Non-invasive Cervical Electrical Stimulation for SCI
Condition: Spinal Cord Injuries
MeSH terms: Spinal Cord Injuries
Study type: Interventional

Summary: 
      Most spinal cord injuries (SCI) are anatomically incomplete - some nerve circuits remain
      intact, even if the individual cannot feel or control them. Activating spared nerve circuits
      may improve functional recovery.

      With this goal, the Investigators have developed a form of electrical stimulation over the
      cervical spinal cord that can activate muscles in both hands simultaneously and comfortably.
      This technique, called cervical electrical stimulation (CES), works at the skin surface - no
      surgery or other invasive procedures are required.

      The long-term goal is to use CES to strengthen residual circuits to hand muscles after SCI.
      Regaining control over hand function represents the top priority for individuals with
      cervical SCI.

      In the current study, the Investigators first need to better understand how CES works. In the
      first half of this study, the Investigators will take a systematic approach to determining
      how CES interacts with other circuits in the spinal cord and the brain. In the second half of
      the study, the Investigators will test combinations of CES with active hand and wrist
      movements to find ways to enhance physical movement with CES.

      These experiments will improve understanding of electrical stimulation in SCI, and may set
      the table for future treatments to prolong any short-term benefits observed in this study.
    

Detailed description: 
      Roughly 60% of spinal cord injuries occur at the cervical level. Most injuries are
      anatomically incomplete. Activating spared nerve circuits augments functional recovery of the
      damaged nervous system. With this goal, the Investigators have developed a novel method of
      non-invasive cervical electrical stimulation (CES). Preliminary data show that CES triggers
      afferent sensory or efferent motor nerve roots depending on stimulus intensity, resulting in
      concurrent activation of multiple muscles on both upper limbs. the Investigators aim to use
      CES to strengthen residual circuits to hand muscles after SCI. Regaining control over hand
      function represents the top priority for individuals with cervical SCI.

      However, much more work needs to be done to better understand underlying CES mechanisms, its
      interactions with segmental and supraspinal circuits, and its optimal stimulation parameters
      for improving neural transmission to the hands. This proposal will address these issues.

      Mechanistic experiments: 15 able-bodied volunteers and 15 subjects with motor-incomplete
      cervical spinal cord injury will undergo systematic combinations of CES with transcranial
      magnetic stimulation (TMS) or peripheral nerve stimuli at varying intensities, sites, and
      interstimulus intervals.

      Mechanistic hypotheses: Conditioning subthreshold CES pulses will potentiate responses to
      test pulses of TMS and peripheral nerve F-wave stimulation, will reduce responses to test
      pulses of peripheral nerve H-reflex stimulation, and will modulate response to test
      suprathreshold CES pulses in either direction depending on conditioning stimulus interval and
      intensity. These experiments will elucidate CES circuit interactions at both the segmental
      and supraspinal levels.

      Combined CES-volitional movement experiments: 15 able-bodied volunteers and 15 subjects with
      motor-incomplete cervical spinal cord injury will undergo systematic combinations of CES with
      volitional wrist and hand movements at varying intensity and effort level.

      Combined CES-volitional movement hypotheses: Conditioning subthreshold CES pulses will
      facilitate concurrent volitional wrist and hand muscle activation. Suprathreshold CES will
      transiently inhibit concurrent volitional wrist and hand muscle activation. These experiments
      will shed light on the clinically relevant possibility of using CES to enhance response to
      physical exercise therapy.

      Completion of the proposed studies will characterize CES circuit timing and distribution, and
      will demonstrate in principle the potential for CES to enhance physical therapy for wrist and
      hand muscles. Furthermore, this approach is compatible with other interventions, including
      drug and cell-based treatments.
    

Intervention name(s): CES at rest; CES plus active hand or wrist movements
Intervention type(s): Device; Device
Intervention description(s): CES will be delivered at rest at various intensities, in combination with either electrical stimulation over peripheral nerves or magnetic stimulation over the motor cortex.
This is an experiment designed to measure CES interactions with other central and peripheral nerve circuits.; CES will be delivered while the participant performs specific finger or wrist tasks at different degrees of effort.
This is an experiment designed to detect momentary changes in muscle function.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: transcutaneous electric nerve stimulation; transcranial magnetic stimulation