Empyema of the nasal conchal bulla as a cause of chronic unilateral nasal discharge in the horse: 10 cases (2013-2014)

Comparison of equine paranasal sinus trephination complications and outcome following standing computed tomography, radiography and sinoscopy guided approaches for the treatment of sinusitis

OBJECTIVE

The recent availability of standing computed tomography (CT) for equine paranasal sinus disease has enhanced diagnosis and enabled more targeted surgery compared to radiography and sinoscopy. To date, there have been no studies which have critically evaluated the benefit of preoperative CT versus radiography and sinoscopy on complications and outcome in horses undergoing sinus trephination.

STUDY DESIGN

Retrospective study.

ANIMALS

A total of 229 equids.

METHODS

The medical records of equids (229) presented for sinusitis treated via trephination that had CT, radiography and/or sinoscopy at time of surgery between 2009 and 2022 were reviewed. Outcome and complications were evaluated for six different pre- and intraoperative imaging modalities.

RESULTS

The six groups did not differ in demographics or disease category, though equids with less weight (p = .0179) and shorter disease duration (p = .0075) were more likely to have radiography and sinoscopy based surgical planning. Short-term postoperative complications occurred in 30.1% and were higher in groups using preoperative CT imaging (p = .01), with hemorrhage being the most common surgical complication. Following initial trephination surgery, 57.0% (127/223) of cases resolved and there was no difference between the imaging groups. Final resolution after follow-up medical or surgical treatment increased to 94.6% (211/223) and was not different between the imaging groups or between primary or secondary sinusitis. Additional nasal fenestrations to improve sinonasal drainage, maxillary septal bulla fenestrations and trephinations to treat nasal conchal bullae were made in the CT groups.

CLINICAL SIGNIFICANCE

CT provided additional diagnostic information and enabled different surgical approaches but did not improve resolution in this study population.

Trephination versus Minimally Invasive Transnasal Approaches for the Diagnosis and Treatment of Sinus Disease in Horses

This retrospective case series aims to highlight the advantages and disadvantages of different treatment options for sinus disease in horses, with a special focus on surgical approaches. The medical records of 25 horses with sinusitis which presented to the equine hospital, Vetmeduni Vienna, between August 2020 and January 2022 were analysed. In 11 cases, conservative treatment by the transnasal endoscopic lavage of the affected sinuses through the sinonasal channel or through a developed, pre-existing sinonasal fistula was performed. In the remaining 14 cases, openings into the sinus for subsequent lavage were surgically created either via classical trephination/bone flaps (8) or by transnasal endoscopically guided minimally invasive approaches (8). In some cases (2), a combination of classical extra-nasal and minimally invasive transnasal approaches was required. The minimally invasive techniques used were comprised of laser surgery (3), electrosurgery (3) and balloon sinoplasty (2). The sinusitis and underlying diseases were successfully treated in all of the horses until hospital discharge. Long-term follow-up could be obtained only from a small number of patients due to the temporal proximity (the study began two years ago) to their initial discharge from the hospital, but they showed the continuous resolution of clinical signs in all cases in which follow up data were available. The results of this case series indicate that if surgical intervention is required, minimally invasive techniques appear to be a promising and potentially cheaper alternative to classical extra-nasal approaches for the treatment of sinus disease in selected cases. In the future, the use of these techniques should be considered more commonly with the broader availability of improved endoscopes and instruments. Additionally, by using small-diameter endoscopes, the need for any surgical intervention might be significantly reduced in many cases.

The Role of Computed Tomography in Imaging Non-neurologic Disorders of the Head in Equine Patients

Computed tomography (CT) imaging of the head in equine patients is now commonly performed as CT scanners are more readily available. Head CT has proven valuable in evaluating spatially complex anatomic structures, where radiographic superimposition, or restricted access via endoscopy or ultrasound, limit complete evaluation of the disease process. Head CT has been demonstrated to be incredibly valuable in the evaluation of dental and paranasal sinus disease, disease of the hyoid apparatus and ear, and in evaluation of skull trauma. CT is an excellent modality for assessment of both osseous and soft tissue structures; however, evaluation of complex vascular anatomy and determination of tissue viability is limited without the use of contrast agents. Therefore, various contrast agent protocols including intravenous and intraarterial iodinated contrast administration techniques have been established. CT also has limitations in the evaluation of brain and spinal cord disease, for which magnetic resonance imaging (MRI) has major advantages. Head CT images are most commonly evaluated in transverse planes. However, standard multiplanar reconstructions of the head including dorsal and parasagittal planes improve the understanding of spatially complex disease processes. These reconstructions can be crucial for accurate identification of diseased teeth and determination of the extent and severity of osseous and paranasal sinus disease. Head CT examinations are becoming an increasingly important diagnostic tool in the evaluation of horses with head disorders, and CT imaging findings are an important aspect in the clinical decision-making process. The following review discusses the indications, benefits, and technical considerations for the use of computed tomography (CT) in evaluating non-neurologic head pathologies in equine patients.

An anatomical study of the dorsal and ventral nasal conchal bullae and middle nasal conchae in normal Shetland ponies: Computed tomographic anatomical and morphometric findings

Equine paranasal sinuses are susceptible to inflammation. Insufficient drainage through the nasal passages and meatus may lead to the accumulation of inspissated purulent discharge. Particularly in ponies, these anatomical structures are suspected to be relatively small. To date, there are no reports considering the morphology of nasal conchal bullae in small horse breeds such as Shetland ponies. The aim of the present study was to evaluate the size of the conchal bullae and the medial nasal conchae of Shetland ponies and their relation to the skull dimension using computed tomography. Reconstructed images of healthy adult heads of Shetland ponies were used. Linear skull measurements as well as two cranial indices of the head dimensions were taken. Length, width and height of the dorsal and ventral conchal bullae and the medial nasal conchae were measured in relation to the skull and compared with the data of skulls of large breed horses. The anatomical proportions of pony heads were characterized by a smaller cranial index and a greater nasal index than those of large breed horses. Shetland ponies showed a longer cranial length compared with the nasal length. Heads are consistently smaller, and the relationship of the bullae to the head length was also smaller than those measured in large breed horses. A negative correlation between the head and bullae size was found. In conclusion, this study suggests that Shetland ponies have distinguishing proportions of the head. These findings are relevant for clinical examination and surgical treatment of equine sinus disease in those breeds.

A long-term study of sinoscopic treatment of equine paranasal sinus disease: 155 cases (2012-2019)

BACKGROUND

There is little objective information concerning the intra- and post-operative complications or the long-term outcome of sinoscopic treatment of equine sinus disorders.

OBJECTIVES

To document the long-term outcome, including intra-operative complications, reasons for treatment failure and other complications, in horses undergoing standing sinoscopic treatment of sinus disorders.

STUDY DESIGN

Retrospective clinical study.

METHODS

Records of sinus disease cases presented to The University of Edinburgh Veterinary School between January 2012 and July 2019 were reviewed. Follow-up information was obtained from clinical records and a telephone questionnaire.

RESULTS

Long-term follow up for 155 cases treated sinoscopically showed that 108/155 (69.7%) fully responded to their initial treatment. Concurrent intranasal lesions were identified in 37.4% of cases. Sinusotomy was later required in 10 cases to improve surgical access or sinonasal drainage. Reasons for failure to fully respond to the initial treatment (n = 47) included: intra-sinus bone sequestra (n = 9), inspissated exudate (n = 6) or insects (n = 2); similar material and/or infected conchal bullae in the middle meatus (n = 7); persistent oro-maxillary fistulae (n = 4), misdiagnosed dental apical infections (n = 4); impaired sinonasal drainage (n = 4), progressive ethmoid haematoma regrowth (n = 3) and undiagnosed causes (n = 5). Further treatment of 43 of these cases (67% as outpatients) showed 34/43 cases fully responding to their second treatment. Only 4/155 cases (2.6%) required sinonasal fenestration. In the long term, 149/155 cases (96.1%) showed full and 2/155 cases (1.3%) showed partial improvement. Sinoscopy portal wound infection occurred in nine cases.

MAIN LIMITATIONS

The length of time between treatment and obtaining follow-up information in some cases. Advances in knowledge and techniques over the duration of the study.

CONCLUSIONS

Sinoscopic treatment is a minimally-invasive technique causing minimal morbidity and was successful in 96.1% of cases. Meticulous care should be taken to ensure that bony sequestrae and inspissated exudate are fully removed from the sinuses and nasal cavity during sinoscopic treatments.

Computed Tomographic Assessment of Individual Paranasal Sinus Compartment and Nasal Conchal Bulla Involvement in 300 Cases of Equine Sinonasal Disease

Background: Computed tomographic (CT) imaging has allowed new anatomical studies and detailed clinical imaging of the complex, overlapping equine sinonasal structures. Despite the widespread use of CT, no study has specifically identified which compartments are most commonly affected with sinus disorders. CT has also shown the presence of intercurrent, ipsilateral nasal disorders, especially infection of the nasal conchal bullae (NCB) in many cases of sinus disease, but the frequency of intercurrent NCB infections has not been reported.

Objectives: To identify which sinus compartments are most commonly affected in horses with clinical sinus disorders and to record the prevalence of NCB involvement in such cases.

Study Design: Retrospective examination of CT images of horses with confirmed unilateral sinus disease.

Methods: The CT images of 300 horses, from three different equine hospitals with clinically confirmed sinus disease [mainly dental (53%) and primary sinusitis (25.7%)] were retrospectively examined to determine which sinus compartments and NCBs were affected.

Results: The rostral, more dependent sinus compartments were most commonly involved, i.e., the rostral maxillary sinus in 284/300 (94.7% affected) and the ventral conchal sinus (87% affected). The caudal maxillary sinus (65.3%), dorsal conchal sinus (52.7%), frontal sinus (26%), ethmoidal sinus (32%) and sphenopalatine sinus (28.7%) were less commonly affected. There was infection or destruction of the ipsilateral NCBs in 56% of horses with sinus disorders, including the ventral NCBs in 42.3%, dorsal NCBs in 29% and both NCBs in 18% of cases.

Main Limitations: The horses with sinonasal disease that underwent head CT imaging include more problematic cases and horses of high value, rather than the general horse population.

Conclusions: The more dependant (i.e., the RMS and VCS) sinus compartments are most commonly involved in sinus disorders, with the RMS involved in nearly every case. The more dorsally located sinuses (i.e., caudal group) are less commonly involved. Many horses with sinus disease also have disorders of their nasal conchal bullae and so the term sinonasal disease seems appropriate for these disorders.

Equine Sinus Surgery

The anatomy of the equine paranasal sinuses is critical to understand to assess the extent of the disease process, the optimal surgical approach, and the ability to drain through the normal nasomaxillary pathway. By following established anatomic landmarks, direct sinus access can be used to further explore the sinus compartments, remove compromised cheek teeth, remove any purulent debris or feed contamination, and establish drainage. Many complications can be avoided or minimized by thoroughly evaluating all sinus compartments and critically assessing the ability of the sinus to drain.

Equine Imaging: Computed Tomography Interpretation

Computed tomography (CT) has revolutionized the veterinarian's ability to image the equine skull and led to improved diagnostic accuracy and clarity for surgical planning. The increased cost for this evaluation is offset by more accurate diagnosis and targeted therapy. As novel technology is developed that allows for increased availability of equine head, the price will continue to decrease and more examinations will be performed. New skills are needed for the veterinarian to accurately interpret this modality. This article reviews the normal CT appearance of the equine skull and presents examples and key features of several common diseases.

A Computed Tomographic Assessment of Osteitis of Sinus Bony Structures in Horses With Sinonasal Disorders

Background: Computed tomographic (CT) imaging has shown some horses with sinonasal diseases to have changes in their sinus bony structures. Scintigraphic and clinical evidence of sinus osteitis have also been reported. However, no study has objectively examined for the presence and degree of osteitis in equine sinonasal disease.

Objectives: To assess for the presence and extent of osteitis of sinus-related bony structures by examination of CT images of horses with clinically and sinoscopically confirmed unilateral sinonasal disease.

Study Design: Retrospective examination of CT images of horses with confirmed, mainly chronic (>2 month duration) unilateral sinus disease of different etiologies.

Methods: Bone thickness at designated sites of the maxillary bone (n = 3), frontal bone (n = 1), infraorbital canal (n = 2), and bony nasolacrimal duct (n = 1) were measured, as were the maximal diameters of the infraorbital canal and the bony nasolacrimal duct on both affected and control sides. Maxillary bone density (in Hounsfield Units) was also assessed bilaterally. Bone thickness was compared between affected and controlled sides using paired statistical tests.

Results: Bone was significantly thicker in the affected sinuses compared to the control sides at the three maxillary bone sites (all, P < 0.001) and at both infraorbital bone sites (both, P < 0.001), but not at the two most dorsal sites examined, i.e. frontal bone (P = 0.188) and bony nasolacrimal duct (P = −0.260) sites. Infraorbital canal and bony nasolacrimal duct diameters were significantly wider in the affected as compared to the control sides (P < 0.001 and P = 0.002, respectively). Maxillary bone density did not differ significantly between the affected (mean = 1,075 HU, SD = 230.01) and control (mean = 1,100, SD = 200.71) sides (t₍₅₈₎ = −1.03, P = 0.306).

Main Limitations: Possible variation in selecting measurement sites. Variation in the severity and chronicity of sinonasal disease between horses.

Conclusions: Osteitis and enlargement of paranasal bony structures commonly occurs in horses with sinonasal disease and can explain the clinical presence of ipsilateral diffuse soft tissue facial swelling, epiphora, and scintigraphic evidence of bone inflammation in sinonasal disease.

Comparative studies on the histological characteristics of equine nasomaxillary aperture and paranasal sinus mucosa considering topographic and age-related differences

Background

Horses may acquire a range of paranasal sinus diseases. Clinical studies show slight differences regarding anatomical regions and age. Histopathological examination of tissue samples could play an important role in the diagnostic process. Therefore, detailed knowledge of the histological appearance of the paranasal sinus mucosa (PSM) and the nasomaxillary aperture mucosa (NAM) is essential. The objective of this study was to determine topographic and age-related differences within the healthy equine PSM. In addition, we aimed to gain detailed knowledge of the histological appearance of the NAM in comparison to the PSM.

Results

The PSM had an average height of 75.72 ± 44.48 μm with a two-row pseudostratified columnar epithelium of 13.52 ± 4.78 μm. The parameters mucosal height, epithelial height and number of goblet cells revealed significant dependency of the sample site and age group. The maxillary and dorsal conchal sinus showed the highest values for these parameters. In terms of age, younger horses showed a significantly higher total mucosal height in contrast to a significantly lower epithelial height than older horses. Positive correlation was seen between the epithelial height and number of goblet cells. The NAM had an average height of 820.27 ± 653.21 μm. Its pseudostratified epithelium was usually arranged in three rows and had an average height of 44.9 ± 12.78 μm. The number of goblet cells in the NAM was five times higher than in the PSM. Serous glands were found in only 4% of the PSM samples and 100% of the NAM samples.

Conclusions

There are significant histological differences between different paranasal sinus sites and between different groups of age. This may be related to an altered susceptibility for certain pathologies. The striking difference in the histological appearance of the NAM compared to the PSM could be due to an enhanced role in mucociliary clearance. Further studies are necessary to improve the understanding of mucosal function in specific paranasal sinus compartments and mucosal changes generated by different diseases.

A bilateral sinus cyst treated via a bilateral frontonasal bone flap in a standing horse

Bilateral paranasal sinus diseases are rarely reported in horses. Treatment using a bilateral frontonasal bone flap on a standing, regular-sized adult horse has not been described previously. A 13-year-old Thoroughbred gelding was evaluated for bilateral mucopurulent nasal discharge. Radiographic, endoscopic and computed tomographic examinations revealed bilateral sinus pathological changes consistent with an ethmoid haematoma involving the maxillary and frontal sinuses. A bilateral frontonasal bone flap was created under standing sedation and local anaesthesia. A tracheotomy was performed initially to ensure a patent airway during the procedure. Additional analgesia had to be given to transect the dorsal part of the nasal septum while elevating the flap. The sinus masses were removed and communications with the nasal cavities created uneventfully. Small sequestra were removed transendoscopically from the left caudal maxillary sinus 4 weeks after the initial procedure. The horse made a complete recovery with an excellent cosmetic outcome. Histopathology revealed the mass to be a sinus cyst. We concluded that a bilateral sinus bone flap can be used in adult regular-sized horses to access the left and right paranasal sinuses simultaneously. Regional nerve blocks should be performed in order to increase analgesia. A temporary tracheotomy prevents any airway obstruction during the procedure. The post-operative cosmesis is excellent.

Computed tomographic assessment of equine maxillary cheek teeth anatomical relationships, and paranasal sinus volumes

Disorders affecting the equine maxillary cheek teeth and paranasal sinuses are relatively common, but limited objective information is available on the dimensions and relationships of these structures in horses of different ages. The aims of this study were to assess age-related changes in the positioning and anatomical relationships of the individual maxillary cheek teeth with the infraorbital canal and maxillary septum and the volumes of the individual sinus compartments. CT and gross examination were performed on 60 normal equine cadaver heads that were aged by their dentition. The intrasinus position of cheek teeth, length of reserve crowns, relationship to the infraorbital canal and measurements of rostral drift and sinus compartment volumes were assessed from CT images. The findings included that Triadan 10 alveoli lay fully or partially in the rostral maxillary sinus (RMS) in 60% of cases. The infraorbital canal lay directly on the medial aspect of the alveolar apex in younger horses. The Triadan 11'sclinical crowns and apices drifted a mean of 2.48 and 2.83 cm more rostral to the orbit, respectively, in the >15 years old vs the <6 years old age group. The mean volumes of sinus compartments ranged from 175 cm³ for the caudal maxillary sinus (CMS) to 4 cm³ for the ethmoidal sinus (ES). This information should be of value in the diagnosis and treatment of equine dental and sinus disorders and as reference values for further studies.

Trans-endoscopic diode laser fenestration of equine conchae via contralateral nostril approach

OBJECTIVE

To describe and report preliminary outcomes of a contralateral trans-nasal endoscopic laser fenestration of the conchae for endoscopic examination and treatment of paranasal sinuses in horses.

STUDY DESIGN

Cadaveric experimental and prospective clinical study.

ANIMALS

Normal cadaveric equine heads (n = 7) and equine patients (horses n = 7, donkey n = 1) diagnosed with sinusitis.

METHODS

Ex vivo: a video-endoscope containing a diode laser fiber in the working canal was passed through the nostril and retroflexed in the nasopharynx toward the contralateral conchae. Ventral or dorsal conchae were fenestrated. Duration of surgery, laser energy, visualization quality, and feasibility of sinoscopy through the fenestrations were recorded. In vivo: sinus drainage, sinoscopy 24 hours postoperatively, stoma persistence, and clinical results after 3 months were evaluated in 8 patients.

RESULTS

Fenestrations were performed in 8 dorsal conchae (6 cadavers, 2 patients), 10 ventral conchae (5 cadavers, 5 patients), and 1 dorsal conchal bulla (1 patient). Visualization was good in 6 patients and affected by bleeding in 2 patients. Drainage through the fenestrations was observed in all patients. Trans-nasal sinoscopy was possible in all cadavers and in 6 out of 8 patients. Masses inside the sinuses precluded sinoscopy in 2 patients. Stomata persisted until discharge of the patients (mean of 14 days). Clinical signs improved in 6/8 patients.

CONCLUSION

The endoscopic approach reported here provides good visualization during the trans-endoscopic laser fenestration of the conchae. The fenestrations may allow a trans-nasal sinoscopic examination and treatment in selected cases of sinusitis in horses.

Anatomical and histological study of the dorsal and ventral nasal conchal bullae in normal horses

The morphology of the dorsal conchal bulla (DCB) and ventral conchal bulla (VCB) are poorly described. The recent recognition that these bullae can become infected, causing chronic unilateral nasal discharge, has stimulated interest in these structures. Fourteen cadaveric horse heads were transected sagittally midline and dissected to expose the nasal conchal bullae. The dimensions of each bulla, the number and orientation of drainage apertures, and cellulae septae were recorded. Randomly selected samples were examined histologically. The mean DCB and VCB lengths were 78  and 57 mm, respectively; equivalent to 13.9 per cent and 10.2 per cent of skull length, respectively. The mean DCB and VCB heights were 29  and 28 mm, respectively; equivalent to 5.2 per cent and 5 per cent of skull length, respectively. The DCB was larger than the VCB, containing more septae, cellulae and drainage apertures. No communications were identified between the bullae and the immediately adjacent paranasal sinuses. Histology revealed that the bullae consist of ciliated, pseudostratified, columnar epithelium over glandular submucosa often overlying turbinate bone and, variably, hyaline cartilage. This more detailed description of equine DCB and VCB anatomy will hopefully facilitate successful treatment of their disorders.

An anatomical study of the dorsal and ventral nasal conchal bullae in normal horses: Computed tomographic anatomical and morphometric findings

REASONS FOR PERFORMING STUDY

Infection of the dorsal nasal conchal bulla and ventral nasal conchal bulla has recently been shown to cause clinical disease in horses, but the anatomy of these 2 structures is poorly documented.

OBJECTIVES

To describe the anatomical features, dimensions and relationships to adjacent structures of the dorsal conchal bulla and ventra conchal bulla in normal horses using computed tomography (CT).

STUDY DESIGN

Descriptive imaging study using cadavers.

METHODS

Computed tomographic images acquired from 60 equine cadaver heads that were shown to be free of sinonasal disease were categorised into 3 age groups (0-5; 6-15; >16 years old). Linear and volumetric measurements and descriptive anatomical assessments of the dorsal conchal bulla and ventral conchal bulla were produced from these CT images and the anatomical relationships between the dorsal conchal bulla and ventral conchal bulla and the adjacent structures, particularly the maxillary cheek teeth, were examined. The associations between bullae dimensions with horse ages and skull dimensions were assessed using linear regression.

RESULTS

Mean (range) dorsal conchal bulla measurements were: length 7.5 cm (4.6-14), width 1.9 cm (1.3-2.5), height 2.8 cm (1.8-4), volume 24 cm³ (5.9-50.5). Mean ventral conchal bulla measurements were: length 5.7 cm (2.5-8.5), width 1.6 cm (0.7-2.9), height 2.4 cm (0.8-3.7), volume 15 cm³ (0.4-30). In both dorsal conchal bulla and ventral conchal bulla, there were significant differences in sizes between the different age groups (smaller in younger animals). In the ventral conchal bulla, this was probably related to protrusion of the large dental alveoli of younger horses into the lateral nasal cavity. Measures of bullae size and volume were significantly associated with head size. The anatomical positions (rostro-caudal boundaries) of the dorsal conchal bulla and ventral conchal bulla were closely associated with specific maxillary cheek teeth.

CONCLUSIONS

Computed tomography was a useful technique to establish the linear and volumetric dimensions of the nasal conchal bullae in normal horses. Both dorsal conchal bulla and ventral conchal bulla sizes increased with animal age. Relatively consistent anatomical relationships were shown between the rostral and caudal limits of the bullae and certain maxillary cheek teeth, which would be of diagnostic value with conventional radiography and act as landmarks in the surgical treatment of nasal bulla disease.