Page 255 - Clinical Manual of Small Animal Endosurgery

Upper Respiratory Tract 243

of unilateral disease, or where one side is more severely clinically affected,
that the most affected side be examined first. The thought behind this
approach is to minimise any potential contamination of blood and detri-
tus from one side to the other. If the side of greatest clinical interest
should become contaminated with irrigant and other materials from the
contralateral side, it may be more difficult for the operator to distinguish
contamination artifact from real pathology.
With the examination of both sides complete, the operator can now
go back and re-examine any areas of clinical interest for the purposes of
taking biopsies for histopathology and culture, removing foreign bodies
or resecting mass or inflammatory lesions (see section on laser surgery,
below). Multiple biopsy samples should be obtained from any regions
with abnormal appearing mucosa, but other representative areas should
also be selected for biopsy. Aggressive saline irrigation should continue
as even the most gentle technique and small biopsy size will result in
haemorrhage that will otherwise limit visibility. Samples should be col-
lected and separated based on anatomical site to aid the pathologist in
correctly identifying regions of disease. Wire or foam endoscopic tissue
baskets will help preserve the small biopsy specimens for adequate trans-
port in formalin to the laboratory.
This procedure as described is identical for both dogs and cats of all
breeds and sizes. It is worth noting, however, that brachycephalic breeds
of dog and cat, and smaller individual cats, will provide for a more chal-
lenging examination. The reduced space available to the operator will
make it more difficult to examine every nook and cranny of the rhina-
rium. In some cases a smaller-diameter or a flexible fibreoptiscope may
be an appropriate choice of equipment. In any event, these patients will
often have less-complete examinations by virtue of their unique anatomy.

Sinusoscopy

If, based on radiographs (frontal sinus skyline view), CT or MRI, it is
suggested that there is pathology present in the frontal sinus, then endo-
scopic examination is of tremendous value. Indeed, given the relatively
simple structure of the sinus space, and the limited redundancy of the
sinus epithelium, the diagnostic yield of the frontal sinus is often greater
than the rhinarium.
The landmarks of the frontal sinus should be identified. These are the
midline of the skull and the bony prominence that forms the top of the
orbit. A 2 cm × 2 cm area should be clipped just medial to this promi-
nence and prepared for aseptic surgery. A hole that is adequate to insert
the endoscope is then made into the frontal sinus. A small incision is
made into the skin to the level of the periosteum. The size of the incision
should be slightly smaller than the diameter of the endoscope and sheath
combination. The entry point into the frontal sinus can be made using
a small Michele trephine, a Steinmann pin and Jacobs chuck, or a Hall