Random Noise Stimulation to Enhance Cortical Drive & Improve Hand Function

Random Noise Stimulation to Enhance Corticomotor Drive for Improved Hand Function

Cervical spinal cord injury (SCI) results in hand and arm function impairments and decreased independence in performance of daily activities such as bathing, eating, dressing, writing, or typing. Recent approaches that involve the application of non-invasive brain stimulation have the potential to strengthen the remaining connections between the brain and the spinal cord for improved hand function. Combining brain stimulation with performing upper limb functional tasks may further increase the ability of individuals with tetraplegia to use their hands. The purpose of this study is to investigate if "random noise", a special type of brain stimulation that most people cannot feel, can be used to enhance upper limb function in individuals with spinal cord injury. Specifically, the investigators will examine if a combined treatment protocol of random noise and fine motor training results in greater improvements in motor and sensory hand function compared to fine motor training alone.

Cervical spinal cord injury (SCI) results in upper extremity (UE) functional impairments that can restrict independence, social participation, and overall quality of life. Evidence shows that short duration of non-invasive brain stimulation (NIBS) can strengthen the transmission of information through the spared corticospinal pathways and improve UE functional recovery in individuals with tetraplegia. Transcranial direct current stimulation (tDCS), which is a clinically accessible NIBS approach, has been used to modulate cortical plasticity and improve hand function. However, the high variability in the reported effects of tDCS raises questions about its clinical value and highlights the need to investigate more robust NIBS protocols. Transcranial random noise stimulation (tRNS) is a novel NIBS approach that produces more consistent facilitatory effects compared to tDCS. TRNS delivers a low alternating current with a continuously changing intensity over a wide frequency range. Further, tRNS has excellent tolerability and no risk of skin burns since it is a polarity independent stimulation approach. When tRNS is applied over the motor cortex, it increases cortical excitability in the hand representation area and enhances motor learning in healthy adults. Despite the potential promise of tRNS in increasing corticomotor drive for improved motor performance, its application in persons with SCI is novel. Therefore, in this study, the investigators propose to use tRNS to augment the therapeutic effects of functional task practice (FTP). Our aim is to compare the efficacy of a 3-day tRNS+FTP protocol on cortical excitability, UE motor, and sensory function to tDCS+FTP and to sham-stimulation+FTP in individuals with tetraplegia.

Inclusion Criteria:

• Spinal Cord Injury level above C8
• ASIA Impairment Scale (AIS) classification level: C, D
• Time since injury: ≥ 1 year
• Active intrinsic hand muscles in at least one UE
• Active extrinsic hand muscles in both UE
• Ability to follow multiple step commands
• Ability to communicate pain or discomfort
• Willingness to participate in testing
• Ability to obtain informed consent

Exclusion Criteria:

• Implanted metallic device in the head and/ or pacemaker
• History of seizures
• History of severe headaches
• Severe contractures of UE that would limit participation in FTP
• Prior tendon or nerve transfer surgery
• Received Botulinum toxin injection in the tested UE in the last 3 months
• Pregnancy