Perineural Invasion of Head and Neck Cancers Involving the Eye

Orbital invasion from head and neck cancers can occur by perineural spread or direct extension through the orbital walls. Perineural spread to the orbit may occur by several mechanisms. It may occur in a retrograde manner extending from distal sites into the orbit via the first division of the trigeminal nerve (V1) or the second division of the trigeminal nerve (V2) via the inferior orbital fissure. It may also occur in an anterograde fashion with spread of the tumor from Meckels cave or cavernous sinus via the V1 through superior orbital fissure.