Investigation of antineuronal antibodies in idiopathic intracranial hypertension (IIH)

Idiopathic Intracranial Hypertension (IIH) is a neurological syndrome presented with features like increased intracranial pressure, headache and visual disturbances which cannot be explained by secondary causes. Typical patient group is overweight women in reproductive age. The pathogenesis of İIH is not clearly understood. Recently, immunological factors have become a new area of interest. Various neurological and psychiatric syndromes have been associated with antineuronal membrane antibodies. Identification of these antibodies is very important in diagnosis and treatment. In this study, we aimed to search for antineuronal membrane antibodies in IIH cases and to identify a target antigen in order to suggest inflammotary factors related to IIH patogenesis. 58 IIH cases were included in the study and sera and CSF samples were obtained. Antigen complexes from sera were isolated by immunoprecipitation using neuroblastoma cells, then analyzed by Liquid Chromatography-Mass Spectrometry (LC-MS) method. Na+/K+ATPase ion pump alpha-3 subunit and glial fibrillary acidic protein (GFAP) were determined as candidate target antigens. IIFT tests were made for validation of Na+/K+ATPase alpha-3 subunit antibodies but the results were negative for both sera and CSF. Cell-based assays were used for GFAP antibodies and found positive in two patients. Concentration of GFAP antibody in one case's serum was higher during the attack period compared to serum obtained during remission. For all CSF samples, the results were negative. IIH and GFAP meningoencephalitis share some symptoms. Therefore we may suggest that IIH may represent a slight form of GFAP astrocytopathy. These results are needed to be clarified by further studies.