Impairment is often seen as a link between pathology and disability: a disease causes symptoms and/or signs which not only give a clue about the disease but also explain the disability. Unfortunately this conception only covers a proportion, quite small, of the phenomena included within the term.
Impairments may arise in other ways. For example, if the movement of a joint such as the shoulder is reduced, perhaps from wearing a sling to support a fractured arm or secondary to a stroke, then the joint becomes stiff and painful because of the immobility, not any pathology. Or, as another example, hyperventilation can lead to sensory changes. In both cases, the link runs from altered activity back to impairment. Expectation, and altered psychological states such as depression also frequently cause or alter impairment. Analysis can be difficult!
Impairment is a label that covers three different types of change or loss. The first, structural impairment, can be observed and relates to a part of the body. The second, impairment of function, has to be deduced from the observed changes or reported changes in body functions. The analysis of a person’s disability may lead a clinician to conclude that a specific impairment of function such as spasticity is causing the disability, not realising that the named impairment is simply a useful construct which allows a complex set of observations to be summarised into one word. For example, someone with obvious problems in grammar, naming objects, and following commands after stroke may be said to have aphasia, an impairment in language functioning.
Beware. Impairments of function can be termed ‘functional impairments’ which might mean or imply that there was no pathology and that the personal had a ‘functional illness”. Be careful with words!
Third, many impairments are entirely experiences that the person reports. The external observer is taking a behaviour, communication by the patient and, using judgement about and interpretation of the given description, the clinician assigns an impairment description such as “pins and needles in hands and feet”.
The first graphic shows a more detailed consideration of the nature of impairment relevant to a rehabilitation analysis. The second graphic shows a similar series of question to that used in all domains, as applied to impairments. The main points to note, which also arise in most other domains are:
- there are inter-relationships in both directions with several other domains if not all domains
- there are relationship between impairment and every domain
- treatments, interventions to reduce the impairment or to alleviate its effects, might be identified in most domains.