Enhancing Corticospinal Excitability to Improve Functional Recovery
Condition: Spinal Cord Injuries; Tetraplegia
MeSH terms: Spinal Cord Injuries; Quadriplegia
Study type: Interventional

Summary: 
      Research indicates that increasing brain excitability might help improve hand function in
      people with spinal cord injury. Brain stimulation that uses electrodes placed on the surface
      of the scalp (also called "non-invasive brain stimulation") increases brain excitability and
      has the potential to make it easier for the brain and nervous system to respond to arm and
      hand training. The purpose of this study is to compare four different types of stimulation
      for increasing brain excitability to determine which types are best for helping people with
      tetraplegia improve their ability to use their arms and hands. To fully evaluate the value of
      brain stimulation on arm and hand function, the investigators will also evaluate the effect
      of sham (fake) stimulation. Each participant will receive a single session of each of the
      five types of stimulation being tested.
    

Detailed description: 
      Restoration of upper extremity function is often the top rehabilitation goal for persons who
      have sustained a cervical spinal cord injury (SCI). Following SCI, beyond the disruption
      caused by the injury itself, maladaptive cortical reorganization further limits descending
      corticospinal drive. Therefore, therapies aimed at increasing the descending drive provided
      by corticospinal and other descending supraspinal tracts could be beneficial adjuncts to
      commonly used rehabilitation therapies. While many rehabilitation research strategies for
      improving function following SCI target the spinal circuitry, relatively few rehabilitative
      approaches are directed toward promoting supraspinal neuroplasticity to reduce impairment by
      increasing volitional control. Spectacular high-tech interventions and elegant high-tech
      outcome measures generate a great deal of excitement in the scientific world. However, the
      technological investment and training required for these approaches and the questionable
      clinical meaningfulness of the outcomes is a major limitation to their real-world value.

      Transcranial direct current stimulation (tDCS) is a clinically accessible form of
      non-invasive brain stimulation (NIBS) that has been shown to improve upper extremity function
      in persons with SCI. Clinical accessibility and the potential for prolonged modulation of
      cortical excitability make tDCS is an attractive tool for non-invasive modulation of
      corticospinal excitability.

      Beyond traditional tDCS, intriguing recent studies in non-disabled individuals suggest a
      novel form of NIBS, transcranial pulsed current stimulation (tPCS), may be more effective for
      inducing changes in corticospinal excitability. tPCS utilizes unidirectional, positive pulses
      of current separated by brief interpulse intervals rather than continuous direct current.
      Some evidence from our lab and others indicates that patterned stimulation has a larger
      influence on neural excitability than uniform stimulation.

      Importantly, the efficacy of NIBS is dependent upon stimulation site. Since persons with
      tetraplegia have bimanual impairments, it has been suggested that bihemispheric anodal
      (excitatory) tDCS may be of value. Bihemispheric anodal tDCS has been studied in non-disabled
      individuals; this approach was found to be safe and was associated with improved bimanual
      control. However, the value of this approach has not previously been assessed in persons with
      tetraplegia.

      The investigators propose a randomized, sham-controlled crossover study in which two forms of
      NIBS (tDCS and tPCS) will be compared with a sham-control intervention to determine their
      relative efficacy for improving upper extremity strength and motor control (Aim 1) and
      corticospinal excitability (Aim 2) in individuals with chronic (≥ 6 months) tetraplegia. The
      efficacy of two different stimulation montages, uni- and bihemispheric, will also be compared
      (Aim 3). Subjects will receive a single session of each NIBS condition (unihemispheric tDCS,
      bihemispheric tDCS, unihemispheric tPCS, bihemispheric tPCS) and a sham-control condition.
    

Intervention name(s): bihemispheric transcranial pulsed current stimulation (tPCS); unihemispheric transcranial pulsed current stimulation (tPCS); bihemispheric transcranial direct current stimulation (tDCS); unihemispheric transcranial direct current stimulation (tDCS); sham-control
Intervention type(s): Other; Other; Other; Other; Other
Intervention description(s): Two sets of sponge electrodes (one set placed on each side of the head) will be placed on the participant's head. The transcranial electrical stimulator will apply unidirectional, positive pulses of current separated by brief interpulse intervals to the scalp via the sponges for 30 minutes.; One set of sponge electrodes will be placed on the participant's head. The transcranial electrical stimulator will apply unidirectional, positive pulses of current separated by brief interpulse intervals to the scalp via the sponges for 30 minutes.; Two sets of sponge electrodes (one set placed on each side of the head) will be placed on the participant's head. The transcranial electrical stimulator will apply continuous, direct current to the scalp via the sponges for 30 minutes.; One set of sponge electrodes will be placed on the participant's head. The transcranial electrical stimulator will apply continuous, direct current to the scalp via the sponges for 30 minutes.; Sponge electrodes will be placed on the participant's head. The transcranial electrical stimulator will apply stimulation to the scalp via the sponges for 1-2 minutes. The stimulator will then be turned off.
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: This is a a randomized, sham-controlled crossover study in which all participants will participate in a single session of each type of intervention.
Masking: Double (Participant, Outcomes Assessor)
Primary purpose: Treatment
Keywords: non-invasive brain stimulation