Ethmoid Hematomas
David
Moores
Dr. Daniel
J. Burba
A hematoma is an abnormal, persistent, localized
collection of blood outside the vessels. The condition of an ethmoid hematoma
is a hematoma that forms in the complex bony structure that exists in the nasal
passages between the eyes. It is an uncommon upper respiratory tract
abnormality found in horses. The
following information is concerned with defining an ethmoid hematoma, how it is
diagnosed, the treatment options, and the prognosis of eliminating this
condition.
Ethmoid hematomas form within the complex bony structure
within the nose that is lined with many fine blood vessels. Sometimes, a small
vessel will begin to bleed and the blood gets trapped between the bone and the
respiratory epithelial lining. The
blood accumulates and separates the lining from the bone causing a hematoma.
The hematoma progressively grows over time and expands into the adjacent
sinuses or the caudal nasal sinus. It
can get large enough that it partially obstructs the airways, leading to
abnormal upper respiratory sounds as well as the characteristic
nosebleeds. Ethmoid hematomas are not
life threatening, but they are locally destructive and will continue to grow.
They are fairly easy to diagnose, but can be difficult to treat successfully.
This is why ethmoid hematomas are considered a chronic, debilitating disease.
This condition is usually seen in middle-aged to older
horses. There is an increased
probability of developing an ethmoid hematoma beyond seven years of age and the
risk rises with age. The highest prevalence among breeds lies with the Arabian,
followed by Thoroughbreds. There have been no cases reported in Standardbreds.
No link to gender has been found.
Horses with ethmoid hematomas usually present with
chronic nosebleeds of weeks to months or even longer. These nosebleeds occur when the hematoma gets large enough that
part of it is no longer covered by the respiratory epithelium or the hematoma
becomes ulcerated and leaks. Other
nasal discharges such as a mucopurulent discharge are associated with the
locally destructive effects the hematoma has on the surrounding area. The other common sign these horses may show
is abnormal noise when breathing. This noise is a result of the mass being so
large that the airways become partially obstructed. Coughing, facial deformity, bad breath, head shaking, and shyness
are other signs associated with ethmoid hematomas. The horse usually appears in excellent health otherwise.
This condition is fairly easy to diagnose based on the
clinical signs of nosebleeds and respiratory noise. Endoscopic examination of
the upper airway with an endoscope along with radiographs of the area are
available diagnostic procedures. However, a biopsy of the lesion still needs to
be done for definitive diagnosis as well as to rule out other possible diseases
such as nasal polyps, ulcerative or mycotic rhinitis, neoplasia, trauma, or
fungal lesions as these can all resemble an ethmoid hematoma on endoscopic
examination.
With the endoscope in the nasal cavity, one can find a
soft tissue mass protruding into the nasal passage or nasopharynx, obstructing
the ethmoid area. This common finding may be only part of the lesion, the
remainder being out of sight within the paranasal sinuses. It is important to
keep in mind that an ethmoid hematoma may be completely located within a
paranasal sinus and have no endoscopically visible component. Therefore, the absence of a lesion does not
completely rule out an ethmoid hematoma.
Radiographs, or x-rays, are used along with the
endoscopic exam to evaluate the ethmoid region and the paranasal sinuses. The
most diagnostic view is a standing lateral (side) view of the paranasal sinus
area, which is an x-ray of the side of the horse’s head and nose while the
horse is standing normally. Ethmoid hematomas appear as soft tissue masses in
association with the ethmoid bones and sometimes in the sinuses. It is
important to define the area affected by the hematoma and whether there is
sinusal involvement or not as that has implications as far as treatment with
the degree of invasiveness of the surgical procedure and prognosis is
concerned. Computed Tomography (CAT
scan) is another high-tech imaging tool that is available to view the lesion.
After observing the lesion, a biopsy must be taken for a
definitive diagnosis. The biopsy report from an ethmoid hematoma describes
respiratory epithelium, fibrous tissue, and hemosidrin-filled macrophages. This
observation rules out neoplasia as there is no evidence of uncontrolled,
progressive cell multiplication is absent.
Once a definitive diagnosis has been made, there are
several treatment options available to choose from. Surgical removal of the
mass through a frontomaxillary sinustomy is a common procedure. A bone flap is
made into the sinus over the mass and the hematoma is removed by curettage,
cryotherapy, electrocautery, or laser.
Another procedure that is less invasive is intralesional
formalin injection through the nostrils guided by an endoscope. In standing, sedated horses, a catheter is
passed to the mass via the endoscope and 10% formalin (4% formaldehyde)
solution is injected intralesionally. Tissue necrosis and sloughing occur
within 5-10 days and the procedure is repeated in intervals of 10-14 days until
all the mass has been removed.
Ethmoid hematomas are considered difficult to resolve.
Studies have shown that no matter which treatment method used, the recurrence
rate of ethmoid hematomas occurs in 30-50% of cases anywhere from several
months to years after removal procedure. Additional treatments are required,
thus an ethmoid hematoma is considered a chronic, debilitating disease.
In summary, this uncommon, benign, respiratory condition,
found mostly in older Arabians and Thoroughbreds is easily diagnosed but
difficult to treat. Complete localization of the lesion through proper
diagnostic procedures is imperative as well as complete removal.
Ethmoid Hematomas
David Moores
Class 2003
LSU School
of Veterinary Medicine
VMED 5010
Advanced
Equine Respiratory
March 6,
2002