GENERAL CONSIDERATIONS

General Considerations

•mean age 11.3 years, with 90% cats > 8 years

•malignant tumors are more common

•LSA is most common although ADC and SCC also reported

•LSA may present as a diffuse thickening of laryngeal mucosa or localized mass

Clinical Features

•clinical signs: voice change, respiratory noise or distress with obstruction, exercise intolerance, dysphagia, and pain with inflammation and ulceration

•diagnosis: ultrasound, survey radiographs, and biopsy under direct endoscopic visualization

•DDx: inflammatory polyps and laryngeal cysts

TREATMENT

General Considerations

•benign tumors and cysts can be removed while preserving function although more radical procedures required for malignant tumors such as permanent tracheostomy and complete laryngectomy

•partial or complete laryngectomy is indicated for proliferative (i.e., granulomatous laryngitis) and neoplastic diseases

•temporary tracheostomy may be required to permit resection

•other options include radiation therapy and chemotherapy depending on tumor type and extent

Total Laryngectomy

•total laryngectomy is indicated for tumors with bilateral laryngeal involvement

•ventral midline cervical incision

•traction sutures are placed around the 4th tracheal ring

•trachea is transected caudal to the cricoid cartilage

•sterile endotracheal tube is placed into the distal trachea and used to maintain general anesthesia

•laryngeal attachments of the thyropharyngeal, cricopharyngeal, sternothyroid, and thyrohyoid muscles are transected

•sternohyoid muscle is preserved

•caudal aspect of the larynx is elevated and mobilized free of all attachments

•sensory and motor nerves to pharyngeal mucosa and muscles and cranial esophagus are preserved to maintain normal swallowing ability

•mucosa is incised at the rostral edge of the larynx and the entire larynx, including the epiglottis, is removed

•pharyngeal mucosa is closed with a continuous inverting pattern of 3-0 absorbable suture material

•transected ends of the thyropharyngeal and cricopharyngeal muscles are sutured together ventral to the pharynx and esophagus

•proximal segment of the trachea is exteriorized

•sternohyoid muscle is sutured to the trachea with interrupted sutures to maintain the trachea in a ventral position

•excess subcutaneous tissue and skin are removed from the stoma site to prevent occlusion of the tracheostomy

•elliptical skin incision is made 25%-30% larger than the trachea

•subcutaneous tissue is sutured to the tracheal wall

•skin is sutured to the tracheal mucosa with 3-0 or 4-0 absorbable suture material in an interrupted pattern

Rotatory Door Myocutaneous Flap

•rotatory door myocutaneous flap was developed to bring vascularized epidermis into the laryngeal defect

•island flap is based on the sternohyoid muscle with the dermis sutured to the mucosa

•ventral midline cervical skin incision forms the medial edge of the myocutaneous flap

•skin is not separated from the sternohyoid muscle and cranial thyroid blood vessels are preserved

•cutaneous segment of the myocutaneous flap is depilated by shaving the epidermis down to the dermis

•adequate dermal shaving prevents regrowth of hair and subsequent dermal scarring supports the graft

•exposed dermal surface is covered by squamous or respiratory epithelium

Segmental Hemilaryngectomy

•indication: small tumors involving the vocal cord and adjacent superficial tissues

•ventral midline laryngotomy

•tumor extent and margins are assessed

•standard vocal cordectomy is performed if the tumor is localized to the vocal cord

•mucosal incisions are deepened through full-thickness laryngeal cartilage if tumor involvement is more extensive

•mucosal and cartilage defect is repaired primarily or filled with free tissue implants

•free tissue implants include costal cartilage, buccal mucosa, and thyroid cartilage

•free tissue implants are only used when the majority of the thyroid and arytenoid cartilages are resected

•free tissue implants are sutured to the remaining cartilage with 3-0 or 4-0 monofilament absorbable suture material on a cutting needle

•strap muscles and subcutaneous tissue are used to support the external aspect of the free tissue implant

Augmented Myomucosal Flap

General Considerations

•augmented myomucosal flap was developed to repair laryngotracheal resection in 2 stages

Stage 1

•ventral midline cervical incision

•free buccal mucosal graft is used to cover the planned defect

•porous high-density polyethylene (0.85 mm thick, average pore size > 150 μm, and pore volume 50%) is sutured over the free buccal mucosal graft

•sternohyoid muscle, with preservation of cranial and caudal attachments, is mobilized and sutured over the free buccal mucosal graft and polyethylene

Stage 2

•composite graft is released

•laryngotracheal resection is performed as planned for tumor excision

•laryngotracheal defect is repaired with the composite graft

•polyethylene does not need to be fully covered by mucosa at the time of reconstruction as the polyethylene will be infiltrated by granulation tissue and rapidly epithelialized

•temporary tracheostomy is performed distal to the resection site and maintained until healing and confirmation of airway patency

Prognosis

•rhabdomyoma: most dogs will live > 1 year and are considered cured

•malignant laryngeal tumors are rare tumors which are not frequently treated hence data not available