Lateral bony decompression may offer several biomechanical advantages and has become a commonly used surgical approach. Preoperative imaging plays a key role in surgical planning by providing information about the locoregional anatomy. The marrow space of the greater wing of the sphenoid is a focal point of the decompression surgery based on the volume that it occupies. Several vessels pass through the sphenoid bone, but most are small caliber vessels. The authors describe a case of an uncommon anatomical variant of the cranial diploic venous system in which the anterior transverse diploic vessel traverses the marrow space of the sphenoid. The vessel was identified on preoperative CT evaluation. Despite anticipation of potential bleeding, lateral decompression was abandoned due to difficulties in maintaining hemostasis which compromised the view for safe surgical progress.