Neuromodulation of Ankle Muscles in Persons With SCI

The ability to voluntarily move the ankles is important for walking. After spinal cord injury (SCI), this ability is impaired because of changes in the communication between the brain, spinal cord, and body. Whole body vibration (WBV) is a treatment that increases voluntary muscle control and decreases uncontrollable muscle movement in people with SCI. The purpose of this study is to understand how WBV can impact ankle control and uncontrollable muscle movement.

Spinal cord injury can result in impaired walking ability and decreased independence in daily activities such as standing and transfers. The ability to voluntarily control the ankle muscles is an important component of walking that is impacted by changes in the corticospinal tract and the spinal reflex circuits. These changes have been associated with the inability to dorsiflex the ankle during swing phase (foot drop) and uncontrollable muscle spasms and stiffness in the ankle during terminal stance (spasticity), as well as during transfers. In order to improve functional outcomes and further develop rehabilitation techniques, the underlying contributions of the corticospinal tract and spinal reflex circuit to ankle control needs to be better understood. Non-invasive tools that target the corticospinal and spinal reflex circuit are being used in clinical settings in order to improve functional outcomes in persons with spinal cord injury. Whole body vibration (WBV) is a non-invasive tool that has been shown to increase voluntary motor output and decrease spasticity in persons with spinal cord injury. These improvements in function may be due to changes in the corticospinal tract and spinal reflex circuits. In order to determine the relative contributions of the corticospinal tract and spinal reflex circuits to increased voluntary ankle control and decreased spasticity, we will measure changes in the corticospinal tract and spinal reflex excitability before and after a single session of vibration. We will then determine which change (corticospinal or spinal) contributes more to increased voluntary ankle control and decreased spasticity. This information will help guide future research to further improve walking ability in persons with spinal cord injury.

Eligibility Criteria:
Inclusion Criteria:

* Ability and willingness to consent and authorize use of Protected Health Information (PHI)
* Be between 18-85 years of age
* Be able to provide a letter of medical clearance for participation, if 70-85 years of age
* Have a SCI level of T12 of above, occurring more than 6 months ago
* Have a motor-incomplete severity classification (AIS C OR D)
* Have self-reported spasticity in at least one ankle
* Have a score of at least 2 indicating at least moderate spasticity on the Spinal Cord Assessment Tool for Spastic Reflexes (SCATS) clonus test in at least one ankle
* Have the ability to voluntarily move at least one ankle
* Must be able to stand and take at least 4 steps with or without assistive devices

Exclusion Criteria:

* Implanted metallic device in the head and/ or pacemaker
* Use of ankle-foot orthoses
* History of seizures
* History of frequent and/ or severe headaches
* Prior tendon or nerve transfer surgery
* Current pregnancy
* Inability or unwillingness to consent and Authorization for use of PHI
* 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
* Problems with following instructions
* Orthopedic problems that would limit participation in the protocol (e.g. knee or hip flexion contractures of greater than 10 degrees).
* Active infection of any type, as infection may exacerbate spasticity resulting in inability to identify the influence of the treatment