Endoscopy-Guided Conchotomy

Take Home Message—Endoscopy guided transnasal fenestration of the medial wall of the ventral conchal sinus might serve as an additional surgical technique for re-establishing drainage in horses suffering from obstructive purulent sinusitis.

I. Aim of the study

The aim of this study was to establish a minimally invasive surgical technique to fenestrate the medial wall of the ventral conchal sinus to improve drainage of the rostral sinus compartment in standing, sedated horses.

II. Introduction

Some cases of sinusitis are complicated by obstruction of epithelium or inspissated pus¹. In these patients drainage of the sinuses through the nasomaxillary opening is complicated or rendered impossible. Surgery or balloon catheterization of the nasomaxillary opening may be required to re-establish drainage.

Surgical techniques to access the sinuses include trephination of the frontal and/or maxillary sinuses^2,3 and bone flap techniques.^3-6 Bone flap techniques are more elaborate compared to trephination techniques and offer better access to the sinuses.^4-6 Although it is possible to create bone flap approaches in standing sedated horses^5,6 these procedures are still more commonly performed in recumbent animals.⁵ Compared to most bone flap approaches, access to the sinus systems is more limited using trephinations. However, trephination of the frontal or maxillary sinuses is usually performed in standing patients in most clinics.⁵

The procedure of partial resection of the medial aspect of the dorsal and ventral conchae has been described for re-establishing sinus drainage in patients with obturated nasomaxillary apertures.⁴ Severe hemorrhage, the need for general anesthesia and surgical site infections are the major disadvantages of this surgical method.⁷

To avoid some of the complications associated with this technique, minimally⁸ invasive methods to enlarge the nasomaxillary aperture or fenestrate the dorsal aspect of the ventral conchal bulla⁹ and the medial wall of the dorsal concha¹⁰ have been published. However, minimally invasive fenestration of the medial wall of the ventral conchal sinus has not been described yet but might be a viable option for re-establishing drainage in obstructed rostral sinus compartments in sinusitis-affected horses.

III. Materials and methods

Instruments

The conchotomes were built by one of the authors (EKH). A spatula shaped blade of varying lengths (5 – 20mm) was forged at a 90° angle on one end of a 6 mm stainless steel rod. At the other end a port for connection to the electrocautery device was drilled. The overall length of the instruments was approximately 45cm. The instrument shafts were insulated with shrinkable tubing.

A cautery instrument with a 4mm diameter ball-tip was also created and used in later patients.

Animals

The patients (6 horses) consisted of two mares, three geldings and one stallion (age: 3 to 23 years). All horses in this study were clinical patients treated for primary or secondary sinusitis. The indication for performing transnasal conchotomy of the ventral conchal sinus was failure to establish drainage of exudate from the rostral sinus system by conventional surgical methods.

Method - Conchotomy

The horses were restrained in stocks and sedated. The ground plate of the electrocautery device was fixed to the side of the neck with bandages. Saline soaked swabs were placed between skin and ground plate.

A flexible endoscope was then introduced into the middle nasal meatus and the site for surgery was identified on the medial wall of the ventral concha, 1-2 cm rostral and 1-2 cm ventral of the “drainage angle”. The nasal mucosa overlying the surgical site was anaesthetized topically (lidocaine 2%) and then injected trans-endoscopically with 2-5 ml of lidocaine (2%) through an endoscopic sclerosing needle. The conchotome was connected to the electrocautery device and inserted into the ventral nasal meatus with the blade pointing dorsally. The blade was advanced to the incision site under endoscopic control, rotated and brought into contact with the conchal wall. Alternating coagulating and cutting currents were used to create the incision in caudo-rostral direction. The tip of the blade was rotated in lateral direction to penetrate the conchal wall; then the instrument was gently pulled rostrally to create a linear incision into the conchal wall. The aim was to create a 3-4 cm long incision. In later patients the coagulation instrument was used to cauterize the mucosa at the incision site before the cutting instrument was used.

Criteria for Success

Following criteria were used to determine the success of the surgery to create an opening into the ventral conchal sinus: pus emanating from the sinus during incision, irrigation of the sinus system immediately after surgery resulting in irrigation fluid exiting the newly created incision, verified by endoscopic control.

Surgery time and blood loss were recorded. Blood emanating from the horse’s nostril was collected in a in a bucket. The amount of blood loss was rounded up to the nearest liter.

IV. Results

Conchotomy was performed in 6 horses (Table 1) after established methods of improving sinus drainage had failed. In 3/6 horses one procedure was sufficient to establish satisfactory drainage. In 3/6 more than one procedure (up to 4) was performed. Eventually drainage from the ventral concha into the nose was achieved in all patients.
 

Surgery time was 15 – 45 (median: 25) minutes. Blood loss ranged from 1 to 4 (mean: 2) liters. In later patients the amount of bleeding could be further reduced due to changes of operation technique.

Hemorrhage, obstructing endoscopic vision, was the most common complication necessitating abandonment of the procedure and requiring another attempt during the following days. If hemorrhage was deemed to be severe the affected nasal passages were packed with gauze bandages to aid hemostasis. For other complications encountered and for details of case management please refer to Table 1.

All but one patient were discharged from hospital. In case 3 severe progressive osteomyelitis of the facial bones was diagnosed prior to conchotomy and the horse was euthanized at the owner’s request. Case 6 was euthanized at home for causes unrelated to sinusitis. The remaining 4 horses were free from symptoms of sinusitis on follow up examination or in a telephone survey. Follow up time ranged from 4 months to 1 year. Sinusitis did resolve and not reoccur during at least six months in 4 patients. The orifice created during conchotomy was still visible after 6 months in 3 cases. During this study the instruments were adapted and the method improved. Further testing with a larger group of patients is necessary to collect sufficient data and evaluate the described surgical technique.

References

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