Page 254 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Musculoskeletal system: 1.6 The hea d 229

VetBooks.ir Aetiology/pathophysiology 1.432
Basilar skull fractures are caused almost invariably
by a backward fall, while dorsal cranial fractures are
usually a consequence of a head-on collision. Facial
fractures usually involve the nasal and/or frontal
bones and occasionally also the maxillary or lacrimal
bones. They occur by direct trauma through falling
forwards, kicks or rearing and striking a solid object
above the head.
Some clinical signs associated with cranial frac-
tures are caused by accompanying brain dam-
age and may increase in severity as pressure from
oedema and subarachnoid haemorrhage grows. The
raised intracranial pressure causes cerebral anoxia.
Concurrent injuries may include avulsion of the lig-
amentum nuchae origin, tearing of the rectus capitis
muscles or fracture of the basisphenoid or basihyoid
bones. The frontal and nasal bones overlie the para-
nasal sinuses and nasal passages. If the fracture is
sufficiently displaced, there may be interference with
breathing. Untreated displaced facial fractures can
lead to permanent facial deformity, sequestrum for-
mation or chronic sinusitis.

Clinical presentation Fig. 1.432 This horse sustained a wound to the
Horses with a cranial fracture may be so severely right side of the skull. Note the depression centred
affected that they are unable to rise. In other cases, over the maxillary region. Radiography revealed a
a progression in central nervous system (CNS) signs slightly displaced fracture of the facial crest.
(e.g. ataxia, depression, head tilt, CN deficits and
nystagmus) and alterations in cardiac and respira-
tory function may be seen. Irregular breathing, with crepitus and subcutaneous emphysema. Distortion
periods of apnoea, is usually indicative of a poor and partial blockage of the upper airways may cause
prognosis. There may also be visible signs of trauma respiratory stridor. Damage to the nasolacrimal duct
in the region of the poll or the dorsal cranium. may result in signs of epiphora.
Where a cranial fracture has exposed the CNS,
cerebrospinal fluid may be seen leaking from an ear Differential diagnosis
canal. Epistaxis is common. In most cases of acute-onset neurological signs, a
Horses with facial or cranial fractures are usu- history of recent trauma involving the head is highly
ally presented as emergencies. Facial fractures may suggestive of a fracture. The neurological signs are
have obvious signs of external trauma (Fig. 1.432) similar to those seen in acute-onset vestibular disease
and in severe cases there may be open communica- and inflammatory disease of the CNS. Facial swell-
tion with the nasal passages or paranasal sinuses. ing and epistaxis after a fall or other trauma in some
There will be overlying swelling due to oedema and cases may only be associated with soft-tissue trauma.
trapped air, and epistaxis and facial asymmetry are
common. A wound may be present, but a fracture Diagnosis
should not be ruled out where the skin has remained Several radiographic views may be needed to
intact. Palpation, if tolerated by the horse, may reveal detect and assess fractures of the face and cranium