Nasal obstruction is one of the most common symptom encountered in otorhinolaryngological practice. Considerable attention has been paid to quantify the degree of nasal obstruction in term of nasal resistance to airflow [6
]. The fact that nasal anesthesia had been reported to increase the sensation of nasal airflow appear to be an unexpected and paradoxical finding [1
]. Camphor, eucalyptus and menthol are traditionally believed to be used in the symptomatic treatment of nasal congestion and their use extends back over 100 years. Despite the popularity of these compounds and their long usage as nasal decongestants there has been little research of their effects on the nose. Previous works [7
] has shown that the vapors of volatile oils: menthol, camphor and eucalyptus increases the nasal airflow without altering objective nasal resistance. If stimulation of nasal mucosa nerve endings leads to an increase sensation of nasal airflow, is the converse true, that anesthesia of the nasal mucosa leads to a sensation of nasal obstruction?
Jones et al. [1
], showed local anesthesia (lignocaine) had no objective effect on nasal resistance to airflow but there was a subjective sensation of improved nasal patency following its topical application. This fact that nasal anesthesia increased the sensation of nasal airflow appeared to be unexpected and paradoxical finding [1
]. Eccles et al. [9
] found that topical anesthesia (Lignocaine) caused decrease sensation of airflow and also reported that the subjects had their nose felt more blocked as a result of the anesthetic spray.
Its well known that following application of cocaine to the nose there occurs an increase in the sensation of nasal airflow. In this case, the local anesthetic also acts as a powerful vasoconstrictor causing a great reduction in the volume of the nasal erectile tissue [10
]. In present we can investigate the effects of these substance on nasal resistance to airflow using standard rhinometric techniques (Acoustic rhinometry, AR). The use of AR is an objective method of measuring the minimal cross sectional area (CSA) at different points in the nasal cavity and also by measuring the volume of the nasal cavity (Vol). Hence the efficacy of each treatment modality can be assessed objectively.
This present study aim to determine these parameters as measured by AR correlating with the patients subjective sensation of nasal obstruction determined using Likert scale. The data produce graphs that display the area in three different valleys (nasal valve, inferior turbinate and nasopharynx). These waves are measurable as minimal cross sectional area 1, 2 and 3 (CSA 1, CSA 2 and CSA 3). Acoustic rhinometry is a non-invasive procedure requiring little cooperation from the patient [11
]. Recommendations for standard operating procedure in clinical use of AR was described by Hilberg and Pedersen [12
]. Clinical application of AR is used as a reliable method to show the dimensional changes of the nasal cavity in pre and post surgical states or in the use to measure outcomes of nasal decongestants and allergic treatment [13
]. According to Grymer [14
]; the minimal CSA 1 which frequently corresponded to nasal valve area, gives clinicians valuable information for documentation and diagnosis of nasal obstruction. Cross sectional area 2 was found to be very helpful in estimating the degree of nasal congestion. Cross sectional area 2 corresponds roughly to the anterior end of middle and anterior one third of inferior turbinate where most nasal erectile tissue is present [15
The measurement of nasal resistance to airflow is gradually becoming an accepted clinical investigation in clinical rhinology. However, the patient attending the clinic with nasal obstruction is complaining of a sensation. This is not necessarily the same as an objective, measurable increase in nasal resistance.
The patients in both normal saline and lignocaine groups demonstrated no significant change based upon Likert scale after the study. The study has shown that in the normal saline group, 76% (19) had no change in nasal sensation, 8% (2) felt clearer and 16% (4) had blocked sensation. Among the lignocaine group, the study found that 52% (13) had no change in nasal sensation, 28% (7) felt clearer and 20% (5) had blocked sensation. There was no significant difference between pre and post normal saline Likert scale.
The mean CSA1 and CSA2 with Vol1 and Vol2 did not vary significantly in both groups. The study also demonstrate no statistically significant relationship between the change in pre and post patient symptom score (Likert scale) and the change in pre and post CSA1 and CSA2 as measured by AR in both groups.
The analysis thus shows that the use of topical anesthetic spray on nasal mucosa produces no objective effect on nasal resistance or subjective sensation of altered nasal patency. Thus the study concludes that, tactile sensation of nasal mucosa does not play a role in the sensation of nasal obstruction.