The Effects of Transcranial Direct Current Stimulation on
Metabolite Changes at the Thalamus in Neuropathic Pain
after Spinal Cord Injury: A Pilot Study
Auvichayapat P, MD¹*, Keeratitanont K, MD²*, Aneksan B, PhD³, Jensen MP, PhD⁴*, Tammaroj J, MD²,
Arayawichanon P, MD⁵, Tunkamnerdthai O, PhD¹, Boonphongsathian W, BSc², Auvichayapat N, MD⁶*
Affiliation : ¹ Department of Physiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand ² Department of Radiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand ³ Department of Physical Therapy, Mahidol University, Nakhon Pathom, Thailand ⁴ Department of Rehabilitation Medicine, University of Washington, USA ⁵ Department of Rehabilitation Medicine, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand ⁶ Division of Pediatric Neurology, Department of Pediatrics, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand * Member of Noninvasive Brain Stimulation Research Group of Thailand
Objective: To evaluate the pain intensity and brain metabolites, N-acetyl aspartate (NAA), myo-inositol (ml), choline (Cho),
and glutamine combined glutamate (Glx) levels in the thalami after transcranial direct current stimulation (tDCS) treatment.
Materials and Methods: Ten spinal cord injury (SCI) with neuropathic pain (NP) patients were given 20 minutes, 2 mA anodal tDCS over the left primary motor cortex for five consecutive days. Measures of numerical rating scales (NRS) and concentration of brain metabolites were performed before and immediately after treatment.
Results: The results showed significant reduction between pre- and immediately post-treatment in NRS (–2.213, 95% CI –0.836 to –3.570; p=0.005), significant decrease in Glx/Cr concentration (–0.025, 95% CI –0.004 to –0.045; p=0.022), and significant increased in ml/Cr (0.049, 95% CI 0.014 to 0.083; p=0.012) after tDCS treatment. No statistically significant pre- to post-treatment differences in NAA/Cr or and Cho/Cr were found in the present study.
Conclusion: The findings suggest that abnormal Glx/Cr and mI/Cr levels in the thalami would cause NP after SCI. The tDCS may be useful in NP reduction by returning the abnormal brain metabolites to normal. Additional research with larger sample size is warranted to evaluate this possibility.
Keywords : Magnetic resonance spectroscopy, Neuropathic pain, Spinal cord injury, Transcranial direct current stimulation
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