Broca (1861) examined a man, who was able to understand what was said to him but was unable to pronounce any words other than ‘tan’ over and over again. Although he was referred to as ‘Tan’, the unfortunate individual was a M. Leborgne who died a mere 6 days after examination. His death gave Broca the chance to examine the brain which revealed that the area damaged was a small region towards the front left hand side of brain – a region that became known as Broca’s area (Fig. 11.2).

Fig. 11.2 • Localisation of Broca’s and Wernicke’s areas

Broca’s area is often referred to as the motor-speech area and it is located adjacent to the precentral gyrus of the motor cortex in the frontal lobes (see Fig. 11.2). This area controls the movements required for articulation, facial expression and phonation. Broca’s patients generally had good overall comprehension but their speech was often limited in their vocabulary and grammar which contained inaccurate pronunciation of words or parts of words which often made their speech unintelligible. More about the clinical presentation of people with Broca’s aphasia can be found below.

Wernicke’s area

Karl Wernicke, a Prussian physician, discovered a different kind of speech and language problem a few years later, which uncovered damage to a completely different region of the brain – unsurprisingly thereafter called Wernicke’s area. Wernicke’s patients generally possessed good articulation, but their speech often didn’t make sense, with words jumbled together in an incoherent sequence. They frequently used ‘made-up’ words with no meaning (neologisms).

Wernicke’s area, which includes the auditory comprehension centre, lies in the posterior superior temporal lobe near the primary auditory cortex at the junction of the parietal, temporal and occipital lobes (see Fig 11.2). Wernicke’s area plays a critical role in understanding both spoken and written messages (See Clinical application box 11.1), as well as being responsible for formulating coherent speech patterns. These ‘commands’ formulated in Wernicke’s area are transferred via a fibre tract, the arcuate fasciculus, to Broca’s area. Wernicke’s receives input from both the visual cortex in occipital lobe (an important pathway in reading, comprehension and describing objects seen) and the auditory cortex (essential for understanding spoken words).

Clinical application box 11.1

To give us some idea of the complexity of these pathways let us consider a couple of everyday processes:

1. Speaking the written word

The information must first get to the primary visual cortex where it is then passed to the posterior speech area, including Wernicke’s area. From there it will travel to Broca’s area via the arcuate fasciculus and on to the primary motor cortex (for initiation of the appropriate motor speech commands).

2. Speaking the heard word

The information must first get to the primary auditory cortex where it is then passed to the posterior speech area, including Wernicke’s area. From there it will travel to Broca’s area via the arcuate fasciculus and on to the primary motor cortex (for initiation of the appropriate motor speech commands).

It is important at this stage to differentiate between repetition (where you would not have to understand the words) and speaking aloud (where you would understand the words). There will be patients who can repeat what is said to them and mislead the therapist into thinking that they understand them.

Aphasia: clinical presentation

As mentioned earlier, communication is a very complex human skill. Damage to the language component of communication, i.e. aphasia, can therefore affect some or all modalities of language processing: expression and comprehension of speech, reading and writing, gesture and the use of language (i.e. pragmatics). The severity can also vary between individuals, so someone may have occasional problems thinking of a word (which means that there will be some pauses or some errors when they are speaking to you), whereas other people may be more severely affected and unable to put their ideas and intentions into spoken and/or written language, having no intelligible communication. As aphasia also affects the understanding of language it can affect the ability of a person to understand even simple sentences or single words. Aphasia can also affect the ability to understand and use various methods of communication other than speech, for example, gesture. And the severity of aphasia can also fluctuate from one day to the next where an individual may have many word-finding problems one day and on another they may speak much more fluently.

So with such an array of complexities how is it possible to describe your patient’s type of aphasia? This is not a new problem. As more information was discovered over the years about the various complexities of language, researchers devised a large number of ways of describing and classifying the different types of aphasia. However, as we mentioned above it is important to remember that the aphasic population is heterogeneous in nature and any number and variations of the characteristics of aphasia can affect individuals. Therefore, it is important for health professionals to understand that aphasia is variable and different for each individual. In saying that, it is very useful to be able to discuss a patient with colleagues, e.g. during a multidisciplinary team (MDT) meeting, in terms of the general type of aphasia a patient presents with, using terminology that is understood. Some of the ways that people with aphasia are classified include: expressive versus receptive aphasia; fluent versus non-fluent aphasia and the Boston Classification approach (who have a localisationalist viewpoint) including Broca’s, Wernicke’s and conduction aphasia. It is likely that this is the terminology that you will come across in a patient’s medical notes and, therefore, they will be described below.

You must remember though that these are only some of the ways to describe aphasia and there are often various issues in determining the exact boundaries between one type of aphasia and another.

Expressive versus receptive aphasia

The division of patients into ‘expressive’ or ‘receptive’ aphasia is a very broad classification which was proposed by Weisenberg and McBride (1935).

Patients with expressive aphasia (also called motor aphasia) have difficulty translating their ideas into meaningful sounds resulting in non-fluent speech with pauses between words and or phrases. Expressive aphasia is associated with damage involving the anterior language centre of the dominant hemisphere, i.e. Broca’s area (see Fig. 11.2). It must be noted that people with expressive aphasia may also present with mild comprehension difficulties.

Receptive aphasia (also called sensory aphasia) is associated with damage to the posterior language area of the dominant hemisphere, i.e. Wernicke’s area (see Fig. 11.2). Patients with receptive aphasia present with difficulty in the comprehension of language. While their speech is normally fluent it is full of errors. For example, it may contain jargon (made-up words) or substitutions of words (paraphasias) amongst others.