paranasal sinuses have an intricate relationship with the ocular adnexa and orbit.13 the bony lacrimal fossa ( lf ) and lacrimal drainage system are closely related anatomically to the ethmoid sinuses.14 the ethmoid air cells develop after birth , become radiologically recognizable by age 2 years , and attain adult dimensions by 12 years of age.1,2 there is a well - known anatomical relationship between the fundus of the lacrimal sac and agger nasi , which is a part of the anterior ethmoid air cells ( aeacs).5,6 numerous papers have reported contiguous pathologies involving the lacrimal drainage system and the sinuses.711 however , very few have specifically studied the relationship of sinuses , specifically eacs , with the lf,12,13 and its subsequent influence on dacryocystorhinostomy ( dcr).1419 the anatomical relationship between the bony lf and the aeacs is categorized into three types.15 in category i , sinuses are behind the posterior lacrimal crest , in category ii , the aeacs are in front of the posterior lacrimal crest but behind the suture at the anterior edge of the lacrimal bone , and in category iii , the sinuses extend into the frontal process of the maxilla , anterior to the lacrimal bone suture . the authors of the present study report their experience of performing powered endoscopic dcr ( pendcr ) in cases where the entire lacrimal sac is within the boundaries of the ethmoid sinus . lv prasad eye institute institutional review board approval was obtained . however , patient consent was not deemed necessary by the institutional review board due to the retrospective nature of the study . retrospective analysis was performed on all patients who had undergone a pendcr in 2014 and 2015 and were documented to have the entire lacrimal sac within the boundaries of the ethmoid sinus . all surgeries were performed by a single surgeon ( mja ) as per a standard protocol published earlier,6,20 with modifications specific to the sac in sinus . data collected include demographics , clinical presentations , associated lacrimal and nasal anomalies , intraoperative findings , intraoperative guidance , complications , postoperative ostium behavior , and anatomical and functional success . complete sac in sinus  when it lies in its entirety within the boundaries of the sinuses , mostly the ethmoid ( figure 1a  c ) . the definitive diagnosis of such a sac in the sinus is established intraoperatively ; however , preoperative examination may provide a few clues that may be suggestive of at - risk patients . the authors observed that their cohort had patients with steep nasal bridges , deeply set eyes , and posterior insertion of medial canthal tendons . intraoperatively , a flatter frontal process of the maxilla along with middle turbinate malpositions may provide useful clues ( figure 1a and b ) . intraoperative guidance in the form of image guidance or transcanalicular light source was helpful in delineating the entire anteroposterior and superoinferior extent of the lacrimal sac within the ethmoid sinus ( figure 1d  f ) . occasionally , the lacrimal sac may be found superoposteriorly in close relation to the frontal recess and frontal sinus - outflow pathways ( figure 2a and b ) . this has been observed more commonly following trauma.17 the surgical principles of pendcr remain the same in these cases;6,20 however , uncinectomy is needed to gain access to the ethmoids , and care should be taken to remove the eacs and mucosa in front of the lacrimal sac . the mucosa of the ethmoid sinus is thin , friable , and whiter compared to the nasal mucosa . the ethmoidal bones are thin and egg shell - like and lined by the ethmoid mucosa . bony ethmoid wall lateral to the sac should be carefully preserved to avoid violations of lamina papyracea and orbital tissues . since most of the surgical intervention happens within the ethmoid sinus , it is important to be aware of ethmoidal vessels and avoid injury to them . if the sac malposition is superoposterior , it is of utmost importance to preserve the frontal recess anatomy and avoid injuries to frontal sinus - drainage pathways . occasionally , a partial middle turbinoplasty may be desired to gain wider access to deeper - situated lacrimal sacs . all patients in the current cohort underwent intubation and mitomycin c ( 0.02% for 3 minutes ) as described earlier.20,21 stents were retained for 4 weeks . postoperatively , these patients required more frequent saline nasal douching ( thrice a day ) and weekly crust cleaning ( for 4 weeks ) compared to regular endcr . it is important for the surgeon to be aware of the pseudocicatrix phenomenon22 observed in sac - in - sinus syndrome on postoperative endoscopic examination . the term  ostium pseudocicatrix  is used when the deeply located ostium is partly covered anteriorly by a minimally mobile scar tissue like a curtain , behind and lateral to which is the usual location of the ostium ( figure 2c and d ) . postoperative endoscopic ostium evaluation can be difficult , because of its deeper location and the pseudocicatrix phenomenon , and hence needs careful endoscopic maneuvering with a 2.7 mm telescope to minimize discomfort to the patient . complete sac in sinus  when it lies in its entirety within the boundaries of the sinuses , mostly the ethmoid ( figure 1a  c ) . the definitive diagnosis of such a sac in the sinus is established intraoperatively ; however , preoperative examination may provide a few clues that may be suggestive of at - risk patients . the authors observed that their cohort had patients with steep nasal bridges , deeply set eyes , and posterior insertion of medial canthal tendons . intraoperatively , a flatter frontal process of the maxilla along with middle turbinate malpositions may provide useful clues ( figure 1a and b ) . intraoperative guidance in the form of image guidance or transcanalicular light source was helpful in delineating the entire anteroposterior and superoinferior extent of the lacrimal sac within the ethmoid sinus ( figure 1d  f ) . occasionally , the lacrimal sac may be found superoposteriorly in close relation to the frontal recess and frontal sinus - outflow pathways ( figure 2a and b ) . the surgical principles of pendcr remain the same in these cases;6,20 however , uncinectomy is needed to gain access to the ethmoids , and care should be taken to remove the eacs and mucosa in front of the lacrimal sac . the mucosa of the ethmoid sinus is thin , friable , and whiter compared to the nasal mucosa . the ethmoidal bones are thin and egg shell - like and lined by the ethmoid mucosa . bony ethmoid wall lateral to the sac should be carefully preserved to avoid violations of lamina papyracea and orbital tissues . since most of the surgical intervention happens within the ethmoid sinus , it is important to be aware of ethmoidal vessels and avoid injury to them . if the sac malposition is superoposterior , it is of utmost importance to preserve the frontal recess anatomy and avoid injuries to frontal sinus - drainage pathways . occasionally , a partial middle turbinoplasty may be desired to gain wider access to deeper - situated lacrimal sacs . all patients in the current cohort underwent intubation and mitomycin c ( 0.02% for 3 minutes ) as described earlier.20,21 stents were retained for 4 weeks . postoperatively , these patients required more frequent saline nasal douching ( thrice a day ) and weekly crust cleaning ( for 4 weeks ) compared to regular endcr . it is important for the surgeon to be aware of the pseudocicatrix phenomenon22 observed in sac - in - sinus syndrome on postoperative endoscopic examination . the term  ostium pseudocicatrix  is used when the deeply located ostium is partly covered anteriorly by a minimally mobile scar tissue like a curtain , behind and lateral to which is the usual location of the ostium ( figure 2c and d ) . postoperative endoscopic ostium evaluation can be difficult , because of its deeper location and the pseudocicatrix phenomenon , and hence needs careful endoscopic maneuvering with a 2.7 mm telescope to minimize discomfort to the patient . a total of 17 eyes of 15 patients underwent pendcr using standard protocols , but with additional intraoperative guidance where required and careful maneuvering in the ethmoid sinus . unilateral cases accounted for 86.6% ( 13 of 15 ) . of the unilateral cases , there was no gross sex predisposition , with females accounting for 53.3% ( eight of 15 ) of the patients . a history of acute dacryocystitis was observed in 26.6% ( four of 15 ) patients . of the 15 patients , 12 were diagnosed with primary acquired nasolacrimal duct obstruction , two had failed endcr , and one had a traumatic secondarily acquired nasolacrimal duct obstruction . epiphora was a common complaint , with 80% of patients showing regurgitation on pressure over the lacrimal sac area . associated lacrimal anomalies were observed in 13.3% ( two of 15 ) of patients , and included one patient each with single punctal agenesis and lower punctal single canalicular wall aplasia . nasal anomalies were observed in 40% ( six of 15 ) of patients , and included middle turbinate malpositions and flat frontal process of maxilla in three patients each . adjunctive procedures performed were septoplasty in 13.3% ( two of 15 ) and partial middle turbinoplasty in 6.6% ( one of 15 ) of patients . intraoperative complications included moderate bleeding in one case and irregular sac flaps in another case . postoperative endoscopic evaluation showed most patients universally demonstrated very deeply situated ostium , with pseudocicatrix being observed in 53.3% ( eight of 15 ) . at a mean follow - up of 6.6 months , anatomical and functional success was observed in 93.3% ( 14 of 15 ) . one patient showed failure secondary to complete cicatricial closure of the ostium and was a revision case . the current study examined the outcomes of pendcr in the setting of the entire lacrimal sac within the ethmoid sinus . left - side involvement and positive regurgitation on lacrimal sac compression were very common . preoperative planning , intraoperative navigation where needed , and a good knowledge of endoscopic sinus anatomy helps in avoiding complications and performing the surgery safely . ethmoid sinuses are usually divided into three groups of cells ; anterior , middle , and posterior . although the anatomical relationship between the lf and ethmoid is definitive , it may show variations and may even be asymmetrical.14,14,15 jiang et al12 studied aeacs in 16 adult cadavers , and found that categories ii and iii were common , accounting for 50% and 31.2% , respectively . blaylock et al15 studied computed tomography scans of 190 orbits with normal ethmoid anatomy , and found that in 93% of the orbits , the aeacs extended anteriorly to the posterior lacrimal crest , with 40% entering the frontal process of the maxilla . they recommended initial entry into the ethmoid sinus during external dcr to avoid injury to the nasal mucosa . talks and hopkisson14 studied the frequency of ethmoid - cell entry while performing an external dcr , and found that it commonly happened ( 46% , 23 of 50 ) via the suture in the medial wall of the lf . contrary to what blaylock et al15 presented , talks and hopkisson14 believed that initial entry into the ethmoid could be a trap , and if not recognized may lead to a blind cul - de - sac in the form of ethmoid sinus and lead to failure of surgery . they also suggested possibilities of suturing lacrimal sac flaps to the ethmoid mucosa without any entry into the nasal cavity . similar apprehensions were put forward by welham and wulc,19 who noticed that in the presence of adjacent eacs , the subsequent scarring of these cells may lead to an increase in complications and failures of dcr . the authors of the current series believe that these apprehensions may not be applicable to an endcr , since the nasal mucosa is fashioned first and it is very easy to identify the ethmoid structures and its mucosa . the current study had good successful outcomes with pendcr , even though it included only cases where the entire lacrimal sac was within the sinus and not regular cases where the lf was adjacent to aeacs . the advances in endoscopic surgeries coupled with intraoperative guidance have significantly improved the surgeon s ability to deal with lacrimal sacs within the ethmoid sinuses . further studies with large sample size with preoperative imaging and intraoperative stereotactic guidance may be helpful in formulating better diagnostic and management guidelines .
backgroundthe aim of this study was to report the outcomes of powered endoscopic dacryocystorhinostomy ( pendcr ) in patients with lacrimal sac within the sinus.materials and methodsretrospective analysis was performed on all patients who underwent pendcr and were intraoperatively documented to have complete lacrimal sac in sinus . 
 data collected included demographics , clinical presentations , associated lacrimal and nasal anomalies , intraoperative findings , intraoperative guidance , complications , postoperative ostium behavior , and anatomical and functional success . 
 a minimum follow - up of 6 months postsurgery was considered for final analysis.resultsa total of 17 eyes of 15 patients underwent pendcr using standard protocols , but with additional intraoperative guidance where required and careful maneuvering in the ethmoid sinus . 
 the mean age of the patients was 37.2 ( range 1760 ) years . 
 of the unilateral cases , 69% ( nine of 13 ) showed left - side predisposition ; 80% of patients showed regurgitation on pressure over the lacrimal sac area . associated lacrimal and nasal anomalies 
 were observed in 13.3% ( two of 15 ) and 40% 
 ( six of 15 ) , respectively . at a mean follow - up of 6.6 months , anatomical and functional success 
 were observed in 93.3% ( 14 of 15 ) . 
 one patient showed failure secondary to cicatricial closure of the ostium.conclusionan entire sac within an ethmoid sinus poses a surgical challenge . 
 good sinus - surgery training , thorough knowledge of endoscopic anatomy , careful maneuvering , and use of intraoperative navigation guidance result in good outcomes with pendcr .