Rating scales for rare neurological diseases

Massimo Pandolfo; Neurol Genet Dec 2019, 5 (6) e380; DOI: 10.1212/NXG.0000000000000380

While only future experience will establish whether these scales are equally effective in FRDA clinical trials or if one proves superior, the point that they are both ataxia rating scales rather than comprehensive assessments of all FRDA neurologic features remains. Can we generalize this conclusion and say that rating scales assessing specific neurologic features are to be preferred to disease-specific scales in rare neurologic disorders? This is an open and controversial question. There have been and there are continuing efforts to develop and validate disease-specific scales for rare and even ultra-rare diseases, with the goal of disposing of robust, sensitive outcome measures for clinical trials, capturing as much as possible of the complexities of each of these conditions. Whether the same goal can be attained by appropriately combining general scales for neurologic impairments as weakness, spasticity, ataxia, and dystonia remains to be determined, but, in the light of our experience with a disease with as complex a neurologic picture as FRDA, this approach may be a viable and possibly even a preferable option.