Table 1.

Andrews et al. [52]
(I)	Limited to the nasopharynx and nasal cavity. Bone destruction negligible or limited to the sphenopalatine foramen
(II)	Invading the pterygopalatine fossa or the maxillary, ethmoid, or sphenoid sinus with bone destruction
(III)	(a) Invading the infratemporal fossa or orbital region without intracranial involvement
	(b) Invading the infratemporal fossa or orbit with intracranial extradural (parasellar) involvement
(IV)	(a) Intracranial intradural without infiltration of the cavernous sinus, pituitary fossa or optic chiasm
	(b) Intracranial intradural with infiltration of the cavernous sinus, pituitary fossa or optic chiasm
Radkowski et al. [53]
(I)	(A) Limited to posterior nares and/or nasopharyngeal vault
	(B) Involving the posterior nares and/or nasopharyngeal vault with involvement of at least one paranasal sinus
(II)	(A) Minimal lateral extension into the pterygopalatine fossa
	(B) Full occupation of pterygopalatine fossa with or without superior erosion orbital bones
	(C) Extension into the infratemporal fossa or extension posterior to the pterygoid plates
(III)	(A) Erosion of skull base (middle cranial fossa/base of pterygoids)—minimal intracranial extension
	(B) Extensive intracranial extension with or without extension into the cavernous sinus
Önerci et al. [54]
(I)	Nose, nasopharyngeal vault, ethmoidal-sphenoidal sinuses, or minimal extension to PMF
(II)	Maxillary sinus, full occupation of PMF, extension to the anterior cranial fossa, and limited extension to the infratemporal fossa (ITF)
(III)	Deep extension into the cancellous bone at the base of the pterygoid or the body and the greater wing of sphenoid, significant lateral extension to the ITF or to the pterygoid plates posteriorly or orbital region, cavernous sinus obliteration
(IV)	Intracranial extension between the pituitary gland and internal carotid artery, tumor localization lateral to ICA, middle fossa extension, and extensive intracranial extension
Snyderman et al. [56]
(I)	No significant extension beyond the site of origin and remaining medial to the midpoint of the pterygopalatine space
(II)	Extension to the paranasal sinuses and lateral to the midpoint of the pterygopalatine space
(III)	Locally advanced with skull base erosion or extension to additional extracranial spaces, including orbit and infratemporal fossa, no residual vascularity following embolisation
(IV)	Skull base erosion, orbit, infratemporal fossa
	Residual vascularity
(V)	Intracranial extension, residual vascularity
	M: medial extension
	L: lateral extension