TRANSIENT ISCHEMIC ATTACK
I. Definition
A.
Classic definition: sudden or rapid onset of
neurologic deficit caused by focal ischemia that
lasts for a few minutes and resolves completely
within 24 hr.
B.
It has been found that with more widespread
use of modem imaging techniques for the brain,
up to one third of patients with symptoms
lasting less than 24 hr actually have a small
infarct.
C.
Updated definition: a transient episode of
neurological dysfunction caused by focal brain,
spinal cord, or retinal ischemia, without acute
infarction
II. Incidence/prevalence
A.
Incidence is 160/100,000; prevalence is
135/100,000
III. Etiology
A.
Atherosclerotic disease
1.
Aorta
2.
Carotid arteries
3.
Vertebral arteries
4.
Intracranial atherosclerosis
B.
Cardiac emboli as seen in arrhythmia (atrial
fibrillation), myocardial infarction (MI),
congestive cardiomyopathy, and valvular
disease
C.
Vasculitis conditions such as moyamoya
disease, fibromuscular dysplasia, lupus, and
others
D.
Hematologic causes
1.
Red blood cell (RBC) disorders
a.
Increased sludging
b.
Decreased cerebral
oxygenation such as in severe
anemia
c.
Polycythemia, sickle cell
anemia
2.
Platelet disorders
a.
Thrombocytosis
b.
Thrombocytopenia
3.
Increased viscosity/hypercoagulable
conditions
a.
Antiphospholipid antibody
syndrome (e.g., lupus
anticoagulant, anticardiolipin
antibody)
b.
Oral contraceptive and/or
estrogen use
c.
Antithrombin III deficiency
d.
Protein S and C deficiency
e.
Tissue-type plasminogen
activator (t-PA) and plasminogen
deficiencies
f.
Patients particularly at risk for
a hypercoagulable state:
Older than 45 years
History of thrombolytic
event
History of spontaneous
abortion
Related autoimmune
conditions (e.g., lupus)
Stroke of unknown cause
Family history of
thrombotic events
4.
Myeloproliferative disorders, leukemia
with white blood cell count greater than
150,000
E.
Intracranial causes
1.
Brain tumor
2.
Focal seizure
3.
Hemorrhage
a.
Subdural hematoma (SDH)
b.
Subarachnoid hemorrhage
(SAH)
c.
Intracerebral hemorrhage
(ICH), which may cause
cerebrovascular dysfunction due
to leakage of blood outside the
normal vessels
F.
Subclavian steal syndrome
1.
Localized stenosis or occlusion of a
subclavian artery proximal to the source
of the vertebral artery, so that blood is
stolen from that artery
2.
Blood pressure (BP) is significantly
lower in the affected arm than in the
opposite arm.
G.
Others
1.
Transient hypotension
2.
Osteophytes that cause compression
of neck vessels
3.
Cocaine abuse
4.
Hypoglycemia
5.
Migraines
IV. Risk factors
A.
A transient ischemic attack (TIA) is an
important predictor of stroke.
1.
The 90-day risk of stroke after a TIA is
as high as 17%
2.
The greatest risk is within the first
week
3.
Approximately one third of stroke
patients have a history of TIA
B.
Hypertension
C.
Cardiac disease, such as the following:
1.
Mitral valve disease
2.
Anterior wall MI
3.
Congestive myopathy
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- Fall '17
- keisha lovence
