Some cases will have a permanent low grade inflammation of sinuses following this procedure - may have a permanent low grade nasal discharge.
Distortion of the sinuses from masses Paranasal sinus: cyst: respiratory neoplasia Respiratory: neoplasia may obviate normal architecture and make fenestration of the rostral portion of the ventral conchal sinus difficult.
Fenestration of the ventral conchal sinus is uncomfortable and may result in patient non-compliance if performed standing.
Lavage of sinuses Paranasal sinus: lavage: in acute cases simple lavage may improve the drainage by liquifying the material in the sinus and forcing it out through the normal ostia - less effective in chronic cases where persistent production of material, often of a thickened nature.
Lavage + ostia enlargement usually undertaken at same time.
Feeding from ground/exercise: useful in acute cases of sinusitis but limited effect in chronic case.
Aseptic skin preparation: 10 min.
General anesthesia induction and maintenance: 20 min.
During frontonasal flap surgery it is common practice to break down the bulla of the ventral conchal sinus and the rostral edge of the frontomaxillary opening to allow access to the rostral maxillary sinus and ventral conchal sinus.
If the lateral and ventral walls of the dorsal conchal sinus and the underlying ventral concha are disrupted (greater access to rostral maxillary sinus and ventral conchal sinus) this will establish an opening from each conchal sinus into the nasal cavity which can be enlarged.
To disrupt the rostral portion of the ventral conchal sinus, therefore creating an ostia from sinus to nasal passage, have an assistant use a Chamber’s catheter threaded with large gauge suture to fenestrate the rostral portion of the ventral conchal sinus by traveling up the ipsilateral nostril.
Once the surgeon visualizes the Chamber’s catheter/suture, the suture may be tied to sterile packing prepared as below to pack the sinus.
Pre-measure the Chamber’s catheter against the horse’s head to gauge depth of placement; injury to the ethmoids by passing the Chamber’s catheter too caudally will result in frank hemorrhage.
In maxillary sinus flaps an opening can be made into the nasal passage through the ventral concha to allow drainage (can be difficult in young horses due to high dental alveoli).
An approach to the ventral conchal sinus from the rostral maxillary sinus can be performed in the bony portion underlying the infraorbital canal.
Damage to infraorbital nerve may cause permanent headshaking and must be avoided at all costs.
Enlarge openings using scissors or rongeurs.
Creation and enlargement of the ostia should be the last step before closure, as hemorrhage following fenestration is usually profuse.
Step 2 - Control hemorrhage
Control hemorrhage (usually profuse) by packing sinuses with gauze bandage soaked in 1% dilute povidone-iodine saline (or occasionally 1:10,000 epinephrine Epinephrine).
Fold bandage into sinus and draw free end: through ostia and out of the nasal passage and suture/tie to false nostril.
Step 1 - Maintain ostia patency
Maintain ostia patency by drawing a gauze bandage or foley catheter/tube out through the ostia, down through the nasal passage and attach to the false nostril and/or head collar. Thin wire guide or suture through the Chamber's catheter will make this easier.
Packing must be removed 24-48 h after surgery to mitigate risk of infection.
Sedation is often indicated, as pulling packing through the nostril is uncomfortable.
To pull packing, cut the suture attaching packing to false nostril and pull robustly in a downward direction.
Have a competent horse-handler hold the horse during the procedure.
The patient may respond to packing pulling by backing up quickly. Ensure a clear path behind the horse and that the horse handler is adequately warned.Hemorrhage may occur after pulling the packing. This usually self-resolves, but should be monitored, especially if hemorrhage was severe during surgery.
Kološ F, Bodeček Š & Žert Z (2017) Trans-endoscopic diode laser fenestration of equine conchae via contralateral nostril approach.Vet Surg46 (7), 915-924 PubMed.
Barakzai S Z & Dixon P M (2014) Standing equine sinus surgery. Vet Clin Equine Pract30(1), 45-62 PubMed.
Dixon P M & O'Leary J M (2012) A review of equine paranasal sinusitis: medical and surgical treatments.Equine Vet Ed24(3), 143-158 WileyOnline.
Dixon P M, Parkin T D, Collins N et al (2012) Equine paranasal sinus disease: a long-term study of 200 cases (1997–2009): ancillary diagnostic findings and involvement of the various sinus compartments.Equine Vet J44 (3), 267-271 PubMed.
Other sources of information
Beard W (2014) Frontonasal and Maxillary Sinusotomy Performed Under General Anesthesia. In: Advances in Equine Upper Respiratory Surgery. Ed: Hawkins J. Wiley. pp 177-183
Nickels F A (2012) Chapter 43 - Nasal Passages and Paranasal Sinuses. In:Equine Surgery. 4th edn. Eds: Auer J A & Stick J A. W B Saunders, USA. pp 557-568.
Tremaine W H & Freeman D E (2007) Disorders of the Paranasal Sinuses. In: Equine Respiratory Medicine and Surgery. Saunders Elsevier, USA. pp 403-404.