Spinal transcutaneous direct current stimulation to

enhance locomotor training after spinal cord injury

Radha Korupolu, MBBS, MS (pgy2)

Physical Medicine & RehabilitationUniversity of Kentucky

Mentor: Lumy Sawaki, MD, PhD

Collaborator: Kenneth Chelette, MS

University of Kentucky & Cardinal Hill Rehabilitation Hospital

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

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

Transcutaneous spinal direct current stimulation (tsDCS)

Preliminary studies in healthy subjects

Suggest possibility of similar modulation in spinal neurons

F. Cogiamanian et al. (2008) Sample size :

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)

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

T. Winkler et al. (2010) Sample size :

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

T. Winkler et al. (2010) Outcome measures:

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

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

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

Active electrode T11 2 cm from spinous process

Reference electrode at infraclavicular area

Direct current stimulator

MEP amplitude

Transcranial Magnetic Stimulation

Improved motor output following cathodal tsDCS

Increased MEPs

Increased F wave and

Decreased H reflex

First phase Anticipated Results

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

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

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

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?

Discussion

If successful the proposed stimulation technique would mark a

significant advancement in the field of SCI rehabilitation

Non-invasive

Inexpensive

Questions