Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_30_библиотеки_им_акад_М_И_Перельмана

Almost one-third of the cases do not have any pre­disposing factor. In others, the cause of obstruction may be inammation, polyps, trauma, surgery or mass lesion [77]. Cystic degeneration of glandular tissue has been postulated to account for muco­cele, but a classical double wall is invariably not found in these lesions [78]. Various bone-resorb­ing factors like PGE2, leukotrienes, IL-1, TNFa have been found in mucoceles [79, 80]. So, it can be assumed that in mucocele, obstruction is fol­lowed by some other event to initiate the produc­tion of these bones resorbing cytokines resulting in bony expansion. The extended endoscopic proce­dures and obliteration of sinuses have more chances of mucocele formation [81].

Computed tomography (CT) is the most relevant radiological investigation. It provides basic ana­tomical detail of the mucocele, its relation with the surrounding structures and helps in surgical planning. CT shows an expansile, homogenous mass with remodelling of the surrounding bone (Figs.7.38 and 7.39). The appearance of muco­cele on magnetic resonance imaging (MRI) depends on the contents. In general, mucoceles are hypo/iso-intense on T1W1 and hyperintense on T2W2 (Fig. the evaluation of intracranial and orbital exten­sion [82].

Early surgical intervention is the treatment of choice. An endonasal endoscopic approach is almost always feasible and involves wide marsu­pialization (Figs.7.41, 7.42, and 7.43). This has the advantage of no scar, no interference with periorbital structures and excellent visualization. It also provides better restoration of normal sinus function. Virtually all ethmoidal, sphenoidal, frontal and maxillary mucoceles can be managed endoscopically [ remodelling after endoscopic surgery may take a long time to recover. So, it is essential to counsel the patient that cosmetic results may not be achieved immediately.

External approaches may include a Lynch– Howarth, Caldwell–Luc or osteoplastic ap approach. These may be relevant in cases with a history of previous surgery with signicant scar­ring or in presence of signicant pathology in the frontal region [89]. Both external and endonasal approaches may be combined when endonasal approach is not possible.

Haemorrhage, cerebrospinal uid rhinorrhea and injury to the orbit can occur at surgical explora­tion. These complications have become uncom­mon with the advent of endoscopic techniques.

The absence of a normal opening is called atre­sia. Choanal atresia was rst described by Roederer in 1755. Choanal opening(s) may be occluded by soft tissue (membranous), bone or both. Recent data based on CT shows mixed bony and membranous atresia to be the most common (70%) and pure bony to be forming the almost 30% percentage of atresia. Pure membra­nous atresia is rarest in radiology [90]. The inci­dence of choanal atresia is 1:5000 to 1:8000 live births [91, 92]. It is more commonly encountered in females (2:1). Choanal atresia may be unilat­eral or bilateral; unilateral presentation being more common than bilateral (65–70%). In unilat­eral cases, right choana involvement is more common than left. The closure part of the nasal cavity is roomy. Choanal atresia is not interfering with the development of the face. Three-fourth cases of bilateral atresia are associated with other congenital anomalies like CHARGE syndrome, Crouzon’s syndrome, Treacher Collins syn­drome, Polydactyly, craniosynostosis, cleft lip/ palate and nasal/palatal deformities.

Neonates are obligate nose breathers as the lar­ynx is placed at a higher level which descends at 4–6weeks of life and mouth breathing is estab­lished. In bilateral choanal atresia, neonate expe­riences episodes of asphyxia and severe distress with or without cyanosis in quiet respiration when the mouth is closed, especially during sleep or feeding. Cyanosis is relieved by crying or gasping when the child opens the mouth widely, releasing air obstruction.

cases, denitive surgery can be postponed to later school-going age group.

Bilateral choanal atresia is an emergency requir­ing immediate airway intervention. Inserting an oral airway is the best initial airway management in such cases. McGovern nipple is also a viable option. It is an intraoral nipple with a large open­ing made by cutting its end off and is secured in the mouth with ties around the infant’s head. If, in spite of this, the patient fails to maintain an adequate airway, endotracheal intubation is the other alternative. If the patient is having associ­ated comorbidities such as cardiopulmonary instability and multilevel airway obstruction tra­cheostomy may be needed [95].

Bilateral choanal atresia with purely bony atretic plate, age less than 10 days, nasopharyngeal reux, gastroesophageal reux and associated malformations are the risk factors for restenosis. Delayed surgery in bilateral atresia has a higher failure rate [103]. Unilateral atresia can be delayed after at least 6months of age and repair should be done by transnasal endoscopic approach [104]. The use of microbebrider, micro­drills reduces the surrounding trauma which reduces the risk of scarring. After a successful repair, a close and long follow-up at 2, 4 and 8 weeks with endoscope-assisted cleaning of the nasal cavity and surgical site should help in reducing restenosis. Use of Mitomycin C (inhib­its broblasts and angiogenesis), stents, mucosal ap preservation and serial balloon dilatations are still a matter of debate as systematic review has depicted similar results even without using them [105]. Customized endotracheal tube, naso­pharyngeal airway and Teon sheet have been used as stents for 48h to 12months in different series (Fig.7.48). Studies favour either no use of stents or use limited to bilateral choanal atresia. Today, the use of stents remains the surgeon’s choice in absence of proven advantage. Stenting

is less likely required for older patients. Surgery with navigation is preferred in syndromic association.

Cerebrospinal uid (CSF) leak occurs as a result of an abnormal communication between the sub­arachnoid space and a pneumatized area in the skull base that includes the sinonasal tract. This communication or stula must involve a breach of the arachnoid and dura matter, the bone of skull base and the underlying mucosa. Spinal uid leak from the intracranial space to the nasal respiratory tract is potentially very serious because of the risk of an ascending infection which could produce fulminant meningitis. CSF rhinorrhea commonly occurs following head trauma (fronto-basal skull fractures), as a result of surgery, or destruction of lesions. In cases where a conrmatory test is needed, the beta-2