Effects of Focal Muscle Vibration Versus Whole Upper Limb Vibration on Spasticity and Upper Motor Control Functions in Post-Stroke Patients

Motor impairment post-stroke, which usually affects the movement of the face, arm, and leg on one side of the body, impacts approximately 80% of individuals who have experienced a stroke. Upper limb motor impairments (involving the arm, hand, and/or fingers) are often long-lasting and debilitating; only about half of stroke survivors with an initially paralyzed upper limb recover some useful function within six months.

Recently, mechanical vibrations have been utilized as a form of somatosensory stimulation to enhance motor function and to address muscle spasticity in the upper limbs following a stroke. When applying vibration stimuli during exercise or physical rehabilitation, these can be broadly classified into two categories: (a) vibrations that are directly applied to a specific muscle or tendon, and (b) indirect vibrations that are not limited to a specific muscle, delivered either through the feet while standing on a platform or through the hands using a handheld device. The direct application of vibrations to a muscle or tendon is often referred to as focal muscle vibration (FMV) or segmental vibration (SV), and it may also be called repetitive muscle vibration (rMV). In contrast, indirect vibrations delivered through the hands are typically known as upper limb vibration (ULV), while those aimed at the lower limbs are referred to as whole-body vibration (WBV).

Vibration therapy (VT) is a form of physical therapy that employs mechanical vibration waves to stimulate the human neuromuscular system for therapeutic benefits. It demonstrates promising potential for use in the rehabilitation of dysfunctions part of bosy resulting from a stroke.

Focal muscle vibration (FMV) OR segmental muscle vibration is a relatively new approach used to enhance motor function and reduce spasticity in the hemiplegic upper limb of stroke patients. In FMV, a vibratory stimulus is delivered to a specific muscle tendon via a mechanical device, which activates the muscle spindle primary endings and generates Ia inputs. Vibration applied to a muscle can elevate the motor-evoked potential recorded from that muscle at rest, indicating an increase in corticospinal excitability during the vibration. Additionally, studies have shown that the duration of the cortical silent period in a forearm flexor muscle can increase when the antagonist forearm extensors are vibrated, providing strong evidence that pure sensory stimulation can influence motor cortical excitability.