The aim of this study was to identify candidate microRNA (miRNA) markers in adults with active IIH in serum samples.

Idiopathic Intracranial hypertension (IIH) is neurological disease associated with obesity and raised intracranial pressure (ICP) which typically leads to severe headaches, visual loss and reduced quality of life. IIH is often misdiagnosed, and diagnosis can only be confirmed after lumbar puncture, which is invasive. Monitoring disease progression in IIH is also complex, requiring repeated visual testing and sometimes repeated lumbar punctures. A reliable non-invasive test to diagnose and monitor disease progression is an unmet need. 

Serum and CSF (n=9) samples were taken from patients with active IIH and 12 months later during disease remission induced by bariatric surgery. RNA was isolated from serum and CSF, converted to cDNA and analysed by qPCR with a panel of 40 miRNAs. Candidate serum miRNAs were also assessed in control participants with obesity and with migraine. Candidate miRNAs identified in patients with active IIH were evaluated against clinical characteristics.

Serum miRNAs (5/40) expression was significantly lower in active IIH patients compared to when patients were in remission.  Of these, hsa-miR-16-5p (p<0.0001) and hsa-miR-7-5p (p=0.0032) were significantly lower in active IIH compared to patients with obesity.  hsa-miR-16-5p (p=0.0354) and hsa-let-7a-5p (0.0310) were significantly raised in CSF of patients with active IIH compared to patients in remission. hsa-miR-16-5p in serum and CSF significantly correlated with ICP (p<0.0001, p=0.046) and papilledema (p=0.0346, p=0.0241).  

We have identified two potential candidate miRNA biomarkers (has-miR-16-5p and hsa-miR-7-5p) in the serum of patients with active IIH which have a high degree of sensitivity and are associated with clinical measures of disease activity. These results are the first step towards developing a less invasive diagnostic and monitoring biomarker which would lead to a step change in patient care.