Hand dysfunction in patients with brain tumors poorly correlates with manual muscle testing

Introduction: Motor deficits are frequently observed in patients with brain tumors. While cognitive impairments are often assessed with quantitative multi-domain testing, motor impairments are infrequently quantified beyond standard manual muscle testing. The purpose of this study, therefore, was to investigate the relationship between manual muscle testing and more in-depth, quantitative assessments of motor function.

Methods: Eleven patients with uni-hemispheric frontal or parietal lobe brain tumors completed quantitative assessments of grip strength, dexterity, and self-reported hand function. Grip strength was assessed using a Jamar handgrip dynamometer. Dexterity was assessed using the 9-hole peg test. Self-reported hand function was assessed using the Duruoz Hand Index. These quantitative measures were correlated with clinically obtained manual muscle testing of the distal upper extremity (standard 0-5 scoring). Grip strength and 9-hole peg test performance were converted to age and sex adjusted Z-Scores. Wilcoxon Sign Rank Test was used to compare between-limb differences. Spearman’s correlations were used to correlate quantitative measures of hand function with each other and with manual muscle testing performance.

Results: Manual muscle testing was poorly correlated with grip strength, dexterity or self-reported function (|rho| < 0.50, p>0.05). Of patients with a manual muscle test of 5, contralesional grip strength ranged from Z=0.39 to Z=-1.95 and dexterity ranged from Z=0.51 to Z=-37.33. This implies that there is a broad range of dysfunction to which manual muscle testing lacks sensitivity.

Conclusion : Clinical assessments of manual muscle testing poorly differentiated normal vs substantially impaired grip strength and dexterity, suggesting that more in-depth, multimodal assessments of sensorimotor function may be required to fully understand motor deficits and their quality-of-life impact in patients with brain tumors.