Surgical interventions in idiopathic intracranial hypertension – a comprehensive multi-center study of outcome and the role of treatment indication

Background

Surgical intervention is recommended in idiopathic intracranial hypertension (IIH) for fulminant or treatment-refractory cases, yet data on outcomes remain limited, particularly regarding indication-specific effects. This study evaluated outcomes and indications for surgery in IIH, aiming to identify predictors of favorable or adverse results.

Methods

A retrospective multi-center study was conducted by the Danish-Austrian IIH Consortium (DASH-IIH). Databases from three centers (Vienna, Odense, Copenhagen) were screened for people with IIH (pwIIH) fulfilling revised Friedman criteria who underwent surgery and had ≥6 months of follow-up. Outcomes at six months included visual function, headache improvement (≥50%), papilledema resolution, and severe adverse events. Multivariable regression was used to adjust for confounders.

Results

Of 1310 pwIIH, only 3.6% required surgery overall. Thirty-six pwIIH were included (100% female; mean age 32.5 years; median BMI 37.0; median CSF opening pressure 41 cmH□O). Of these, 27 (75%) underwent CSF diversion and 9 (25%) optic nerve sheath fenestration (ONSF). The primary indication for surgery was acute visual deterioration in 83.3% and refractory headache in 16.7%.

Visual function improved in 41.7%, papilledema resolved in 89.7%, and headache improved in 30.6%. No significant differences in outcomes were found between CSF diversion and ONSF. Importantly, no visual improvement occurred in cases operated for headache alone, and the odds of headache improvement were significantly lower in this group (OR 0.11, p=0.012).

Conclusion

CSF diversion and ONSF are effective in IIH with acute visual threat, improving vision and, to a much lesser extent, headache. Refractory headache alone appears insufficient indication for surgical intervention.

What is already known on this topic

Surgical interventions such as cerebrospinal fluid (CSF) diversion and optic nerve sheath fenestration (ONSF) are established treatments for fulminant or treatment-refractory idiopathic intracranial hypertension (IIH), particularly when vision is acutely threatened. However, previous studies are limited to small, single-center case series and lack robust analyses of how treatment indication – particularly refractory headache versus visual deterioration – affects clinical outcomes.

What this study adds

This multi-center, population-based study document that only a selected subset of IIH patients need surgery and provides the first comparative analysis of surgical outcomes in IIH stratified by treatment indication. It shows that both CSF diversion and ONSF are similarly effective in preserving vision when performed for acute visual deterioration. In contrast, surgical intervention for refractory headache alone improves headache markedly less and has no visual benefit, suggesting that headache alone may not justify invasive treatment.

How this study might affect research, practice, or policy

These findings reinforce the importance of precise, indication-based patient selection for surgical treatment in IIH. They support current consensus guidelines recommending multidisciplinary evaluation and suggest that refractory headache, in the absence of visual threat, should not be considered a standalone surgical indication. The results may inform clinical decision-making and prioritize non-surgical management for headache-dominant IIH. Future research should investigate tailored treatment strategies and alternative therapies for this subgroup.