Page 819 - Clinical Small Animal Internal Medicine

71 Disorders of the Forebrain 787

used commonly in humans in the diagnosis of acute supply may reverse the initial damage. However, the win-
VetBooks.ir stroke. DWI sequences detect the random diffusion of dow of opportunity for this to occur is approximately
six hours, making it very rarely achievable in animals.
water molecules through tissues. When brain paren-
chyma loses its blood supply, energy delivery to neurons
are important, as is maintaining normal blood pressure.
fails and water becomes trapped within cells by cell Monitoring and correction of basic physiologic variables
membranes. This can be detected on DWI sequences as The most important consideration in hemorrhagic
a hyperintense region within the brain representing stroke is maintenance of cerebral perfusion by treatment
brain parenchyma in which water diffusion is restricted of hypotension and elevated ICP, as well as treating the
as a result of this energy failure. In addition to DWI, per- underlying cause if one has been identified. The medical
fusion‐weighted imaging is employed to depict regions management of dogs with intracranial hemorrhage com-
of hypoperfusion in the brain and can document the tis- monly includes:
sue “at risk” (i.e., penumbra) by comparing the results stabilization of the patient (airway protection, moni-
with the findings on DWI. In addition, MRA can nonin- ● toring and correction of vital signs)
vasively assess the intracranial vessels of stroke patients. assessment and monitoring of the neurologic status
Cerebrospinal fluid analysis is unlikely to confirm a ●
diagnosis of CVA but helps to rule out inflammatory ● determination and treatment of potential underlying
causes of the hemorrhage
CNS disease. CSF is variable in dogs and cats with CVA. assessment of the need for specific treatment meas-
In most cases, it is either normal or reflects a mild mono- ● ures, including management of increased ICP.
nuclear or neutrophilic pleocytosis. CSF proteins are
occasionally elevated. The risk of neurologic deterioration and cardiovascular
instability is highest during the first 24 hours after the
Identification of Underlying Causes of Stroke onset of an intracranial hemorrhage, as the space‐occu-
In the case of presumptive or confirmed ischemic stroke, pying lesion slowly expands and cerebral vasogenic
ancillary diagnostic tests should focus on evaluating the edema develops. During this phase, if the neurologic sta-
animal for hypertension (and its potential underlying tus deteriorates, aggressive therapy to control ICP with
causes), endocrine disease (hyperadrenocorticism, mannitol (0.25–1 g/kg administered IV over 20 min) or
hypothyroidism, hyperthyroidism, diabetes mellitus), other agents may need to be considered, and in rare cases
kidney disease (especially protein‐losing nephropathy), craniotomy to alleviate cerebral edema.
heart disease, and metastatic disease. Diagnostic tests in The prognosis for ischemic or hemorrhagic stroke
presumptive or confirmed cases of hemorrhagic stroke depends overall on the initial severity of the neurologic
should focus on screening the animal for a coagulopathy, deficit, the initial response to supportive care, and the
hypertension (and potential underlying causes), and severity of the underlying cause if one has been identified.
metastatic disease (particularly hemangiosarcoma). Most cases of ischemic stroke recover within several
weeks with only supportive care and there appears to be
Treatment and Prognosis no association between the region of the brain involved,
Once the diagnosis of a stroke has been made, any poten- the type of infarction (territorial or lacunar), and out-
tial underlying or associated disease should be identified come. However, dogs with a concurrent medical condi-
and treated accordingly. Generally, treatment of these tion have a significantly shorter survival time than those
patients aims to provide supportive care, maintain ade- with no identifiable medical condition. Dogs with a con-
quate tissue oxygenation, and manage neurologic and current medical condition are also significantly more
nonneurologic complications. Nursing management of a likely to suffer from recurrent neurologic signs due to
recumbent dog will be vital to the success of more spe- subsequent infarcts.
cific therapies. Such management includes attention to
the prevention of decubital ulceration, aspiration pneu- Feline Ischemic Encephalopathy
monia, and urine scald, in addition to physical therapy
and enteral nutrition provision. More specific therapies Feline ischemic encephalopathy (FIE) represents a
are aimed at preventing further neurologic deterioration. peculiar variant of cerebrovascular disease. FIE is an
Most cases of ischemic stroke recover within several ischemic necrosis of cerebral tissue that has been
weeks with only supportive care. Potential underlying reported sporadically in male and female cats of all ages,
causes should be investigated and treated accordingly to especially in summer months in the US. Clinical signs
limit the risk of recurrences. Definitive therapy in people are usually acute in onset, nonprogressive, and variable,
involves thrombolytic therapy in an attempt to salvage and typically suggest unilateral cerebral or brainstem
the ischemic penumbra – tissue surrounding the involvement. Signs may include depression, head tilt,
ischemic core in which rapid restoration of the blood anisocoria, circling, seizures, and changes in attitude/