List of abbreviations
CT — computerized tomography
CTC — computerized tomographic cisternography
Currently, endoscopic endonasal accesses according to Draf and its modification according to Lothrop are widely used for the treatment of various frontal sinus pathologies. These accesses are minimally traumatic, allow performing the operation effectively under visual control and provide full drainage of the sinus in the postoperative period [1, 2]. Despite good results and safety, in some cases, the use of these accesses has limitations and therefore combined and extranasal accesses to the frontal sinus are used [3].
Closure of a CSF fistula in the frontal sinus has historically been performed using transcranial access through a bicoronal incision with dissection of an aponeurotic flap [4]. The development of modern equipment and improvement of surgical techniques led to the wide application of the endoscopic method for the treatment of defects in the frontal sinus area. For example, Virginia Jones et al. reported in their study that the effectiveness of frontal sinus defect plasty using endoscopic access was 91.9 % [5]. Combined intra-extranasal access, which combines the advantages of both endoscopic and transcranial approaches, is also widespread. Qintai et al. recommend performing it for lateral defects because this approach is minimally traumatic, allows working under conditions of a good visualization and in the line-of-sight area, which cannot be achieved by endoscopic access for this localization [6].
According to a number of authors, the anatomy of the cells of the labyrinth, nasofrontal pocket, and frontal sinus is of paramount importance to decide whether it is possible to perform endoscopic plasty of the defect of this area [7–9]. However, there is no clear algorithm in the literature for selecting surgical access for liquorrhea nasalis based on anatomical features.
Chaaban MR et al. [10] report that endoscopic access for frontal sinus defects has several limitations: lateral location of the fistula, large defect size, convex posterior sinus wall, which may limit the passage and manoeuvring of instruments, narrow sinus (with anteroposterior distance less than 1 cm). According to their study, once a Draf III sinusotomy is performed, the defects in the frontal sinus laterally can be visualized, but endoscopic instruments can reach them only 64 % of the time. Shi et al. [11] do not recommend endoscopic access if the anteroposterior size of the sinus entrance is less than 6 mm (i.e., narrow junction), presence of poorly pneumatized Agger nasi cells. The authors suggest a combined approach (endoscopic and external access) for such anatomy.