It is important to capture pain and associated symptoms for subjects experience significant pain as many NMD are associated with significant chronic pain. Of course, they may not use one word to describe this pain, and this can be a helpful way to identify the aetiology. You can use a simple body chart to document pain or a Visual Analogue Scale.
Visual Analogue Scale
A Visual Analogue Scale (VAS) is an instrument for subjective rating of pain. The pain VAS is most often used as a unidimensional measure of pain intensity.
The VAS is a straight horizontal line of fixed length, usually 100 mm. The ends are defined as the extreme limits of the parameter to be measured, hence the left end is usually labelled ‘no pain’, and the right end ‘extreme pain’ or (as with the NPRS) some other verbal anchor. Scales can also be used vertically but are no more reliable.
Using a ruler, the score is determined by measuring the distance (mm) on the 10-cm line between the “no pain” anchor and the patient’s mark, providing a range of scores from 0–100. As with the NPRS, categories may be imposed on this (no pain 0–4 mm; mild pain 5-44 mm; moderate pain 45–74 mm; severe pain 75–100 mm) but this is arbitrary and does not necessarily reflect patients’ meanings.
Verbal Rating Scale (VRS)
The Verbal Rating Scale consists of a list of adjectives describing different levels of pain intensity. Patients are asked to select the adjective that best represents their pain. This should reflect the extremes of this dimension; from ‘no pain’ to ‘extremely intense pain’ and sufficient intervening adjectives to capture gradations of pain intensity that may be experienced between extremes.
- no pain = 0
- mild pain = 1
- moderate pain = 2
- severe pain = 3
- very severe pain = 4
VRSs are scored as above but these are ranks, not equal intervals.
This article provides further information on the: Assessment of pain and health-related quality of life in slowly progressive neuromuscular disease – Abresch 2002