The disorder ``apraxia of speech'' (AOS) has been a subject of some controversy during
the 30 or so years since Frederick Darley and his colleagues at the Mayo Clinic first
described it, particularly with regard to its distinction from aphasia syndromes such
as Broca's aphasia and the pure articulatory impairment called ``aphemia.''
Interestingly, the schools of thought regarding AOS have had a rather regional bias
in the United States. Those trained in the ``Boston'' tradition of aphasia classification
(as delineated by Norman Geschwind and Harold Goodglass) tend to believe that the
term ``apraxia'' should be reserved for disorders of purposeful movement that are
not specific to language (e.g., limb apraxia, buccofacial apraxia). Furthermore, they
argue that many of the speech behaviors described in association with AOS can be explained
on a linguistic basis. Those trained by Darley and his colleagues and their students
at the Mayo Clinic in Minnesota accept AOS as a disorder that can exist in a pure
form, although it often accompanies aphasia.
The issue of accurate diagnosis is of great importance to rehabilitation in so far
as any diagnosis implies a certain understanding of the underlying nature of the disorder.
For example, it is known that ``naming'' problems are a core symptom of aphasia. The
approach to treating word-retrieval problems may differ, however, according to the
form of aphasia. For example, using a serial-stage, cognitive model of naming, a person
with anomic aphasia may have greater deficits in the semantic system than the person
with Wernicke's aphasia, whose deficits are mainly at the level of the phonological
lexicon. It is also the case that many speech-language disorders are associated with
distinct lesion sites. This knowledge is important to neurobehavioral treatment approaches
based on spared and impaired brain regions and pathways such as Alexander Luria's
intersystemic and intrasystemic reorganization methods.
Trained as I am in the ``Boston'' school of thought, my understanding of AOS was ``fuzzy''
because AOS was never used to describe the individuals seen in our clinical service.
Yet, I think it is important for all of us to understand this disorder because it
is frequently diagnosed by speech-language pathologists who choose treatment approaches
in accordance with this diagnosis. Some individuals who have been referred to our
clinic with diagnoses of ``apraxia'' (which we assume means ``apraxia of speech'')
have been treated accordingly for sound production problems. These same individuals
may then be diagnosed as having Broca's aphasia and treated for language problems.
With all these considerations in mind, it seemed time to dedicate an issue of Seminars in Speech and Language to the topic of apraxia of speech. I could think of no better person to serve as
Guest Editor for this issue than Dr. Malcolm McNeil. Dr. McNeil has been a leading
investigator of this disorder and has written extensively and in great depth about
it. He is also part of an international community of scientific and clinical researchers
pursuing this line of study. I am most grateful that he agreed to take on the task
of putting this issue together and that he was able to recruit such a prestigious
group of contributors.
Here, then, is an issue of Seminars directed at students and clinicians who have questions about AOS: what it is, what
causes it, how to recognize it, and how to treat it. I have learned a great deal about
AOS in the process of reading and editing the papers. It has helped enormously in
overcoming the ``regional'' bias of my training. I think that other readers will find
it highly educational and that it has good clinical applicability.
