Cerebrospinal fluid otorrhea--new trends in diagnosis.

In this paper we describe the different causes of cerebrospinal fluid (CSF) otorrhea and their pathomechanisms, followed by a short description and illustration of the most common methods used until now for identifying CSF. We then present a new and modern method, immunologic identification of CSF using beta 2-transferrin (tau band). This protein variant is found only in CSF, not in any other body fluids, such as tears, nasal secretions, saliva, or blood serum. Analysis of CSF using this method always indicates two bands, the beta 1-transferrin and the beta 2-transferrin band. The latter is typical for CSF. The analysis of all other body fluids shows just one band, the beta 1-transferrin band. It is therefore possible to identify CSF accurately. The required reagents and equipment are listed and methods of taking samples are explained, followed by a detailed description of sample preparation, electrophoresis, immunofixation, and silver staining. Staining with alkaline silver nitrate has a 40-fold higher sensitivity than staining with the commonly used coomassie brilliant blue. With this method, 1 microliter pure CSF (corresponding to approximately 1/50 of a drop) and 100 microliter CSF (two drops) per 1 ml wound secretion can be identified.