Page 832 - Problem-Based Feline Medicine

824 PART 10 CAT WITH SIGNS OF NEUROLOGICAL DISEASE

Evidence of external trauma to the head and face such Mannitol is used to decrease cerebral edema and ICP.
as facial lacerations, bleeding from the nose and mouth, Mannitol has been thought to decrease cerebral edema
bruising, or hemorrhage in the external ear canals may primarily through its associated osmotic effects,
be clues to the traumatic etiology. although other effects such as concurrent decreases in
blood viscosity and free-radical scavenging may, in
Diagnosis fact, be more beneficial. By decreasing blood viscosity,
cerebral perfusion will be increased at the same level of
The diagnosis of trauma is usually straightforward
systemic blood pressure. Vasoconstriction will result,
when the trauma is witnessed.
lowering cerebral blood volume and concurrently low-
In some instances, when animals are presented with an ering ICP. Mannitol is administered at 1 g/kg IV over
acute onset of neurological signs and an unknown his- 5–10 minutes. Maximal lowering of ICP most often
tory, examining for external signs of trauma such as occurs in 10–20 minutes.
lacerations or skull fractures is important.
Furosemide (0.7 mg/kg IV) is a loop diuretic that may
Evaluating the retinas and external ear canals for help to lower ICP primarily or may potentiate the
acute hemorrhage may also provide clues to the diag- effects of mannitol. Furosemide given 15 minutes after
nosis. mannitol administration potentiates the intracranial
pressure-lowering effects of the latter.
Advanced imaging studies such as CT or MR imaging
are useful, primarily for determining structural damage The antioxidant drug, desferoxamine mesylate has
to the brain. been shown to reduce cold-induced brain edema in cats.
Surgical treatment centers on evacuation of sub-
Differential diagnosis dural hematomas, removal of depressed skull frac-
tures, or debridement of damaged tissue and foreign
External evidence of a traumatic incident is helpful to
material.
separate traumatic causes of stupor and coma from
● Craniectomy and durotomy has been shown to
other intracranial diseases.
lower ICP acutely by 15–65%, respectively, in cats,
Sometimes cats with intracranial disease are unbal- however, long-term benefits are uncertain.
anced, weak or have seizures and fall. This may result
in external injuries being misconstrued as the actual
Prognosis
cause of the intracranial signs.
Prognosis for life is good if signs are not severe.
Treatment
Cerebrocortical and cerebellar injuries are more readily
Basic life support measures may be necessary includ- recoverable from than brain stem injuries.
ing blood or isotonic fluid administration.
Corticosteroid administration for treatment of head Prevention
trauma is commonly used but efficacy is often based
Keep cats in a controlled environment and prevent free-
upon anecdotal evidence. Beneficial effects of methyl-
roaming.
prednisolone sodium succinate (30 mg/kg IV slowly)
in nervous system injury include inhibition of lipid per-
oxidation and its associated detrimental effects. The BRAIN TUMOR***
role of corticosteroids in the treatment of head trauma,
however, is unclear and are currently not recommended Classical signs
in humans suffering from head trauma.
● Middle-aged to older cats.
Hyperventilation keeping PaCO concentrations ● Signs include seizures, circling, blindness,
2
between 28 and 32 mmHg can decrease ICP due to behavior changes, and may progress to
the established effects of PaCO concentrations on stupor and coma.
2
cerebral blood flow.