Diffuse nasal polyposis: Postoperative long-term results after endoscopic sinus surgery and frontal irrigation

Diffuse nasal polyposis: Postoperative long-term results after endoscopic sinus surgery and frontal irrigation JEAN-MICHELKLOSSEK,MD, LOUISPELOQUIN,MD, FRCSC,WILLIAMH. FRIEDMAN,MD, FACS,JEAN-CLAUDEFERRIER,MD, and JEAN-PIERRE FONTANEL, MD, Poitiers, France, Montreal, Canada, and St. Louis, Missouri

Diffuse nasal polyposis remains a challenge despite recent improvements in endonasal surgery. The purpose of this study is to evaluate the results after a radical complete sphenoethmoidectomy with peroperative and postoperative frontal irrigation in cases of diffuse nasal polyposis. In this prospective study, we include 50 consecutive patients with diffuse nasal polyposis suffering from nasal obstruction, anosmia, and other symptoms of chronic sinusitis. All patients were refractory to medical therapy. In each patient an endoscopic complete sphenoethmoidectomy including total excision of all diseased ethmoid mucosa was performed. Preoperative and postoperative frontal irrigation was performed systematically. The patients were followed closely with serial endoscopic examination, and CT scanning was performed between 2 and 3 years after surgery. There were no complications. Thirty-nine of the 50 patients regained satisfactory olfaction. Partial nasal obstruction persisted in four of the 50 patients. Endoscopically, polyp recurrence was noted in 3% of posterior ethmoids, 23% of anterior ethmoids, and 50% of frontal recesses. We conclude that in cases of refractory and extensive nasal polyposis, a total sphenoethmoidectomy with perioperative frontal irrigation followed by long-term postoperative topical steroid therapy provides excellent improvement or cure with safety and reliability. (©tolaryngoi Head Neck

Surg 1997;117:355-61.)

Endoscopic sinus surgery is used increasingly in the treatment of diffuse nasal polyposis. Most publications on ethmoidectomy have focused on technique and complications. 1-3 Two different philosophies have been proposed to manage diffuse inflammatory disease: some authors state that a functional approach removing only pathologic tissue is superior to a more radical technique in which the ethmoidal mucosa is removed entirely. 4-7 Few long-term studies have been published and most of them contain miscellaneous diseases that are difficult to compare. 8-12 The aim of this prospective study is to

From the Departments of Otolaryngology-Head and Neck Surgery (Drs. Klossek and Fontanel), CHU de la Miletrie, Hopital Jean Bernard, Universit6 de Poitiers, the Universit6 de; Montr6al (Dr. Peloquin), and Park Central Institute and of Otolmyngology (Dr. Friedman), Deaconess Hospital, St. Louis. Presented at the Annual Meeting of the American Rhinological Society, Palm Springs, Ca., April 29-May 2, 1995. Reprint requests: Jean-Michel Klossek, MD, Ddpartement d'Otorhinolaryngologie et de chirurgie cervico-faciale, Centre Hospitalier Universitaire de la Mildtrie, Hopital Jean Bernard, Poitiers 86021 Cedex, France. Copyright © 1997 by the American Academy of atolaryngologyHead and Neck Surgery Foundation, Inc. 0194-5998/97/$5.00 + 0 23/1/79028

observe the effects of radical surgical extirpation in cases of diffuse nasal polyposis. To report a uniform series, we attempted to study a small but homogeneous population suffering from diffuse polyposis categorized as stage IV nasal polyposis according to the classification of Friedman et al. 13 The secondary aim of this study was to reevaluate the correlation between CT scans, postoperative symptoms, and the clinical presence or absence of postoperative disease when evaluated by nasal endoscopy. In evaluating the efficacy of radical exenteration of ethmoidal mucosa, we hope to improve or at least shed light on the dismal prognosis that has long been associated with stage IV hyperplastic rhinosinusitis.

METHODS AND MATERIAL Twenty-seven men and 23 women with a mean age of 46.7 years (range 18 to 66 years) are included in this study. Each patient was categorized as having stage IV disease according to the classification of Friedman et al.13 (i.e., each patient had extensive nasal polyposis with hyperplastic disease involving all sinuses and no symptomatic response to medical therapy). Before deciding on surgery, at least 1 year of topical steroids

355

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Fig. 1. Preoperative CT scan of typical patient suffering from diffuse nasal polyposis.

Table 1. Preoperative symptoms and bronchopuimonary function Symptom Bilateral nasal obstruction Anosmia at least 6 mo/yr Posterior rhinorrhea Facial pain Asthma (n = 47) Asthma and allergy ASA triad Asthma alone

No. of patients 50 50 48 2 21 14 12

(%) 100 100 96 4 44,6 29.7 25.5

ASA, Aspirin-sensitive asthma.

Table 2. CT scan results on 50 patients with a diffuse endonasal polyposis according to each paranasal sinus Opacification (%)

Localization Maxillary sinus Anterior ethmoid Posterior ethmoid Sphenoid sinus Frontal sinus (n = 97)*

Complete

Partial

Normal (no opacification)

76 95 81 53 31.9

21 5

3 0

19 39 62.1

0 8 4

*Three patients had a single frontal sinus.

(400 to 800 gg beclomethasone daily) and a minimum of three courses per year of oral steroids (1 mg/kg prednisone daily for 8 days) were provided as clinical trials. All patients in this study were considered to have failed this medical treatment. In each of the 50 patients, longterm nasal polyposis included subjective anosmia and bilateral nasal obstruction as the most prominent symptoms for at least 6 months before surgery. Preoperative symptoms are summarized in Table 1. Forty-seven of 50 patients had abnormal bronchopulmonary function before surgery. The incidence of allergy and aspirin intolerance is reported in Table 1. Preoperative nasal endoscopy revealed diffuse nasal polyposis extending to the inferior portion of the inferior turbinate in each patient. Preoperative CT scans were performed in each case 2 or 3 weeks after an 8-day treatment with oral steroids (1 mg/kg prednisone daily). Results of CT scans with both axial and coronal evaluation appear in Table 2. The same surgeon (J.M.K.) performed all surgeries, which included bilateral total sphenoethmoidectomy with wide middle antrostomies and frontal irriga-

tion. 14 Total excision of all ethmoidal cells was performed in a forward to backward direction. All mucosal layers and bony septa were removed except in the region of the frontal ostia, where meticulous attention was given to leaving an intact mucosal collar. After forehead trephination of the frontal sinuses, frontal irrigation facilitated identification of the frontonasal duct and management of the surgery in the frontal recess. 15 The middle turbinate was removed routinely at the end of surgery. Its superior attachment to the ethmoidal roof was left in place. Figs. 1 and 2 show the typical results of preoperative and postoperative CT scans. At the end of the procedure, a small nonobstructive nasal packing was placed over the dissected ethmoids with neomycin, polymycin B, and triamcinolone (Corticotulle; Laboratoires LTM Sarbach, Suresnes Cedex, France). Nasal packing and frontal needles were removed on the third postoperative day. Postoperative care included frontal irrigations three

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Fig. 2. Postoperative aspect on CT scan of same patient 3 years after total sphenoethmoidectomy.

Fig. 3. Metallic frontal needle left in place at end of procedure.

times daily with 250 ml saline solution through the frontal needles (Fig. 3). Nasal washings and topical corticosteroid solutions were introduced Jn the sinus (4 mg prednisolone) twice daily after irrigation of the frontal sinus. After removal of the packing nasal irrigations were done three times daily for a few weeks with saline solution. Long-term topical beclomethasone therapy was continued twice daily. Postoperative evaluation took place at 15 days, 3 months, 12 months, and at least once a year after surgery for a totat of 3 years. Postoperative clinical symptoms were recorded at each visit by a subjective follow-up questionnaire. Patients evaluated their overall improvement, as well as improvement in specific symptoms. Subjective

Fig. 4. Postoperative cavitary anatomic areas: 1, frontal recess; 2, anterior ethmoid; and 3, posterior ethmoid.

improvement scales were classified as no improvement, mild improvement, and marked improvement (Table 3). At each postoperative examination of the cavity, mucosal changes were noted. The cavity was divided into three vaults (Fig. 4) based on the endoscopic examination (according to the anatomic terminology proposed by Stammberger et al.16). The postoperative frontal recess corresponds to the area located in the most anterior and superior parts of the cavity that leads and communicates with the frontal sinus. The anterior ethmoid vault is located between the frontal recess and

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Table 3. P o s t o p e r a t i v e s y m p t o m s a t 3 m o n t h s , 1 year, a n d 3 years Follow-up 3 Mo Symptoms

Nasal obstruction (n = 50) n % Anosmia (n = 50) n % Posterior rhinorrhea (n = 48) n %

3 Yr

1 Yr No

Mild

No

Mild

Marked

0 0

0 0

50 100

1 2

3 6

8 16

7 14

35 70

8 16

14 30

21 43

13 27

17 35

Marked

No

Mild

Marked

46 92

1 2

3 6

46 92

12 24

30 60

11 22

10 20

29 58

25 51

6 14

15 31

19 39

14 30

No, No improvement; Mild, mitd improvement; Marked, marked improvement.

Table 4. E n d o s c o p i c m u c o s a l a s p e c t 3 years a f t e r surgery w i t h i n t h e p o s t o p e r a t i v e ethmoidal cavity Polyp recurrence (%)

Anterior ethmoid (100%) Posterior ethmoid (100%) Frontal recess (97%)

Edema (%)

Normal mucosa (%)

23

36

41

3

9

88

49,4

19,5

31.1

the superior attachment of the basal lamella of the middle turbinate. The posterior ethmoid corresponds to the area behind the superior attachment of the basal lamella of the middle turbinate. In each area any evidence of mucosal hypertrophy, polyposis, or discharge was recorded. Polyps were defined as any localized mucosal swelling forming a detectable mound or roll at endoscopy. Medical therapy for asthma was monitored and all changes in therapy were recorded during the 3year follow-up. RESULTS A total o f I 0 0 sphenoethmoidectomies were per-

formed associated with 100 middle meatal antrostomies. No major complications were encountered. There were no episodes of postoperative epistaxis that required packing or transfusion. Discomfort was generally minor. There were no scars of frontal skin after removal of the needles. All patients were followed up closely for at least 3 years. Overall, 96% of the patients reported an improvement in symptoms at the time of the final follow-up examination. Three years after surgery, 46

(94%) of 50 patients were free of nasal obstruction, 39 (78%) retained a subjective sense of smell, and 14 (30%) were free of postnasal discharge (Table 3). There were no episodes of exacerbation of asthma in any patient during the 3-year follow-up. Sixteen of the 47 patients with asthma had a reduction in medical therapy for asthma. Ethmoidal vaults were closely examined endoscopically 3 years after surgery. Despite excellent subjective improvement, many patients had residual evidence of hyperplastic disease on endoscopic examination. There was a significant difference in the recurrence rates for the three different areas of the sphenoethmoidectomy cavity. Recurrence of polyps, as defined previously, occurred in 3% of posterior ethmolds, 23% of anterior ethmoids, and 50% of frontal recesses (Table 4). Table 5 shows that the endoscopic mucosal findings in the frontal recesses at the end of the study related to the preoperative evaluation of the frontal sinus on CT. There were no significant differences in recurrence of polyps in the frontal recess in patients with either complete or partial opacity of the frontal sinus on preoperative CT scanning. Nineteen (62%) of the 31 frontal recesses associated with preoperative partial opacification of the frontal sinus revealed polypoid recurrence on endoscopy. Twentynine (46.5%) of the 62 totally opacified frontal sinuses on preoperative CT also had polypoid recurrences. Nineteen additional patients (20%) had a diffuse regional edema. A total of 50% recurrences of nonobstructive polyps (48 sinuses) were found in the 97 frontal recesses noted. No stenosis of the frontal recess or frontal sinusitis was found in this postoperative period. The middle meatal antrostomies had an overall patency rate of 100%. Eighteen percent of these antrostomies were markedly narrowed but none were closed.

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Table 5. Postoperative e n d o s c o p i c a s p e c t of the frontal recess a c c o r d i n g to the p r e o p e r a t i v e a s p e c t of the frontal sinus on CT scan Endoscopic aspect of frontal recess I Yr after surgery Frontal sinus aspect on preoperative CT scan (n = 97)*

Normal

Edema

Polyps

Normal

Edema

Polyps

13 41.9

12 38.7

6 19.3

7 22.5

5 16.1

19 61.4

27 43,5

31 49.9

4 6,6

20 32.2

13 20,9

29 46.9

1 25

2 50

1 25

3 75

1 25

41 42.2

45 46.4

11 11.4

30 30.9

19 19.6

ii

Partial opacity (n = 31) n % Complete opacity (n = 62) n % Normal aspect (n = 4) n % Total (n = 97) n %

3 Yr after surgery

i

0 0 48 49,5

*Three cases with a unilateral absence of frontal sinus

DISCUSSION

Extensive nasal polyposis has provided a discouraging outlook for patients and surgeons alike. Many otolaryngologists believe that stage IV chronic hyperplastic rhinosinusitis is not a surgical disease. There are few long-term studies on the result of endoscopic sinus surgery in patients with diffuse polyposis. 5,a,9,t2 However, because this is a multifactorial disease, longterm follow-ups are necessary to determine the efficacy of any specific treatment for chronic severe potyposis. 1'8'10'12'17 There remains a controversy as to how much or how little ethmoidal mucosa to remove in patients with polyposis. 4,5,7J8,19 HoweveJ5 it is our belief that complete removal of all ethmoidal mucosa in a meticulous dissection leaving only a frontal ostium mucosal collar leads to the formation of new mucosa with a fibrous layer that is less apt to produce new polyps. The use of the endoscope provided a very low morbidity rate and reduced requirement for obstructive nasal packing in this series of 100 complete sphenoethmoidectomies. Nevertheless, a decision tc undertake this large surgery should never be taken lightly or without adequate preoperative evaluation of the previous medical treatment and informed consent. It would also appear reasonable that the otolaryngologist should receive special training in this technique to manage diffuse polypos]s safely. Although a local anesthetic appears helpful for some authors 4,5 to minimize complications and blood loss, in our experience; this technique associated with complete exenteration of ethmoidal mucosa requires a general anesthetic. In this study no major complications or bleeding were encountered. No patient required return visits to the operating

Table 6. Comparison b e t w e e n residual anterior e t h m o i d a l cells on postoperative CT a n d preoperative o p a c i t y in the frontal sinus in 20 patients with recurrent polyposis or e d e m a in the frontal recess Preoperative CT results in frontal sinus Anterior ethmoidal cells i,

i i

Partial opacity i

Residual cells (n = 24) n 7 % 29.1 No residual cells (n = 16) n 1 % 6.25 Total (n = 40) n 8 % 25

Complete opacity u

Normal opacity

i

3 12.5

14 58.4

4 25

11 68.75

7 17.5

25 57,5

room or revision surgery in the postoperative follow-up of 3 years. Results of histologic analysis after these procedures have already been demonstrated within the maxillary antrum. 2° These patients are informed that 4 to 8 weeks after surgery a relatively normal mucosal membrane covering will be obtained. However, nasal secretions and crusts may be considerable in the immediate postoperative period. These do not require any repetitive endoscopic care as is usual after functional endoscopic surgery. 5,7 Endoscopic postsurgical care was reduced to a cleaning in the third or fourth postoperative week. Healing of the cavity was observed 6 to 8 weeks after surgery. Infrequently, cleaning and removal of crusts and residual fragments of bone were necessary. This relatively undemanding postoperative care

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Table 7. C o m p a r i s o n b e t w e e n e n d o s c o p i c findings a n d residual a n t e r i o r e t h m o i d a l cells o n CT in 20 p a t i e n t s w i t h r e c u r r e n t polyposis or e d e m a in t h e frontal recesses Endoscopy Anterior ethmoidal cells Residual cells (n = 24) n % No residual cells (n = 16) n % Total (n = 40) n %

Polyps

Edema

Total

16 66.7

8 33.3

24 100

10 62.5

6 37.5

16 100

26 65

14 35

40 1O0

compares favorably with the frequent postoperative care suggested after functional endoscopic procedures. 5,6 Postoperative CTS were performed systematically in the period between 2 and 3 years after surgery. These results were correlated with endoscopy, with particular emphasis being placed on analysis of recurrent polyposis. In Table 6 we note that postoperative CTs of 40 ethmolds (20 patients with recurrent polyposis) showed that 25 (57.5%) of the 40 frontal sinuses appeared normal on CT scanning despite the fact that endoscopically each of these patients had asymptomatic recurring polyposis or edema in the frontal recess. This fact suggests that no correlation exists between state of the mucosa in the frontal recess and the presence of frontal sinus opacification and is confirmed by Neel et al.,21 who demonstrated that after surgery recurrent or persistent disease may not become symptomatic for many years. Many factors may cause these recurrences, particularly the presence of residual anterior ethmoidal mucosa. 4,5,9 Table 7 summarized the correlation between residual anterior ethmoidal cells on CT and recurrence of polyps in the frontal recess. These data are based on the observation that 24 polypoid or edematous ethmoidal vaults (60%) showed one or two anterior ethmoidal residual cells. In return, 16 polypoid vaults (40%) were not associated with residual cells in this group of 20 patients. In these last cases, polyps appeared to originate from either the orbital wall or the superior remnant attachment of the middle turbinate. On the other hand, CT scans from 10 patients with no recurrence at endoscopy in the frontal recess were analyzed. Residual anterior ethmoidal cells were found in eight of 10 of these patients, with no recurrence. These data suggest that there is no correlation between the

persistence of a few anterior ethmoidal cells and the recurrence of polyps in the frontal recess. Most probably these recurrences originate from the mucosa left around the frontal ostium. Thus a higher percentage of recurrence of polyps (50%) was noted in the frontal recesses than in other areas of the marsupialized cavity. Surgery was less radical in these cases with regard to the mucosal lining. The 50% rate in the frontal recess compares with 23% in the anterior ethmolds and 3% in the posterior ethmoids, where no macroscopic mucosal lining was left. These results suggest that nasal polyposis may be considered a diffuse nonreversible inflammatory process of the ethmoidal mucosa. Thus a radical exenteration in a safe procedure is appropriate to minimize recurrence of massive polyps. A long-term comparative study between functional and radical approaches remains necessary to confirm this opinion. Nevertheless, the management of the frontal recess continues to be the most difficult problem in ethmoidectomy in terms of prevention of recurring polyposis and cicatrization. Considerable research in this area describing external approaches 22 and complication rates with these procedures 23,24 has done nothing to minimize the high complication rates encountered with external approaches. Numerous techniques have been proposed to prevent inadvertent complications resulting from both microscopic and endoscopic sinus surgery. 25-3° Nonetheless, stenoses or synechiae in the frontal recess has been common. In this study the technique of perioperative frontal irrigation enabling precise location of the frontal recess and ostium permits safe endonasal drainage of purulent debris and mucopus entrapped in the frontal sinus. Frontal irrigation was first described by Lemoyne 15 in 1947. The author's technique of preservation of a collar of mucosa around the frontal ostium of each frontal sinus is an evolution of previous attempts at mucosal preservation in the frontal recess already discussed in the literature. 31 Because a temporary inflammation is encountered routinely after any functional endoscopic sinus surgery, the use of postoperative frontal irrigation appears to be helpful. A control study is necessary to confirm that frontal irrigation is effective in the management of cicatrization of the frontal recess. Nonetheless, despite the use of topical steroids for years after surgery, the unoperated collar of mucosa in the frontal recess evidently retains its potential for producing polyps and ensuing chronic inflammation. Interestingly, only five patients were seen with unilateral disease of the frontal recess, most frontal recurrences being a bilateral process. Agger nasi cells, frequently missed during surgery, 7'11 are easily ablated by this technique because they are

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identified anteriorly to the f l o w o f the frontal irrigation. P o s t o p e r a t i v e irrigation does not s e e m to p r e v e n t p o l y p recurrences totally in the frontal recess as s h o w n in Table 4. Table 4 points out the differences b e t w e e n the potential for r e c u r r e n c e in the frontal recess and anterior and p o s t e r i o r e t h m o i d s . T h e best results w e r e obtained posteriorly, with an 88% rate o f n o r m a l m u c o s a l lining 3 years after surgery. The 48 p o l y p recurrences noted in frontal recesses and 23 in the anterior e t h m o i d s (Table 4) are p r o b a b l y related to the residual m u c o s a l collar around the frontal ostium. K e n n e d y 5 reports Similar results after surgery for nasal polyposis. In his series, only 23.5 % of operated cavities w e r e r e m u c o s a l i z e d with a n o r m a l m u c o s a d e v o i d o f i n f l a m m a t i o n , m u c o s a l swelling, polyposis, or scarring. In spite o f the m u c o s a l abnormalities, 46 o f our patients r e m a i n e d s y m p t o m free with regard to nasal obstruction during the 3 years after surgery. With regard to the p o s t o p e r a t i v e h y p o s m i a and anosmia, the surgery was p e r f o r m e d with great care in the area m e d i a l to the m i d d l e turbinate (cribriform plate) to p r e v e n t c o m p l i c a tions, w h i c h certainly explains the polyps or persistence o f edema. T h e s e results m a y explain the differences in the extent o f the disease within the e t h m o i d a l cavity 3 years after surgery. 11,32 This p r o s p e c t i v e study on a small but carefully controlled group of c o n s e c u t i v e patients suffering f r o m stage IV e x t e n s i v e nasal p o l y p o s i s c o n f i r m s that a c o m plete endonasal s p h e n o e t h m o i d e c t o m y associated with frontal irrigation is a safe and reliable p r o c e d u r e in the m a n a g e m e n t o f patients with diffuse hyperplastic nasal rhinosinusitis refractory to m e d i c a l therapy.

REFERENCES 1. Lawson W] The intranasa] ethmoidectomy: an experience with 1077 procedures. Laryngoscope 1991; 101:367-71. 2. Toffel PH. Secure endoscopic sinus surgery with middle meatal stenting. Op Technot Otolaryngot Head Neck Surg 1995; 6:157-62. 3. Friedman WH, Katsantonis G. Intranasal and transantral ethmoidectomy: a 20-year experience. Laryngoscope 1990; 100:343-8. 4. Stammberger H. Endoscopic endonasal surgery: concepts in treatment of recurring rhinosinusitis, part I: anatomic and pathophysiologic considerations. Otolaryngol Head Neck Surg 1986;94:14.3-7. 5. Kennedy DW. Prognostic factors, outcomes, and staging in ethmoid sinus surgery. Laryngoscope 1992; t 02(suppl): 1-18. 6. Wigand ME, Steiner W, Jaumann M. Endonasal sinus surgery with endoscopical control: from radical operation to rehabilitation of the mucosa. Endoscopy 1978;10:255-60. 7. Schaefer SD, Manning S, Close L. Endoscopic paranasal sinus surgery: indications and considerations. Laryngoscope 1989;99:1-5. 8. Levine HL. Functional endoscopic sinus surgery: evaluation, surgery, and follow-up of 250 patients. Laryngoscope 1990; 100:79-84.

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9. Rice D. Endoscopic sinus surgery: results at 2-year follow-up. Otolaryngol Head Neck Surg 1989; 101:477-9. 10. Lund V, Scadding GK. Objective assessment of endoscopic sinus surgery in the management of chronic rhinosinusitis: an update. J Laryngol Otoi 1994; 108:749-53. 11. Wigand ME, Hosemann WG. Results of endoscopic surgery of the sinuses and the anterior skull base. J Otolaryngol 1991 ;20:385-90. 12. Wigand ME, Hosemann W. Microsurgical treatment of recurrent nasal polyposis. Rbinol Suppl I989;8:25-9. 13. Friedman WH, Katsantonis GR Sivore M, Kay S. Computed tomography stating of the paranasal sinuses in chronic hyperplastic rhinosinusitis. Laryngoscope 1990; 100:1161-5. 14. Klossek JM, Fontanel JR Dessi PF, Serrano E, Cbirurgie endonasale sous guidage endoscopique. 2nd ed. Paris: Masson; 1995. 15. Lemoyne J. La ponction du sinus frontal. Ann Otol Laryngol (Paris) 1947;64:648-55. 16. Stammberger H, Kennedy DW, Lurid VJ, et al. Paranasal sinuses: anatomic terminology and nomenclature. Ann Otol Rhinol Laryngol Suppl 1995;104:7-16. 17. Matthews BL, Smith LE, Jones R, Miller C, Brookschmidt JK. Endoscopic sinus surgery: outcome in 155 cases. Otolaryngol Head Neck Surg 1991;104:244-6. 18. Pentilla MA. Endoscopic findings after functional and radical sinus surgery: a prospective randomized study. Am J Rhinol 1994;8:71-6. 19. Forsgen K, Fukami M, Penillfi M, et al. Endoscopic and Caldwell-Luc approaches in chronic maxillary sinusitis: a comparative histopathologic study on preoperative and postoperative mucosal morphology. Ann Otol Rhinoi Laryngol i995;104: 350-7. 20. Benninger MZS, Sebeck BA, Levine HL. Mucosal regeneration of the maxillary sinus after surgery. Otolaryngol Head Neck Surg 1989;!01:33-7. 21. Neel HB III, McDonald TJ, Facer GW. Modified Lynch procedure for chronic frontal sinus diseases: rationale, technique, and long-term results. Laryngoscope 1987;97:1274-9. 22. Montgomery WW. Surgery of the frontal sinuses. Otolaryngol Clin North Am 1971 ;4:97-126. 23. Hilding A. Experimental surgery of the nose and sinuses, 1I: gross results foliowing the removal of the intersinus septum and strips of mucous membrane from the frontal sinus of the dog. Arch Otolaryngol 1933;47:321-7. 24. Walsh TE. Experimental surgery of the frontal sinus: the role of the ostium and nasofrontal duct in postoperative healing. Laryngoscope 1943;53:75-92. 25. Neel BH, Whicker J, Lake C. Thin rubber sheeting in frontal sinus surgery: animal and clinical studies. Laryngoscope 1976;1868:536-42. 26. Draf W. Endonasal micro-endoscopic frontal sinus surgery, the Fulda concept. Op Technol Otolaryngol Head Neck Surg 1991 ;2:234-40. 27. Weber R, Draf W, Constantidinis J. Osteoplastic macroscopic and microscopic frontal sinus surgery. Am J Rhinot 1994;8: 247-50. 28. May M. Frontal sinus surgery: endonasal endoscopic osteoplasty rather than external osteoplasty. Op Technol Otolaryngol Head Neck Surg 1991 ;2:247-56. 29. Loury MC. Endoscopic frontal recess and frontal sinus ostium dissection. Laryngoscope 1993;103:455-8. 30. Close LG, Lee NK, Leach JL, Mannig SC. Endoscopic resection of the intranasal frontal sinus floor. Ann Otol Rhinol Laryngol 1994;103:952-8. 31. Moriyama H, Fukami M, Yanagi K. Endoscopic endonasal treatment of ostium of the frontal sinus and the results of endoscopic surgery. Am J Rhino1 1994;8:67-70. 32. Vleming M, de Vries N. Endoscopic paranasal sinus surgery: results. Am J Rhinol 1990;4:13-7.