Abstract
Background The clinical relevance of emissary veins (EVs) is often neglected. However, for posterior
fossa approaches, especially in semisitting positions, these transosseous connections
become potentially life threatening. Therefore, knowledge of the presence and configuration
of EVs is essential in preoperative planning. We report on the use of preoperative
computed tomography (CT) imaging techniques to visualize EVs reliably.
Methods A total of 100 consecutive patients were evaluated by helical CT in bone window mode
reconstructed using the standard technique (4.5-mm slices) and the high-resolution
technique (1 mm) for the posterior fossa. The presence and size of the EVs, their
entry point in the sigmoid sinus, their predilection site, and their visibility using
either CT technique were evaluated. Statistical analyses included a comparison of
the data from both sides of the head.
Results We noted impressive anatomical variations (high standard deviations) in the number,
size, and intraosseous length of the EVs among the study population and between the
sides (right and left) of an individual patient; however, no statistical significance
was observed for any of these parameters. The detection rate of EVs in thin-slice
CT scans versus standard CT scans is significantly different (p = 0.0001 on both sides).
Conclusions Thin-slice CT is essential in the preoperative planning of posterior fossa approaches
to identify the presence and the course of EVs, reducing preventable approach-related
morbidity during surgery.
Keywords
skull base - emissary vein - computed tomography
