Intracranial pressure directly predicts headache morbidity in idiopathic intracranial hypertension.

OBJECTIVE: Headache is the predominant disabler in idiopathic intracranial hypertension (IIH). The aim was to characterise headache and investigate the association with intracranial pressure. METHODS: IIH:WT was a randomised controlled parallel group multicentre trial in the United Kingdom investigating weight management methods in IIH. Participants with active IIH (evidenced by papilloedema) and a body mass index (BMI) ≥35 kg/m2 were recruited. At baseline, 12 months and 24 months headache characteristics and quality of life outcome measures were collected and lumbar puncture measurements were performed. RESULTS: Sixty-six women with active IIH were included with a mean age of 32.0 years (SD ± 7.8), and mean body mass index of 43.9 ± 7.0 kg/m2. The headache phenotype was migraine-like in 90%. Headache severity correlated with ICP at baseline (r = 0.285; p = 0.024); change in headache severity and monthly headache days correlated with change in ICP at 12 months (r = 0.454, p = 0.001 and r = 0.419, p = 0.002 respectively). Cutaneous allodynia was significantly correlated with ICP at 12 months. (r = 0.479, p < 0.001). Boot strap analysis noted a positive association between ICP at 12 and 24 months and enabled prediction of both change in headache severity and monthly headache days. ICP was associated with significant improvements in quality of life (SF-36). CONCLUSIONS: We demonstrate a positive relationship between ICP and headache and cutaneous allodynia, which has not been previously reported in IIH. Those with the greatest reduction in ICP over 12 months had the greatest reduction in headache frequency and severity; this was associated with improvement of quality of life measures. TRIAL REGISTRATION: This work provides Class IIa evidence of the association of raised intracranial pressure and headache. ClinicalTrials.gov number, NCT02124486 .

Differing presenting features of idiopathic intracranial hypertension in the UK and US.

AIM: Demographic factors potentially influencing the presentation and severity of idiopathic intracranial hypertension (IIH) in the US vs. UK populations include obesity and ethnicity. We aimed to compare the presenting features of IIH between populations in the UK and US tertiary referral centres, to assess what population differences exist and whether these cause different presentations and impact on visual function. METHODS: Clinical data were collected on 243 consecutive UK IIH patients and 469 consecutive US IIH patients seen after 2012 in two tertiary centres. Visual function was defined as severe visual loss when Humphrey visual field mean deviation was <-15 dB, when Goldmann visual fields showed constriction or when visual acuity was <20/200. RESULTS: US patients were more commonly of self-reported black race (58.9% vs. 7.1%) than UK patients, but had a similar mean body mass index (38.3 ± 0.63kg/m2 UK vs. 37.7 ± 0.42kg/m2 US; p = 0.626). The UK cohort had lower presenting Frisén grade (median 1 vs. 2; p < 0.001) and severe visual loss less frequently (15.4% vs. 5%; p = 0.014), but there was no difference in mean cerebrospinal fluid-opening pressure (CSF-OP) (35.8 ± 0.88cmH2O UK vs. 36.3 ± 0.52cmH2O US; p = 0.582). African Americans had poorer visual outcomes compared with US whites (19.4% vs. 10% severe visual loss; p = 0.011). Visual function was weakly associated with CSF-OP (R2 = 0.059; p = 0.001), which was similar between UK and US patients. CONCLUSIONS: The UK and the US cohorts had a similar average presenting BMI. However, the worse presenting visual function in the US IIH cohort was partially attributable to differences in the black populations in the two countries.