external dacryocystorhinostomy ( dcr ) was initially described by toti in 1904 and further modified by dupuy - dutemps and bourguet in 1921 . since its introduction , external dcr has been successfully performed with some modifications all over the world and remains the gold standard for lacrimal surgery . external dcr can be completed under either local or general anesthesia ( la or ga ) [ 25 ] . current insight into how much pain is experienced while under la is limited to results from a single study by maheshwari . to gain additional information on pain during dcr , the visual analog scale ( vas ) was used to quantify pain experienced during the surgical procedure . these scores were then compared to pain scores following an intramuscular ( i m ) gluteal injection of prophylactic antibiotic administered at the beginning of surgery . each patient experienced both procedures within a short time interval and was able to compare them . the results from this study can translate into patient education , thereby equating the pain associated with dcr under la to the pain from a universal experience ( i m gluteal injection ) . the prospective study included 50 patients who underwent external dcr on 1 side with ga , followed 2 days later by external dcr on the opposite side with la , between 2006 and 2008 . the same surgeon , anesthesiologist , and scrub nurse were involved in every case . furthermore , all surgeries were performed in the same operating room ( or ) with the same set of instruments , using the same surgical technique . the inclusion criterion for our study was bilateral dacryocystitis , and we selected 73 patients . twenty - three patients were excluded from the study for 1 of the following reasons : 1 ) an unwillingness to participate in the research in 14 cases ; 2 ) a history of midface trauma in 1 case ; 3 ) poor candidacy for ga in 6 cases ( american society of anesthesiology ( asa ) status iv ) ; 4 ) lacrimal sac asymmetry ( 1 was dilated ) ; and 5 ) concurrent treatment with warfarin in 1 case . careful preoperative explanation of the proposed anesthesia , surgical procedure , and expectations during surgery , including both tactile and auditory sensations was provided to each patient . oxymetazoline 0.1% solution was sprayed into the nose of every patient 1 hour before surgery . at the same time , an i m gluteal injection of prophylactic antibiotic ( cefuroxime 1.5 g ) was administered . a 22 g cannula was introduced into the cubital vein to establish venous access , if needed . all patients were given intranasal oxygen at 4 l / min and subjected to constant monitoring of the electrocardiogram , blood pressure , and pulse oximetry throughout the procedure . bp ( blood pressure ) , hr ( heart beat rate ) and oxygen saturation ( os ) in the beginning of the procedure were noted . minimal and maximal values and time ( when it was reached during surgery ) of bp , hr and os were noted . a fiberoptic coaxial headlight facilitated illumination for the dcr . to monitor pain levels during dcr , we subdivided the surgical technique into stages easily understood by the patients : in the or , 3 to 5 cotton tipped applicators ( depending on nostril diameter ) , moisturized with oxymetazoline 0.1% , were introduced into the nostrils for 1015 minutes . three minutes after installation of the applicators , 5 drops of tetracaine - hydrochloride 2% were instilled to anesthetize the nasal mucosa . topical anesthetic drops ( tetracaine hydrochloride 2% ) were also instilled in both conjunctival sacs . each patient received 3 1.5ml injections of 1 : 1 ( v / v ) mixture of lidocaine 2% epinephrine 1 : 200,000 and bupivacaine 0.75% via a 16 mm 25 g needle : 1 ) above the infraorbital foramen and immediately above the lower orbital floor periosteum , at the maximum depth needle length , 2 ) into the medial extraconal orbit and above the medial ligament , at the maximum depth permitted by the needle length , and 3 ) subcutaneously into the lacrimal sac region . after the 3 injections , 0.3 ml of mixture was used to moisturize the cotton tipped applicators previously introduced into the nose . a medial canthal incision was performed with blunt dissection of the orbicularis muscle carried down to the level of the medial canthal tendon . the medial canthal tendon and periosteum were incised and reflected with a periosteal elevator to expose the lacrimal fossa . the thin lacrimal bone was infractured , and a 3 mm tip kerrison punch was used to create an osteotomy . silicone stents were passed along the canalicular system and into the osteotomy site , exiting via the naris . the anterior nasal mucosal flap was anastomosed to the anterior aspect of the lacrimal sac , and the incision was closed in a layered fashion using a 6 - 0 vicryl suture . the patients were asked to rest for 12 hours without applying ice packs following surgery and to avoid nose - blowing for 1 week . all patients were asked 30 minutes after surgery to rate the intensity of pain experienced during the i m gluteal injection of prophylactic antibiotic and at each stage of the surgery using the vas scale ( 0= the least amount of pain , and 10= the greatest amount of pain ) . to assimilate the pain data from all surgical stages , sample size for the study was calculated and 18 patients were sufficient to get reliable results . the wilcoxon signed - rank test was used to assess the significance of the differences between vas pain levels during different stages of surgery . in the or , 3 to 5 cotton tipped applicators ( depending on nostril diameter ) , moisturized with oxymetazoline 0.1% , were introduced into the nostrils for 1015 minutes . three minutes after installation of the applicators , 5 drops of tetracaine - hydrochloride 2% were instilled to anesthetize the nasal mucosa . topical anesthetic drops ( tetracaine hydrochloride 2% ) were also instilled in both conjunctival sacs . each patient received 3 1.5ml injections of 1 : 1 ( v / v ) mixture of lidocaine 2% epinephrine 1 : 200,000 and bupivacaine 0.75% via a 16 mm 25 g needle : 1 ) above the infraorbital foramen and immediately above the lower orbital floor periosteum , at the maximum depth needle length , 2 ) into the medial extraconal orbit and above the medial ligament , at the maximum depth permitted by the needle length , and 3 ) subcutaneously into the lacrimal sac region . after the 3 injections , 0.3 ml of mixture was used to moisturize the cotton tipped applicators previously introduced into the nose . a medial canthal incision was performed with blunt dissection of the orbicularis muscle carried down to the level of the medial canthal tendon . the medial canthal tendon and periosteum the thin lacrimal bone was infractured , and a 3 mm tip kerrison punch was used to create an osteotomy . silicone stents were passed along the canalicular system and into the osteotomy site , exiting via the naris . the anterior nasal mucosal flap was anastomosed to the anterior aspect of the lacrimal sac , and the incision was closed in a layered fashion using a 6 - 0 vicryl suture . the patients were asked to rest for 12 hours without applying ice packs following surgery and to avoid nose - blowing for 1 week . all patients were asked 30 minutes after surgery to rate the intensity of pain experienced during the i m gluteal injection of prophylactic antibiotic and at each stage of the surgery using the vas scale ( 0= the least amount of pain , and 10= the greatest amount of pain ) . to assimilate the pain data from all surgical stages , sample size for the study was calculated and 18 patients were sufficient to get reliable results . the wilcoxon signed - rank test was used to assess the significance of the differences between vas pain levels during different stages of surgery . a total of 50 patients ranging in age from 3183 years ( 63.649.64 ) underwent external dcr . the group included 40 females between 31 and 74 ( 63.809.32 ) years of age and 10 males between 46 and 83 years of age ( 63.0011.35 ) . no statistically significant differences in pain levels , blood pressure and variations of bp during surgery , heart beat rate and hr variations and oxygen saturation and variations of os during surgery existed between groups with respect to gender ( for all p>0.005 ) ( table 1 ) . patients were divided in 3 groups based on their level of education ( primary school , secondary school and college ) . there were no statistically significant differences between groups in pain levels during any stage of surgery and in overall level of pain . pain recorded at all stages of dcr was minor ( figure 1 ) . among these minor pain values , the lowest vas pain level ( median , 1 ) was present at multiple times : 1 ) at the introduction of the cotton tipped applicators ; 2 ) at the beginning of the surgical procedure ( skin incision and dissection of the lacrimal sac ) ; 3 ) during nasal manipulation after bone cracking ( incision and suture of nasal mucosa ) ; 4 ) during intubation ; 5 ) during wound closure ; and 6 ) during nasal packing at the end of the procedure . medium levels of pain ( median , 2 ) were noted during the i m gluteal injection of prophylactic antibiotic , the la injection , and the ostium opening , and for overall pain ( table 2 ) . no statistically significant differences in pain levels between i m gluteal injection , la injection , and ostium opening were observed ( p>0.05 ) . la injection did not result in hemorrhage , and none of the patients experienced uncontrolled intranasal bleeding during the procedure . no cases of postoperative epistaxis requiring nasal packing occurred , and no one experienced dislodged tubing . success was confirmed with patent lacrimal passages on irrigation in 49 of 50 patients after 6 months . one patient ( 2% ) complained of recurrence of profuse watering after the procedure and required further surgery . forty - seven of the 50 participants ( 94% ) stated that they preferred the next procedure to be performed in the same way . the remaining 3 patients ( 6% ) preferred ga ; they did not complain of pain , and the vas pain levels were not statistically different from the rest of the group ( p>0.05 ) . in 2 cases , ga was selected because participants did not want to be consciously involved in the procedure ( they preferred to be asleep and remain unaware ) . in the third case , we have not received another such a complaint in the 300 + procedures that we have performed using la . performing dcr under la has been an accepted procedure for years , especially for elderly patients [ 68 ] . the specific risks of ga are , of course , avoided with la . a much lower incidence of postoperative nausea and vomiting ponv after dcr was observed with la compared with ga in a previous study . anesthetics used for ga also act as vasodilators and enhance bleeding . based on these findings , the use of la is often recommended to the patient . however , when patients inquire about pain experienced during surgery with la , little scientific data exists to support claims that patients do not complain and that the procedure is not painful . measuring pain levels during different stages of our surgical technique generated more precise data on when pain occurred . by comparing bone cracking to an i m injection , we tried to associate 2 painful events . bone cracking showed the highest levels of pain experienced during surgery according to the vas scores ( range 0 to 4 , median 2 ) . the median value of pain experienced during ostium opening was the same as the median pain values during the administration of la and i m injection ( difference was not statistically significant ) . all manipulations involving the nasal structures ( introducing cotton tipped applicators , forming nasal mucosa flaps , and intubation ) induce similar levels of pain ( median 1 ) , and the differences among those procedures was not statistically significant . we did not perform syringing in the beginning of surgery in order to measure exact level of pain during syringing . the syringing procedure is similar to intubation , so we may presume that level of pain during manipulations involving nasal structures is similar to syringing . none of the 50 patients included in study needed any tooth removal so we could not make this comparison . maheshwari tried to measure the level of pain during dcr using a verbal rating scale ( vrs ) and concluded that la was acceptable for patients . we compared our vas - based pain scores with maheshwari s vrs scores ( table 3 ) and achieved similar results . minor differences existed in the procedure itself , including opening the lacrimal sac at the beginning after elevating periosteum in our cases . the formation of the sac flap was recorded as being as painful as the creation of bone ostium in our series , and as painful as the creation of the nasal mucosa flap in maheshwari s study . patients may not have distinguished opening the lacrimal sac from creating the nasal mucosa flap because the procedures occurred right after each other in maheshwari s study . the fact that recorded pain levels for both procedures is the same strongly suggests that patients put the 2 stages of maheshwari s study together . few other studies have addressed pain during dcr , and all concluded that patients did not complain of pain [ 1012 ] . the following sentences are direct quotes from these papers :  all patients found the technique acceptable , and none stated afterwards that they would have preferred to have had a general anesthetic  .  in our technique of la , properly localized and sufficient nerve block effectively eliminates patient pain and provides hemostasis which ensures surgeon s comfort during dcr  . patients in both groups reported that they were comfortable during and immediately after surgery  . hurwitz jj et al . reported procedures with la but did not comment on the effectiveness of la or the level of patient acceptance . pain was likely tolerable and not severe enough for the patient to complain of discomfort . smith et al measured pain during injection of la in the region of the lacrimal fossa using vas . the percentage of patients experiencing levels of pain lower than 2.6 were almost identical to our results ( table 4 ) . one major difference was noted between the results of our study and smith et al . if any of the patients respond during injection of la that the pain was the worst imaginable ( pain level 7 , 610 ) , anesthesia should be converted at that time to ga . clearly , the pain threshold varies from patient to patient and may be related to cultural differences as well . all of our patients were satisfied with the procedure , similar to previously published studies [ 6,7,1013 ] . distinguishing pain directly related to the operation site from discomfort associated with sensory clues ( ie , unpleasant tastes , sights , or sounds ) that patients record as pain is a limitation to this study . dcr can be associated with unpleasant sounds ( bone cracking ) and unpleasant tastes ( blood in the throat ) . a comparison of dcr with tooth extraction ( the only commonly performed procedure with la that involves the sound of bone cracking ) may provide useful information about this perceived pain based on the experience of these 50 patients , we can claim that pain experienced during external dcr under la , if it is present , is low on the vas scale . furthermore , the most painful stage of external dcr under la ( bone cracking ) was no more painful than the i m injection experienced at the beginning of the procedure . other stages ( opening nasal mucosa , intubation , and nose packing ) induced even lower levels of pain on the vas and can be compared to syringing . pain experienced under la during external dcr can best be described to patients as similar to the pain experienced from an i m gluteal injection . patients should also be informed before and during the procedure that there will be a sound of bone cracking , not unlike when a tooth is extracted , and that they may experience pain equal to or less than that associated with an i m injection .