In 94% of cases angioedema involves structures in the head and neck including face, lips, palate, and tongue with laryngeal involvement occurring less frequently.
Ten percent of Americans can expect to have at least one episode of angioedema, specifically seen in the third and fourth decades of life. There is an equal male to female ratio. Attacks are usually self-limiting and resolve within 24 to 48 hours. The principal cause of mortality is airway compromise.
The basic pathophysiology of an angioedematous episode is increased vascular permeability in the submucosal, subcutaneous and deep dermal tissues. This is mediated by vasoactive substances including histamine, bradykinin and other products of the complement cascade including C3a and C5a ( anaphylatoxins).
There are four main causes of angioedema:
Hereditary or acquired C1 inhibitor deficiency.