Modulations in high-density EEG during the suppression of phantom-limb pain with neurostimulation in upper limb amputees.

Phantom limb pain (PLP) is a distressing and persistent sensation that occurs after the amputation of a limb. While medication-based treatments have limitations and adverse effects, neurostimulation is a promising alternative approach whose mechanism of action needs research, including electroencephalographic (EEG) recordings for the assessment of cortical manifestation of PLP relieving effects. Here we collected and analyzed high-density EEG data in 3 patients (P01, P02, and P03). Peripheral nerve stimulation suppressed PLP in P01 but was ineffective in P02. In contrast, transcutaneous electrical nerve stimulation was effective in P02. In P03, spinal cord stimulation was used to suppress PLP. Changes in EEG oscillatory components were analyzed using spectral analysis and Petrosian fractal dimension. With these methods, changes in EEG spatio-spectral components were found in the theta, alpha, and beta bands in all patients, with these effects being specific to each individual. The changes in the EEG patterns were found for both the periods when PLP level was stationary and the periods when PLP was gradually changing after neurostimulation was turned on or off. Overall, our findings align with the proposed roles of brain rhythms in thalamocortical dysrhythmia or disruption of cortical excitation and inhibition which has been linked to neuropathic pain. The individual differences in the observed effects could be related to the specifics of each patient's treatment and the unique spectral characteristics in each of them. These findings pave the way to the closed-loop systems for PLP management where neurostimulation parameters are adjusted based on EEG-derived markers.

Consecutive Transcutaneous and Epidural Spinal Cord Neuromodulation to Modify Clinical Complete Paralysis-the Proof of Concept.

Objective: To evaluate the effect of transcutaneous (tSCS) and epidural electrical spinal cord stimulation (EES) in facilitating volitional movements, balance, and nonmotor functions, in this observational study, tSCS and EES were consecutively tested in 2 participants with motor complete spinal cord injury (SCI). Participants and Methods: Two participants (a 48-year-old woman and a 28-year-old man), both classified as motor complete spinal injury, were enrolled in the study. Both participants went through a unified protocol, such as an initial electrophysiological assessment of neural connectivity, consecutive tSCS and EES combined with 8 wks of motor training with electromyography (EMG) and kinematic evaluation. The study was conducted from May 1, 2019, to December 31, 2021. Results: In both participants, tSCS reported a minimal improvement in voluntary movements still essential to start tSCS-enabled rehabilitation. Compared with tSCS, following EES showed immediate improvement in voluntary movements, whereas tSCS was more effective in improving balance and posture. Continuous improvement in nonmotor functions was found during tSCS-enabled and then during EES-enabled motor training. Conclusion: Results report a significant difference in the effect of tSCS and EES on the recovery of neurologic functions and support consecutive tSCS and EES applications as a potential therapy for SCI. The proposed approach may help in selecting patients with SCI responsive to neuromodulation. It would also help initiate neuromodulation and rehabilitation therapy early, particularly for motor complete SCI with minimal effect from conventional rehabilitation.

Neuromodulation and quality of life for patient with spasticity after spinal cord injury.

RATIONALE: Spasticity develops in 80% of spinal cord injury cases and negatively affects the patents' quality of life. The most common method of surgical treatment for severe spasticity is a long-term intrathecal baclofen therapy (ITB). Long-term spinal cord stimulation is another possible treatment technique. This paper aims to evaluate the changes in quality of life for patients with spasticity who have been treated with neuromodulation (SCS or ITB) in 12 months after the surgery, as well to compare the changes in quality of life for patients who have been treated with spinal cord stimulation and those who received long-term intrathecal baclofen therapy. MATERIALS AND METHODS: The influence of spasticity, experienced by the patients with a spinal cord injury, on their quality of life was analyzed before the surgery and 12 months after it. The severity of the spinal cord damage was determined with the scale of the American Spinal Injury Association (ASIA); spasticity was evaluated with the modified Ashworth scale, Penn Spasm Frequency Scale; pain levels were determined with visual analogue scale (VAS), anxiety and depression levels - with HADS. Functional activity of the patients was evaluated with the help of the Functional Independence Measure (FIM). RESULTS: The treatment results for 33 patients (25 men and 8 women), aged from 18 to 62, are presented. After the trial stimulation, the patients were randomly assigned to either SCS or ITB group (18 and 15 people respectively). The decrease of spasticity in both experimental groups caused lower levels of pain, less functional dependency on other people, lower stress and depression rates and, as a consequence, better quality of life and social adaptation. The obtained results for SCS and ITB groups are statistically similar.

Peripheral nerve stimulation enables somatosensory feedback while suppressing phantom limb pain in transradial amputees.

To simultaneously treat phantom limb pain (PLP) and restore somatic sensations using peripheral nerve stimulation (PNS), two bilateral transradial amputees were implanted with stimulating electrodes in the proximity of the medial, ulnar and radial nerves. Application of PNS evoked tactile and proprioceptive sensations in the phantom hand. Both patients learned to determine the shape of invisible objects by scanning a computer tablet with a stylus while receiving feedback based on PNS or transcutaneous electrical nerve stimulation (TENS). Оne patient learned to use PNS as feedback from the prosthetic hand that grasped objects of different sizes. PNS abolished PLP completely in one patient and reduced it by 40-70% in the other. We suggest incorporating PNS and/or TENS in active tasks to reduce PLP and restore sensations in amputees.

Neuromodulation as a basic platform for neuroprotection and repair after spinal cord injury.

Spinal cord injury (SCI) is one of the most challenging medical issues. Spasticity is a major complication of SCI. A combination of spinal cord stimulation, new methods of neuroprotection and biomedical cellular products provides fundamentally new options for SCI treatment and rehabilitation. The paper attempts to critically analyze the effectiveness of using these procedures for patients with SCI, suggesting a protocol for a step-by-step personalized treatment of SCI, based on continuity of modern conservative and surgical methods. The study argues the possibility of using neuromodulation as a basis for rehabilitating patients with SCI.

Spinal cord stimulation and intrathecal baclofen therapy for patients with severe spasticity after spinal cord injury.

RATIONALE: Spasticity is one of the main complications after the spinal cord injury (SCI). Most commonly, severe cases of spasticity are treated surgically with intrathecal baclofen therapy (ITB). Spinal cord stimulation for chronic pains (SCS) serves as an alternative for ITB. Both methods have their benefits and limitations. This study is aimed at development of a personalized SCS and ITB treatment algorithm for patients with severe cases of spasticity after SCI. MATERIALS AND METHODS: The paper analyzes the treatment results of 66 patients with severe spasticity after SCI (50 men and 16 women, age ranging from 18 to 62), average age is 36.03±12.29 y.o. Patients who chose surgery as a spasticity treatment option, received experimental stimulation, and after muscle tone reduction to a comfort level they were surgically implanted with a SCS system for chronic pain management. Patients with negative response to experimental stimulation were tested for baclofen and, based on the results, had a baclofen pump implanted. The patients were examined after 1, 3, 6 and 12 months. RESULTS: Surgical implantation of a SCS system was performed for 18 patients, ITB was used for 15 patients. After first 3 months of observation both groups demonstrated a significant improvement of spasticity index, but the SCS patients had better results. However, 6 months later the MAS scores, frequency of spasms and reflexes in both groups were the same. After 12 months of observation the ITB group exhibited a significant improvement of the MAS scores, compared with the control group, and reached the results, similar to the SCS group. CONCLUSIONS: Surgical treatment of patients with severe spasticity after SCI should start with experimental spinal cord stimulation, and, in case of a positive response, be followed by SCS system implantation. Patients with positive response to the experimental stimulation exhibit a significantly prolonged response to treatment, without substantial differences from ITB patients.