Page 80 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

Chapter 5 · Surgery of the ear

Administration of anti-inflammatory doses of gluco-
WARNING
corticoids, such as prednisolone at an initial starting dose
VetBooks.ir associated with a reduced risk of polyp recurrence In cats, the sympathetic fibres run along the surface of
of 1–2 mg/kg/day with tapering over 3–4 weeks, may be
a bony prominence – the ‘promontory’ – on the dorsal
following removal by traction (Anderson et al., 2000; Greci
surface of the bulla at the level of the septum and are
et al., 2014). In cases with radiographic evidence of
severe changes to the tympanic bulla (e.g. pathological easily damaged, particularly if the inner compartment
of the bulla is curetted. The round window and oval
expansion, sclerosis or lysis of the bulla wall), those in window are also located on the dorsal surface of the
which the polyp cannot be adequately removed by bulla near the septum; curetting the rostrodorsal
traction avulsion, or where there has been polyp recur- surface of the bulla could result in Horner’s syndrome
rence following traction avulsion, ventral bulla osteotomy or signs of OI (ataxia, nystagmus, head tilt). Bulla
is the treatment of choice (see above for description of lavage should be performed gently and with warm,
the technique in dogs). Ventral bulla osteotomy to loosen sterile saline to prevent barotrauma
and remove the stalk of the polyp is usually performed
before removal of the protruding part of the polyp in the
horizontal ear canal. The remainder of the ear polyp can Prognosis: Regrowth of polyps has been reported in
be removed from the canal with alligator forceps and 17–50% of cats treated with traction removal alone. In a
gentle traction by a non-sterile assistant. more recent study describing a technique of polyp removal
via perendoscopic transtympanic traction, polyp recurrence
Ventral bulla osteotomy in cats: The cat is placed in was reported in only five of 37 cats (13.5%). Twenty-one of
dorsal recumbency, with the head and neck extended and 37 cats in this study were also treated with glucocorticoids
stabilized and the forelegs pulled caudally. The large round after polyp traction (Greci et al., 2014). In one study, cats
bullae are readily palpable caudomedial to the mandible in with normal bullae on radiographs had no recurrence of
this position. The approach and bulla entry are initially the polyps after traction removal, whilst cats with radiographic
same as for the dog (see above), but with the incision evidence of OM had a 56% recurrence rate with traction
centred over the palpable bulla. The bulla is palpated removal (Veir et al., 2002). In another study, recurrence
frequently for orientation during dissection. was reported in nine of 14 cats that received traction alone
The initial osteotomy exposes the larger ventromedial and in none of the eight cats that received glu co corticoids
compartment, which contains the cochlear (round) after polyp traction (Anderson et al., 2000).
window on the dorsocaudal wall of the bulla near the Neurological damage often occurs during ventral bulla
septum, and the promontory, a bony process on the osteotomy and polyp removal. Horner’s syndrome (Figure
dorsomedial aspect of the bulla. The sympathetic nerve 5.8) from sympathetic nerve damage has been reported in
>80% of cats after bulla osteotomy and can also occur with
fibres course along the surface of the promontory, pass-
ing through a narrow fissure in the dorsal aspect of the traction alone. Clinical signs (miosis, ptosis and third eyelid
septum into the dorsolateral compartment. The sympa- prolapse) usually resolve within a month. Intraoperative
trauma to the sympathetic nerve fibres is most common
thetic nerve fibres continue along the dorsomedial wall of
that compartment before entering the petrous temporal with curettage of the ventromedial compartment, where the
bone just medial to the opening of the auditory tube at nerves are less protected by surrounding fibrous tissue.
Persistent Horner’s syndrome does not seem to affect a
the rostral apex of the bulla.
cat’s behaviour. About 40% of cats may have signs of
Once the outer bulla has been opened, the inner
septum in the lateral half of the outer bulla is perforated peripheral vestibular disease after bulla osteotomy for
polyp removal (Faulkner and Budsberg, 1990; Trevor and
with a Steinmann pin or burr; the perforation is enlarged
Martin, 1993). The signs are transient in most cats.
gently with the burr, rongeurs or a curved haemostat. The
bone in the septum is more fragile than that of the outer
bulla and should be removed carefully to avoid trauma to
the promontory.
The polyp’s attachments to the bulla wall are removed
gently, often by traction with a haemostat, and the
extracted tissue is saved for culture and histological eval-
uation. Curettage to remove epithelial remnants is usually
unnecessary; when this is performed, the surgeon must
avoid curetting the caudomedial and dorsal portions of
the bulla in cats to prevent damage to the round and oval
windows, ossicles and sympathetic fibres.
The bulla is flushed gently with warm, sterile saline. As
in dogs, a drain is usually unnecessary but should be
placed if the bulla contains infected material that cannot
be completely removed.
5.8 Horner’s syndrome in a cat after ventral bulla osteotomy.
PRACTICAL TIP

In cats, once the ventral bulla wall has been removed, Nasopharyngeal polyps
the inner septum will cross the rostrolateral third of the
bulla. The septum can usually be removed in pieces These are removed under anaesthesia. The soft palate is
with a small haemostat after it has been perforated retracted rostrally with stay sutures or a spay hook, and
with a Steinmann pin or haemostat tip the polyp is digitally displaced ventrally into the orophar-
ynx. Incision of the soft palate is usually not necessary for

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