So I have a brain parasite that needs to enter the skull of a host organism (in this case humans) with the least amount of effort, but is too large to enter through the circulatory system and must physically crawl inside a host. Drilling through the skull is the most difficult option and will likely cause fatal infections. This is fine for brain parasitoids that eat the host from the inside out, but not for parasites that need the host alive for longer periods. Going through the ear canal still requires destroying the middle and inner ear which would cause deafness and loss of balance in addition to still drilling through the skull and causing fatal infections. At this point the most efficient and least destructive options seem to be to enter through the nostril/nasal cavity or eye socket where the brain casing is thinnest or absent and drenched in insulating mucus.
What option makes the most sense?