Objective

Clinical assessment of upper extremity in multiple sclerosis is mainly limited to 9-hole peg test (9-HPT), which is commonly criticized due to its limited sensitivity. There is a need for sensitive outcome measures for the assessment of motor symptoms in individuals with multiple sclerosis (iMS). We evaluated our recently developed brief force pulse protocol to simultaneously quantify the motor control of hand function and neuromuscular quickness in iMS. Additionally, we compared the sensitivity of the studied outcome measures with 9-HPT in detecting the differences between iMS and controls.

Methods

Twelve iMS and 12 controls grasped a grip- (GF; perpendicular force) and load-force (LF; tangential force) measuring handle and produced around 100 isometric LF pulses to various submaximal levels by pushing down on it as quickly as possible, followed by quick relaxation. The GF-LF ratio quantified the motor control of hand function. The slopes of linear regressions between peak forces and corresponding peak rates of force development (rate of force development scaling factor; RFD-SF) and relaxation (rate of force relaxation scaling factor; RFR-SF) quantified the control of neuromuscular quickness.

Results

All of the selected variables were different between groups (all p-values < .05), and the effect sizes obtained from RFD-SF (d = 2.87) and RFR-SF (d = 1.93) were larger than the effect sizes obtained from 9-HPT (d = 1.07).

Conclusion

Measures of neuromuscular quickness are more sensitive to detect disease related differences than 9-HPT and, therefore, can be used as a tool in clinical and rehabilitative settings to objectively evaluate therapeutic interventions and disease progression in iMS.