Table 1.

Mechanisms of injury to the olfactory function from sinonasal surgery

Mechanical injury/mechanical factors:	Direct trauma to the olfactory epithelium:
	1. Resulting from use of electrocautery.
	2. Lasers direct or scattered to the olfactory region.
	3. Traction on the olfactory filia due to cribriform plate motion with superior septoplasty or osteotomies.
	4. Mechanical abrasion after direct trauma.
	Scarring in the olfactory region.
	Atrophic rhinitis secondary to aggressive resection of the sinonasal tissue, especially inferior turbinectomy, which can lead to excessive crusting, dryness and mechanical occlusion of the olfactory cleft by crust.
Airflow modifiers:	Scarring or anatomical narrowing/widening that would alter airflow to the upper nasal olfactory neuroepithelium.
Vascular/neural injury:	Vascular compromise to the olfactory neuroepithelium secondary to surgically created ischemia.
	URI in early post-operative period (Herpes, influenza, Rhino and Corona viruses are known to affect the olfactory pathway).
Other:	Medications:
	1. Local anesthetics applied either topically or injected
	2. Topical Zinc products
	Psychological factors: anxiety, stress which may lead to the complaints of olfactory dysfunction.
	Unrecognized preexisting anosmia/hyposmia.
	Loss of major areas of healthy olfactory epithelium with only few functioning areas that still give “normal” olfactory function.