Background & Aims
Phantom limb pain (PLP) is a chronic condition that is perceived in a limb that no longer exists1. Affects about 85% of amputated patients. Frequently, it can be overwhelming and challenging to manage, often necessitating a mix of treatments to improve patient pain and satisfaction, leading to poor quality of life2. Percutaneous Electrical Nerve Stimulation (PENS) is a therapy that involves inserting fine needles through the skin accessing nerves to deliver electrical impulses to alleviate pain conditions3,4.Transcranial Direct Current Stimulation (tDCS) is a non-invasive form of neuromodulation that involves applying a low electrical current to specific cortex areas through electrodes over the scalp. It modulates brain activity and has shown potential in various neuroscience fields, including pain treatment5,6. The aim of this study is to demonstrate the efficiency of a combination of peripheral and central neuromodulation therapies such as PENS and tDCS in amputee patients with PLP.
Methods
This series of cases comprise patients under treatment in a outpatient pain clinic of a tertiary university hospital in the south of Brazil from January 2017 to February 2020. Eligibility criteria were: age ? 18 years old with phantom lower limb pain for at least 6 months already in pharmacologic treatment with anticonvulsants and/or tricyclic antidepressants. Patients underwent 10 sections on a twice-a-week frequency of 20-minute tDCS with anodal stimulation over the primary motor cortex (M1) contralateral to the pain side, concurrently with PENS targeting the ipsilateral sciatic nerve, with alternate current at 2 Hz frequency, with current intensity setted to stimulus perception at the phantom part of the member. Pain scores were evaluated before and after each section and compared during the first, fifth, and last treatment sessions in the present study.
Results
Twelve patients were included (8 males and 4 female patients), all of which had lower limb amputations. Most were amputees due to vascular ischemic disease. Ten (83.3%) experienced a decrease in pain intensity by the end of the first session. By the fifth treatment session, eight patients (66.6%) had lower pain intensity upon arrival compared to their first session; two patients (16.6%) reported higher pain intensity than in their first session; two patients (16.6%) reported the same pain intensity as in their first session, and four patients (33.3%) reported no pain at all. By their last treatment session, all 12 patients had experienced a significant decrease in their pain. Six patients (50%) reported no pain at all. The average reduction in pain score was 4.8 points on the Numeric Pain Scale (NPS), comparing scores from the first to the last session.
Conclusions
To our knowledge this is the first study that describes the combination of these neuromodulation techniques for the treatment of PLP. The pathophysiology of PLP is not completely understood but recent studies have shown ectopic discharges7, cortical reorganization8 and deafferentation9 mechanisms may be interplaying to promote this complex phenomenon. It is hypothesized that PENS could stabilize ectopic discharge by creating an organized afferent current10 which could also affect cortical reorganization11. Besides, it is proposed that tDCS on M1 can activate corticothalamic connections and influence brain areas such as the prefrontal cortex, the cingulate gyrus, and the periaqueductal gray matter, thus modulating both affective-emotional and sensory aspects of nociception, as well as producing endogenous opioids12. However, the magnitude of clinical effect of the treatment surprised both us and the patients since phantom limb pain is known to be a refractory neuropathic pain condition.
References
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Presenting Author
Leonardo Botelho
Poster Authors
Topics
- Specific Pain Conditions/Pain in Specific Populations: Pain in Amputees