1. Spinal transcutaneous direct current stimulation to enhance locomotor training after spinal cord injury
Radha Korupolu, MBBS, MS (pgy2)
Physical Medicine & Rehabilitation
University of Kentucky
Mentor: Lumy Sawaki, MD, PhD
Collaborator: Kenneth Chelette, MS
University of Kentucky & Cardinal Hill Rehabilitation Hospital

2. Background Transcranial direct current stimulation
Modulates cortical excitability
Anodal stimulation increases neuronal firing rate
Cathode stimulation decreases neuronal firing rate
Effects may last for >1 hr after stimulation
Inexpensive
Non-invasive
Nitsche et al., 2008; Nitsche et al., 2003; Priori, 2003

3. Transcranial direct current stimulation (tDCS)
Possible Mechanism:
Changes the resting membrane potential of the neurons in cortex
Adjuvant treatment options for pts suffering from
Stroke
Chronic pain
Depression
Cognitive deficits
Hummel et al., 2005;Fregni et al., 2006a,b

4. Transcutaneous spinal direct current stimulation (tsDCS)
Preliminary studies in healthy subjects
Suggest possibility of similar modulation in spinal neurons

5. F. Cogiamanian et al. (2008) Sample size : Intervention:
12 healthy subjects
Intervention:
tsDCS over T10 spinous process
2.5 mA for 15 mins
anodal or cathodal
Outcome Measures:
Post. Tibial N & Median N SEPs were recorded
Before, at current offset & 20 min after tcDCS (anodal/ cathodal DC)
PF, L1, C6, U3, RE lobe

6. F. Cogiamanian et al. (2008) Results
Anodal tcDCS decreased PTN SEPs amp by 25%
Effect lasted at least 20 min
Serum neurone specific enolase (NSE), a marker of neuronal damage
NSE level before & 1 h after stimulation measured in 5 subjects was not elevated after tsDCS

7. T. Winkler et al. (2010) Sample size : Intervention:
10 healthy subjects
Intervention:
tcDCS at T11 level 2 cm paravertebrally
2.5 mA applied for 15 min
Cathodal, anodal or sham
Each subject received all modes of stim 1 week apart

8. T. Winkler et al. (2010) Outcome measures: Results H-reflex
Before, at current offset, & 15 min after anodal, cathodal or sham tsDCS.
Results
Anodal tsDCS:
Down-regulated spinal excitability
Cathodal tsDCS:
Up-regulated spinal excitability

9. Our research plan Aim to study effects of tsDCS in 3 phases
Proposed objectives for the first phase:
Establish a reliable & reproducible spinal tsDCS methodology to modulate spinal excitability in healthy subjects

10. Proposed methods for first phase
Sample size: 10 healthy subjects
Intervention:
Anodal, cathodal or sham tsDCS at T11 2 cm paraspinally
2mA for 15 mins
Outcome measures:
MEPs will be evoked using trans magnetic stimulation
MEPs, H-reflex and F-wave will be recorded via surface electrodes over gastrocnemius muscle & abductor hallucis muscle bilaterally before & after tsDCS

11. Reference electrode at infraclavicular area
Active electrode T11 2 cm from spinous process
Direct current stimulator

12. Transcranial Magnetic Stimulation
MEP amplitude
Transcranial Magnetic Stimulation

14. First phase Anticipated Results
Improved motor output following cathodal tsDCS
Increased MEPs
Increased F wave and
Decreased H reflex

15. Preliminary results:
Preliminary testing in a single healthy subject suggests that cathodal tsDCS at T11 has greater facilitatory effects on MEPs compared to anodal tsDCS

17. Scientific plan Second phase:
Apply the tsDCS methodology developed in phase one to subjects with SCI
Evaluate modulation of spinal excitability
Same outcome measures as in 1st phase
If measures show favorable findings then we will progress to phase three

18. Scientific plan Third Phase:
Our long term objective is to evaluate the effects of tsDCS on functional motor recovery, paired with robot-assisted treadmill training in subjects with SCI

19. Potential Problems
Skin irritation & lesions have been reported following transcutaneous DC stimulation (caution in SCI)
Pain
Duration of the effects
Is there any potential for inducing autonomic dysreflexia?

20. Discussion
If successful the proposed stimulation technique would mark a significant advancement in the field of SCI rehabilitation
Non-invasive
Inexpensive

21. Questions