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Epiglottis: entrapment – repair

ISSN 2398-2977


Podcast: Epiglottis: entrapment - repair

Overview

  • Epiglottic entrapment Larynx: epiglottic entrapment occurs when the ary-epiglottic (arytenoepiglottic) folds become abnormally positioned above the dorsal epiglottic surfaceEpiglottis: entrapment 01 - endoscopy.
  • The condition is treated surgically using a number of techniques:
  • Currently techniques that allow axial midline division of the fold are preferred because of preservation of fold mucosa (retracts ventrally and heals in normal position), reduced scarring, lower recurrence rates and minimal invasiveness.

Transendoscopic techniques

Advantages

  • Standing out-patient correction with minimal invasiveness.
  • Minimal hemorrhage and post-operative swelling.
  • Rapid healing.
  • Minimal complications.

Disadvantages

  • Cost of equipment.
  • Specialized training in laser operation.
  • Potential damage to epiglottis.

Requirements

Equipment

Duration

  • Total surgery time 30-50 min.

Restraint

Nd-YAG laser or diode technique

Procedure

  • Pass a flexible contact chisel probe laser fiber through the biopsy port of the endoscope.
  • Divide the entrapping membrane along its midline, starting at the apex of the epiglottis and working caudallyEpiglottis: entrapment - transendoscopic laser repair 01Epiglottis: entrapment - transendoscopic laser repair 02Epiglottis: entrapment - transendoscopic laser repair 03Epiglottis: entrapment - transendoscopic laser repair 04.
  • Diode laser:
    • A technique in which a silicone-covered laser guide is placed between epiglottis and entrapped folds can be utilized to minimize adjacent tissue damage.
    • With this technique, a horizontal incision is made with transendoscopic diode layer until silicone guide is visualized.
    • A vertical incision is then made along the axial midline between the horizonal incision and end of the fold caudally.

Prognosis

  • The re-entrapment rate in a large series of cases was approximately 5% (corrected on second laser procedure) and 10-15% of horses experienced dorsal displacement of the soft palate Soft palate: dorsal displacement after laser correction.
  • Most horses returned to training within 1-2 weeks and raced within 1 month of surgery.

Monopolar electrosurgical cutting technique

Procedure

  • Pass an active electrode through the biopsy channel of a flexible endoscope.
  • Conduct surgery as for Nd:YAG/diode laser technique as above.

Prognosis

  • This technique has not had large numbers of cases reported, but 2 of 5 cases treated with this technique developed a minor degree of re-entrapment although, none had dorsal displacement of the soft palate.

Special risks

  • The main disadvantage of this procedure is the potential for serious electrical accidents and burns to both operator and patient.
  • The precautions necessary to minimize the above risk make this technique impractical.

Transnasal or transoral bistoury techniques

Requirements

Equipment

  • A bistoury – a long gently curving wire with a hook and cutting edge at one end to engage the membrane and slit it by pulling the instrument in a rostral direction.

Restraint

Either Standing sedation with the pharynx topically anesthetized Anesthesia: standing chemical restraint.
Or General anesthesia (GA) Anesthesia: general – overview.

Advantages

  • Cheap instrumentation.
  • Minimal invasiveness.
  • Minimal complications.

Disadvantages

  • Potential for lacerating soft palate, epiglottis or pharynx (reduced by performing this technique transorally under anesthesia) allows more accurate placement and controlled cutting.

Post-operative care

  • Variable post-operative appearance of epiglottic area, particularly in amount and persistence of post-operative subepiglottic swelling, pre-operative and peri-operative NSAIDs Phenylbutazone and post-operative nebulization with anti-inflammatory solution are helpful Therapeutics: anti-inflammatory drugs.
  • Training can begin once the swelling has subsided; usually 7-10 days.

Prognosis

  • Re-entrapment rate 5-10%.

Nasal approach

Procedure

Oral approach

Procedure

  • Pass hand holding the hooked end of the bistoury into oral pharynx (under GA Anesthesia: general – overview).
  • Engage on the membrane covering the epiglottic tip via palpation.
  • Cut epiglottic fold as above.

Surgical resection

Advantages

  • Can be used to treat excessively thickened or scarred membrane entrapments (5%) often combined with severe epiglottic hypoplasia.

Disadvantages

  • Invasive.
  • General anesthesia Anesthesia: general – overview required.
  • Potential for epiglottic cartilage damage.
  • Higher recurrence rate.
  • High post-operative occurrence of dorsal displacement of soft palate (DDSP) Soft palate: dorsal displacement (up to 20%) – intermittent or persistent – may occur immediately post-operatively or as late as 1 week afterwards. This may be because of previously existing epiglottic hypoplasia or deformity, or because of inflammation and scarring in the epiglottic mucosa limiting epiglottic mobility.
  • Epiglottic mobility is directly affected by the amount of mucosa resected which should be the minimal amount to prevent entrapment recurrence.

Restraint

Procedure

Approach

  • Perform ventral laryngotomy Larynx: ventral laryngotomy.
  • Withdraw endotracheal tube temporarily to allow direct visualization of the caudal margin of the entrapped membrane.

Core

  • Grasp edge of membrane on its midline with sponge forceps or Allis tissue forceps and retract into larynx, thereby everting apex of epiglottis.

If epiglottis has become un-entrapped during intubation – the end of a curved sponge forceps can be hooked under the epiglottis base and used to evert the epiglottis toward the larynx. Then grasp aryteno-epiglottic tissue with forceps and retract into larynx.

Avoid trauma to epiglottic cartilage during resection or chondroma formation or cartilage deformity can occur.

  • Attach Allis tissue forceps to free edge of retracted membrane on each side of midline in order to symmetrically spread out the tissue before resection.
  • Identify the apex and lateral margins of the epiglottis by digital palpation.
  • Divide membrane using Metzenbaum scissors – in the midline down towards the tip of the epiglottis.
  • Continue incision along both edges of the epiglottis for approximately 1/3 of its length before the folds are amputated.

The resection should be made at least 5 mm from the epiglottis to avoid cartilage damage.

  • The exact amount of resection depends upon the individual case and some surgeons remove only a central V portion and no lateral folds.
  • A staphylectomy Soft palate: trimming may be carried out concurrently by some surgeons although this is contra-indicated in epiglottic hypoplasia cases.

Aftercare

  • Laryngotomy management is routine Larynx: ventral laryngotomy.
  • Post-operative care is similar to the bistoury technique as above.
  • Start exercise after healing is complete; about 4 weeks.

Further reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Curtiss A L, Aceto H & Embertson R M (2020) Race performance following epiglottic entrapment surgery in Thoroughbred yearlings. Equine Vet J 52 (1), 52-58 PubMed. 
  • Beste K J et al (2020) Transendoscopic correction of epiglottic entrapment with a silicone-covered laser guide and diode laser in 29 horses. Vet Surg 49 (1), 131-137 PubMed. 
  • Shaw D J & Rosanowski S M (2019) Race-day performance of horses with epiglottic entrapment, and following surgical correction using intra-oral curved bistoury hook in anaesthetised horses. Vet J 250, 24-27 PubMed. 
  • Kieffer PJ et al (2018) Using quarterly earnings to assess racing performance in 66 thoroughbreds after transendoscopic laser surgery for treatment of epiglottic entrapment. Vet Surg. 47 (5), 605-613 PubMed. 
  • Coleridge M O et al (2015) Endoscopic, transoral, reduction of epiglottic entrapment via wire snare technique. Vet Surg 44 (3), 348-351 PubMed. 
  • Aitken M R & Parente E J (2011) Epiglottic abnormalities in mature nonracehorses: 23 cases (1990-2009). JAVMA 238 (12), 1634-1638 PubMed. 
  • Lacourt M & Marcoux M (2011) Treatment of epiglottic entrapment by transnasal axial division in standing sedated horses using a shielded hook bistoury. Vet Surg 40 (3), 299-304 PubMed. 
  • Perkins J D, Hughes T K & Brain B (2007) Endoscope-guided, transoral axial division of an entrapping epiglottic fold in fifteen standing horses. Vet Surg 36 (8), 800-803 PubMed. 
  • Dixon P M & Collins N (2004) The equine epiglottis. Equine Vet Educ 16 (6), 299-301 VetMedResource.
  • Lumsden J M et al (1994) Surgical treatment for epiglottic entrapment in horses – 51 cases (1981-1992). JAVMA 205 (5), 729-735 PubMed.
  • Ross M W et al (1993) Transoral axial division, under endoscopic guidance, for correction of epiglottic entrapment in horses. JAVMA 26 (3), 416-420 PubMed.
  • Tulleners E P (1991) Correlation of performance with endoscopic and radiographic assessment of epiglottic hypoplasia in racehorses with epiglottic entrapment corrected by use of contact neodymium – yttrium aluminum garnet laser. JAVMA 198 (4), 621-626 PubMed.

Other sources of information

  • Ducharme N G & Rossignol F (2019)Larynx. In: Equine Surgery. 5th edn. Eds: Auer J & Stick J. Saunders, USA. pp 734-769.