Developmental Patterns and Characteristic Symptoms of Petroclival Meningiomas

Thirty-six cases of petroclival meningiomas with clearly defined anatomical features were selected to analyze the site of tumor attachment and the displacement of the trigeminal nerve. The tumors were classified into four categories according to the origin and extension of the tumor: clival origin medial to the trigeminal nerve (upper clivus type), clival origin with dumbbell extension to the cavernous sinus (cavernous sinus type), tentorial origin over the trigeminal nerve (tentorium type), and petrous apex origin lateral to the trigeminal nerve (petrous apex type).