Abstract
Two operated cases are reported. The hereditary nature of this rare anomaly was obvious in one of the patients. An explanation is given for the occurrence of a postoperative facial paresis in one of the cases. A complete removal of the fistulas in combination with a conservative radical operation, viz. tympano-plastic for the concomitant chronic otitis, seems imperative for a successful therapeutic result. To obtain information of the entire course of such fistulas, it is considered necessary to perform a fistulography prior to operation. Postoperative complications may thereby be avoided. Ordinary roentgenological examination combined with tomography may prove valuable in detecting various anomalies of the temporal bone.