Contribution of the Dura & the Pericranium in Absorption of Cranial Bone

Many craniofacial and neurosurgical procedures rely on cranial bone as a bone graft. In the majority of instances, the bone heals and gives good results. But we found that if either the dura or the pericranium were missing adjacent to the cranial bone, bone absorption would be increased. We studied a single animal model, investigating the contribution of the dura and the pericranium in the process of cranial bone absorption. The animals were divided into four groups of each five animals depending on the differential blockade of the dura and/or the pericranium by silastic sheet. Bilateral 100-mm2, parietal bone flaps were harvested from mature rabbits. Animals were humanely killed after 12 weeks, and histomorphometric analysis was performed. The volume maintenance is as follows; Group I; 89.0%, Group II; 80.0%, Group III; 63.3%, Group IV; 52.4%. The weight maintenance; Group I; 87.1%, Group II; 79.4%, Group III; 61.6%, Group IV; 51.1%. The histological contribution of living bone; Group I; 92.9%, Group II; 85.6%, Group III; 71.1%, Group IV; 56.2%. Significantly increased bone absorption occurred in Group II, III, IV compared with Group I. Conclusions are: 1. Cranial bone absorption is effected by both the dura and the pericranium. 2. The dura is more important than the pericranium in preventing cranial bone absorption. 3. The dura to be the source of central cranial bone and the pericranium to be the source of peripheral cranial bone.

The Role of Transfacial Approach in Skull Base Surgery

Even though there are diverse tumors invading skull base, it is impossible to completely remove the tumor only by transcranial approach due to its anatomical complexity. Therefore we operated by transfacial approach as well which allows to have a good vision and remove the tumor from different directions. Transfacial approach is to approach tp the skull base for the tumor located on the margin of skull and face through exposing such as nasal cavity, paranasal cavity, nasopharyngeal cavity, etc. after separating facial bone. In 1990 Janecka introduced it, dividing the face into 4 groups: mini, standard, expanded, and bilateral facial translocation, based on neurovascular and aesthetic line. Transfacial approach makes it possible to do three dimensional tumor resection, remove the tumor, check its margin directly, and have functionally and aesthetically satisfactory reconstruction. In such cases that tumor invades lower part of skull base, the tumor can be removed only by transcanial approach. Although tumor can be removed by transcranial approach to find the location three dimensionally, transfacial approach can be used as adjunctive means which allow to get a good vision and remove the remnant completely. For 36 months, we have executed 16 cases of tranfacial approach, removing tumors located at the skull base. We classify and suggest the role of tranfacial approach based on our documents.