Optico-carotid recess and anterior clinoid process pneumatization â€" proposal for a novel classiï¬cation and uniï¬ed terminology: an anatomic and radiologic study.

BACKGROUND

The aims of this study were to propose a novel and uniï¬ed classiï¬cation system of the optico-carotid recess (OCR) and anterior clinoid process (ACP) pneumatization, determine their frequency in a Caucasian population and measure the size of the OCR.

METHODOLOGY

A total of 200 specimen (400 sphenoid sinuses) were evaluated in a separate anatomic cadaveric study (n=100) and radiologic study (n=100) by using sphenoidal sinus cast and computed tomography (CT) scan. OCR was divided according to its location to the optic nerve into sub-optical and latero-optical OCR grade I-III.

RESULTS

An OCR was found in 39% of the samples (78/200) and in 19% (38/200) it occurred bilaterally. Both, sub-optical and latero-optical OCR were identiï¬ed in 14% of the sides (58/400), with a mean length and depth of 6.9 mm; 7.7 mm and 2.3 mm, 7.1 mm, respectively. We determined the pneumatized ACP frequency with 23% (46/200) and deï¬ned 3 uniï¬ed different types of pneumatization.

CONCLUSIONS

The OCR is a reliable landmark to identify the optico-carotid region in endoscopic sphenoid sinus surgery, and can even be visualized by CT. Hence, preoperative investigation of the sphenoid region is mandatory. In our opinion, the classiï¬cation presented in this study can be useful in order to avoid surgical complications.