The nasal cycle in health and disease

Abstract

All mammals, including man, have two nasal passages. However, air¯ow is not symmetrical, due to anatomical and physiological factors.The anatomical factors are the ®xed structural dierences between the two nasal passages and the physiological factors are related to spontaneous congestion and decongestion of nasal venous sinuses (venous erectile tissue), often referred to as the nasal cycle. 1 This review will be restricted to the understanding of the physiology and pathophysiology of the`nasal cycle' and a case will be made that these factors must be taken into account when considering the surgical treatment of nasal obstruction.In the clinical assessment of a patient presenting with nasal obstruction the otorhinolaryngologist must consider:(1) the anatomical factors; (2) the physiological factors; and (3) the pathophysiology of the nasal mucosa in relation to in¯ammatory conditions, recumbency and posture. The surgeon, when asked to correct anatomical and physiological abnormalities, should consider the nose as two separate nasal passages that exhibit spontaneous and often reciprocal changes in nasal air¯ow. Physiology of the`nasal cycle' R E C I P R O C I T Y A N D P E R I O D I C I T YIn the healthy nose the ®xed anatomy of the two nasal passages, consisting of bony and cartilaginous components, is symmetrical. However, the air¯ow through the nasal passages is normally asymmetrical and this is the result of spontaneous changes in nasal airway resistance which are often reciprocal in nature. 2,3 These changes normally result in asymmetrical air¯ow that alternates from one nasal passage to the other over a period of several hours and this phenomenon is known as the`nasal cycle'. Many studies have been conducted investigating this phenomenon but, as yet, a clear functional signi®cance for the nasal cycle in health and disease remains unde®ned.One problem with using the term`nasal cycle' is a lack of de®nition of what constitutes a`nasal cycle'. Earlier observational studies have reported this`cycle' to be present in I 80% of the population, 3,4 but more recent quantitative studies using numerical parameters have shown this ®gure to be much lower. 5,6 In these studies the authors quantitatively measured reciprocity (truly reciprocal changes in air¯ow between right and left passages) and periodicity (the regularity of changes in air¯ow occurring with time in each nasal passage). Their results indicate that true periodicity and reciprocity of nasal air¯ow exists in 21%À39% of the population. Therefore it appears that, on quantitative analyses, the term`nasal cycle' is a misnomer.The nasal epithelium has a very complex vasculature with a submucosal plexus of venous sinuses lining the nasal mucosa. These venous sinuses form erectile tissue that is well developed in the anterior part of the nasal septum and the inferior turbinate. 7 These submucosal cushions of venous sinuses expand and shrink, depending upon the degree of congestion, hence altering the calibre of the nasal passages and in¯uencing the nasal air¯ow. Whe...

Effect of Postural Change on Nasal Airway and Autonomic Nervous System Established by Rhinomanometry and Heart Rate Variability Analysis

“…31 In the anatomically healthy nose, however, the total nasal airflow and resistance remains relatively constant despite the changes in the unilateral resistance of each nasal passage. 31,32 To prevent the possible confounding effects of the nasal cycle, the total nasal airflow and total nasal resistance were used to evaluate nasal patency in the study. The subjects with any anatomic abnormality or any history of nasal disease were excluded also.…”

Total nasal resistance among Sasang constitutional types: a population-based study in Korea

“…Facial anatomical structures such as dimensions of the external nose, nasal width, and nostril diameters and difference in nasal mucosal blood flow could be contributing factors although it requires further studies [18,21]. …”

“…A nasal adapter was placed inside the obstructed nostril. The value of unilateral nasal resistance measurements may show daily variation even in the same subjects due to alternation between nostrils, the so called nasal cycle [18], thus nasal resistances were measured for both nostrils at a transnasal pressure of 100 and 150 Pascal (Pa). The resistance of inspiratory airflow at each nostril was represented as a transnasal differential pressure (Pa) divided by nasal airflow (V), as follows:…”

‘Valve-stabilised’ rhinospirometry can predict the benefit of septal surgery: a pre- and post-operative correlation study

“…First described by Hanif [15], the NPR is a measure of ratio between the two nasal passages rather than developing an accurate model of nasal anatomy. It gives a value on the relative asymmetry of nasal airflow.…”