Sunday, May 30, 2010

Nasal mucosal congestion index and how to measure it.


Nasal mucosal congestion is an important determinant in deciding whether the patient needs medical / surgical therapy. It goes without saying that if the nasal mucosa is thickened due to mucosal oedema than it would respond better to nasal decongestants, while if the thickening is due to underlying submucosal fibrosis then it doesn't respond to decongestants and needs to be surgically removed to improve nasal airway patency. Nasal mucosal compliance cannot be estimated by CT scans alone.

It has been demonstrated that tissue remodelling which is the repair response of nasal mucosa to insults is characterised by decrease in vascular density, and an increase in fibrosis causing the nasal mucosa to thicken irreversibly. This thickened mucosa reduces drug permeability through osmosis causing a reduction in the effectiveness of the drug.

Nasal mucosa congestion index:

This measurement helps in identifying mucosal oedema from mucosal thickening due to fibrosis involving submucosa. This can be measured by performing acoustic rhinomanometry before and after decongesting the nose with epinephrine. If the nasal mucosal congestion index is large then medical management is preferred and if the index is small then surgery should be resorted to in the management of chronic rhinosinusitis. For sake of objectivity congestion index of the nasal mucosa can be classified as normal, mild, moderate, severe and very severe.

Acoustic rhinometry:

This procedure was first introduced by Hilberg as an objective method in assessing the nasal cavity. This procedure is based on the principle that sound waves traveling through the nasal cavity is reflected by local changes in acoustic impedance. Four areas of the nasal cavity have been shown to be the cause of nasal resistance. They are:

1.Nasal valve area (internal nasal valve)
2.Nasal vestibule
3.Head of inferior turbinate
4.Head of middle turbinate

Nasal resistance caused contributed by these areas can be clearly assessed by acoustic rhinomanometry. This method is very accurate in studying the nasal resistance at the level of nasal valve area. The accuracy progressively reduces for nasal resistance contributed by posterior structures like head of the middle turbinate.

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