E-Book, Englisch, 152 Seiten, ePub
Hosemann / Lund / Weber Minimally Invasive Endonasal Sinus Surgery
1. Auflage 1999
ISBN: 978-3-13-258098-5
Verlag: Thieme
Format: EPUB
Kopierschutz: 6 - ePub Watermark
Principles, Techniques, Results, Complications, Revision Surgery
E-Book, Englisch, 152 Seiten, ePub
ISBN: 978-3-13-258098-5
Verlag: Thieme
Format: EPUB
Kopierschutz: 6 - ePub Watermark
Werner G. Hosemann, Rainer K. Weber, Rainer Keerl
Zielgruppe
Ärzte
Autoren/Hrsg.
Fachgebiete
Weitere Infos & Material
1 Introduction
2 Endonasal Sinus Surgery: Basic Principles and Approaches
3 Technique of Endoscopic Endonasal Surgery
4 Results of Endonasal Sinus Surgery for Chronic Rhinosinusitis
5 Results in Defined Patient Groups
6 Extended Spectrum of Endoscopic Endonasal Surgery
7 Complications, Side Effects, and Sequelae
8 Postoperative Care following Endoscopic Procedures
9 Technical Innovations
2 Endonasal Sinus Surgery: Basic Principles and Approaches
Surgical Aspects of the Pathophysiology of Chronic Sinusitis
It is very likely that the term chronic sinusitis in fact covers a number of different disease processes due to a range of pathogeneses (Fig. 2.1). These chronic diseases include, for example, the circumscribed, chronic recurrent paranasal sinusitis that develops as a consequence of a definable anatomic obstruction. An extreme form is the diffuse nasal polyposis occurring in patients with the ASA triad (polyps, asthma, aspirin sensitivity). As yet, the causal and formal pathogenesis of nasal polyposis is still poorly understood.
Circumscribed forms of chronic recurrent sinusitis develop generally as a result of microanatomic anomalies, especially narrow passages or clefts and areas of pathological mucosal contact. These occur mainly in the middle nasal meatus in the region of the central “ostiomeatal unit” and result in a disturbance of mucociliary clearance and ventilation of the functionally dependent paranasal sinuses (see Fig. 2.3). The functional term “ostiomeatal unit” was introduced by Naumann [653] and refers to the anatomic region lateral to the anterior two-thirds of the middle turbinate. It includes the uncinate process, the hiatus semilunaris, the bulla ethmoidalis, the remaining anterior ethmoidal cells and the frontal recess, and the ostium of the maxillary sinus. The maxillary and frontal sinuses are functionally subordinate to the anterior ethmoid complex. The effects of the narrow clefts are potentiated by disturbances of mucociliary clearance associated with areas of tissue contact or inflammatory cell reactions associated with the release of mediators. In addition to the above factors, microbial colonization, dysregulation of transepithelial fluid transport and the immigration of inflammatory cells result in a vicious circle consisting of obstruction of the ostium, followed by changes in the milieu of the dependent sinuses and further mucosal congestion.
The diagnosis of chronic, treatment-resistant sinusitis is made on the basis of a review of the patient's specific history and complaints in conjunction with the findings on endoscopic examination of the nasal cavity and the condition of the functionally dependent sinus mucosa. The functional condition of the mucosa is conventionally equated with the degree of congestion and determined by imaging techniques (CT or MRI).
In circumscribed forms of the disease, surgical treatment is in principle based on the identification and targeted elimination of anatomic bottlenecks. Areas of mucosa that appear to be irreversibly damaged are simultaneously removed. When optimal ventilation and drainage have been restored, the remaining sinus mucosa is allowed to heal spontaneously.
What microanatomic bottlenecks or pathological anatomic variants can be defined? The list below gives a summary of the most common anatomic variants that are considered responsible in the literature for triggering or maintaining chronic paranasal sinusitis. The anatomy of the paranasal sinuses is diverse and unique to each individual. Accordingly, the list of possible bottlenecks is infinite effectively [448, 449]. A pathogenically significant obstruction can only be diagnosed in an individual case on the basis of extensive experience of the microanatomy and with a knowledge of a number of clinical principles. Thus, the presence of a concha bullosa alone, as is found in 14–50% of the population, is not necessarily synonymous with obstruction [112, 190, 512, 1026]. Only the individual shape and a critical overall size, in combination with the adjacent anatomic structures, determine whether there is a surgically relevant obstruction [64, 1019, 1026]. In practice, only pneumatization that extends to the inferior portion of the middle turbinate appears to be of pathogenic significance [64, 930]. The situation is similar with Haller's cells (infraorbital cells) which occur in 10% (8–20%) of the population [190, 403]. The microanatomic changes are sometimes complex and interconnected. Thus, Earwaker [190] distinguished six different types of alteration of the ostiomeatal complex. To date, CT screening has generally been unsuccessful in providing unequivocal evidence of the pathogenetic significance of any anatomic variants of the ethmoid bone or establishing threshold values for their significance [64, 94, 512, 513, 1019]. Many variants are also found in healthy individuals [527]. Table 2.1 gives a breakdown of the incidence of anatomic variants in patients with paranasal sinusitis complaints. Table 2.2 summarizes the results of several studies in healthy individuals, patients with chronic sinusitis and children.
Nasal septal deviations over and above a certain critical size and position also result in an increased incidence of inflammation of the paranasal sinuses [94, 513, 716]. Deviations at the level of the ostiomeatal unit appear to be especially relevant [1019]. Septal deviations are frequently associated with further anatomic variants of the ethmoid bone [527]. Areas of opacification in the anterior and posterior ethmoid complex have been observed in association with septal deviations [94], as have opacifications in the contralateral sinus system [1019]. Moreover, inflammatory changes in the mucosa of the paranasal sinuses are frequently associated with hyperplasia of the nasal turbinates [716].
Table 2.1 Incidence of anatomic variants in patients with paranasal sinusitis complaints [437]| Anatomic variant | Incidence in patients with complaints |
| Concha bullosa | 36% (bilateral in 44% of cases) |
| Septal deviation | 21% |
| Paradoxically bent middle nasal turbinate | 15% |
| Haller's cells | 10% |
| Large bulla ethmoidalis | 8% |
| Lateral rotation of the uncinate process | 3% |
| Pneumatized uncinate process | 0.4% |
Anatomic variants that foster the development of paranasal sinusitis
Septal deviation: convexity, septal spur [858]
Variants of the middle nasal turbinate: concha bullosa; paradoxically convex or bent turbinate; juxtaposition against the lateral wall and the middle meatus [190, 403, 405, 527, 858, 865]
Variants of the uncinate process: rotation particularly medial or anterolateral; displacement following fracture, contact with the middle nasal turbi-nate; pneumatization [190, 403, 405, 527, 858, 865, 1019]
Variants of the bulla ethmoidalis: variations in shape or size [403, 405, 527, 858]
Variants of the agger nasi: pneumatization with crowding of the frontal recess [403, 527]
Haller's cells [403, 405, 527]
Radiological studies on the incidence of the anatomic obstructions reveal that these are only one of many factors involved in the development of chronic sinusitis [433, 512]. Neither the concept of the ostiomeatal unit nor functional endoscopic sinus surgery can be applied indiscriminately in all forms of chronic sinusitis. [212]. On the other hand, not every area of obstruction is necessarily detectable on the CT. Certain individual factors and variations can be established only by a thorough endoscopic examination [860].
Fig. 2.1a,b Types of chronic rhinosinusitis (a)
Coronal CT of chronic rhinosinusitis associated with anatomic narrowing (medially deviated uncinate process and concha bullosa on both sides) in the middle nasal meatus. (b) A 91-year-old woman with extreme nasal polyposis. Secondary mucocele of the lacrimal sac on the left side
Hyperplastic pansinusitis, in particular, cannot be explained by radiologically or endoscopically detected areas of obstruction alone. Other conditions are necessary for nasal polyps to develop. The origins of many polyps are located beyond these obstructions, in the superficial portions of the middle meatus, but similarly, different forms of polyp growth have been observed, including diffuse involvement of the entire sinus system [483].
The paranasal sinuses are dependent upon undisturbed drainage of secretions and unobstructed ventilation. Mucociliary flow follows fixed transport pathways out of the frontal and maxillary sinuses and the anterior ethmoidal cells through the narrow clefts of the ostiomeatal unit into the middle meatus. Compromising factors (inflammation, anatomic variants with narrow passages and secondary mucositis) are most frequently encountered in the region of the anterior ethmoid. They result in a secondary obstruction of drainage of the dependent sinuses and thus in a rhinogenic or centrifugal spread of disease. If the underlying pathogenetic factors are eliminated, ventilation and mucociliary drainage are restored and the mucosa of the dependent sinuses can recover...
