Therapeutic Transcutaneous Spinal Stimulation for Improved Recovery after Cervical Spinal Cord Injury in the Rat
Steve Perlmutter PhD, Research Associate Professor, University of Washington (UW) Department of Physiology & Biophysics
Co-Investigator: Christoph Hofstetter MD, PhD, Assistant Professor, UW Medicine Department of Neurological Surgery
Research Scientist: Nicholas Tolley, UW post-baccalaureate student
Recently, transcutaneous stimulation of the cervical spinal cord in combination with intensive physical therapy has shown promise as an effective treatment for deficits in hand motor function after spinal cord injury (SCI). However, it is difficult to explore a broad range of possible stimulation parameters and to investigate underlying mechanisms in human subjects. Such inquiries will be helpful to refine the clinical therapy and effectively combine it with other treatments, such as pharmacological or, in the future, cellular replacement interventions. In this study, the research team is developing a rat model of transcutaneous electrical stimulation for rehabilitation of forelimb movements after SCI.
Heat map showing size of muscle response (dark blue=no response; yellow=large response) to stimulation of different spinal segments (y-axis) and current amplitudes in t he anesthetized rat; stimuli delivered below the superficial neck musculature. Responses show some specificity and amplitude-dependent recruitment and are similar to transcutaneous cervical stimulation in humans.
To date, the team has established that a subcutaneous stimulation site activates the rodent spinal cord similarly to transcutaneous stimulation in humans, using the unique waveform used in the human studies. A series of experiments determined an appropriate depth and spinal segment for activating different forelimb muscles (Figure). In addition, the research team has designed an electrode implant that can deliver long-term stimulation to the rat spinal cord. Currently, the team is using this implant to investigate a range of stimulation parameters in rats with chronic SCI, to identify stimulation protocols with therapeutic effects on motor function. This will be followed by studies to explore the mechanisms underlying the improvement in recovery.