Balance Training-Related Changes in Intracortical Inhibition and Symptom Severity in a Patient with Chronic Neuropathic Pain: A Single-Case Study

Background/Objectives: It is widely recognized that malfunctions in the GABAergic system can be one of the underlying mechanisms in chronic pain. However, the use of GABAergic drugs to improve pain perception has strong and unwanted side effects, particularly in terms of sedation. Therefore, the present exploratory single-case study tested an alternative treatment using balance training to upregulate the GABAergic system in a 62-year-old patient with widespread chronic pain. Previously, balance training was shown to increase short-interval intracortical inhibition (SICI), a neurophysiological marker commonly associated with GABA-mediated intracortical inhibition, as assessed using paired-pulse transcranial magnetic stimulation (TMS), in healthy young and older adults. Therefore, we hypothesized that the balance-training-induced increase in GABAA-related intracortical inhibition would alleviate pain and increase quality of life. Methods: After two baseline measures, the patient participated in two balance training periods of 4 weeks each, followed by two detraining phases of 2 months each. At baseline and after each intervention and each detraining, intracortical inhibition (i.e., SICI) as well as pain and ‘well-being’ (questionnaires) was assessed. Results: Our results demonstrated enhanced and better modulated intracortical inhibition after 4 weeks of balance training, which was in line with analgesia and improved sleep and mood scores. However, after the first detraining, all parameters went back to baseline. In a subsequent second period of 4 weeks of balance training, intracortical inhibition was again increased, even above the values of the first training period. Pain, sleep, and mood scores were also further improved. After the second detraining period, all values dropped back close to their baseline values. Conclusions: The findings support the assumption that the GABAergic system is highly relevant in the processing and perception of pain. More importantly, our results suggest the possibility that balance training may be an effective way not only to upregulate intracortical inhibition but also to alleviate pain and improve well-being in patients with unspecific chronic pain.