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Department
of Podiatry - Vascular Assessment
CVA/TIA
Cerebrovascular
accident (CVA), also known as Cerebrovascular disease and clinically as
“stroke”, is an abnormal condition of the brain characterized
by occlusion or haemorrage with resulting ischaemia of brain tissues normally
perfused by the effected vessels (Anderson, 1999).
Pathophysiologically,
CVA can be classified into two processes:
1) Hypoxia, ischaemia and infarction resulting from impaired
blood supply and thus oxygen of central nervous system (CNS) tissue.
This may occur due to functional hypoxia from low partial pressure of
oxygen (Po2), or more commonly, as a local state of ischaemia from large
vessel disease such as embolic or thrombotic arterial occlusion (Cotran
et al, 1999). Atherosclerosis is the underlying disease in the majority
of thrombotic occlusions that lead to CVA, with the middle cerebral
artery and carotid bifurcation the common sites. Embolism to the brain
may occur from a range of sources, but most often from cardiac mural
thrombi or thromboemboli originating in the carotid arteries (Cotran
et al, 1999; Lorimer, 1997).
2) Haemorrhage resulting from rupture of CNS vessels. These may
occur at any site within the CNS, either secondary to underlying pathology
such as partial or transient vessel occluded infarcts; or primarily
due to trauma. Non-traumatic haemorrhage occurs in either the intraparenchymal
space, mostly by rupture of small intraparenchymal vessels primarily
caused by hypertension; or haemorrage may also occur in the subarachnoid
space, usually caused by rupture of berry aneurysm in the anterior cerebral
artery (Cotran et al, 1999; Lorimer, 1997).
Clinically, CVA may present with a vast array of signs and symptoms, however
all can be related back to disturbances in brain function. Two-thirds
of CVA victims are over 65 years, and is the third most common cause of
death behind cancer and heart disease in developed countries (Lorimer,
1997). CVA of infarct aetiology presents as sudden onset of neurological
deficit, and because of the contralateral relationship between the brain
and the body, the opposite side of the body to the infarct is affected
(Lorimer, 1997).
CVA’s are clinically divided into arbitrarily defined groups: neurological
deficits that resolve in less than 24 hours are consider transient ischaemic
attacks (TIA’s); resolve in less than a week are termed minor strokes;
and major strokes present with deficit longer than one week. CVA’s
may be fatal, 20% of patients die with a month of a major stroke, 50%
who survive are permanently disabled, and 70% show obvious neurological
deficit (Lorimer, 1997).
For the podiatrist and vascular assessment, it is important to ascertain
the cause of the stroke from the medical history. If vessel disease is
the underlying pathology, there is reason to assume similar vascular manifestations
are occurring in the lower extremity. If undiagnosed stroke is suspected,
referral to a vascular surgeon or laboratory for duplex ultrasound, CT,
X-ray and MRI scans is recommended.
Podiatrists also have a role in examining and treating the biomechanical
complications that CVA victims often have.
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