[Sneezing as a mechanical defence - a numerical simulation and analysis of the nasal flow]. / Niesen als mechanische Abwehr - Numerische Simulation mit Analyse der durchströmten Nasenbereiche.

INTRODUCTION: The nose is responsible for humidification, heating and cleaning of the inhaled air. The sneeze reflex leads to a shock-like cleaning of the nose in strong particle exposure. The aim of this study was the simulation of intranasal air flow of sneezing in a realistic computer model. MATERIALS AND METHODS: Based on the CT scan of a 40 year old man a three-dimensional computer model of the nasal cavity and the ethmoid sinuses was created. Flow simulations were performed for different inspiratory and expiratory velocities (± 2 m/s to ± 45 m/s) in order to simulate sneezing. RESULTS were visualized and analyzed by video simulation. RESULTS: During inspiration the main airflow takes place along the middle turbinate. During expiration, the flow is located more cranially. This effect is caused by the shape of the nasopharynx and the posterior portions of the nasal turbinates. During very high speeds (sneezing) also adjacent ethmoid sinuses and the olfactory region are covered by the shock-like expiratory flow. A large vortex formation in the nasopharynx is responsible for a uniform distribution of the airflow also on lower nasal areas. CONCLUSION: Sneezing is a protective reflex that provides for cleaning of the nose. From a flow rate of 10 m/s, the cranial nasal areas as well as adjacent ethmoid sinuses are covered by the -airflow. Compared to the inspiratory airflow the exhalation is not just vice versa. Particles that deposed in the cranial nasal areas during quiet breathing are removed.

A biofilm exists on healthy mucosa of the paranasal sinuses: a prospectively performed, blinded, scanning electron microscope study.

OBJECTIVES: Based on our hypothesis that biofilm is nothing else but normal, otherwise abundantly colonised mucosal mucous blanket, the aim of this study was to check out whether bacterial biofilm exists exclusively at the diseased mucosal surfaces or at healthy mucosa of paranasal sinuses as well. DESIGN: Prospective and blinded. SETTING: Tertiary academic hospital. PARTICIPANTS: The patients suffering from the diseases not related to the chronic inflammation of the paranasal sinuses. Mucosal tissue samples from healthy sphenoid sinuses were taken from 48 patients who underwent pituitary gland surgery and from ethmoidal sinuses mucosa of the 17 patients who underwent endonasal endoscopic orbital decompression because of Graves' disease. MAIN OUTCOME MEASURES: The samples were submitted blindly along with similar samples from patients with chronic rhinosinusitis to two scanning electron microscope experts. In all samples the looked for the main signs of biofilm presence of: the 'towers', rod-shaped bacteria and water channels. RESULTS: Signs of biofilm presence were found in 45 out of 48 pituitary gland surgery patients (94%) and in all of 17 EEOD patients (100%). CONCLUSIONS: Our study showed the presence of the biofilm at the surface of the healthy mucosa of the paranasal sinuses. This suggests that perhaps so called bacterial biofilm is nothing else but regular respiratory mucosal blanket, a part of the mucociliary system itself, containing a great number of bacteria.

[Leptomeningeal dissemination after ethmoidal sinus adenocarcinoma surgery: a rare complication]. / Dissémination leptoméningée après chirurgie d'un adénocarcinome de l'ethmoïde.

INTRODUCTION: Although rare, adenocarcinoma is the most frequent neoplasm of the ethmoid sinus and must be regarded as an occupational disease secondary to chronic wood dust exposure. Few cases with neurological metastasis have been reported. CASE REPORT: We report the cases of two patients who developed a multiple cranial nerve disorder for the first case and a cauda equina syndrome for the second, after ethmoid adenocarcinoma surgery. CONCLUSION: Diagnosis of carcinomatous meningitis is difficult and is based on clinical data, CSF analysis and gadolinium-enhanced T1-weighted brain and spinal cord MRI. The implication of surgery is discussed. Prognosis of such a disorder is poor.

Ventilation of the paranasal sinuses studied with dynamic emission computer tomography.

This investigation's aim was to study a noninvasive method for determining the ventilation of the nasal sinuses. For this purpose, different insufflation techniques using xenon 133 were tried, along with different scintillation camera techniques. Xenon 133 gas was used for insufflation in the nose and sinuses, and the half-time of the washout curves was determined with the aid of digital scintillation cameras, one of which was capable of dynamic tomography. The tomographic procedure was superior because it made it possible to study the washout from the ethmoidal/sphenoidal sinuses as well. The washout was followed for up to 150 minutes. Great variations in washout were found between different sinuses and also in the same sinus over time. The single photon emission computed tomography (SPECT) technique, which is easy to perform and gives a limited absorbed dose to the patient, seems promising for the future evaluation of sinus ventilation and ostial function.

Physiologic mucosal changes within the nose and ethmoid sinus: imaging of the nasal cycle by MRI.

Magnetic resonance studies frequently demonstrate increased T2-weighted signal in the nasal area. To further evaluate this phenomenon, several MRI examinations of the nasal cavity were performed within an 8- to 12-hour period. The study demonstrated that changes alternated from side to side and were interrupted by the administration of topical vasoconstriction, confirming imaging of the normal nasal cycle. Changes were also observed within the ethmoid sinuses. Signal intensity on T2-weighted images during the congested phase was similar to inflammatory mucosa. Occasionally, these changes make interpretation of the extent of pathology difficult in patients with sinus disease, and raise the possibility of inflammatory pathology in asymptomatic patients. Awareness of MRI imaging of nasal cycle should reduce the likelihood of diagnostic errors and provides another method for study of this physiologic phenomenon.