Influence of Transcutaneous Spinal Stimulation Intensity on Spasticity After SCI

Neuromodulation of Spinal Circuits: Effects on Spasticity, Nociception, and Motor Activation

Transcutaneous spinal stimulation (TSS) is a form of electrical stimulation delivered over the skin of the spine that may be valuable for reducing spasticity without the side effects of antispasticity medications. The intensity of stimulation, or dose, that promotes the best response is not known. Understanding the response to different intensities of stimulation and how they affect spasticity will help guide rehabilitation for persons with SCI. Therefore, this study aims to identify the effects of TSS as a non-drug intervention for spasticity management.

Spasticity involves involuntary muscle activity in persons with spinal cord injury (SCI) that can include increased response to muscle stretch and physical touch, as well as muscle stiffness. Due to the combination of symptoms, several drug therapies are currently prescribed to reduce spasticity but they may have negative side effects including fatigue and muscle weakness. Transcutaneous spinal stimulation (TSS) is a form of electrical stimulation delivered over the skin of the spine that seems to have effects that are similar to drug therapy. Prior studies of TSS in persons with SCI suggest that TSS can reduce spasticity without negative side effects. The intensity of stimulation, or dose, that promotes the best response is not known. In addition, sensitive measurements are necessary to assess the changes that can be seen in multiple presentations of spasticity. Understanding the response to different intensities of stimulation and how they affect spasticity will help guide rehabilitation for persons with SCI. Therefore, this study aims to identify the effects of TSS as a non-drug intervention for spasticity management.

Inclusion Criteria:

The participant must meet all of the following criteria to be eligible for the study:

• Ability and willingness to authorize the use of protected health information (PHI)
• Be 16 years of age or older
• Have a SCI with any severity classification (AIS A, B, C, or D) that occurred at least 3 months ago
• Have at least mild "spasticity" affecting lower extremity muscles, as indicated by a pendulum test first swing excursion angle of ≤ 77° or ≥ 5 beats of clonus on the ankle drop test
• Use of prescription medications is acceptable, as long as the dosage has not changed in the last 2 weeks and notification of medication changes is made during study participation
• Ability to follow multiple commands
• Ability to communicate pain or discomfort

Exclusion Criteria:

The presence of any one of the following criteria leads to exclusion:

• Progressive or potentially progressive spinal lesions, including degenerative, or progressive vascular disorders of the spine and/or spinal cord
• Neurologic level below spinal level T12
• History of cardiovascular irregularities (e.g. atrial fibrillation)
• Active cancer or a history of cancer
• Orthopedic pathology that would limit participation in the protocol (e.g. knee or hip flexion contractures of greater than 10 degrees)
• Use of semi-permanent or permanent anti-spasmodic treatment (i.e. botox, selective dorsal rhizotomy)
• Women who are pregnant, or who have reason to believe they are, or may become pregnant due to unknown risks to the fetus associated with TSS
• Persons who have implanted stimulators of any type will be excluded due to unknown potential of electrical stimulation effects (e.g. baclofen pump, epidural spinal stimulator, implanted cardiac defibrillator, diaphragmatic pacemaker)
• Active infection of any type, as infection may exacerbate spasticity resulting in inability to identify the influence of the treatment
• Skin irregularities, sensitivity, or lesions that would increase the risk of stimulation-associated adverse events