Diffuse nasal polyposis: Postoperative results after endoscopic sinus surgery frontal irrigation

long-term and

JEAN-MICHEL KLOSSEK, MD, LOUIS PELOQUIN, MD, FRCSC, WILLIAM H. FRIEDMAN, MD, FACS, JEAN-CLAUDE FERRIER, 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 sphe- noethmoidectomy 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 systemat- ically. The patients were followed closely with serial endoscopic examination, and CT scan- ning 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 per- sisted in four of the 50 patients. Endoscopically, polyp recurrence was noted in 3% of pos- terior 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 peri- operative 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 com- plications. 1-3 Two different philosophies have been pro- posed 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 atolaryngology- Head 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 classi- fication 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 evalu- ated 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 hyper- plastic 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 No. of patients (%)

Bilateral nasal obstruction 50 100 Anosmia at least 6 mo/yr 50 100 Posterior rhinorrhea 48 96 Facial pain 2 4 Asthma (n = 47)

Asthma and allergy 21 44,6 ASA triad 14 29.7 Asthma alone 12 25.5

ASA, Aspirin-sensitive asthma.

(400 to 800 gg beclomethasone daily) and a minimum of three courses per year of oral steroids (1 mg/kg pred- nisone 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, long- term nasal polyposis included subjective anosmia and bilateral nasal obstruction as the most prominent symp- toms 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 surg- eries, which included bilateral total sphenoethmoidec- tomy with wide middle antrostomies and frontal irriga-

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

Localization Complete

Maxillary sinus 76 Anterior ethmoid 95 Posterior ethmoid 81 Sphenoid sinus 53 Frontal sinus (n = 97)* 31.9

Opacification (%)

Normal (no

Partial opacification)

21 3 5 0

19 0 39 8 62.1 4

*Three patients had a single frontal sinus.

tion. 14 Total excision of all ethmoidal cells was per- formed in a forward to backward direction. All mucos- al 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 irri- gation 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

Otolaryngology- Head and Neck Surgery Volume 117 Number 4 KLOSSEK et ai. 357

Fig. 2. Postoperative aspect on CT scan of same patient 3 years after total sphenoeth- moidectomy.

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 irriga- tions were done three times daily for a few weeks with saline solution. Long-term topical beclomethasone therapy was continued twice daily. Postoperative eval- uation 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 exam- ination (according to the anatomic terminology pro- posed 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. Pos topera t i ve s y m p t o m s a t 3 months, 1 year, a n d 3 years

3 Mo

Symptoms No Mild Marked No

Nasal obstruction (n = 50) n 0 0 50 1 % 0 0 100 2

Anosmia (n = 50) n 8 7 35 8 % 16 14 70 16

Posterior rhinorrhea (n = 48) n 14 21 13 17 % 30 43 27 35

Follow-up

1 Yr

Mild

3 6

12 24

25 51

Marked

46 92

30 60

6 14

3 Yr

No Mild Marked

1 3 46 2 6 92

11 10 29 22 20 58

15 19 14 31 39 30

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

Table 4. E n d o s c o p i c mucosa l a s p e c t 3 years a f te r surgery wi th in t he p o s t o p e r a t i v e e t h m o i d a l cav i t y

Polyp Normal recurrence (%) Edema (%) mucosa (%)

Anterior ethmoid 23 36 41 (100%)

Posterior ethmoid 3 9 88 (100%)

Frontal recess 49,4 19,5 31.1 (97%)

the superior attachment of the basal lamella of the mid- dle turbinate. The posterior ethmoid corresponds to the area behind the superior attachment of the basal lamel- la of the middle turbinate. In each area any evidence of mucosal hypertrophy, polyposis, or discharge was recorded. Polyps were defined as any localized mucos- al swelling forming a detectable mound or roll at endoscopy. Medical therapy for asthma was monitored and all changes in therapy were recorded during the 3- year follow-up.

RESULTS

A total o f I00 sphenoethmoidectomies were per-

formed associated with 100 middle meatal antros- tomies. No major complications were encountered. There were no episodes of postoperative epistaxis that required packing or transfusion. Discomfort was gener- ally 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 fol- low-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 thera- py for asthma.

Ethmoidal vaults were closely examined endo- scopically 3 years after surgery. Despite excellent sub- jective improvement, many patients had residual evi- dence of hyperplastic disease on endoscopic examina- tion. There was a significant difference in the recur- rence rates for the three different areas of the sphe- noethmoidectomy cavity. Recurrence of polyps, as defined previously, occurred in 3% of posterior eth- molds, 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 differ- ences 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 preop- erative partial opacification of the frontal sinus revealed polypoid recurrence on endoscopy. Twenty- nine (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 nonob- structive 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 peri- od. The middle meatal antrostomies had an overall patency rate of 100%. Eighteen percent of these antros- tomies were markedly narrowed but none were closed.

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Table 5. Postoperative endoscop ic aspect of the frontal recess accord ing to the preoperat ive aspect of the frontal sinus on CT scan

Endoscopic aspect of frontal recess

I Yr after surgery 3 Yr after surgery

Frontal sinus aspect on preoperative CT scan (n = 97)* Normal Edema Polyps Normal Edema Polyps

i i i

Partial opacity (n = 31) n 13 12 6 7 5 19 % 41.9 38.7 19.3 22.5 16.1 61.4

Complete opacity (n = 62) n 27 31 4 20 13 29 % 43,5 49.9 6,6 32.2 20,9 46.9

Normal aspect (n = 4) n 1 2 1 3 1 0 % 25 50 25 75 25 0

Total (n = 97) n 41 45 11 30 19 48 % 42.2 46.4 11.4 30.9 19.6 49,5

*Three cases with a unilateral absence of frontal sinus

DISCUSSION

Extensive nasal polyposis has provided a discourag- ing outlook for patients and surgeons alike. Many oto- laryngologists believe that stage IV chronic hyperplas- tic 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, long- term follow-ups are necessary to determine the efficacy of any specific treatment for chronic severe potypo- sis. 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 sphenoeth- moidectomies. Nevertheless, a decision tc undertake this large surgery should never be taken lightly or with- out 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 dif- fuse polypos]s safely. Although a local anesthetic appears helpful for some authors 4,5 to minimize com- plications and blood loss, in our experience; this tech- nique associated with complete exenteration of eth- moidal mucosa requires a general anesthetic. In this study no major complications or bleeding were encoun- tered. No patient required return visits to the operating

Table 6. Comparison be tween residual anterior e thmoidal cells on postoperat ive CT and preoperat ive opac i ty in the frontal sinus in 20 patients with recurrent polyposis or edema in the frontal recess

Preoperative CT results in frontal sinus

Anterior Partial Complete Normal ethmoidal cells opacity opacity opacity

i , i i i u i

Residual cells (n = 24) n 7 3 14 % 29.1 12.5 58.4

No residual cells (n = 16) n 1 4 11 % 6.25 25 68.75

Total (n = 40) n 8 7 25 % 25 17.5 57,5

room or revision surgery in the postoperative follow-up of 3 years. Results of histologic analysis after these pro- cedures 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 imme- diate 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 postop- erative 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 neces- sary. This relatively undemanding postoperative care

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Otolaryngology- Head and Neck Surgery

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Table 7. Compar i son b e t w e e n e n d o s c o p i c f indings a n d residual anter ior e t h m o i d a l cells on CT in 20 pat ients wi th recurrent polyposis or e d e m a in the f rontal recesses

Endoscopy

Anterior ethmoidal cells Polyps Edema Total

Residual cells (n = 24) n 16 8 24 % 66.7 33.3 100

No residual cells (n = 16) n 10 6 16 % 62.5 37.5 100

Total (n = 40) n 26 14 40 % 65 35 1 O0

compares favorably with the frequent postoperative care suggested after functional endoscopic proce- dures. 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 polypo- sis. In Table 6 we note that postoperative CTs of 40 eth- molds (20 patients with recurrent polyposis) showed that 25 (57.5%) of the 40 frontal sinuses appeared nor- mal on CT scanning despite the fact that endoscopical- ly each of these patients had asymptomatic recurring polyposis or edema in the frontal recess. This fact sug- gests 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 persis- tent disease may not become symptomatic for many years. Many factors may cause these recurrences, par- ticularly 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 ede- matous 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 ana- lyzed. 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 marsupi- alized 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 eth- molds and 3% in the posterior ethmoids, where no macroscopic mucosal lining was left. These results sug- gest 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 func- tional and radical approaches remains necessary to con- firm 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 compli- cation 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 tech- nique of perioperative frontal irrigation enabling pre- cise location of the frontal recess and ostium permits safe endonasal drainage of purulent debris and muco- pus 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 rou- tinely 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 cica- trization of the frontal recess. Nonetheless, despite the use of topical steroids for years after surgery, the unop- erated 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

Otolaryngoiogy- Head and Neck Surgery Volume 117 Number 4 KLOSSEK et at. 361

ident i f ied anteriorly to the f low of the frontal irrigation.

Pos topera t ive i r r igat ion does not seem to p reven t polyp

recurrences total ly in the frontal recess as shown in

Table 4. Table 4 points out the differences be tween the

potent ial for recur rence in the frontal recess and anteri-

or and pos ter ior e thmoids . The best resul ts were

obta ined posteriorly, wi th an 88% rate o f normal

mucosa l l ining 3 years after surgery. The 48 polyp

recurrences noted in frontal recesses and 23 in the ante-

r ior e thmoids (Table 4) are probably related to the

residual mucosa l col lar around the frontal ost ium.

Kennedy 5 reports Similar results after surgery for nasal

polyposis . In his series, only 23.5 % of opera ted cavi t ies

were r emucosa l i zed with a normal mucosa devo id o f

in f lammat ion , mucosa l swell ing, polyposis , or scarring.

In spite o f the mucosa l abnormali t ies , 46 o f our

patients r emained s y m p t o m free wi th regard to nasal

obstruct ion during the 3 years after surgery. With regard

to the pos topera t ive hyposmia and anosmia, the surgery

was pe r fo rmed with great care in the area media l to the

middle turbinate (cr ibr i form plate) to prevent compl ica-

tions, which certainly explains the polyps or pers is tence

o f edema. These results may expla in the differences in

the extent o f the disease wi th in the e thmoidal cavi ty 3 years after surgery. 11,32

This p rospec t ive study on a small but careful ly con-

t rol led group of consecut ive patients suffering f rom

stage IV ex tens ive nasal polypos is conf i rms that a com-

plete endonasal sphenoe thmoidec tomy associated with

frontal i rr igat ion is a safe and rel iable p rocedure in the

m a n a g e m e n t o f patients with diffuse hyperplast ic nasal

rhinosinusi t is refractory to medica 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 patho- physiologic considerations. Otolaryngol Head Neck Surg 1986;94:14.3-7.

5. Kennedy DW. Prognostic factors, outcomes, and staging in eth- moid 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 rehabilita- tion 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.

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 hyper- plastic 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 sinus- es: 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 com- parative 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 proce- dure 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 osteoplas- ty 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.