Summary

Objective and quantitative measures to assess the severity and progression of Huntington's disease (HD) are desirable. Several studies have demonstrated quantifiable deficits in the coordination of precision grasping in patients with Huntington's disease. Correlation analysis revealed that the amount of grip force variability while holding an object was correlated to the total motor score of the Unified Huntington's Disease Rating Scale (UHDRS) in a cross-sectional study. In addition, grip force variability increased in all HD patients during a 3-year follow-up. The UHDRS total motor score did not change significantly in the same subjects. The results suggest that neurophysiological analysis of isometric grip forces may detect disease progression more sensitively than clinical rating scales. The applicability of the assessment of grip forces in clinical studies is currently tested in large multicenter studies. Possible applications of the technique as a biomarker in clinical studies in HD are discussed.

Introduction

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder with a prevalence of about 7–10 symptomatic patients per 100,000 individuals and about double the number of pre-symptomatic gene carriers (Harper, 1996). Expansion of a CAG-repeat within exon 1 of the HD gene results in the development of the HD phenotype (The Huntington's Disease Collaborative Research Group, 1993), with longer repeats associated with earlier manifestation and faster progression of disease (Andrew et al., 1993).