Objective: To kinematically assess abnormalities of voluntary upper limbs movements in patients with amyotrophic lateral sclerosis compared to healthy subjects. To investigate possible relationships between altered movement kinematics and neurophysiological measures of motor neurons involvement in patients with amyotrophic lateral sclerosis.

Background: Amyotrophic lateral sclerosis is primarily characterized by a progressive degeneration of motor neurons, leading to muscle weakness and motor impairment. There are some clinical reports of bradykinesia in patients with amyotrophic lateral sclerosis, but no studies have objectively assessed the movement abnormalities in these patients. Moreover, the relationship between motor neurones involvement and movement abnormalities in this condition is largely unknown.

Method: Thirteen patients with a definite diagnosis of amyotrophic lateral sclerosis and 13 healthy subjects were enrolled in the study. Repetitive finger tapping was assessed by means of a motion analysis system. Patients with amyotrophic lateral sclerosis underwent to a motor nerve conduction study of bilateral median and ulnar nerves. The two groups were compared by one-way analysis of variance. Possible relationships between clinical, kinematic and neurophysiological data were assessed in patients with amyotrophic lateral sclerosis.

Results: Patients with amyotrophic lateral sclerosis performed less movements and they were slower than healthy controls (P<0.01). Patients also showed an altered movement rhythm (P<0.05). Finally, the number of movements correlated with the amplitude of the compound muscle action potential recorded form the first dorsal interosseus muscle in patients (P=0.02). We found no other significant correlations between kinematic and neurophysiological data.

Conclusion: This study provides new information on the evidence of voluntary movement impairment in amyotrophic lateral sclerosis, particularly movement slowness and altered movement rhythm without decrement. In amyotrophic lateral sclerosis movement slowness likely depends on the lower motor neurons involvement.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/kinematic-assessment-of-bradykinesia-in-patients-with-amyotrophic-lateral-sclerosis/