Blood Markers in Adult Patients With Sudden Sensorineural Hearing Loss (SSNHL)

To recruit adult consecutive outpatients referred for SSNHL to the otolaryngologist clinic of our university hospital starting June 2016 and prospectively until december 31th 2018.

Plasma sampling and biomarkers quantification : After a 48-hours diet excluding serotonin- and tryptophan-rich food, fasting blood samples were collected into vacuum tubes containing 109 mM sodium citrate (Becton-Dickinson, Le Pont de Claix, France) with a 9:1 blood-to-anticoagulant ratio. After removing 0.5 mL of whole blood for serotonin measurements, the remainder was centrifuged at 1,000 x g for 10 minutes, and the supernatant was then centrifuged at 3,000 x g for 15 minutes to isolate platelets and obtain platelet-poor plasma. Importantly, the time between blood sampling and platelet/plasma isolation was less than one hour. Aliquots of whole blood, platelets, and plasma were kept frozen (-20°C) until serotonin and homocysteine measurements performed within one week after congelation. Whole blood, platelet and plasma 5-HT as well as plasma homocysteine (Hcy) levels were measured by high pressure liquid chromatography coupled to fluorimetric detections .

Thrombophilia screening included measurements of antithrombin , protein C, protein S, factor V Leiden, prothrombin G20210A, methylene tetrahydrofolate reductase (MTHFR) C677T, antiphospholipid antibodies anticardiolipin IgG and IgM and anti-beta2 glycoprotein 1 IgG), dilute Russell viper venom time , Rosner index, factor VIII, von Willebrand factor (vWF) activity and antigen. Tests were performed on citrated plasma, serum or DNA as appropriate and as previously described

Inclusion criteria

• adult idiopathic SSNHL

Exclusion criteria

• secundary hearing loss