Functional endoscopic sinus surgery (FESS): What radiologists need to know

Transcription

1 Functional endoscopic sinus surgery (FESS): What radiologists need to know Poster No.: C-0793 Congress: ECR 2013 Type: Educational Exhibit Authors: R. Grech, L. Galvin, S. Looby, J. Thornton, A. O'Hare, P. Brennan; Dublin/IE Keywords: Ear / Nose / Throat, Head and neck, CT, Structured reporting, Education, Education and training DOI: /ecr2013/C-0793 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 10

2 Learning objectives To explain why a systematic radiological approach is required when evaluating the paranasal sinuses, in order to answer the most pertinent pre-operative questions. Background Since its introduction in the United States in 1985, functional endoscopic sinus surgery (FESS) has increasingly gained popularity. It aims to improve the mucociliary clearance along the sino-nasal physiological pathways. Dedicated sinus imaging is nowadays considered a prerequisite for FESS. Imaging findings OR Procedure details A systematic approach for multiplanar evaluation of the paranasal sinuses with computed tomography will be demonstrated. The radiological appearance of the conventional sinusoidal anatomy, anatomical variations and post-fess appearances will be discussed. Imaging provides an essential roadmap for surgical planning and the morphologic detail provided is essential in recurrent disease. The radiologist should describe the pattern and location of sinus opacification, the status of the drainage pathways, and the presence of anatomical variants. He should not overlook the brain and soft tissues included in the scans, as incidental findings are common. All the ostia and recesses should be carefully evaluated to check for patency as they are the main targets during FESS. The complex anatomy of the paranasal sinuses makes evaluation using multiplanar reconstructions necessary. Anatomical variants are very common, and these should not cause confusion. Overlooking such variants, especially those described as 'critical' may have serious consequences. Such complications include CSF leak, meningitis, carotid vascular injury, and optic nerve transection. ANATOMICAL VARIANTS Nasal Septum Deviation Coronal and axial CT images showing severe septal deviation to the right. Significant deviation may obstruct the ipsilateral osteo-meatal complex. Page 2 of 10

3 Septal Spur A mid-septum bony spur is seen pointing to the right, adjacent to the ostium of the maxillary sinus. Asymmetry of the Ethmoidal Roof There is subtle (image A) and significant (image B) asymmetry in the height of the ethmoidal roofs. The right side is shallower compared to its counterpart. Pneumatisation of the Middle Turbinates Variations in the degree of pneumatisation of the middle turbinates. A left lamellar concha bullosa (LCB), right bulbous concha bullosa (BCB) and bilateral extensive concha bullosa (ECB) are seen in images A to C respectively. Attachment of the main Spenoid Septum The main sphenoid septum is often eccentric resulting in asymmetry of the spenoid sinuses. Figure A shows a central septum. Note that both carotid canals (*) are well covered with bone. Figure B shows attachement of the sphenoid septum to the left carotid canal, while in figure C it attaches to the left optic canal. Identification of such variants is of utmost impostance, to avoid iatrogenic vascular or neural injury. Aplasia / Hypoplasia of Paranasal Sinuses Underdevelopment of the paranasal sinuses is not an uncommon finding, and can either be symmetrical or asymmetrical. The frontal sinuses are the most frequently affected. Figures A and B: Coronal and axial CT showing asymmetrical hypoplasia of the left maxillary antrum. Figures C and D: Complete aplasia of both spehoid sinuses. Mucosal infalmmatory changes are seen within the ethmoidal air cells. SINUS PATHOLOGY Acute Sinusitis There are dependent secretions within the right sphenoid sinus - a 'bubbly' appearance to the secretions is typical of acute sinusitis. Chronic Sino-Nasal inflammation Image A: Two nasal polyps are seen just above the right middle turbinate. Image B: Chronic pansinusitis in a patient with history of atopia. Note the lack of osseous destruction. Page 3 of 10

4 Fungal Infection CT shows evidence of pansinusitis with high density inspissations within the maxillary antra. Fungal infections may also cause bony erosion/destrcution. Wegener's Granulomatosis There is a soft tissue mass within the right maxillary antrum which has breeched the orbital floor. Note the diffuse osseous sclerosis and thicknening characteristic of the disease. Radicular Cyst Inflammatory mucosal changes are seen in the floor of the right maxillary sinus. On closer inspection there is an expansile lesion within the alveolar process of the maxilla surrounding a premolar root. Findings are characteristic of a radicular cyst. Fibrous Dysplasia Axial and coronal reconstructed CT images demonstate a well circumscribed lesion within the left middle ethmoidal air cells with characteristic 'groundglass' matrix compatable with fibrous dysplasia. POST FESS APPEARANCES Post-Op Changes Coronal and axial CT images show evidence of previous extensive FESS, including bilateral uncinectomies, antrostomies, turbinectomies and ethmoidal bullectomies. Images for this section: Page 4 of 10

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10 Conclusion Radiologists should be familiar with the technicalities of FESS, and should adopt a systematic approach when evaluating the paranasal sinuses in relation to FESS. References 1. Hoang J, Eastwood J, Tebbit C, Glastonbury C.Multiplanar Sinus CT: A Systematic Approach to Imaging Before Functional Endoscopic Sinus Surgery. AJR June 2010 vol. 194 no. 6 W527-W Bolger WE, Butzin CA, Parsons DS.Paranasal sinus bony anatomic variations and mucosal abnormalities: CT analysis for endoscopic sinus surgery. Laryngoscope 1991; 101: Personal Information Page 10 of 10