Speech

BACKGROUND

Abnormalities of speech need to be considered first, as these may interfere with your history taking and subsequent ability to assess other aspects of higher function and perform the rest of the examination.

Abnormalities of speech can reflect abnormalities anywhere along the following chain shown.

Problems with deafness are dealt with in Chapter 12.

1 Aphasia

In this book, the term aphasia will be used to refer to all disorders of understanding, thought and word finding. Dysphasia is a term used by some to indicate a disorder of speech, reserving aphasia to mean absence of speech.

Aphasia has been classified in a number of ways and each new classification has brought some new terminology. There are therefore a number of terms that refer to broadly similar problems:

• Broca’s aphasia = expressive aphasia = motor aphasia

• Wernicke’s aphasia = receptive aphasia = sensory aphasia

• nominal aphasia = anomic aphasia.

Most of these systems have evolved from a simple model of aphasia (Fig. 2.1). In this model, sounds are recognised as language in Wernicke’s area, which is then connected to a ‘concept area’ where the meaning of the words is understood. The ‘concept area’ is connected to Broca’s area, where speech output is generated. Wernicke’s area is also connected directly to Broca’s area by the arcuate fasciculus. These areas are in the dominant hemisphere and are described later. The left hemisphere is dominant in right-handed patients and some left-handed patients, and the right hemisphere is dominant in some left-handed patients.

Figure 2.1 Simple model of speech understanding and output

The following patterns of aphasia can be recognised and are associated with lesions at the sites as numbered on the figure:

1. Wernicke’s aphasia—poor comprehension; fluent but often meaningless (as it cannot be internally checked) speech; no repetition

2. Broca’s aphasia—preserved comprehension; non-fluent speech; no repetition

3. Conductive aphasia—loss of repetition with preserved comprehension and output

4. Transcortical sensory aphasia—as in (1) but with preserved repetition

5. Transcortical motor aphasia—as in (2) but with preserved repetition

Reading and writing are further aspects of language. These can also be included in models such as the one above. Not surprisingly, the models become quite complicated!

2 Dysphonia

This is a disturbance of voice production and may reflect either local vocal cord pathology (such as laryngitis), an abnormality of the nerve supply via the vagus, or occasionally a psychological disturbance.

3 Dysarthria

Voice production requires coordination of breathing, vocal cords, larynx, palate, tongue and lips. Dysarthria can therefore reflect difficulties at different levels.

Lesions of upper motor neurone type, of the extrapyramidal system (such as Parkinson’s disease) and cerebellar lesions disturb the integration of processes of speech production and tend to disturb the rhythm of speech.