Comparison of maximal voluntary isometric contraction and Drachman's hand-held dynamometry in evaluating patients with amyotrophic lateral sclerosis

Maximal voluntary isometric contraction (MVIC) is a standard tool for asses sment of muscle strength in treatment trials for amyotrophic lateral sclero sis (ALS). There is need for more practical bedside techniques especially f or severely disabled patients. Hand-held dynamometry (HH-Dyn) is an inexpen sive and easy-to-handle device. MVIC was measured in five proximal muscle g roups bilaterally and compared with HH-Dyn in 43 ALS patients. After a trai ning period we found good intrarater correlation for HH-Dyn (r = 0.99), wit h a low coefficient of variation. Measurements tended to become more accura te after repeated testing due to practice effects in examiners and patients . Overall correlation between HH-Dyn and MVIC was good [r = 0.85 (P < 0.01) ]. Strength-range-specific analysis showed a significant linear correlation up to 20 kg (44 lbs.) [r = 0.57 (P < 0.01)]. However, we found a tendency to underestimate muscle strength above 10 kg by HH-Dyn as compared with MVI C, but this became meaningful only above a force of 20 kg. HH-Dyn provides a strength estimate with a precision close to MVIC in weak muscle groups (M RC grade 4). With standardization and appropriate training, HH-Dyn is a use ful bedside test, providing an alternative to MVIC for follow-up assessment in ALS. (C) 1999 John Wiley & Sons, Inc.