Page 669 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

644 CHAPTER 3

VetBooks.ir 3.84 the swelling and discharge from the arytenoid car-
tilage for a reasonable period in some established
cases. This is usually associated with improvement
in arytenoid motility. Significant axial granulomas
and kissing lesions do not usually resolve with this
treatment regime, but they can be removed, either
by transendoscopic laser surgery or by conventional
surgery via a laryngotomy.
Surgical management of arytenoid chondritis is
by arytenoidectomy, which is also used as a treat-
ment for RLN, typically after failure of a laryngo-
plasty. Partial arytenoidectomy, involving removal
of all the arytenoid apart from the muscular process,
has been shown to be superior to subtotal arytenoi-
dectomy, where a rim of corniculate cartilage is left
in situ. The procedure is performed through a lar-
Fig. 3.84 ‘Kissing lesion’ (arrow) on the right
arytenoid cartilage with a discharging granuloma on yngotomy and can be associated with a number of
the left arytenoid cartilage (arrowhead). complications. Careful reconstruction of the mucosa
is necessary to restore airway function (Fig. 3.85).
3.85
Prognosis
Partial arytenoidectomy has a guarded to fair prog-
nosis for return to athletic activity. The procedure
is associated with complications such as dyspnoea
in the short term, caused by marked postoperative
swelling and dysphagia. Coughing during eating
is quite common, especially in bilateral cases, and
aspiration pneumonia is not unusual. The conser-
vative approach also warrants a guarded prognosis,
but with this regime the majority of the more mildly
affected cases will be able to perform, probably at a
lower level.

LARYNGEAL DYSPLASIA (FOURTH
BRANCHIAL ARCH DEFECT SYNDROME)
Fig. 3.85 Postoperative endoscopy after
arytenoidectomy, showing swelling and Definition/overview
reconstruction of the mucosa.
Embryologically the larynx is derived from the
fourth and sixth branchial arches. The cricoid and
a very narrowed rima glottides. Palpation over the arytenoid cartilage, along with the principal intrin-
affected arytenoid may increase the clinical signs of sic muscles, derive from the sixth arch, while the
airway obstruction and noise. Lateral radiographs of wing of the thyroid cartilage, the crico- and thy-
the larynx may reveal focal mineralisation. ropharyngeus muscles (the upper oesophageal
sphincter) and the cricothyroid muscle (responsible
Management for tension in the vocal fold) derive from the fourth
A prolonged course of antibiotics and NSAIDs arch. A variety of laryngeal abnormalities caused by
(6 weeks) may control the condition and can reduce hypo- or aplasia of the structures that derive from