Article
Anatomical variations in pneumatization of anterior clinoid process
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Published: | May 8, 2006 |
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Objective: The anterior clinoidectomy provides enormous benefit facilitating the management of paraclinoid and upper basilar artery lesions, but it also carries the potential risk of cerebrospinal fluid leaks. The aim of this study was to assess the variation of pneumatization of the anterior clinoid process (ACP) in order to contribute to reducing the complications of anterior clinoidectomy.
Methods: Between January 2002 and September 2005, MDCT scans of 300 consecutive patients were studied. Patients were ranged in age from 3 to 87 years (mean, 56.7 years). Among these, 13 patients were under 20 years old.
In each of the patients, helical CT scans of the head were made by using a CT scanner with a quadruple detector array (Aqulion; Toshiba Medical Systems Corporation, Tokyo, Japan). Helical CT scans were made with a field of view of 120-180mm, collimation of 0.5 mm, effective section thickness of 0.5 mm, increment of 0.3 mm. The digital CT data was transferred to the ZIOSTATION M900 (ZIOSOFT Inc., Tokyo, Japan) for review. Coronal and sagittal reconstruction, and three dimensional analysis were performed on the ZIOSTATION M900. These images were assessed for pneumatization of the ACP and optic strut (OS). Furthermore, identification of original paranasal sinus of pneumatized ACP and passing region of pneumatization were discussed.
Results: Pneumatization of ACP was found in 9.2% of all sides. Origin of the pneumatization was the sphenoid sinus in 81.8% of all the sides, the ethmoid sinus in 10.9%, and both sinuses in 7.3%. Pneumatized patterns were divided into 3 groups according to passing region. 74.5% were Type I, in which pneumatization was via the OS, 14.5% were Type II, in which pneumatization was via the anterior root (AR), and 10.9% were Type III, in which pneumatization was via both the OS and the AR. The factor between origin of pneumatization and pneumatization pattern showed statistical bias. (p<0.001) Pneumatization of OS beyond the narrowest point was found in 6.8% of all sides.
Conclusions: Awareness of these different variations in pneumatization may prevent the destruction of mucous membrane and will facilitate orientation during reconstruction by cranialization. In anterior clinoidectomy, preoperative CT assessments are necessary to evaluate pneumatization of the ACP.