Biomedical subjects

Alexander G Chiu

Publications and source records attributed to Alexander G Chiu.

22 records · Page 2Linked to original sources

PubMedDate not supplied

Altered sinonasal ciliary dynamics in chronic rhinosinusitis.

BACKGROUND: Although multiple etiologies contribute to the development of rhinosinusitis, a common pathophysiological sequelae is ineffective sinonasal mucociliary clearance, resulting in stasis of sinonasal secretions, with subsequent infection, and persistent inflammation. The respiratory cilia beat continually at a basal rate, while during times of stress, such as exercise or infection, ciliary beat frequency (CBF) increases, accelerating mucus clearance. Previous investigations have led to conflicting results with some authors reporting decreased CBF while others have found normal values of CBF in patients with chronic rhinosinusitis (CRS). Additionally, these studies have only analyzed basal CBF. The goal of this study was to compare the basal as well as the stimulated sinonasal CBF in patients with CRS versus controls. METHODS: A dual temperature controlled perfusion chamber, differential interference contrast microscopy, and high-speed digital video were used to analyze both basal and adenosine triphosphate (100 microM)-stimulated CBF in human sinonasal mucosal explants. RESULTS: Although no difference in basal CBF was detected between control and CRS patients, a marked difference in stimulated CBF was noted. Exogenously applied adenosine triphosphate resulted in a 50-70% increase of CBF in control tissue with a minimally observed CBF increase in explants from CRS patients. CONCLUSION: Dynamic regulation of respiratory ciliary activity is critical for the respiratory epithelium to adapt to varying environmental situations. Thus, diminished or absent adaptation could predispose the sinonasal cavity to accumulation of inhaled infectious and noxious particulate matter resulting in infection/inflammation. Our findings suggest that CRS patients have decreased sinonasal ciliary adaptation to environmental stimuli.

Adenosine Triphosphate↗

PubMedDate not supplied

Management of the lateral frontal sinus lesion and the supraorbital cell mucocele.

BACKGROUND: Masses that radiographically appear in the lateral aspect of the frontal sinus can be difficult to access and often are approached through external approaches. Supraorbital ethmoid cells pneumatize the orbital plate of the ethmoid bone to lie posterior and lateral to the frontal sinus. Opacification of a supraorbital cell may radiographically give the appearance of a laterally based frontal sinus lesion. Often, these represent mucoceles, in which their drainage can be achieved through endoscopic techniques and without the need for an external approach. METHODS: Retrospective review of patients treated for lateral frontal sinus lesions at a tertiary sinus center was performed. Radiology, endoscopic findings, operative reports, and patient symptoms were reviewed. RESULTS: Ten patients were identified with lateral frontal sinus lesions based on radiography of the paranasal sinuses and nasal endoscopy. All patients were determined to be supraorbital mucoceles. These patients underwent surgical drainage using computer-aided endoscopic techniques. Initially, endoscopic drainage of the mucocele was successful in all patients. One patient was lost to follow-up after 3 months and one patient underwent a revision endoscopic surgery with trephination 5 months after the initial drainage. The remaining eight patients remain free of disease by nasal endoscopy and postoperative computed tomography scans (median follow-up of 25 months; range, 8-38 months). CONCLUSION: Knowledge of the anatomy of the ethmoid complex and presence of various cells within the frontal recess such as supraorbital cells are important in the management of the laterally based frontal sinus lesion. Often, these lesions may represent supraorbital cell mucoceles amenable to endoscopic drainage. Given the nature of mucoceles, long-term follow-up is needed before endoscopic drainage of these lesions can be validated. However, preliminary data suggest that an endoscopic approach provides for adequate drainage and helps avoid external approaches.

Drainage↗

PubMedDate not supplied

Surgical decisions in the management of frontal sinus osteomas.

BACKGROUND: The development of chronic rhinosinusitis, a mucocele, or persistent headaches is a common indication for the removal of a frontal sinus osteoma. The best surgical approach to ensure complete and safe removal of the lesion is less clearcut. The advent of specialized frontal sinus instruments, angled endoscopes, and surgical navigational systems has made removal of frontal sinus osteomas possible through an endoscopic approach. The aim of this study is to review our recent experience with the surgical management of frontal sinus osteomas, and the anatomic features that make specific lesions more or less amenable to endoscopic resection. METHODS: A retrospective review of all frontal sinus osteomas surgically resected from the years 1999 to 2003 was used. This period was selected to reflect the invention and popularization of surgical navigation systems and specialty instruments designed specifically for the frontal sinus. CT scans, operative reports and postoperative course were reviewed. RESULTS: Nine patients were identified. A grading system was devised to reflect the three variables involved in the limitations for endoscopic removal. These are the location of the base of attachment, relative size to the frontal recess, and location in relation to a virtual sagittal plane through the lamina papyracea. Three osteomas were removed through an endoscopic approach. Four were removed by a combined osteoplastic flap and endoscopic dissection of the frontal recess. Two were removed through an osteoplastic flap with obliteration of the sinus. CONCLUSION: The ability to remove a frontal sinus osteoma endoscopically can be determined preoperatively, taking into account the location and size of the lesion. There is still a role for external procedures in the surgical management of these lesions, and such procedures may be combined with endoscopic techniques for optimal results.

Adult↗

PubMedDate not supplied

Regional analysis of sinonasal ciliary beat frequency.

BACKGROUND: Mucociliary clearance, a primary host defense mechanism, depends on mucus production and its clearance by the coordinated beating of cilia lining the airways. Numerous investigations have analyzed ciliary activity in brushings from the inferior turbinate. To date, only one study has investigated whether there exists variation in ciliary beat frequency (CBF) within the sinonasal cavity. We analyzed CBF from the inferior turbinate, uncinate process, and sphenoethmoid recess in nonsinusitis patients to determine regional variability of ciliary activity within the sinonasal cavity. METHODS: Explants of sinonasal epithelium were analyzed at 37 degrees C. Beating cilia were visualized with differential interference contrast microscopy. Images were captured using a high-speed digital camera with a sampling rate of 250 frames per second. A one-dimensional tracking algorithm analyzed individual pixel grayscale values within each frame of the video. The differences in grayscale were plotted as a time-dependent waveform, and frequency was calculated as the inverse of the peak-to-peak distance. A minimum of three areas of beating cilia were analyzed per regional sample. Statistical analysis was performed with repeated-measures analysis of variance. RESULTS: Complete sampling of all three sites was accomplished in 10 patients. No difference in CBF within the sinonasal cavity was identified (p < 0.05). The mean CBF for all sites in all patients was 12.6 +/- 2.9 Hz, in agreement with published values. CONCLUSION: This study shows no regional differences in CBF within the sinonasal cavity, supporting previous work and validating analysis of inferior turbinate cilia.

Adult↗