds ratio [OR] = 2.63; 95% CI, 1.11–6.48; P = 0.030), greater SDH thickness (OR = 1.26 per mm increase; 95% CI, 1.13–1.43; P < 0.001), non-low-density SDH—including isodense, hyperdense, mixed-density, and layering patterns—(vs low-density; OR = 0.35; 95% CI, 0.14–0.88; P = 0.025), and smaller pontomesencephalic angle (OR = 0.95 per degree; 95% CI, 0.91–0.99; P = 0.030) were significantly associated with increased risk. The nomogram demonstrated strong discrimination in the development cohort (C-index = 0.87; 95% CI, 0.82–0.93) and maintained good performance in the validation cohort (C-index = 0.84; 95% CI, 0.73–0.94). Calibration was satisfactory in both cohorts, and a decision curve analysis confirmed the model’s clinical value.

LIMITATIONS: While the sample size is the largest among similar studies, it remains relatively modest. Our exclusion of iatrogenic SIH and cases with cerebrospinal fluid fistulas may limit generalizability. Additionally, reliance on heavily T2-weighted magnetic resonance myelography without a reference standard for cerebrospinal fluid leak localization may affect generalizability. Prospective, multicenter trials are warranted to validate and refine the model.

CONCLUSIONS: Our study presents a validated nomogram incorporating 4 key predictors—gender, SDH thickness, SDH density, and pontomesencephalic angle—that accurately estimates treatment failure risk following an EBP in patients with SIH and a concurrent SDH. This tool offers practical value for individualized risk assessment and clinical decision-making.

KEY WORDS: Nomogram, treatment failure, spontaneous intracranial hypotension, epidural blood patch, subdural hematoma