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/m 2 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/m 2 . 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