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4.12 Uvular edema


Presentation

A patient complains of a foreign body sensation or fullness in the throat, possibly associated with a muffled voice and gagging. Upon examination of the throat, the uvula is swollen, pale, and somewhat translucent (uvular hydrops). If greatly enlarged, the uvula might rest on the tongue and move in and out with respiration. There might be an associated rash or a history of exposure to phsical stimuli, allergens, or a recurrent seasonal indicence.

What to do:

What not to do:

Discussion

The uvula (Latin for "little grape") is a small conical pedulous process hanging from the middle of lower border of the soft palate. It is composed of muscle, connective tissue and mucous membrane, with the bulk of the uvula consisting of glandular tissue with diffuse muscle fibers intersperced throughout. During the acts of degluttination and phonation, the uvula and soft palate are directed upward, thereby walling off the nasal cavity from the pharynx. During swallowing, this prevents ingested substances from entering the nasal cavity.

Angioedema, also known as angioneurotic edema and Quincke's disease, is defined as a well-localized edematous condition that may variably involve the deeper skin layers and subcutaneous tissues as well as mucosal surfaces of the upper respiratory and gastrointestinal tracts.

Immediate hypersnesitivity type I reactions, seen with atopic states and specific allergen sensitivities, are the most common causes of angioedema. These reactions involve the interaction of an allergen with IgE antibodies bound to the surface of basophile or mastocytes. Physical agents, including cold, pressure, light and vibration, or processes that increase core temperature, may also cause edema throuth the IgE pathway.

Hereditary angioedema, a genetic disorder of the complement system, is characterized by either an obsence of functional deficiency of C'1 esterase inhibitor. this allows unopposed activaation of the first component of complement, with subsequent breakdown of its two substrates, the second (C'2) and fourth (C'4) components of the complement cascade. This process, in the presence of plasmin, generates a vasoactive kinin-like molecule that causes angioedema. Acquired C'1 esterase inhibitor deficiency and other complement consumption states have been described in patients with malignancies and immune complex disorders, including serum sickness and vasculidities.

Other causes of angioedema include a direct degranulation effect on mast cells and basophils by certain medications and diagnostic agents (opiates, d-tubocurarine, curare and radiocontrast materials); substances such as aspirin, nonsteroidal anti-inflammatory drugs, azo dyes and benzoates that alter the metabolism of arachidonic acid, thus increasing smooth muscle permeability; and angiotensin converting enzyme inhibitors, implicated presumably by promoting the production of bradykinin.

The known infectious causes of uvulitis include group A streptococci, Haemophilus influenzae, and Streptococcus pneumoniae. An associated cellulitis may contiguouly involve the uvula with the tonsils, posterior pharynx, or epiglottis.

References:


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from Buttaravoli & Stair: COMMON SIMPLE EMERGENCIES
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