Bradykinesia in motoneuron diseases.

Area of Science:

• Neuroscience
• Neurology
• Movement Disorders

Background:

• Voluntary movement abnormalities in motoneuron diseases (MNDs) are understudied.
• Understanding neurophysiological correlates of these movements is crucial for diagnosis and management.

Purpose of the Study:

• To kinematically assess finger tapping abnormalities in amyotrophic lateral sclerosis (ALS) and primary lateral sclerosis (PLS) patients.
• To investigate the relationship between kinematic abnormalities and motoneuron involvement.

Main Methods:

• Finger tapping was assessed using motion analysis in 14 ALS and 5 PLS patients.
• Neurophysiological assessments included central motor conduction time, motor nerve conduction studies, and electromyography.
• Data were compared to 79 healthy controls (HCs).

Main Results:

• ALS and PLS patients showed significantly slower finger tapping compared to HCs.
• Movement slowness correlated with reduced muscle strength in both patient groups.
• In ALS patients, slowness also correlated with compound muscle action potential amplitude and denervation activity.

Conclusions:

• This study offers novel insights into voluntary movement abnormalities in MNDs.
• The findings underscore the critical role of motoneurons in generating movement slowness in these conditions.