Chemical Liquor Diagnostic

Glucose-Protein Test

Liquor has a higher glucose and protein concentration than nasal secretion; hence, by determining the concentration of glucose and protein in a fluid, a differentiation can be made between regular nasal secretions and liquorrhea.

A laboratory-tested glucose concentration >40 mg% and a protein level <100 mg% (maximum 200 mg%) characterizes liquor. However, liquor testing for glucose and proteins with test sticks is not safe.

Immunological Liquor Diagnostic

Beta-2 Transferrin Determination

Nowadays the immunological evidence of beta-2 transferrin in a liquid suspected to be liquor is the standard test (Oberascher and Arrer 1986; Ernst et al. 2004). It should always be performed to exclude a dural defect with a liquor fistula. If there is a suspicion of liquorrhea, even with a negative test result (3% of the results are false negative), the beta-2 transferrin test method can be improved by marking the liquor (see below) (Bachmann et al. 2004).

Beta-Trace Protein

Beta-trace protein, which has a higher specifity than beta-2 transferrin, is preferentially used to diagnose liquorrhea (Ernst et al. 2004; Bachmann et al. 2004).

Liquor Marking Methods

The marking test agent (sodium fluoride/Na-fluorescein) has to be instilled intrathecally by lumbar puncture. Later the marked fluid leaking through open defects in the nose or the sinuses may be detected by nasal endoscopy.

Additionally high-resolution coronal computed tomography (CT) of the paranasal sinuses and the anterior skull base, a Jotrolan CT or an MRI and, if necessary, a liquor scintigraphy (In111/Tc 99-DTPA) may be integrated to detect dural defects with liquor leakages (Goshujra 1980; Chow et al. 1989; Horch et al. 1991). These methods should be applied in situations of unclear or recurrent liquor loss and are apt not only to detect small dural leakages but also help to localize the defect site (Ernst et al. 2004).

The combined use of different liquor leakage detecting methods guarantees an exact diagnosis and results in better preoperative planning (Ernst et al. 2004) (Fig. 6.2).

Concept of detecting liquor fistulas (Ernst et al. 2004)

Depending on the individual situation, diagnosis of liquor fistulas can be based on the following types of tests:

•Clinical

•Chemical (glucose-protein)

•Immunological (beta-2 transferrin/beta-trace protein)

•Liquormarkingmethods(endoscopicNa-fluorescein identification/liquor-scintigram)

•High-resolution CT/CT-based cisternography