Finger tapping impairments are highly sensitive for evaluating upper motor neuron lesions

Area of Science:

• Neurology
• Neuroscience
• Clinical Assessment

Background:

• Accurate neurological examination components are vital for identifying clinical deficits.
• Central nervous system (CNS) demyelinating lesions, such as those in multiple sclerosis (MS) or clinically isolated syndrome (CIS), can affect motor function.
• Investigating simple, reliable tests for early detection is crucial.

Purpose of the Study:

• To compare finger tapping performance between patients with CNS demyelinating lesions and healthy controls.
• To determine the sensitivity and inter-evaluator reliability of specific finger tapping tasks for detecting neurological impairment.

Main Methods:

• 35 participants (23 with CNS demyelinating lesions, 12 healthy controls) performed index finger to thumb tapping tasks.
• Tapping involved both thumb tip and distal crease, using dominant and non-dominant hands.
• Videos were independently assessed by 10 evaluators (neurologists, residents, advanced practice providers) for sensitivity and reliability.

Main Results:

• Finger tapping against the distal thumb crease of the non-dominant hand showed the highest sensitivity (84%) for detecting impairment, particularly when evaluated by neurologists.
• Tapping the thumb crease was more sensitive than tapping the thumb tip across all evaluator types.
• Neurologists' evaluations of non-dominant hand thumb crease tapping yielded the best inter-evaluator reliability (kappa = 0.83).

Conclusions:

• Impaired finger tapping against the distal thumb crease of the non-dominant hand is a sensitive indicator of CNS demyelinating lesion-related impairments.
• This finding underscores the significance of examining the non-dominant side for subtle fine motor control deficits, potentially indicating earlier detection of upper motor neuron injury.