UK Stroke Assembly 2014
Predicting Language Outcome and Recovery after
Stroke (PLORAS)
Professor Cathy Price
Key Points about PLORAS
Introduction
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Aphasia is a language disorder which can occur after a stroke.
People with aphasia can have difficulty with speaking, understanding, reading and writing.
Some patients recover better than others and our aim is to explain why.
Patients and their carers typically want to know when and how they will recover.
Accurate predictions are not currently available and we want to change this.
Why is it difficult to predict recovery?
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Language is very complex.
Many different brain areas support our ability to use language.
Many factors affect recovery.
The strongest predictor of recovery is stroke site.
Stroke site indicates which language regions are damaged, and
which language areas are preserved and can support recovery.
The effect of damage to each brain area therefore depends on
the presence or absence of damage to other brain areas.
Recovery also depends on time post stroke, with improvement
continuing for years.
When we control these factors, the effect of stroke damage becomes highly predictable.
A practical solution
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We base our predictions on what we know about other patients with similar strokes.
Our database stores information from hundreds of patients with many different stroke sites.
We can investigate a range of factors that affect recovery including “lesion factors” (stroke
site and size) and non-lesion factors (e.g. age, gender, type and amount of therapy, etc).
Figure showing how we generate predictions for speech recovery over time.
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Speech score = how good one aspect of speech production or comprehension is expected to be.
The red dot indicates the speech score in the new patient.
The black line illustrates that speech scores of other patients increased with time since stroke.
The width of the black line indicates how variable the scores were in other patients.
The thinner the line, the more confident we can be in how a new patient will recover.
Identifying lesion sites that predict speech & language abilities and difficulties
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We use a computer program to find the exact location and shape of the stroke.
We then group patients with the same aphasic symptom and find the brain areas that are
consistently damaged in patients with the same symptoms.
The figure below uses different colours to illustrate the number of patients with damage at
every location in the brain. Dark red indicates the most consistently damaged area.
We refer to consistent lesion sites as ‘critical lesion sites’ because they are consistently
associated with aphasic symptoms. They are therefore “critical” for speech or language.
Testing whether the critical lesion sites predict speech abilities in other patients
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We test whether the same sites cause aphasic symptoms in other patients and whether
preservation of these sites is associated with better recovery.
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In the figure above, the picture of the brain shows a large dark area that has been damaged
by a stroke. Fortunately, the dark (damaged) area does not fall within the area outlined in red.
The red area is a critical lesion site that is damaged in patients who only recover very slowly.
The dots in the right side of the figure above shows the speech scores of other patients
who have similar damage to the patient whose brain is illustrated on the left.
As can be seen, the speech scores are mostly in the aphasic range in the first three years
after stroke but speech is consistently close to normal after three years.
We therefore predict that the brain on the left should recover their speech within four years.
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Creating a clinical tool
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Our findings of consistent lesion effects are helpful for patients.
We are therefore creating a clinical tool to:
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Predict how long it will take for patients to regain language.
Provide individualised information about their likely recovery.
Provide a framework to test how effective new therapies are.
PLORAS Research Team
 0207 813 1538
 ploras@ucl.ac.uk
E.g. Doctor tells patient:
“90% of patients with the
same stroke site as you
recovered within 4 years”
 www.ucl.ac.uk/ploras