Enhancing Corticospinal Excitability to Improve Functional Recovery
| Status: | Recruiting |
|---|---|
| Conditions: | Hospital, Neurology, Orthopedic |
| Therapuetic Areas: | Neurology, Orthopedics / Podiatry, Other |
| Healthy: | No |
| Age Range: | 18 - 65 |
| Updated: | 9/8/2018 |
| Start Date: | May 3, 2018 |
| End Date: | July 2019 |
| Contact: | Jennifer Iddings, PhD |
| Email: | jennifer.iddings@shepherd.org |
| Phone: | (404) 367-1239 |
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.
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.
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.
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.
Inclusion Criteria:
- Cervical (neurological level C1-C8) SCI occurring more than 6 months ago
- Any severity classification (ASIA/ISNCSCI A, B, C, D)
- Self-reported functional limitation in at least one upper limb
- Ability to voluntarily move thumb or index finger (visible twitch) of both upper limbs
- Ability and willingness to consent to participate in the study and authorize use of
protected health information
Exclusion Criteria:
- Pacemaker or metal implant in the head
- History of seizure
- History of frequent or severe headaches
- Damage to the nerves of the arms/hands (lower motor neuron damage) as documented in
medical record, per participant report, or during in-person screening
- Prior tendon or nerve transfer surgery
- Severe pain or hypersensitivity of the arm/hand that would limit participation in arm
and hand training
- Severe contractures of the arm/hand that would limit participation in arm and hand
training
- Current pregnancy
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