Any disease is diagnosed by the doctor on the basis of a 3-step process
This three step process – or some modification of it is applied in every clinical situation.
The diagnosis of stroke also depends on this process. Sometimes, the history is enough to give the doctor a fair idea about some things: that it is probably a stroke, that possibly it is this or that part of the brain which is affected, and some idea of the underlying mechanism as well as severity of stroke.
What remains is to perform a scan to differentiate between stroke resulting from brain bleeding or a clot blocking an artery.
A CT scan is mandatory in nearly all cases of stroke – it gives the doctor an immediate understanding of the probable cause of the stroke. It is also easily performed, less expensive, and widely available, and not all that dangerous either!
Once the CT scan is done, it is the time for some decision-making: the stroke has been confirmed, the type of stroke – bleed or infarct – has been clarified; the exact location and extent of damage – both temporary and permanent has been visualized. Treatment decisions are taken and then the patient is started on a Stroke Rehabilitation program.
is occasionally a better means of identifying an ischemic stroke; it gives a complete idea about location, size, and any additional problems, such as infarct with bleeding (hemorrhagic-infract
). An MRI is a little more cumbersome (some people complain about the noise, others about the claustrophobic sensation), somewhat more expensive, and not as widely available as a CT scan.
Simultaneously to this, a Secondary Stroke Prevention program is initiated; the effort here is to prevent the NEXT and ALL FUTURE strokes.
Several tests are done as part of routine evaluation of stroke; the basic question to which the answer is sought, is about the Mechanism of the stroke.
- Is it a clot arising from the Heart? – for this a 2D-Echo of the heart
- Did the clot arise from the blood vessels in the neck? – a Color Doppler of the neck vessels will identify various things, such as an active clot or thrombus, evidence of atherosclerosis in the form of plaques, or partial occlusion (stenosis) or complete block of a blood vessel.
- Did the clot arise from an artery inside the skull?
The same vessels as are in the neck continue inside the skull, and in Asian populations the incidence of atherosclerosis in these arteries is slightly higher than in the neck, whereas Western populations more commonly have what is called Extra-cranial atherosclerosis.
This has treatment implications, since blockages in these arteries in their course in the neck – the extra-cranial part – are amenable to treatment easily – surgery, called endarterectomy
, or an endo-vascular technique called stenting
of these vessels is a possible solution.
Efforts have been made to stent the intra-cranial parts of the arteries in those stroke survivors who have significant blocks there, and technology has improved enough to make this not only feasible but also safe – but a clear-cut improvement in terms of stroke prevention has been hard to come by; that is why intra-cranial stenting has not yet caught-on as a stroke prevention strategy, even in those patients with significant disease in these vessels.
As a consequence, imaging the intra-cranial vessels – which is possible using either MRI Angiography or conventional catheter angiography – is a test which is used only occasionally to elucidate the mechanism of stroke; it’s routine use has not been shown to significantly alter treatment plan.
The tests mentioned here are those which may be required in almost every stroke patient; in some patients, additional tests may be ordered for specific reasons.