Table 1.

Classification of anterior skull base defects.

Location [3]	Cribriform plate
	Ethmoidal roof
	Sphenoid
	Frontal sinus
	Sella turcica
	Clivus
Size [2]	<1 cm
	>1 cm
Etiology [3,4,5,6,7,8,9]	Iatrogenic	Planned
		Accidental	Cribriform plate/fovea ethmoidalis
			Frontal
			Sphenoid
	Neoplastic	Meningioma, olfactory fossa, planum sphenoidale, tuberculum sellae
		Craniopharyngeoma
		Chordoma
		Esthesioneuroblastoma
		Sinonasal carcinoma
		Sarcoma, chondrosarcoma
		Benign	Osteoma
			Inverted papilloma
	Infectious/ Inflammatory	Invasive fungal sinusitis
		Inflammatory pseudotumor
		Osteomyelitis
		Mucocele
	Trauma	Sphenoid
		Frontal
		Cribriform plate/fovea ethmoidalis
	Spontaneous	Congenital
		Idiopathic	Benign intracranial hypertension
			Connective tissue disorder
CSF leak [1,2]	Low	Less than 1 cm dural defect, CSF weeping
	High	Greater than 1 cm dural defect, involvement of ventricle or cistern