Motofumi Ohki

Reduced nasal resistance after simple tonsillectomy in patients with obstructive sleep apnea

Background The aim of this study was to investigate the effects of simple tonsillectomy on nasal resistance in patients with obstructive sleep apnea syndrome (OSAS). Methods Conventional tonsillectomy was performed in 20 patients who were refractory to treatment with continuous positive airway pressure. The subjects consisted of 17 men and 3 women (mean age, 32.9 ± 6.3 years). The effects of tonsillectomy were evaluated with preoperative and postoperative polysomnography and nasal resistance. Results After tonsillectomy, nasal resistance decreased significantly from 0.39 ± 0.30 Pa/cm3 per second to 0.27 ± 0.16 Pa/cm3 per second (p < 0.05). Simultaneously, the apnea–hypopnea index decreased significantly from 55.7 ± 22.5 to 21.2 ± 14.2 (p < 0.05). There was no significant correlation between tonsillar weight and percentage of change in bilateral nasal resistance (p > 0.05). Conclusion The reduction in nasal resistance induced by simple tonsillectomy could play an important role in improving OSAS, as does nasal surgery or adenotomy.

Effects of Posture on the Nasal Cycle

The effects of posture on the nasal cycle were studied in 26 normal subjects whose spontaneous nasal cycle had been confirmed before the experiment. Nasal resistance was measured by anterior rhinomanometry with nozzles. With 14 subjects, the changes in nasal resistance were observed consecutively on changing from sitting to supine and from supine to sitting. Six reversals of the cyclic phase occurred in 56 postural changes (reversal rare: 10.7%). The reversal occurred once per 2.9 hours. By contrast, with 12 subjects, 27 reversals were induced in 60 postural changes (reversal rate: 45%), on changing from one lateral recumbent position to the other. The reversal occurred once per 27 minutes. Lateral recumbency tends to switch the phase of the cycle and affects its duration.

The Open Mouth and Oronasal Breathing

Effects of nasal resistance on distribution of respiratory airflow between nose and mouth were investigated by a minimally invasive computer-assisted method using a modified CPAP nasal mask/pneumotach and a head-out body plethysmograph. In 18 subjects nasal resistance (p = 0.091), breathing frequency (p = 0.084), tidal volume (p = 0.352), and minute (p = 0.433) volumes were undisturbed by the masking procedure. Partial nasal breathing persisted in 16 of 33 healthy adults instructed to breathe through the mouth. Artificial additions to nasal airflow resistance that were made in 10 volunteers from the 16 persistent partial nose breathers whose nasal fraction > 25% increased the oral fraction of respiratory airflow. It is concluded that while the palate provides a switching mechanism for oronasal routing of respiratory airflow, the oral and nasal vestibules provide variable resistors that regulate its distribution.

Evaluation of Nasal Ohstruction with Acoustic Rhinometry

The measurement of nasal resistance is important for understanding the pathophysiology of nasal obstruction. However, it is difficult to define the normal range of nasal resistance because of various physiological factors. Several authors have reported that nasal resistance is not correlated with the sensation of nasal obstruction. On the other hand, acoustic rhinometry was introduced by Hilberg et. al. (1989) to determine the geometry of the nasal cavity. The method based on sound reflection analysis provides an estimate of the cross-sectinal area of the nasal cavity as a function of the distance from the nostril. Recently, the measurement by acoustic rhinometry is becoming popular also in our country. However, the assessment by acoustic rhinometry may be different from that by measuring nasal resistance because the cross-sectional area is measured without studying the air flow. The aim of this study was to investigate the benefit of acoustic rhinometry using a nasal model. First, 4 pieces of nasal model LM005 (KOKEN, Co., Japan) made of silicone were coated with resinous putty. Then, the changes in the area-distance curve were measured with an acoustic rhinometer RHIN 2100 (SRE, Co., Denmark) in which this putty was scraped off gradually from anterior to posterior. In the next study, the quality of coated putty was increased at three points of the nasal area: anterior part, middle part, and posterior part. Thereafter the changes in the area-distance curve were observed in the same way. As a result, neither a decrease or an increase in the putty changed the area-distance curve at the posterior part. Therefore, it is suitable that the degree of the changing of nasal mucosa is defined as the change in the nasal volume between the top the I-notch and the end of the C-notch. In conclusion, acoustic rhinometry is useful to investigate nasal obstruction, especially the change in the nasal mucosa. Therefore, further clinical study is required for the different purpose of measuring nasal resistance.

Exercise-Induced Nasal Obstruction in Patients with Allergic Rhinitis

Exercise-induced nasal obstruction was studied in 90 patients with allergic rhinitis and 26 normal subjects. Allergic patients as well as normal subjects showed marked decreases of nasal resistance immediately after exercise. In allergic patients, however, the total nasal resistance returned to the pre-exercise level quickly after exercise and surpassed it. Meanwhile, the total nasal resistance gradually returned to the pre-exercise level in the post-exercise period in normal subjects. The profile of the total nasal resistance changes in the allergic patients was statistically different from that in the normal subjects. As far as unilateral nasal resistance is concerned, marked increases of nasal resistance appeared 10–30 minutes after exercise in 20 of 90 allergic patients. On the contrary, this phenomenon was not found in any normal subject. This unilateral nasal obstruction, which appeared only in allergic patients, is probably due to excessive dilatation of the capacitance vessels in the nasal mucosa and considered to appear as an enhancement of the nasal cycle. In this paper, the role of the nasal cycle is discussed in relation to exercise-induced nasal obstruction.

P173: Observation of Nasal Cycle Using a Portable Rhinoflowmeter

oculomotor nerve palsy caused by paranasal-sinus desease. Clinical course and computed tomography (CT) image are documented, and pathogenesis relating to local anatomy is discussed. METHODS: Retrospective case report and review of pertinent literature. RESULTS: Report of three cases of isolated oculomotor nerve palsy caused by paranasal-sinus desease. All the patients complained of double vision and had unilateral disturbance of ocular movement and ptosis, but no visual impairment in opthalmologic examination. In two cases, CT demonstrated soft tissue density (STD) in the posterior ethmoid and the sphenoid sinuses and also inside the ipsilateral anterior clinoid precess (ACP) of sphenoid bone. In the remaining case, CT showed STD in the ethmoid sinus and pneumatization in the ACP. Endoscopic sphenoidectomy was performed on the former two cases, and the last case was treated conservatively with steroid and antibiotics. Their ocular movement returned to normal approximately one month later. In all the cases, CT demonstrated a bony defect at the inferior wall in ACP, which is adjacent to the superior orbital fissure. CONCLUSIONS: Since the oculomotor nerve runs just under the ACP, the authors speculate that compression and/or inflammation through the pneumatized ACP might easily cause isolated oculomotor nerve palsy as in the present cases.