The Dorello's canal, first described by Gruber, in 1859, as an osteofibrous canal at the apex of the petrous bone containing the abducens nerve and the inferior petrosal sinus.' Dorello, in 1905, and Vail, in 1922, also studied the anatomy of this area.2'3 Since then, the canal has been considered clinically important in interpreting sixth nerve palsy.Recently, the interest in this anatomic structure has been revived because of advances in skull base surgery, especially in the surgery of petroclival area.410The first microanatomic study of the Dorello's canal was performed by Umansky et al and reported in 1991.11 This study represents a significant contribution to our knowledge of this specific area. The authors used the operating microscope to present a series of measurements concerning the Dorello's canal's anatomic elements. They also defined its complex relationship to the cavernous, basilar, and inferior petrosal sinuses. Further, they noted the controversies surrounding the canal's definition and proposed their own opinion in this topic.In contrast to the surgical need for a detailed knowledge of the microanatomy of this area, only a few references to the Dorello's canal can be found in the literature. All the above studies disclosed several variations that emphasize the need for further dissections. Our study was performed to contribute further to the definition of the Dorello's canal microanatomy.
MATERIALS AND METHODSTwenty cadaveric wet bone specimens of sphenoid bone and the petrous apex, with the dura mater, nerves, and soft tissue intact, were obtained from cadavers. The specimens were fixed in 10% formalin solution. After fixation, the specimens were examined and immobilized on a special base. The operating microscope was used for dissections and photographs. Microsurgical instruments were used, as well.During the first stage, the specimens were inspected for anatomic variations of the petroclival area. The abducens nerve was also examined at its entrance to the interdural space at the clivus.During the second stage, we performed dissections on the right side to expose the Dorello's canal. We began at the posterior petroclinoid fold, above the petrous apex, and dissected down to the endosteal dura of the petrous bone to reveal the petrous apex, the Meckel's cave, and the posterior third of the cavernous sinus. The abducens nerve was identified where it crosses the lateral wall of the cavernous internal carotid artery (ICA). Further dissections to the dorsum sellae and the clival dura exposed the confluence of cavernous, basilar, and inferior petrosal sinuses, the petrosphenoidal or Gruber's ligament, and the Dorello's canal.
