Modulating pain in CRPS with tDCS Giridhar Gundu, M.D. PGY IV Co-investigator: Kenneth Chelette,...
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Transcript of Modulating pain in CRPS with tDCS Giridhar Gundu, M.D. PGY IV Co-investigator: Kenneth Chelette,...
Modulating pain in CRPS with tDCS
Giridhar Gundu, M.D.PGY IV
Co-investigator: Kenneth Chelette, M.S.
Dept. of PM&R
University of Kentucky 5/23/2013
Complex regional pain syndrome
O CRPS is a highly painful, limb-confined condition, which arises usually after trauma.
O Associated with a particularly poor quality of life, and large health-care and societal costs.
O Crossroads of interests of several disciplines including rheumatology, pain medicine, neurology, physiatry.
Clinical presentation of CRPSEarly CRPS of the right hand:
Clearly visible signs include swelling, red color and a shiny skin.
As the disease progresses some of these visible signs can partially or completely disappear while pain may persist unabated.
There are currently eight major concepts about CRPS etiology.
1. Inflammatory process
2. Sympathetically mediated disorder
3. Autoimmune condition
4. Limb ischemia/ischemia reperfusion injury
5. Cortical reorganization
6. Nerve damage
7. Neurogenic inflammation
8. Alternative concepts
O The IASP has proposed dividing CRPS into two types based on the presence of nerve lesion following the injury:
O CRPS type I (reflex sympathetic dystrophy). Minor injuries or fracture of a limb precede the onset of symptoms.
O CRPS type II (causalgia) develops after injury to a major peripheral nerve.
Treatment
O Pharmacological (Gabapentin, corticosteroids,antidepressants, anticonvulsants, opioids capsaicin, lidocaine, clonazepam, ketamine, bisphosphonates)
O Interventional
O Neurostimulatory
O Psychological/CBT
O Physical and vocational rehabilitation
O Patient education
There is a desperate need for further research into the treatment of CRPS
Transcranial direct current stimulation (tDCS)
O Uses weak electrical currents (1-2mA) to modulate the activity of neurons in the brain
O In tDCS, the anodal electrode placed over the cortical target results in increased cortical excitability, whereas cathodal stimulation decreases local cortical excitability.
O The primary action of tDCS for pain reduction is direct modulation of activity in certain areas of the brain that are involved in pain processing, such as the thalamus and inhibitory corticospinal mechanisms.
O tDCS is used in other pain syndromes, such as fibromyalgia, phantom pain and central pain in traumatic spinal cord injury.
Objectives
Our proposed study has 2 specific aims:
Determine the effect of tDCS on pain and quality of life associated with CRPS.
Determine the specificity of tDCS site for modulation of pain and quality of life associated with CRPS.
Study Design
ODouble-blind, randomized, placebo-controlled study
OSubjects stratified based on pain intensity and duration of CRPS.
OSubjects then randomly assigned to 1 of the following 3 groups: Group 1: anodal tDCS over DLPFC Group 2: anodal tDCS over M1 Group 3: sham tDCS over DLPFC
4 evaluation sessions and 10 treatment sessions with each subject
T0 T1 T3Begin treatment
1 week 1 week1 week1 week
T4
Study Population
Inclusion criteria: Subjects must be at least 18 years of age with diagnosed CRPS following the recently updated Budapest criteria
Exclusion criteria:• Within 1 month of recruitment, addition or change in the dosage of drugs
known to interfere with pain• Untreated depression• History of head injury with loss of consciousness, severe alcohol or drug abuse,
or psychiatric illness, Seizure disorder• Pregnancy • Presence of ferromagnetic material in the cranium except in the mouth,
including metal fragments from occupational exposure, and surgical clips in or near the brain.
Intervention One 35 cm2 saline-soaked sponge electrodes placed over the scalp
sites overlying the relevant cortex and reference electrode placed supraorbitally.
Battery-operated direct current stimulator for delivery of stimulation (Magstim Ltd., Wales, UK).
With the exception of the control group, each subject will receive 20 minutes of tDCS at an intensity of 1.4mA. (These values result in a current density of 0.04mA/cm2 and a charge density of 480 Coulombs/M2)
For the control condition, stimulation intensity will be ramped up then ramped down over a 30-second window.
Assessment
O Short-Form McGill Pain Questionnaire, which will serve as the primary behavioral outcome for this study.
O The SF-36 Health Survey will be used to measure changes in quality of life.
O We have secured approval by the University of Kentucky Institutional Review Board and begun enrollment of subjects.
O Three subjects with chronic CRPS were enrolled after informed consent (projected total enrollment: n=30).
O Each subject was randomly assigned to 1 of 3 groups: 1) anodal stimulation over left dorsolateral prefrontal cortex, 2) anodal stimulation over left primary motor cortex, or 3) sham.
O We delivered tDCS daily for 10 consecutive weekdays.
O Assessments of pain and quality of life including the Short-Form McGill Pain Questionnaire and The SF-36 Health Survey were performed by a blinded evaluator at four time points:
O 1-week prior to start of intervention, immediately prior to start of intervention, after intervention day 5, and after intervention day 10
Baseline 1 Baseline 2 Midpoint Post20
25
30
35
40
45
50McGill Total Pain Rating Index
DLPFC DLPFC M1
Results
?
Baseline 1 Baseline 2 Midpoint Post0
5
10
15
20
25
30
35
40
45 SF-36 PCS
DLPFC DLPFC M1
Baseline 1 Baseline 2 Midpoint Post0
10
20
30
40
50
60
70
80 SF-36 MCS
DLPFC DLPFC M1
Results