A thesis submitted in partial fulfilment of - Queen Margaret University

person’s current cognitive status (Staff et al., 2004; Starr, Nicolson, Anderson,
Dennis and Deary, 2000). One difficulty in assessing and estimating pre-morbid
intelligence is that the measurement of intelligence is only as good as the
assessment used, not all intellectual capabilities can currently be measured, for
example, creativity or wisdom and there is not a general consensus as to what
intelligence actually is (Deary, 2001). Starr et al. (2000) note the difficulty in the
accurate measurement of cognitive impairment and intelligence following a
stroke as many assessments are inappropriate for use with people post-stroke
and also that pre-morbid cognitive function usually needs to be estimated after
the stroke has occurred. The impact of stroke could impair test performance
particularly when related to linguistic and visuospatial deficits therefore someone
with aphasia may not be able to demonstrate their intellectual capabilities where
verbal responses are required.
2.6.2 Biological limitations
As already discussed (see section 2.5) recovery following stroke and the
potential for recovery is limited by the capabilities and limitations of the physical
brain. However, this is not a straightforward relationship. Research on the
different aetiologies of stroke, i.e. infarct versus haemorrhage, and their effect
on recovery is rare and has produced conflicting results (Basso, 1992). Other
studies have attempted to evaluate the location and extent of the lesion on
recovery. However, it is difficult to assess this factor independently from the
initial severity of aphasia which in turn is directly associated with location and
extent of lesion (Basso, 1992).
2.6.2.1 Lesion size and site
As discussed (see section 2.5.1) a minimal ‘critical mass’ of neurone cells are
required to survive if neuronal repair and reconnection is to occur (Robertson,
1999; Robertson and Murre, 1999). This suggests that the greater the damage,
the less chance of this minimal number of neurones surviving with the possible
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