INTRODUCTION:

BACKGROUND

Transcranial Direct Current Stimulation (tDCS) is the most commonly used transcranial electrical stimulation. tDCS resulted a weak current directed to the surface of the head in order to manipulate nerve impulses non-invasively through membrane polarization¹. Neuropathic pain syndrome with heat sensation can cause a spontaneous high degree of pain, and is often chronic. In most cases, oral and topical pharmacological therapy is used for patients complaining allodynia on the skin surface, however the result still unsatisfactory². Therefore, this study aimed to assess tDCS as conventional analgesic in chronic neuropathic pain with a heat sensation as there are only limited studies regarding this matter.

Case Report:

A 46 years old male with a chief complain of pain in both palms and feet for the last 4 years ago came to the hospital (2017).

The patient described the pain as heat sensation with NRS 7. The pain is triggered by heat and sweat and relieved with cold. The patient experienced pain every day with a duration of approximately 3-6 hours. Relieving factors are medications or cold compress (NRS reduced to 5).

The pain interferes his daily activities and work, therefore the patient decided to stop working. In 2017, the patient was diagnosed as Rheumatoid Arthritis (RA) by an internal medicine doctor and was treated for 12 months with Doxycycline, Chloroquine, Methylprednisolone and Methotrexate. However, there was no significant improvement. The patient was then treated with Imuran, Sulfazaline and Arava for 4 months. Yet, there is still no improvement. The patient was then referred to a neurologist and diagnosed as peripheral polyneuropathy. He was given pregabalin 1x75mg and Tramadol 3x50mg. Although the intensity of pain improved, the patient still experienced pain everyday. The patient did not have diabetes mellitus, hypertension, stroke, and tumor. The patient never smoked and consumed alcohol. On his free time, the patient likes to do sport, so he often get small, insignificant trauma.

General examination found within normal limits. Neurological examination found allodynia at 37C in the palms and soles of the feet. Diagnostic examinations such as MRI, EMG, EEG and perspiration were within normal limits.

tDCS with a duration of 20 minutes is performed every day for 3 weeks. tDCS anode is placed in the C3 region and tDCS cathode is placed in FP2 with a power of 2000mA. The duration of fade in and fade out phase is 10 seconds. During the treatment, the patient took duloxetine and experience NRS 7. Post-tDCS, his NRS reduced to 5.

Figure 1: Implementation of tDCS on a patient. Picture (1A) shows the placement of tDCS anode in the C3 area while picture (1B) shows the placement of the tDCS cathode in the FP2 area

DISCUSSION:

Chronic pain with central sensitization are more common in female than the male. Pain intensity prior and post treatment was assessed using NR. Twenty six percent of patient experiencing chronic pain had neuropathic pain, while 35.3% had musculoskeletal pain and 38.5% had atypical pain³. The pain (NRS=7) experienced by the patient impedes his activities of daily life. Treatment of chronic pain can be classified into various categories such as NSAIDs, weak opioids, strong opioids, paracetamol, anti-depressants, and anticonvulsants.³ This patient was initially diagnosed as RA and underwent routine treatment for 1 year without any improvement. The pain intensity decreased with gabapentin 1x75m and tramadol 3x50mg after 1 year of usage.

Neuropathic pain is often resistant to medication, therefore brain stimulation is needed. Among various types of non-invasive brain stimulation techniques, transcranial direct current stimulation (tDCS) has been widely used to reduce pain in patients with neuropathic pain⁴. tDCS works through anodal and cathodal stimulation. Anodal stimulation (applying the anode over the target area) will increase cortical excitability by depolarizing the membrane potential. While cathodal stimulation (applying the cathode over the target area) will inhibit cortical stimulation by hyperpolarizing the membrane potential. The after-induced effect on cortical excitability also depends on factors such as intensity and duration of stimulation. Due to its neuromodulatory effects, tDCS is a promising approach for pain management. In particular, placing tDCS over the primary motor cortex (M1) has been shown to attenuate pain perception in healthy participants, patients with increased pain thresholds and patients with decreased levels of pain perception. One potential mechanism underlying this phenomenon is the activation of subcortical structures of endogenous pain inhibitory pathways such as the thalamus, cingulate gyrus, periaqueductal gray midbrain, and subnucleus reticularis dorsalis^5-16.

CONCLUSION:

In this case report, the NRS decreased from 7 to 5 with the use of 20-minutes daily tDCS for one week with a power of 2 A.

ACKNOWLEDGMENTS:

Further study regarding the usage of tDCS in patients with neuropathic pain with heat sensation is needed.

REFERENCE:

1. Knotkova H, Woods AJ, Bikson M, et al. Transcranial Direct Current Stimulation (tDCS): What Pain Practitioners Need to Know. Pract Pain Manag. 2017; 6. DOI: 10.5958/0974-3.2

2. Baron R. Neuropathic Pain: A Clinical Perspective. In: Canning BJ, Spina D (eds) Sensory Nerves. Berlin, Heidelberg: Springer Berlin Heidelberg, pp. 3–30. DOI: 10.5960.2

3. Schliessbach J, Siegenthaler A, Streitberger K, et al. The prevalence of widespread central hypersensitivity in chronic pain patients. Eur J Pain. 2013; 17: 1502–1510. DOI: 10.5958560.2

4. Yang S, Chang MC. Transcranial Direct Current Stimulation for the Management of Neuropathic Pain: A Narrative Review. Pain Physician. 2021; 24: E771—E781. DOI: 10.595860.2

5. Yao J, Li X, Zhang W. Analgesia induced by anodal tDCS and high-frequency tRNS over the motor cortex: Immediate and sustained effects on pain perception. Brain Stimul. 2021; 14: 1174–1183. DOI: 10.5958

6. Wan-Seo Park, Sea-Hyun Bae, Kyung-Yoon Kim. Combination Effects of Sensorimotor Training and Transcranial Direct Current Stimulation on Balance Ability in Soccer Players. Research J. Pharm. and Tech. 2019; 12(7):3323-3327. DOI: 10.5958/0974-360X.2019.00560.2

7. Rafiei H, Ahmadinejad A, Amiri M, Esmaeili Abdar. Effect of nursing implemented sedation and pain protocol on the level of sedation, pain and amount of sedative and analgesic drugs use among opium addicted critically ill patients. Asian J. Nur. Edu. and Research. 2013; 3(1): 37-41.

8. Joy RAP. Effect of Foot Reflexology on Pain among Cancer Patients in Oncology Ward, Sri Ramakrishna Hospital, Coimbatore. Asian J. Nur. Edu. and Research. 2011; 1(4): 107-108.

9. Ahmadinejad M, Rafiei H, Amiri M. Comparison between Intravenous and Epidural Injections of Fentanyl in Critically Ill Patients with Thoracic Trauma: effects on Pain Level, Static Pulmonary Compliance, and Arterial Blood Gas. Asian J. Nur. Edu. and Research. 2014; 4(1): 11-14.

10. Sampoornam W. Eutony on Chronic Low Back Pain. Asian J. Nur. Edu. and Research. 2015; 5(1): 121-123. DOI: 10.5958/2349-2996.2015.00026.9

11. Shruthi Keerthi G, Malathi K, Sangamesh N. Effectiveness of Foot Bath in Reducing Selected Joint Pain among Elderly People. Asian J. Nursing Education and Research. 2018; 8(1): 118-126. DOI: 10.5958/2349-2996.2018.00025.3

12. Syahrul S, Imran I, Fajri N. Clinical characteristics of traumatic brain injury patients in Dr. Zainoel Abidin Public Hospital Banda Aceh, Indonesia. Bali Med J. 2020; 9(1): 194-200.

13. Arifin MT, Setiawan FE, Prihastomo KT, Bintoro AC, Harahap S, Sasongko H, Bakhtiar Y, Priambada D, Risdianto A, Brotoarianto HKBK, Andar EB, Kusnarto G, Karlowee V, Muttaqin Z. Awake craniotomy procedure for near eloquent cortical area for brain tumor case series: initial experience and the anesthetic challenges. Bali Med J. 2020; 9(2): 531-6.

14. Tini K, Samatra IDPGP, Wiryadana KA, Supadmanaba IGP. Clinical profile of patients with cerebrovascular disease at Stroke Unit, Sanglah General Hospital, Denpasar, Bali. Bali Med J. 2020; 9(1): 129-36.

15. Mutiawati E, Syahrul S, Musadir N. Brain alteration in chronic pain and the relationship with pain score. Bali Med J. 2020; 9(2): 461-5.

16. Abidah SN, Anggraini FD. The effect of ginger compress on reducing back pain on the third trimester pregnant women. Bali Med J. 2022; 11(2): 918-20.

Received on 07.09.2022 Modified on 14.10.2022

Research J. Pharm. and Tech 2023; 16(7):3172-3174.

DOI: 10.52711/0974-360X.2023.00521