[Basal encephalocele--a report of two cases and consideration of its pathogenetic classification].

The authors have experienced two cases of basal encephalocele without intra and extra cranial anomalies. We have reviewed previous reported cases and studied, from the view point of developmental pathology, reasons why these cases did not have associated anomalies. In this paper we will report our two cases of basal encephalocele and propose a new classification for it, based upon the developmental pathology of the basal part of the skull and associated anomalies. Case 1. A 32 year old male complained of continuous rhinorrhea for 8 months. Coronal CT scan demonstrated a defect of the right sphenoid and ethmoid bone, and a protrusion of isodensity mass, which was enhanced by administration of metrizamide in the subarachnoid space. During the operation, the protruded mass was removed, and the defects of bone and dura mater were repaired. Postoperative course was uneventful. Case 2. A 33 year old male was referred from the department of otology to the department of neurosurgery, because of rhinorrhea and the presence of brain tissue at the time of nasal operation 3 months before. Coronal CT scan revealed a defect of the left ethmoid bone and a protrusion of isodensity mass in it. RI cisternography clearly demonstrated the leakage of CSF through the left nasal cavity. During the operation, the protruded mass was removed and the bone and dura mater defects were repaired. Postoperative course was uneventful. The common findings of both cases are that they were diagnosed by accident in adulthood cases of rhinorrhea, and midsagittal basal bone structure was preserved without extra and intra cranial anomalies.(ABSTRACT TRUNCATED AT 250 WORDS)