Page 1105 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

1080 CHAPTER 10

VetBooks.ir radiographs and endoscopy. It may provide vital CENTRAL NERVOUS SYSTEM
TRAUMA/ACCIDENTS
information to aid in choosing the most appropri-
ate therapeutic plan.
LIGHTNING STRIKE
Management
While not many cases of THO are caused by otitis Signs from mild ataxia to sudden death may be seen.
media/interna, antimicrobial therapy is justified Evidence such as singed lines in the coat or evidence
in all suspected cases of THO because of the risk of lightning strike on nearby trees may be present.
of CNS infection from bacterial invasion of the Multiple animals may be affected, particularly if
petrous temporal bone fracture sites. Conservative they have taken shelter under the same tree during
management also includes treatments to reduce a storm. Commonly, no evidence is found and there
the pain and inflammation at the site of the osteo- is simply a history of a thunderstorm in the area.
arthropathy, such as steroids and NSAIDs. There Also, animals may on occasion become frightened in
is a report of the benefit of oral gabapentin in a a storm and collide with fixed objects, resulting in
case of THO that presented with acute onset spinal injuries and death.
headshaking signs. THO cases with facial nerve
paralysis should be closely monitored for exposure CEREBRAL TRAUMA (FRONTAL/
keratitis and decreased tear production. A subpal- PARIETAL IMPACT)
pebral lavage catheter can be employed to apply
lubrication and any corneal ulcer treatments, in Definition/overview
addition to a tarsorraphy to protect the cornea. Signs related to cerebral trauma most frequently
Care should be taken to avoid mouth gags and occur following trauma to the frontal or parietal
nasogastric intubation. regions of the head. Horses are susceptible to such
Historically, a unilateral or bilateral stylohy- injuries because of their size, behaviour and rela-
oidectomy was used to reduce loading on the TH tively thin calvarium.
articulation, reduce instability at the fracture site,
reduce pain and reduce the risk of repeat fracture Aetiology/pathophysiology
of the petrous temporal bone. However, given the Abnormal neurological signs may be the result of
adverse consequences of this surgical procedure mechanical injury to the brain, cerebral oedema,
(such as disease recurrence and dysphagia), cerato- parenchymal haemorrhage and ischaemia produced
hyoidectomy was introduced and it is now the rec- by brain swelling and intravascular clotting. The
ommended surgical procedure for cases of THO. type of mechanical forces acting on the cerebrum
Usually performed under general anaesthesia, a include so-called ‘to’, ‘fro’ and also rotational forces,
recent case report demonstrated that ceratohyoid- sending the soft tissue of the brain smashing against
ectomy could be performed in the standing sedated the irregular, unyielding surface of the calvarium.
healthy horse, but at this time the procedure has This violent trauma to the brain results in injury
not been published in a case series of standing to the intracranial vasculature, cell bodies, glia and
sedated THO cases. axons. The optic nerves may be stretched, leading to
optic nerve avulsion or secondary ischaemic/reper-
Prognosis fusion injury that may take several days to become
The prognosis is fair to good, with the major- apparent. Mechanical injury, intracranial haemor-
ity of horses returning to their previous level rhage and cerebral oedema are the most important
of competition following treatment. Vestibular factors in animals with cerebral trauma involving
and facial nerve deficits may take up to a year to fractures. Compound and/or displaced fractures
improve. of the frontal and parietal bones are likely to cause
cerebral laceration, haemorrhage and potential