Does galvanic vestibular stimulation decrease spasticity in clinically complete spinal cord injury?

The aim of this study was to determine changes in clinical and biomechanical measures of spasticity after administering galvanic vestibular stimulation in patients with a complete spinal cord injury (SCI). The spasticity in the lower limbs was assessed using the Modified Ashworth Scale and the pendulum test in seven SCI patients (grade A on the ASIA Impairment Scale) before (0), immediately after (0), and at 5 and 30 min after the real versus sham galvanic vestibular stimulation (15 s each, anode over the right mastoid). Overall, the changes in spasticity were not significantly different between the real and sham galvanic vestibular stimulation. However, the Modified Ashworth Scale and the pendulum test indicated a reduction in spasticity in two out of seven patients. The results suggest that galvanic vestibular stimulation may modify spasticity in some patients with complete SCI, presumably through the residual vestibulospinal influences. Future studies should determine clinical and neurophysiological profiles of responders versus nonresponders and optimize parameters of galvanic vestibular stimulation.

Assessment of Spasticity by a Pendulum Test in SCI Patients Who Exercise FES Cycling or Receive Only Conventional Therapy.

Increased muscle tone and exaggerated tendon reflexes characterize most of the individuals after a spinal cord injury (SCI). We estimated seven parameters from the pendulum test and used them to compare with the Ashworth modified scale of spasticity grades in three populations (retrospective study) to assess their spasticity. Three ASIA B SCI patients who exercised on a stationary FES bicycle formed group F, six ASIA B SCI patients who received only conventional therapy were in the group C, and six healthy individuals constituted the group H. The parameters from the pendulum test were used to form a single measure, termed the PT score, for each subject. The pendulum test parameters show differences between the F and C groups, but not between the F and H groups, however, statistical significance was limited due to the small study size. Results show a small deviation from the mean for all parameters in the F group and substantial deviations from the mean for the parameters in the C group. PT scores show significant differences between the F and C groups and the C and H groups and no differences between the F and C groups. The correlation between the PT score and Ashworth score was 0.88.

Stimulation map for control of functional grasp based on multi-channel EMG recordings.

Transcutaneous activation of muscles with electrical stimulation has limited selectivity in recruiting paralyzed muscles in stroke patients. However, the selectivity could be increased by the application of smaller electrodes and their appropriate positioning on the skin. We developed a method for selecting the appropriate positions of the stimulating electrodes based on electromyography (EMG). The EMG activity maps were estimated from signals recorded with two electrode arrays and two 24-channel wearable amplifiers positioned on the nonparetic and paretic forearms. The areas where the difference between the EMG maps obtained from the nonparetic and paretic arms was significant were identified as the stimulation sites. The stimulation was applied through array electrodes with magnetic holders and two wearable stimulators with four output channels each. The measures of functionality included joint angles measured with goniometers (hand opening) and grasp force measured with a multi-contact dynamometer (grasping). The stimulation protocol comprised co-activation of flexors and extensors to stabilize the wrist joint and prevent pronation/supination.

Electrical stimulation for the suppression of pathological tremor.

Pathological tremor is manifested as an involuntary oscillation of one or more body parts. Tremor greatly decreases the quality of life and often prevents the patient from performing daily activities. We hypothesized that sensors-driven multichannel electrical stimulation could stabilize affected joints by activating the antagonistic muscles during involuntary activation of agonist muscles and vice versa (out-of-phase stimulation). Here, we present the new system (hardware and software) and the testing of its operation. The hardware consists of a multichannel stimulator and inertial sensors for feedback. The software implements adaptive sensors-driven control for the out-of-phase stimulation. The system was initially applied to healthy persons at the wrist and elbow joints to test the efficiency of the hardware and software solutions. Predefined rhythmic stimulation resulted in tremulous movement, which subjects could not prevent; yet, they were still able to functionally use their hand. The system was then applied to seven patients with Parkinson's disease and essential tremor for minimization of the wrist joint tremor. In six patients, the adaptive out-of-phase stimulation resulted in a significant decrease in the amplitude of tremor (67 ± 13%). In one patient, the stimulation did not result in the expected reduction of tremor.