A speech disorder or an impediment is where the normal speech pattern is affected and verbal communication is adversely affected or completely nullified. It may range from stuttering, cluttering, muteness to voice disorders. The causes for these conditions may be cerebral in origin, or of the cerebellum, may be of the muscles or psychological. Here we will discuss on the site of origin, presentations, and management strategies which vary and overlap in apraxia and aphasia.
Apraxia is a disorder of the brain and the nervous system, in which the person is unable to perform tasks and movements even though the auditory input, comprehension of the task, psychological willingness and the learning is all present. This is due to damage to the brain which may be due to brain tumour, neurodegenerative disease, stroke, head trauma etc. This may occur in conjunction with aphasia which is the cerebral incapability to understand (auditory- Wernicke’s area) or to vocalize (motor-Broca’s area). In apraxia there is a difficulty to put word together in the correct order, or to reach for the correct word, or to enunciate longer words although they can use shorter words put together (“Who are you?”). Also the writing is better than the speech in these individuals. This is managed through speech and language therapy, occupational therapy and treating depression. This can get complicated with learning problems and social problems.
Aphasia occurs due to inability to use or comprehend spoken or written words. This is associated with damage to one or more of the language centers in the brain. This may occur due to a problem in the brain (tumour, stroke) or due to a cerebral infection or trauma to the head. These individuals have a difficulty in comprehending spoken or written words, reading or writing grammatically correct sentences and finding words to express the required emotion. They are managed with speech and language therapy and also treating associated psychological ailments. They can also use communication assist devices like picture and word matching, etc. Commonest complication associated with this is depression.
Both apraxia and aphasia has nervous system aetiology, has difficulty in communicating, with common investigative methods, common management strategies and common complications. Both these conditions are cerebral in origin. Apraxia is inconsistent, unpredictable, with islands of clear speech. Aphasia is also inconsistent, but is predictable and without islands of clear speech. The aspect affected in aphasia depends on the affected language centre or the cluster and only articulation is affected in apraxia. In apraxia increased speech rate increases the intelligibility, whereas it has the opposing effect in aphasia. Dyspraxia is associated with aspiration pneumonia as a complication, whereas aphasia has no such relevance.
These two have to be understood as separate entities but resulting in a bit similar results. But a careful investigator would find aspects which we have described earlier which separate out the two. The management for these two is similar in that the causative mechanisms are irreversible and only compensatory efforts can be taken.