{
  "abstract": "Background There is growing evidence that idiopathic intracranial hypertension (IIH) increases risk for epilepsy, particularly through the formation of encephaloceles. 1,2 Population-level estimates of the bidirectional association of epilepsy and IIH are lacking. We evaluated (1) the prevalence of epilepsy among adults with IIH and (2) the prevalence of IIH among adults with epilepsy, including sex-stratified analyses, and compared IIH prevalence in epilepsy patients to published general population estimates.Methods A retrospective analysis was performed using the TriNetX Research Network (112 healthcare organizations). Adults (≥18 years) with IIH (ICD-10 G93.2) between January 1, 2000 and February 10, 2026 comprised the IIH cohort (n = 135,324). Epilepsy group was defined as ICD-10 G40, ICD-10 R56.9, or levetiracetam exposure. In a reciprocal analysis, adults meeting the epilepsy definition comprised the epilepsy cohort (n = 3,135,121). Prevalence, incidence proportion, and incidence rate of IIH amongst epilepsy cohort and epilepsy amongst IIH cohort were calculated overall and stratified by sex.Results Among adults with IIH (n = 135,324), the prevalence of epilepsy was 21.67% (prevalence 0.2167; incidence proportion 0.2161; incidence rate 6.31×10 −5 cases/person-day).Among adults in the epilepsy group (n = 3,135,121), the prevalence of IIH was 0.93% (prevalence 0.00934; incidence proportion 0.00932; incidence rate 2.82×10−6 cases/person-day). Sex-stratified IIH prevalence within the epilepsy cohort was higher in females (1.16%) than males (0.71%). When expressed per 100,000 individuals, IIH prevalence in adults with epilepsy (~934 per 100,000 overall; ~1,157 per 100,000 in females) substantially exceeded contemporary general population estimates (~9.9 per 100,000 in 2022), representing an approximate 90-100-fold higher prevalence.2Conclusion In this large adult EHR-based population, epilepsy or epilepsy-directed therapy was present in approximately one in five patients with IIH, while IIH was identified in nearly 1% of adults with epilepsy, with a higher prevalence among females. Relative to contemporary general population estimates, IIH prevalence in adults with epilepsy appeared substantially higher. 3 Taken together, these findings suggest a bidirectional association with a sex-based gradient. However, interpretation is limited by the observational nature of EHR data, potential residual confounding, surveillance bias, and coding variability; causal relationships cannot be inferred from these results. There is a growing body of literature linking IIH and epilepsy, particularly focal temporal epilepsy.4 A biologically plausible mechanism involves pressure-mediated skull remodeling and subsequent encephalocele formation.5 In light of this, clinicians and radiologists should consider potential overlapping pathology. More granular longitudinal clinical and imaging data are needed to clarify temporal relationships between IIH and epilepsy with special attention to the evolution of symptoms and imaging changes.References Chen BS, Britton JOT. 2023 Feb 1; 36(1):43–50. doi: 10.1097/WCO.0000000000001131.2.Urbach H, et al. Neuroradiol J. 2022 Apr;35(2):183–192. doi: 10.1177/197140092110344803.Shaia JK, et al. Neurology. 2024 Feb 13;102(3):e208036. doi: 10.1212/WNL.0000000000208036.4.Al-Balushi N, et al. Neuroophthalmology. 2023 Sep 11;47(5-6):248–254. doi: 10.1080/01658107.2023.22515795.Urbach H, et al. Neuroradiology. 2018 Jan;60(1):51–60. doi: 10.1007/s00234-017-1929-5Disclosures A. Brake: None. S. Byer: None. K. John: None. M. Hayakawa: None. N. Shekhrajka: None.",
  "authors": [
    {
      "affiliations": [
        "Radiology, University of Iowa Healthcare, Iowa City, IA"
      ],
      "name": "A Brake"
    },
    {
      "affiliations": [
        "Cardiology, University of California, Los Angeles, Los angeles, IA"
      ],
      "name": "S Byer"
    },
    {
      "affiliations": [
        "Radiology, University of Michigan, Ann Arbor, MI"
      ],
      "name": "K John"
    },
    {
      "affiliations": [
        "Radiology, University of Iowa Healthcare, Iowa City, IA"
      ],
      "name": "M Hayakawa"
    },
    {
      "affiliations": [
        "Radiology, University of Iowa Healthcare, Iowa City, IA"
      ],
      "name": "N Shekhrajka"
    },
    {
      "affiliations": [
        "Neurology, Neurosurgery and Radiology, University of Iowa Hospitals and Clinics, Iowa City, IA"
      ],
      "name": "E Samaniego"
    }
  ],
  "title": "E-344 Bidirectional prevalence of epilepsy and idiopathic intracranial hypertension: large federated EHR network study",
  "uid": "3ac4e5d8-aaa8-53f9-81c6-237278a1e023"
}