Otoliquorrhoea is as a rule associated with a history of an injury, previous surgical operation on the temporal bone, chronic otitis, possibly a tumour of the temporal bone. Cases of spontaneous otoliquorrhoea are usually associated with a defect of the temporal osseous wall of the posterior cranial fossa with possible development of a fistula, meningocele, or meningoencephalo- cele (in adult patients). Mondini’s dysplasia with penetration of liquor through the fenestra ovalis across a defect of the dura mater in the internal auditory meatus is described in child patients. The initial symptoms may be similar as in chronic secretory otitis - conduction hypacusia and a B curve on tympanometry. The incidence of intracranial complications (meningitis) is reported in 20 - 25% of patients, more frequently in child patients. Diagnostic methods are CT, MR, possibly contrast examinations. In the paediatric hospital in Brno at the Paediatric ENT Clinic the authors had a case of otoliquor- rhoea in a patient after bilateral antromastoidectomy (1992). In 1995 - 1998 on both sides fluid was removed from the middle ear and ventilation tubes were inserted. After the last insertion of a ventilation tube in 1998 discharge of liquor occurred. Subsequent CT of the pyramids revealed on the right side a postoperative defect of the mastoid process near the posterior cranial fossa and an impaired outline of the pyramid on the ventral side and communication of the defect with the middle ear cavity. During surgical revision of the right middle ear a perforated meningocele was found which emerged from a defect of the tegmen tympani bone. The sac of the meningocele was resected and the diagnosis was confirmed by histological examination. The bone defect was covered by a patch from a fascia of the m. temporalis, Zenoderm and an osseous bridge. During treatment no acute inflammatory complications developed. Since the operation the patient is for more than one year free from complaints.

        Key words: otoliquorrhoea, meningocele, Mondini’s dysplasia, CT of the pyramids.