or cribriform plate and the ethmoidal cells, then both the transfrontal extradural and intradural access are used.

Neurosurgical indications for the intradural approach (Schmidek and Sweet 1988) are:

•Intracranial hemorrhages.

•Impalement injuries with lesions of the brain tissue.

•Complicated craniofacial fractures with severe cranio-cerebral trauma, ramified dural tears and profound cerebral injuries.

•Treatment of skull base lesions, dural injuries and cerebral wounds, in extreme posterior positions, whereby the border is denoted by the anterior ethmoidal artery. The region dorsal dorsal to this vessel corresponds with the posterior ethmoid.

•Large dislocated depressed fractures of the frontal bone.

Fig. 8.18  Schematic diagram of the transfrontal extradural approach to the frontobasal area with exposure of the posterior basal fractures after sacrificing of the olfactory nerves (mod. a. Samii et al. 1989; Weerda 1995)

•Unclear localization of liquor fistulae. A common situation, in which the intradural approach is of advantage because of its clear view.

•In situations in which fistula closure presents the main problem, the intradural approach is more reliable than the extradural (Probst 1986). This is particularly relevant in cases of secondary intervention (delayed treatment). The olfactory fibers can be preserved with the intradural approach.

Technical Aspects

With the intradural approach the frontal skull base can be reached from a medial, fronto-lateral, or interhemispherical access, depending on the location of the dural defect (Imhof 2000).

Following dural incision and division of the superior sagittal sinus, the frontal lobe is raised with a cerebral spatula and the frontal base presented in full view. Potential contusion hematomas and regions of cerebral necrosis, which might obliterate the basal dural defect and so mask a rhinoliquorrhea, can be removed (Ewers et al. 1995).

After temporarily covering the outer cerebral surface, bone fragments from the orbital roof and the anterior cranial fossa are repositioned to prevent enophthalmus (Figs. 8.20 and 8.21).

•The intradural access provides a good view of the dura in the frontal skull base and cerebral fossa. This approach is, however, not well adapted for acute treatment following severe cranio-cerebral trauma as the risk of further cerebral injury exists during the inevitable retraction of the frontal lobe (Lehmann et al. 1998).