A Large Frontonasal Bone Flap for Sinus Surgery in the Horse

Veterinary Surgery, 19,2, 122-1 30, 1990

A Large Frontonasal Bone Flap for Sinus Surgery in the Horse

DAVID E. FREEMAN, MVB, MRCVS, PhD, DiplomateACVS, PAUL G. ORSINI, DVM, MICHAEL W. ROSS, DVM, DiplomateACVS, and JOHN 8. MADISON, VMD, DiplomateACVS

A large frontonasal bone flap was created to treat diseases of the paranasal sinuses in 14 horses. The bone flap was made as wide as possible within the confines of the nasolacrimal duct so the floor of the frontal sinus and the dorsal and ventral conchae could be opened. These openings exposed the nasal passages, maxillary sinuses, and ventral conchal sinus thereby facilitating removal of diffuse and localized lesions from these sites. Diseases treated were ethmoid hematomas (4 horses), sinus cysts (5 horses), cryptococcal granuloma, osteoma, hemangiosarcoma, pus in the ventral conchal sinus, and periapical infection of a second molar. Four horses were euthanatized during or after surgery, one because of postsurgical pleuritis and pneumonia (horse with osteoma) and three because of their primary problems (cryptococcal granuloma, hemangiosarcoma, pus in the ventral conchal sinus). Skin suture abscesses that responded to treatment developed in four horses. Ten horses returned to their intended uses, the sinus flaps healed without blemish, and the original problems did not recur. The frontonasal flap technique provided greater access to all paranasal sinuses than methods described previously.

wo RECOGNIZED BONE FLAP APPROACHES for sinus T surgery in horses are the frontal flap'-3 and the maxillary f l a ~ . ~ - ~ The maxillary flap offers excellent access to the maxillary sinuses, which are common sites of disease in the horse,* but limited access to the sphenopalatine and conchofrontal ~ i n u s e s . ~ This limitation is of considerable importance because many diseases in the sinuses originate from or involve the latter sites.'-' The maxillary approach allows access to the ventral conchal sinus through a narrow space dorsal to the infraorbital canal or through a hole created in the bony plate beneath

However, in young horses, access to the ventral it. 10- I3

conchal sinus is dificult because the prominent reserve crowns of cheek teeth reduce the space above the infraorbital canal."' Also, reserve crowns fill the bony plate beneath the infraorbital canal in young horses so that access through this plate is possible only if a tooth is removed (Fig. I ) . ' '

The triangulated flap technique is a frontal flap approach modified to improve access to lesions in the conchofrontal sinus, ethmoturbinates, caudal maxillary sinus, and caudal nasal cavity.' However, its versatility was not tested in a wide variety of sinus diseases and some sites that are commonly involved are not exposed directly through the method described. I Examples are le-

sions confined to the ventral conchal both maxillary sinuses. and cheek teeth.' We describe the use of a large frontonasal bone flap to improve access to these sites and hence to be more versatile than frontal and maxillary flaps described previously.

Materials and Methods

Clinical Cuses

Sinus diseases in 14 horses were treated surgically through a large frontonasal bone flap (Table 1). The need for surgery was determined by history and the results of physical, radiographic, and endoscopic examinations. Definitive diagnosis was based on intraoperative findings and on results of histologic and microbiologic examinations. Long-term follow-up information was obtained by telephone or by written questionnaire.

SI irgical Procedi ire

Each horse was anesthetized and placed in lateral re- cumbency, and the dorsal and lateral aspects of the face were prepared for aseptic surgery. Balanced polyionic fluids were administered intravenously throughout sur-

From the Department of Clinical Studies, New Bolton Center, Kennett Square. Pennsylvania. Reprint requests: David E. Freeman, MVB, New Bolton Center, 382 West Street Rd, Kennett Square, PA 19348.

122

FREEMAN, ORSINI, ROSS, AND MADISON 123

Fig. 1. Transverse section through head of a 3 year old horse at the level of the second molar, rostral view of the right side. A. Anatomy. 1- second molar; 2-facial crest; %-root of first molar; 4-rigid bony septum between caudal and rostral maxillary sinuses; 5-infraorbital nerve in infraorbital canal; 6-rostra1 maxillary sinus (plate of bone behind numeral 6 is the conchal bulla); 7-ventral conchal sinus; 8-nasolacrimal duct; 9-medial canthus of eye; 10-frontal sinus; 11-dorsal conchal sinus (10 and 11 combined form the conchofrontal sinus); 12-ventral nasal meatus; 13-ventral nasal concha; 14-dorsal nasal concha; 15-middle nasal meatus; 16-dorsal nasal meatus; 17-nasal septum. The curved arrow passes through the conchomaxillary opening, which is the communication between the rostral maxillary sinus and ventral conchal sinus. B. Structures that must be removed (within white lines) to expose the sinus cavities demonstrated in Figure 3B. Arrowheads point to the medial and lateral edges of the frontonasal flap at this level. The wider the flap, the greater the access to maxillary and ventral conchal sinuses. The section is cut at a level with numeral 2 in Figure 38.

gery and a compatible blood donor was made available in case of severe blood loss. Temporary, bilateral, carotid artery occlusion was used in horse 12 for 16 minutes to reduce intraoperative hem~rrhage . '~ Both arteries were approached through an 8 cm long incision in the uppermost jugular groove with blunt dissection over the tra- chea to expose the opposite vessel.

The caudal margin of the bone flap was a line at right angles to the dorsal midline, midway between the supra- orbital foramen and medial canthus of the eye (Fig. 2). The lateral margin started 2 to 2.5 cm medial to the medial canthus of the eye and extended to a point approximately two-thirds the distance from the medial canthus of the eye to the infraorbilal foramen. It was placed to widen the flap as much as possible within the confines of the nasolacrimal duct. The approximate course of the

duct was regarded as a line from the medial canthus of the eye to the nasoincisive notch and, in some horses, the lateral margin of the flap had to be angled rostrally to avoid it. The rostral margin ofthe flap was at right angles to the dorsal midline. When the flap was completed, its base was along the dorsal midline of the face and it was approximately 8 cm wide and I0 cm long. A 15 cm flap was used in horse 1 1 (Table I ) .

The combined skin and fascia1 incision was 5 mm larger than the proposed bone incision and its corners were slightly rounded. The periosteum was incised and the exposed bone was cut with an oscillating saw along the outlines ofthe rectangular flap. No attempt was made to bevel the bone edges.'.' The small bony attachments or lamellae between the underside of the flap and the floor of the sinus were cut with an osteotome until the

124 FRONTONASAL BONE FLAP

TABLE 1 . Summary of Data for Horses Treated with a Frontonasal Flap (Continues)

Horse Age Breed/ Clinical Signs at Endoscopic Radiographic Diagnosis Follow- No. (yrs) Intended Use Sex History Admission Findings Findings (side involved) up (yrs)

TB/ hunter

TB/ broodmare

T W broodmare

QHI pleasure

STD/ racehorse

TW event

MC

F

F

MG

M

MC

F

MC

MC

F

Mild epistaxis at rest for 24 hrs before admission

Nasal discharge for 1 yr. mild-to- moderate spontaneous epistaxis for 21 days

Mild spontaneous epistaxis for 4 days

Mild eDistaxis Large mass occluding nasal passage

Large mass on ethmoturbinates

Smooth ovoid mass on ethmoid and in nasal passage

Smooth ovoid mass on ethmoid and in nasal passage

Ethmoid 12 hematoma (R)

Mild bilateral epistaxis, worse on left side

Ethmoid 2 hematoma (L)

Slight mucous discharge from nostril

Small mass on ethmoturbinates

Smooth lobulated mass on ethmoid region. only on lateral view

Small ovoid mass in dorsal concha1 sinus (see Fig 4)

Large well-defined mass in sinuses. fluid line, deviated nasal septum

Ethmoid hematoma (L)

1

Spontaneous epistaxis 7 and 17 days before admission

mucopurufent nasal discharge for 2 mos

Bilateral

No abnormalities on physical examination

Normal Ethmoid hematoma (L)

0.5

5.5 Enlargement of maxillary sinus, dullness on percussion, epiphora. nasal mucopurulent discharge

Mucopurulent nasal discharge

Pus in middle meatus

Sinus cyst (R)

Sinus cyst (R) Mucopurulent nasal discharge for 9 mos, mild epistaxis on two occasions, slight stertor at work

Severe facial swelling of unknown duration

Normal Large diffuse mass in sinuses

6

Large diffuse mass in sinuses, dental displacement (Ml). deviated nasal septum

Sinus cyst (L) 3 7 1 ASB/ broodmare

Facial swelling, dyspneaand stertor at rest, sinuses dull on percussion, epiphora. decreased airflow

Nasal discharge, dullness on percussion of sinuses, mild facial deformity

Narrowing of both nasal passages

TBI jumper

Intermittent nasal discharge of 2 yrs duration. trephined sinuses 1 yr before admission

Epiphora of 6 mos duration, stertor at work, mild epistaxis 6 mos before admission, trephined sinuses 4 mos before admission

Facial deformity of 3 yrs duration, draining tract and exophthalmos

Narrowing of nasal passage

Large diffuse mass in sinuses, deviated nasal septum

Sinus cyst (R) 2

TW show

Epiphora, slight stertor at rest

Narrowing of nasal passage

Large diffuse mass in sinuses

Sinus cyst (R) 1

NA Cryptococcal granuloma (L)

12 AR1 pleasure

Severe facial deformity, exophthalmos. stertor at rest, copious nasal discharge, sinus tract and softening of maxilla

Narrowing of nasal passageand pus in ventral meatus

Diffuse opacification throughout sinuses, deviation of nasal septum


TABLE 1 . (Continued)

Horse Age Breed/ Clinical Signs at Endoscopic Radiographic Diagnosis Follow- No (yrs) Intended Use Sex History Admission Findings Findings (side involved) up (yrs)

11

12

13

14

5

20

9

3

TB/ pleasure

QH/ pleasure

TBI pleasure

TB/ racehorse

MC

MC

F

F

Mucopurulent nasal discharge for 3 mos. stertor at work

Mild. intermittent epistaxis for 3 wks

Stertor during work for 1 yr. mucopurulent nasal discharge

Mucopurulent fetid nasal discharge for 1 mo

Mucopurulent nasal discharge, fa( deformity, dullness on percussion of sinuses

Mild epistaxis, anemia, PCV 20%

Pus in middle meatus

:la1

Blood from middle meatus

Mucopurulent nasal discharge, stertor at rest, mild polyuria and polydypsia

Mucopurulent fetid nasal discharge. dullness on percussion of sinuses. pain on percussion

Pus in nasal passage

Pus in R nasal passage

Dense, large, circumscribed mass in sinuses, deviation of nasal septum

Fluid lines in sinuses and small round density on ethmoid labyrinth

Opacification in ventral conchal sinus deviation of nasal septum

Fluid in R maxillary sinuses, fluid and gas in periapical bony cavity above M2

Osteoma (L)

Hemangiosarcoma (R)

Inspissated pus in ventral conchal sinus (R) Streptococcus SP

Apical granuloma and abscess of M2, sinusitis

NA

NA

NA

3

TB-Thoroughbred MC-male castrated R-right side. F-female L-left side, OH-Quarter horse, STD-Standardbred, M1-1 st upper molar, ASB- American Saddlebred AR-Arabian, NA-not applicable (these horses were euthanatized with 2% months after surgery) M2-2nd upper molar All clinical signs were unilateral unless stated otherwise

flap could be pried upward and fractured along the dorsal midline.

The opening created in this way allowed direct access to the conchofrontal sinus, ethmoid labyrinth, and the frontomaxillary opening (Fig. 3 ) . The frontomaxillary opening allowed access to the caudal maxillary sinus, second and third upper molars. and sphenopalatine sinus. When sinus architecture was not disrupted by disease, the bulla of the ventral conchal sinus could be scen beneath the rostral edge of the frontomaxillary opening.

The floors of the frontal sinus and dorsal conchal sinus were opened with scissors or rongeurs to expose the middle nasal meatus. caudal part of the nasal passages, and ethmoturbinates (Figs. 1 and 3). The ventral concha, its conchal bulla. and the bony septum could then be removed to improve access to the rostral maxillary sinus and ventral conchal sinus (Figs. I and 3) . These procedures caused moderate-to-severe hemorrhage that could be reduced by sponge pressure or application of hemostats to cut edges of bone and mucosa. Access to the ventral conchal and maxillary sinuses was greater in older horses because their reserve crowns were shorter (Fig. 3 ) . Many of the normal sinus partitions and conchae were distorted in horses with cysts and were obliterated in the horses with

cryptococcosis (horse 10) and osteoma (horse 1 1). The ventral conchal sinus and rostral maxillary sinus were not opened in horse 4 because its ethmoid hematoma was confined to the conchofrontal sinus (Fig. 4).

Before closure, the sinuses and nasal passages were packed with gauze soaked in 1: 10,000 epinephrine solution (horse l) , 5% cocaine in saline (horses 4-7, 11, and 14) or saline alone (horses 2 ,3 ,8 ,9 , 12, and 13). The free end of gauze was brought out through a trephine hole in the maxillary sinus in horses I , 4, 5 , 6, I I , and 14. In eight horses, it was drawn through the nasal passage and sutured to the false nostril.

The bone flap was repaired by drilling four pairs of holes equidistantly along the flap edges with a 2 mm Steinmann pin. Simple interrupted sutures of size 2 poly- glactin 910* (horses 2-14) or 25 gauge wire (horse 1 ) were used to secure the bone flap in place and subcutane- ous fascia and skin were closed in separate layers. A tracheotomy was performed in horses 1 and 13.

Post opera i i LV Cure Nasal packing was removed 72 to 96 hours after sur-

gery. The sinuses were irrigated through the trephine

* Vicryl, Ethicon Inc. Somerville. NJ

FRONTONASAL BONE FLAP

Fig. 2. Relationship of large frontonasal bone flap approach to the paranasal sinuses in the horse. A. Outline of the bone flap is represented on the left by broken lines, with a-caudal margin; b-lateral margin; c-rostra1 margin. The rostral part of the lateral margin is angled toward the midline to avoid the approximate course of the nasolacrimal duct. On the right the conchofrontal sinus is the area shaded with horizontal lines and the underlying maxillary, sphenopalatine and ventral conchal sinuses are represented as the strippled area. The black ellipse is the frontomaxillary opening. B. Enlarged view of the sinuses. Outlines of the conchofrontal sinus and the frontomaxillary opening are represented by dotted lines. Shading represents the rostral and caudal maxillary sinuses, the ventral conchal sinus, and the sphenopalatine sinus. 1 -frontal sinus; 2-caudal maxillary sinus; 3-rostra1 maxillary sinus;which is separated from the caudal maxillary sinus by an oblique bony septum; 4-ventral conchal sinus; 5- dorsal conchal sinus; 6-sphenopalatine sinus; 7-infraorbital foramen which leads into the infraorbital canal. The infraorbital canal separates the rostral maxillary sinus from the ventral conchal sinus and the caudal maxillary sinus from the sphenopaiatine sinus. The open arrow points to the caudal bulla of the ventral conchal sinus which is continu- ous at the infraorbital canal with the bony septum that separates the maxillary sinuses.

hole in horses 4, 5, 6, and 1 1 for 7 days and in horses 1 and 14 for 28 days. Saline or 10% povidone-iodine solution in saline was infused for the first 3 to 7 days and then water from a hose. The trephine hole was packed with gauze sponges soaked in antibiotic solution between ir- rigations and was subsequently covered with gauze and adhesive tape until healed. Tracheotomy tubes in horses I and 13 were removed on days 5 and 6, respectively. Procaine penicillin G (22000 IU/kg intramuscularly bid) was administered before surgery to all but horses 3 and 9 and was continued postoperatively for 3 to 5 days. Phe- nylbutazone (2 mg/kg intravenously) was administered

to horses 5, 7, 8, 1 1 , 12, and 14 on the first day after surgery and continued twice daily orally for the next 3 to 6 days.

Results

Intraopera f ive Findings

In three of the four horses with ethmoid hematoma, large lesions that appeared to originate from the ethmoturbinates and ethmoid labyrinth extended into the sinuses and caudal nasal passage. In horses 1 and 3 , the hematoma was covered by irregular bony bullae that projected into the conchofrontal and maxillary sinuses (Fig. 5). They appeared to arise from the ethmoid labyrinth and had to be broken down to expose the lesion. In horse 4, the hematoma originated from the floor of the conchofrontal sinus, which was removed with it (Fig. 4). Sinus cysts were extensive lesions that filled the maxillary and ventral conchal sinuses, extended dorsally into the conchofrontal sinus and, in horse 8, invaded the opposite conchofrontal sinus. Surgical removal of these lesions re- sulted in complete ablation of the ventral conchal sinus, giving the impression that they originated from this site.

Horse 10 had an extensive cryptococcal granuloma consisting of pale, greasy material that could be stripped easily from its attachments. A poor prognosis was given for rapid recovery and the horse was euthanatized. Horse 11 had an osteoma that measured 15 X 9 X 8 cm and weighed 972 g (Fig. 6). It was located largely in the conchofrontal sinus but its attachments could not be identified. Two small fragments were sawed off the osteoma (Fig. 6) to facilitate removal and 4 mm Steinmann pins were placed obliquely through its rostral and caudal poles to provide points for traction.

In horse 12, a tentative diagnosis of ethmoid hematoma was based on clinical signs and radiographic findings (Table I ) , but the only abnormality found at surgery was an area of mucosal thickening, ulceration, and hemorrhage on the floor of the frontal sinus. The abnormal mucosa and associated bone were removed and all sinus cavities except the most rostral end of the rostral maxillary sinus were explored. When signs recurred 2 weeks later and the sinuses were reexplored through the same flap, a friable, dark, hemorrhagic mass was found in the most rostral extent of the rostral maxillary sinus. A trephine hole was made in the maxilla to expose the most rostral attachments of the mass, which was identified his- tologically as a hemangiosarcoma.

In horse 13, the conchomaxillary opening was sealed with granulation tissue and infection was confined to the ventral conchal sinus. In horse 14, the infected second upper molar was repelled and an opening was created


Fig. 3. Interior of the right conchofrontal sinus through the frontonasal bone flap in cadaver specimens. A. The rostral part of the head is to the left and the lateral margin is uppermost. 1-reflection of dorsal nasal concha; 2-dorsal conchal sinus; 3-ethmoid labyrinth; 4-infraorbital canal; 5-caudal maxillary sinus; 6-concha1 bulla; 7-floor of the frontal sinus. Frontomaxillary opening is indicated by arrowheads. The arrow points to the sphenopalatine sinus, below the ethmoid labyrinth and medial to the infraorbital canal. This is a 6 year old horse. B. Same view as Figure 3A except that parts of the floor of the frontal sinus, the dorsal and ventral conchae, and the conchal bulla have been removed. 1 -dorsal nasal concha; 2-dorsal conchal sinus; 3-ethmoid labyrinth; 4-infraorbital canal; 5-caudal maxillary sinus; 6-bony septum between the maxillary sinuses; 7-rostra1 maxillary sinus; 8-infraorbital canal and underlying 2nd molar within the rostral maxillary sinus; 9-ventral conchal sinus. Asterisk indicates area on floor of dorsal conchal sinus that must be opened to expose the ethmoturbinates within the caudal nasal cavity. The catheter has been inserted into the middle nasal meatus between the cut edges of the dorsal and ventral conchae. These edges can be trimmed back further to improve exposure. C. Similar exposure of sinus cavities as in Figure 38, except in an older horse. View angled to allow inspection of the rostral maxillary sinus. 1 -dorsal conchal sinus; 2-ethmoid labyrinth; 3-infraorbital canal; 4-root of third molar; 5-caudal maxillary sinus; 6-edge of frontomaxillary opening; 7-septum; 8-rostra1 maxillary sinus

into the nasal passage through the ventral conchal sinus. The dental alveolus was packed with methylmethacrylate, most of which was removed through the mouth at month 1. At month 4, surgery was repeated through the same frontonasal flap because of persistent sinusitis and three methylmethacrylate fragments were removed from the dental alveolus.

Outcome

In horse 1 1 , pleuritis and pneumonia developed by day 3 . Two and a half months after surgery, the horse was euthanatized because of poor response to treatment. At necropsy, the sinus flap had healed and there was no gross evidence of residual osteoma within the sinuses; however, persistent tumor was found on histologic examination of a small portion of nasal bone.

Horse 12 was euthanatized 2 weeks after the second surgery because mild epistaxis recurred and hemangiosarcoma had a poor prognosis. Horse 13 was euthanatized 2 weeks after surgery because severe sinusitis devel-

oped and the owner did not wish to continue treatment. At necropsy, the mucosa of the sinuses and conchae were inflamed and thickened; however, the ventral conchal sinus did not contain pus and the drainage opening into the nasal passage measured 3 X 5 cm. Other findings were an adrenal adenoma of approximately I6 cm in di- ameter and a spindle cell sarcoma in the right upper eyelid.

Horses 3, 6, 8, and 9 had mucopurulent nasal discharge from the affected side for 10 to 2 1 days after surgery and abscesses developed in one to two skin sutures at the rostral end of the flap by days 3 to 7. The abscesses were treated by suture removal, daily cleaning with di- lute antiseptic solutions, and 3 to 4 days of antibiotic therapy. They healed within 3 weeks after surgery.

Ten horses recovered fully and returned to their intended uses without recurrence of their original problems (Table I ) . Horses 6 and 8 had a mild but permanent mucous discharge from the affected nasal passage, slightly worse in the morning or after work. Sinusitis developed in horse 8 on the affected side 6Y2 months after

FRONTONASAL BONE FLAP

Fig. 4. Xeroradiograph of head of horse 4, lateral view, rostral end to the left. The ethmoid hematoma (1) in this horse arose from the conchofrontal sinus and did not extend into the nasal passage. 2- ethmoid labyrinth; 3-caudal maxillary sinus: 4-rostra1 maxillary sinus; 5-infraorbital canal; 6-dorsal conchal sinus; 7-frontal sinus.

surgery but it resolved after treatment by nebulization with antibiotics. By results of endoscopic examination at this time, the opening created into the nasal passage was estimated to be approximately 3 X 5 cm. In horse 6 at month 1, the opening into the nasal passage appeared endoscopically to be so large that the nasal passages and sinuses appeared to form a single cavity. Horses 8 and 9 had exaggerated breathing sounds through the nasal passages at work, but exercise tolerance was not reduced. Facial deformity in horses 7 and 8 resolved completely and incisions in all survivors healed without blemish.

Discussion

The frontonasal bone flap described in this report differs from the triangulated flap technique' in ways that were designed to improve versatility. In the triangulated flap technique the lateral bone incision follows the outline of the conchofrontal sinus closely, which reduces the width ofthe flap. The nasofrontal flap is made as wide as possible within the confines of the nasolacrimal duct to improve access in a lateral direction to the maxillary sinuses. teeth roots, and ventral conchal sinus. Additional steps are required to expose these areas and these steps can be accomplished more easily through a wide flap. The purposes of these steps are to remove as much abnormal tissue as possible, especially the origins of lesions, and to establish a large drainage opening into the nasal passages.

lntraoperative hemorrhage was slight after the sinus flap was opened (Figs. 5 and 6) and this facilitated complete removal of lesions. Hemorrhage induced by removal of cysts, ethmoid hematomas, and floor of the

conchofrontal sinus was copious in some horses, but blood drained out over the base of the flap and did not obscure the surgical field. Creation of an opening through the ventral concha into the nasal passage should be the last step because this procedure causes profuse hemorrhage. Hemorrhage was reduced in horse 12 bq temporary ligation of both external carotid arteries. Thc ligation procedure was modified from previous descrip. tionsI4 by approaching both arteries through a single in. cision so that carotid dissection could start at the same time as sinus surgery. This eliminated the need to turn the horse over to expose the opposite artery; thus, surgery time was reduced.

The most common postoperative complications in this series were skin suture abscesses and minor skin wound dehiscence along the rostral margin. This compli- cation might be prevented by repairing the flap with sutures in soft tissues only.' All horses in this series had sutures through the bone flap that may have provided a nidus and route for infection from the sinuses into sub- cutaneous spaces.

In contrast to previously described frontal approaches in the h ~ r s e , ' - ~ . ' ~ soft tissues were left attached to the bone flap. Dissection of skin and fascia from the bone flap appears to offer no advantage and could predispose to hematoma formation and cellulitis in the subcutane- ous dead space and to necrosis of bone. Also, intact soft tissue attachments can combine with incomplete points of fracture on the bone flap to provide a strong hinge and a solid support for repair.

The frontonasal flap allows considerable latitude in size and this is an advantage because many sinus diseases are extensive by the time diagnosis is made. A large flap obviates the need for two sinus openings, as have been

Fig. 5. View of left conchofrontal sinus through frontonasal flap in horse 3 shows several bullae that were covering an ethrnoid hematoma. Arrow points toward the left medial canthus and rostral end of the head is to the right. Asterisk indicates dorsal nasal concha.


described previously for removal of large sinus In horse 1 I , it allowed removal of a large oste-

oma without the need to break it into several fragments.” An osteoma is more amenable to treatment than other sinus tumors because it is benign, grows slowly, forms a well-circumscribed mass, and has small areas of attachment. Recurrence is although residual tumor in the nasal bone could have proliferated in horse 1 I , had it survived. I t has been noted previously,1x and confirmed in this and other reportslh~”~”~”’ that sinus osteoma in horses appears to occur exclusively in young males.

Although ethmoid hematomas are reported to have a high recurrence rate,’ none recurred in horses in this report with follow-up periods up to I2 years (Table I ). It is probably crucial to remove points of origin of ethmoid hematomas and this can be accomplished readily through frontal flaps.’.’’ The frontonasal approach also allowed excellent access to sinus cysts, which involved predominantly sinus cavities medial and dorsal to the infraorbital canal.

Severe postoperative sinusitis in horse I3 was attributed to increased susceptibility to infection as a conse- quence of the adrenal adenoma.*? It was evident at necropsy that drainage had been provided from the ventral concha1 sinus but spread of infection to adjacent areas could not be controlled. Hyperadrenocorticism was not diagnosed in this horse preoperatively but other clinical signs, such as polydypsia and polyuria. were attributed retrospectively to the tumor.”

Repulsion of the second upper molar and subsequent

Fig. 6. Osteoma in horse 11. A. lntraoperative view of mass in the left conchofrontal sinus. Arrow points toward the left medial canthus and rostral end of the head is to the right. The bone flap was 8 cm wide and 15 cm long. B. Osteoma after removal, ventral surface. Two fragments between the arrows were broken off during surgery to facilitate removal.

tooth socket were easily accomplished in horse 14 through a frontonasal approach. However, the first molar, which is the tooth most commonly diseased,6 is more readily accessible through a small maxillary bone flap over the tooth root. The greatest disadvantage of the frontonasal approach is limited access to the most rostral extent of the rostral maxillary sinus, and this was well illustrated in horse 12. The hemangiosarcoma in this sinus cavity was overlooked during the first operation because the objective was removal of a suspected ethmoid hematoma on the ethmoid labyrinth. When clinical signs recurred, the hemangiosarcoma was removed from the rostral maxillary sinus through the frontonasal approach but access was difficult.

Any single approach may not be ideal for surgical treatment of all sinus diseases. However, in the cases described in this report, which were representative of those most often encountered in equine practice,9 it was evident that the frontonasal approach could be modified to extend its usefulness beyond the procedures described to date. By combining a large flap with ventral dissection through the floor of the frontal sinus and dorsal and ventral conchae, access could be gained to the nasal passage and all parts of the sinuses, with the exception of the most rostral end of the rostral maxillary sinus.

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18. Cook WR. Skeletal radiology of the equine head. J Am Vet Rad

19. Fisher AK. A compact osteoma in the skull of a horse. J A m Vet Med Assoc 1952; I2 I :42-44.

20. Kold SE, Ostblom LC. Headshaking caused by a maxillary osteoma in a horse. Equine Vet J 1982; 14:167-169.

21. Meagher DM. The elevation and surgical treatment of ethmoid hematomas in the horse (abstract). Vet Surg 1986: IS: 128.

22. Feldman EC. The adrenal cortex. In: Ettinger S. ed. Ti.\./booli uf I iverinar!~ Intrmal Medkinr. Discust.r ofrhr Dog and C’ut. 2nd ed. WB SaundersCo. 1983:1650-1696.

SOC 1970; 11135-54.

ACVS COLLEGE CALENDAR

Veterinary Surgical Forum October 28-30,1990 Chicago

European Surgical Forum April 12-1 4, 1991 Nice, France

ACVS Veterinary Symposium October 1 1-1 8,1991 San Francisco

European Surgical Forum May 8-1 0,1992 Wurtzburg, West Germany

ACVS Veterinary Symposium October 30-November 6,1992 Miami

ACVS Veterinary Symposium October 22-29,1993 San Francisco

and Annual Meeting

and Annual Meeting

and Annual Meeting

Documents

A Large Frontonasal Bone Flap for Sinus Surgery in the Horse