Idiopathic intracranial hypertension presenting with migraine phenotype is associated with unfavorable headache outcome

Abstract Background: Migrainous headache is common in idiopathic intracranial hypertension (IIH). The aim of this study was to assess its prognostic impact.Methods: We investigated patients with IIH from the Vienna-IIH-database and differentiated migraine (IIH-MIG) from non-migrainous and absent headache (IIH-noMIG). Using multivariate models, we analyzed the impact of IIH-MIG on headache and visual outcomes 12 months after diagnosis. Results: Among 97 patients (88.7% female, mean age 32.9±11.1 years, median BMI 32.0, median CSF opening pressure 31cmH2O), 46.4% were assigned to IIH-MIG and 53.6% to IIH-noMIG (11.3% tension-type, 25.8% unclassifiable, 16.5% no headache). At baseline, IIH-MIG differed from IIH-noMIG with respect to headache frequency (22 vs. 15 days/month, p=0.003) and severity (6.5/10 vs. 4.5/10; p<0.001).At follow-up, the rates for improvement and freedom of headache were lower in IIH-MIG than in IIH-noMIG for all patients (66.7% vs. 88.5%, p=0.009; 11.1% vs. 42.3%, p=0.006) and for those with resolution of papilledema (n=60; 62.1% vs. 93.6%, p=0.003; 17.2% vs. 61.3%, p<0.001). In contrast, visual worsening was significantly less common in IIH-MIG (8.9% vs. 25.0%, p=0.037). Adjusting for covariates, IIH-MIG was independently associated with a significantly lower likelihood of headache improvement (odds ratio [OR] 0.57, p<0.001) and freedom of headache (OR 0.28, p<0.001), but also a lower risk for visual worsening (OR 0.39, p<0.001). Conclusions: In IIH, migrainous headache is associated with unfavorable outcomes for headache, even when papilledema has resolved, and possibly favorable visual outcome.