The main objective of this study is to investigate the relationship between the number of cranial nerves passing through the cavernous sinus affected by a lesion and the percentage of lesions located in the cavernous sinus itself. We collected cases retrospectively and classified them into groups according to the number of involved cranial nerves. The diagnoses were confirmed either with MRI, angiography or pathological examination. Sixty-eight cases in total were collected. In the increasing order of cranial nerve involvement (from 1 to 4 nerves), 17.7, 44.4, 56.3 and 77.8% of cases were found to have lesions in the cavernous sinus. A linear regression model with a least square estimator showed an approximately linear correlation. We concluded that there was an approximately linear correlation between the number of cranial nerves affected by a lesion and the percentage of lesions located in the cavernous sinus.