Idiopathic intracranial hypertension: key factors influencing visual outcomes

Severe papilloedema in idiopathic intracranial hypertension (IIH) is associated with macular ganglion cell layer (GCL) thinning and visual loss worsening. This was the main result of a study in a large prospective real-world cohort of IIH patients. Patients with the most elevated retinal nerve fibre layer (RNFL) thickness had worse long-term visual outcomes, which only became apparent after 12 months.

The study, presented by Dr Mark Thaller (University of Birmingham, UK), evaluated the impact of the severity of papilloedema on visual outcomes, as well as both visual and headache outcomes in a medically treated cohort of patients with IIH [1]. The researchers analysed data from 490 patients with a confirmed diagnosis of IIH from a longitudinal clinical examination dataset from the prospectively collected IIH: Life database 2012–2021; 98% were women and the mean body mass index (BMI) was 38 kg/m².

The study focused on the key variables predicting vision and headache in 426 medically treated patients. Visual outcomes included visual acuity, perimetric mean deviation, and papilloedema, measured by optical coherence tomography (OCT) imaging. Headache outcomes were determined by the number of headache days per month and the headache impact test-6 (HIT-6) questionnaire.

The results showed that participants with the highest RNFL thickness on OCT had the worst visual outcomes. An important observation was a delay of more than 12 months before any decline became apparent in the visual field and OCT measurements. Regression analyses showed that the most important visual prognostic factors were:

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  • change in BMI (influencing visual field, RNFL, and macular GCL);
  • disease duration (influencing RNFL and total retinal thickness); and
  • diagnostic lumbar puncture opening pressure (influencing total retinal thickness).

The 281 participants who were managed medically and had active IIH experienced a high headache burden. Dr Thaller added that this burden showed a marked variability, with some patients struggling daily. Prognostic factors of headache were:

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  • daily headache at diagnosis (headache frequency, migraine-like headache frequency, and headache severity);
  • personal history of migraine (headache frequency, migraine-like headache frequency, and headache severity);
  • family history of migraine (headache severity); and
  • disease duration (headache severity).

Dr Thaller claimed that these prognostic factors should be used in future trials and that targeted therapy remains an unmet clinical need.

1. 
   
   1. Thaller M, et al. The idiopathic intracranial hypertension prospective cohort study: evaluation of prognostic factors and outcomes. A16, EHC 2022, 07-10 December, Vienna, Austria.

 

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Posted on 5 January 2023