Diagnosis and evaluation of therapy in Apraxia of Speech

Apraxia of speech is described as a speech deficit that occurs due to brain
damage. It is characterized by problems in (the planning of) different sound
segments. There is a lot of debate in the literature about the underlying cause
of apraxia of speech. The fact that apraxia of speech almost never occurs in
isolation (cf. Ogar et al., 2006) forms a very prominent limitation. The
absence of clear evidence for one of the theories on the underlying deficit in
apraxia of speech is probably also due to the fact that often no proper
diagnosis is made due to the failure of a test that can come up with a
differential diagnosis.
Worldwide no adequate diagnostic test batteries are available and this often
leads to diagnosis on the basis of a very subjective clinical judgements based
on test scores. Therefore, it is very important that a valid and reliable
diagnostic test will be developed. In order to also evaluate therapy that fits
with this diagnosis, a measure for change in speech (either improvement of
deterioration) is needed. Such a measure has never been described in literature
and consequently the development of this measure will also be part of the
current study.

The aim of this study is twofold. First a normed and validated diagnostic test
for apraxia of speech will be developed and second a measure will be set up to
evaluate the effectivity of the therapy SMTA. A test to diagnose apraxia of
speech is unavailable in the Netherlands and also worldwide no adequate tests
have been described. Nevertheless, such a test is important to determine the
origin and severity of the underlying deficit. Besides this, it is often
difficult to differentiate apraxia of speech from other neurogenic speech
deficits, like dysarthria, but also from speech errors in aphasic subjects.
This means that the test that will be developed needs to be able come up with
this differentation.

In a first session the participants will be administered with the diagnostic
test for apraxia of speech. This test will consist of 5 repetition tasks in
which combinations of sounds, alternating in difficulty, are asked to be
reapeted. Next, written picture naming task wil be tested. Third, the test for
buccofacial apraxia will be administered in which the particpant is asked to
execute some facial, mouth or tongue movements. In a second session the test
for the effectivity of therapy will be administered. Participants are asked to
repeat sequences of speech sounds. These sequences are either repeating or
alternating.

The study to the diagnosis of apraxia of speech, as described in the protocol,
does - according to us - not entail any risks for the participants. Only
cognitive tasks will be administered. These are tests in which sounds and words
must be repeated. Next, the participants are asked to write down the names of
some pictures. Finally, the test for buccofacial apraxia is administered in
which the particpant is asked to execute some facial, mouth or tongue movements.
Two sessions are planned, both lasting maximally two hours. Part of the
subjects will be tested with the same tests twice in order to account for the
test-retest variability.