It is a very positive step to use these questionnaires alongside the VNG tests to support your diagnosis, guide decision-making and chart progress of patients.
Let us touch on the DHI first.
This is a widely used tool for quickly capturing the impact of dizziness. The answers to the 25 questions are marked to give a total score (from 0 to 100 points), which provides an indication of the handicapping effect of dizziness. However, the questions are also groups into three domains (physical, functional and emotional) and referring to the responses in each of these domains may help the clinician to gauge the area of most handicap, and thus help to understand where they might place the emphasis in terms of rehabilitation strategies.
If the DHI is being used as an outcome measure (i.e. to chart progress e.g. after a programme of vestibular rehabilitation therapy), then a change of 18 points in the overall score is needed for the clinician to consider this a true change.
It is important to note that the scores someone provides on the DHI will not always relate closely with the evidence of peripheral vestibular dysfunction that is indicated by the vestibular test battery. For example, someone may have a high degree of handicap and negative impact on their quality of life, and yet have little or no apparent vestibular dysfunction.
The second tool that you mentioned is the VRBQ. This can be used similarly to the DHI, in that is can be used to provide a snapshot of the overall status at the beginning of a treatment programme (which might well be at the point of vestibular assessment), and it can be repeated after a treatment programme (Vestibular Rehabilitation) to assess any changes in the patient’s self-reported status.
The questionnaire has two halves. The first assesses the symptoms (and the responses can also be broken down into 3 domains, the dizziness, anxiety and motion related aspects). The second half assess the impact of dizziness upon quality of life. The scoring provides a percentage scale, where 0% is no deficit compared with the patient’s own normal state, and 100% is the maximum deficit.
A change of 7% in the overall score is needed for the clinician to consider this a true change. Changes of 6% and 9% are needed for the clinician to consider a true change in the Symptoms and Quality of Life halves, respectively
References and caveats
Jacobson, G.P. and Newman, C.W. (1990) The development of the dizziness
handicap inventory. Archives of Otolaryngology Head Neck Surgery, 116 pages 424 - 427.
Morris, A., Lutman, M., and Yardley, L. (2008) Measuring Outcome from Vestibular
Rehabilitation, Part I: Qualitative development of a new self-report measure. International Journal of Audiology, 47 pages 169-77.
Morris, A., Lutman, M., and Yardley, L. 2009. Measuring Outcome from Vestibular
Rehabilitation, Part II: Refinement and validation of a new self-report measure.
International Journal of Audiology, 48 pages 24-37.