Angiographic anatomy of the laterocavernous sinus.

BACKGROUND AND PURPOSE The laterocavernous sinus (LCS) has recently been recognized as one of the major drainage pathways of the superficial middle cerebral vein (SMCV). Our purpose was to investigate the drainage pattern of the SMCV, with special emphasis on the angiographic anatomy of the LCS. METHODS The drainage pathways of the SMCV were evaluated prospectively on 100 selective carotid angiograms obtained in 65 consecutive patients. RESULTS The SMCV was absent in 19% of cases. A classic termination into the cavernous sinus (CS) was found in 20%, a paracavernous sinus in 39%, and an LCS in 22%. The LCS drained toward the pterygoid plexus (27%), the superior petrosal sinus (18%), the posterior aspect of the CS (32%), or a combination of these pathways (23%). A complete absence of connection between the LCS and CS was observed in 63.5% of the patients. CONCLUSION The LCS is a laterosellar venous space that is anatomically and angiographically distinct from the CS. Secondary small anastomoses between the LCS and CS may make it difficult to differentiate the two structures. Appreciation of the course and connection pattern of the LCS is important, particularly when planning an endovascular approach to treatment of lesions in the region of the CS.