Topographic diagnosis of facial paralysis by the assay of lysozyme concentration in tears

Lysozyme in tears is secreted from the main lacrimal gland innervated by a parasympathetic nerve via the greater petrosal nerve. Lysozyme activity in tears was analysed in 10 cases of unilateral facial paralysis due to the cerebellopontine angle (CPA) tumor and 10 normal cases. The lysozyme concentration in tears on the paralysed side collected by Schirmer No. 2 test was significantly lower than that on the healthy side, or bilateral sides of normal subjects. This decreased concentration on the paralysed side is due to the interruption of the reflex arc at the level of CPA. It is concluded that our new method is more useful for topographical diagnosis of facial paralysis than is the conventional Schirmer's filter paper test.