Etiology
Approximately 90% of epistaxis is caused by bleeding originating from blood vessels in Little's area, located at the anterior inferior septum. This area contains a confluence of vessels from the various nasal sources called the Kiesselbach plexus. [Figure caption and citation for the preceding image starts]: Nasal vasculature demonstrating the vessels that form the Kiesselbach plexusFrom the collection of David A. Randall, Springfield Ear Nose Throat and Facial Plastic Surgery, MO [Citation ends].
Posterior epistaxis originates from the posterior nasal cavity or nasopharynx.[3][4]
Vessels may bleed due to:
Mucosal compromise
Impairment of vasoconstriction and inadequate activation of the clotting mechanism.
Neoplasm represents an atypical and, if located in a paranasal sinus, elusive cause of nosebleed and includes:
Sinus tumors: associated with exposure to wood dust and certain chemicals
Juvenile nasopharyngeal angiofibroma: a rare nasopharyngeal tumor of adolescent men that can produce significant unilateral hemorrhage in the presence of nasal obstruction.[8][11][12]
Adults with nosebleed often have elevated blood pressure (BP), although difficulty exists in determining whether hypertension is a causative factor or whether the elevated BP is secondary to anxiety. Conclusive proof is lacking.[8][13][14][15] A Korean population cohort study of more than 70,000 people found that those with hypertension appeared to have an increased risk of epistaxis, had more emergency department visits, and required more posterior nasal packing procedures than people without hypertension.[16]
Whether atherosclerotic change, secondary to hypertension, increases vessel fragility is also debated. In the manner that elevated BP impairs intraoperative surgical hemostasis, it may be reasonably inferred that it would similarly prolong and worsen active nasal bleeding.[13][14]
Pathophysiology
The physiologic demands of the nose require a robust blood supply. Loss of mucosal integrity, for any reason, exposes underlying vessels, which may be violated and bleed.
Vasoconstriction and activation of the clotting mechanism normally regains hemostasis. Impairment of these processes may prolong bleeding.
Classification
Commonly used classification according to site of bleeding source
Anterior epistaxis:
Accounts for approximately 90% of nosebleeds
Usually originates from the Kiesselbach plexus, a rich vascular anastomosis located at the anterior nasal septum; this region is called Little's area.
Posterior epistaxis:
Originates from the posterior nasal cavity or nasopharynx[5][6]
Posterior nasal and nasopharyngeal vessels often have a larger caliber and may produce more active bleeding.
Commonly used classification according to cause of bleeding
Erosion or injury to mucosa resulting in blood vessel exposure and bleeding.
Fracture or other trauma disrupting the mucosa in atypical areas of the nose, such as lateral nasal wall with nasal fracture.
Neoplasm: uncommon cause of nosebleed. The diagnosis should be considered when epistaxis occurs without a typical anterior or posterior source.
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