Obstructive Sleep Apnea Common in Women With Idiopathic Intracranial Hypertension

Alexandra J. Sinclair, MBChB, MRCP, PhD

Investigators of a recent substudy concluded obstructive sleep apnea (OSA) has a high prevalence in women with idiopathic intracranial hypertension (IIH) with a body mass index (BMI) greater than or equal to 35 kg/m2 and that the STOP-BANG questionnaire was the most effective in detecting OSA. Further studied were the impact of weight loss on OSA, with investigators finding that bariatric surgery improved OSA and led to greater reductions in apnea-hypopnea index (AHI).

A total of 40 women between the ages of 18 and 55 years were included in the substudy, of the 66 that participated in the multicenter, randomized, controlled, parallel-group trial comparing bariatric surgery to community weight management intervention (CWI) and the impact on outcomes for women with IIH (IIH: WT; NCT02124486). Alexandra J. Sinclair, MBChB, MRCP, PhD, professor of neurology, Institute of Metabolism and Systems Research, University of Birmingham, and head, Metabolic Neurology Research Group, and colleagues found that 47% of participants (n = 19) also had OSA, and the most sensitive detection method was the STOP-BANG questionnaire (84%), compared to both the Epworth Sleepiness Scale (ESS) (69%) and the Berlin questionnaire (68%). 

At baseline and 12 months, OSA was evaluated using at-home polygraphy (ApneaLink Air, ResMed), with OSA parameters were set as an AHI greater than or equal to 15 or greater than or equal to 5 with excessive daytime sleepiness (ESS ≥11). AHI median index was 7.6 events per hour (interquartile range, 4.3-16.0). A total of 25 patients (63%) had an AHI greater than or equal to 5 events/hour, 13 patients (33%) had an AHI between 5 and less than 15 events/hour, 8 patients (20%) had an AHI between 15 and less than 30 events/hour, and 4 patients (10%) had an AHI greater than or equal to 30 events/hour.

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Compared to CWI cohort, which saw a reduction in AHI events per hour from baseline (–1.5 [95% CI, –10.4 to 2.2]; P = .213), patients with IIH who had bariatric surgery saw a greater decrease in AHI (–2.8 [95% CI, –11.9 to 0.7]; P = .017). Investigators noted that the study was underpowered for analysis when comparing the 2 cohorts at 12 months but found an insignificant difference between the two (1.7 [95% CI, –5.7 to 7.4]; P = .657). 

Independent of adjustments for changes in BMI (R² = 0.522; P = .017), investigators also found positive association between changes in papilledema and AHI (ρ = 0.543; P = .045) over the 12-month period. When examining the relationship between the AHI and intracranial pressure (ICP), investigators found a significant correlation with falling ICP (percentage change over time; ρ = 0.537; P = .018). Although, this later became non-significant in the multivariable analysis when adjusted for BMI change (R² = .086; P = .348). 

“The impact of OSA on the clinical course of IIH has not been previously determined. Previous cross-sectional studies have not shown an association between OSA and IIH clinical features,” Sinclair, the corresponding author, et al wrote. “Our results provide initial evidence that OSA in IIH impacts papilloedema. Over a 12-month study duration, our data suggests that improving OSA was associated with improving papilloedema independent of changes in BMI. Interestingly, amongst the IIH patients diagnosed with OSA, our descriptive data suggested that papilloedema and visual field recovery at 12 months was worse compared to those without OSA, despite similar changes in ICP. These data indicate that OSA may exacerbate papilloedema and visual dysfunction in addition to risks driven by ICP and weight.”

In the sub-study, patients were randomized into the bariatric surgery group or the CWI group, which granted them access to and provided vouchers for 52 weeks of WeightWatchers. The study was limited, as OSA testing was performed in patients’ homes and would have been optimized if performing in a hospital with complete polysomnography. The study also only included women with IIH and a BMI greater than or equal to 35, limiting the ability to generalize results outside of this group. 

“This was the largest prospective study assessing OSA status in a cohort of IIH patients,” Sinclair et al wrote. “The results suggest that OSA might be associated with worse IIH outcomes and improvements in OSA severity were associated with improvements in papilledema. Clinicians treating women with IIH need to have low threshold to suspect OSA and the STOP-BANG questionnaire can aid screening.”

REFERENCE

Yiangou A, Mitchell JL, Nicholls M, et al. Obstructive sleep apnoea in women with idiopathic intracranial hypertension: a sub-study of the idiopathic intracranial hypertension weight randomised controlled trial (IIH: WT). J Neurol. Published online August 22, 2021. doi:10.1007/s00415-021-10700-9