Neurosurgical Approaches to and through the Frontal Sinus using Osteoplastic Frontal Sinusotomy

The frontal sinuses are paired pyramidal cavities with a centrally positioned intersinus septum although several septa can be observed in many patients. The sinuses are located within the squamous portion of the frontal bone above the nasal root and medial orbits, and therefore are in the way of transcranial approaches to the medial cranial base. By age 20, they reach adult size, measuring 28mm high, 24mm wide in each side, and 20mm deep on the average with wide individual variation. The medial anterior cranial fossa is often invaded by tumors originating in the nasal cavity and paranasal sinuses. Intradural neoplasms such as olfactory groove or tuberculum sellae meningiomas also occupy the medial anterior cranial fossa. For the patients with large frontal sinuses, osteoplastic frontal sinusotomy can provide an appropriate window to gain access to the medial frontal fossa in addition to the frontal sinus itself. In this report we present our clinical experiences based on four variations of the neurosurgical approaches to and through the frontal sinus using osteoplastic frontal sinusotomy (so-called transfrontal sinus approach).