Spontaneous intracranial hypotension is diagnosed by a combination of lipocalin-type prostaglandin D synthase and brain-type transferrin in cerebrospinal fluid

Background: Spontaneous intracranial hypotension (SIH) is caused by cerebrospinal fluid (CSF) leakage. Definitive diagnosis can be difficult by clinical examinations and imaging studies. Methods: SIH was diagnosed with the following criteria: (i) evidence of CSF leakage by cranial magnetic resonance imaging (MRI) findings of intracranial hypotension and/or low CSF opening pressure; (ii) no recent history of dural puncture. We quantified CSF proteins by ELISA or Western blotting. Results: Comparing with non-SIH patients, SIH patients showed significant increase of brain-derived CSF glycoproteins such as lipocalin-type prostaglandin D synthase (L-PGDS), soluble protein fragments generated from amyloid precursor protein (sAPP) and brain-type transferrin (Tf). Serum-derived proteins such as albumin, immunoglobulin G, and serum Tf were also increased. A combination of L-PGDS and brain-type Tf differentiated SIH from non-SIH with sensitivity 94.7% and specificity 72.6%. Conclusion: L-PGDS and brain-type Tf can be biomarkers for diagnosing SIH. General significance: L-PGDS and brain-type Tf biosynthesized in the brain appears to be markers for abnormal metabolism of CSF.