Hand strength and fatigue in patients with hereditary motor and sensory neuropathy (types I and II)

Objectives: To compare maximal isometric hand strength and fatigue between subjects with hereditary motor and sensory neuropathy (HMSN) and healthy controls and to test the reproducibility of handgrip strength (peak force of handgrip [PFgrip]) and fatigue. Design: PFgrip and the decline in PFgrip during 3 sets of 15 contractions were compared. Setting: University hospital in The Netherlands. Participants: Twenty subjects with HMSN and 20 age- and sex-matched healthy controls; 15 healthy subjects for the reproducibility part of the study. Interventions: Not applicable. Main Outcome Measures: PFgrip and the decline in PFgrip were compared by using a digital handgrip dynamometer. Two-point and lateral pinch measurements of subjects with HMSN were standardized against reference values. Reproducibility measurements were performed on 15 healthy subjects on 2 separate occasions within a 1-week interval. Results: PFgrip was significantly lower in the HMSN subjects compared with controls (P <.05). Pinch measurements also showed a large variance from average normal performance. No significant difference was found in the decline in percentage of PFgrip. Reproducibility was excellent for PFgrip (intraclass correlation coefficient [ICC]=.98; 95% confidence interval [CI],.95-99) but poor for fatigue (ICC=.62; 95% CI,.20-85). Conclusion: PFgrip and 2-point and lateral pinch in HMSN subjects were significantly reduced compared with healthy controls. Our findings indicated that the rate of decline of PFgrip during effort does not vary between groups