Repetitive transcranial magnetic stimulation (rTMS) as a primary tool for radicular back pain: A case report on improved pain perception, autonomic function, and cognitive potential

INTRODUCTION

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique that has demonstrated effectiveness in reducing pain and enhancing function for patients with chronic pain, including low back pain, nerve root impingement cervical radiculopathy, and chronic neuropathic pain. Randomized controlled trials and meta-analyses have highlighted rTMS as a valuable treatment option for these conditions.^1-3 Furthermore, a systematic review and meta-analysis of 15 studies provided evidence supporting the effectiveness of rTMS in alleviating pain and improving function in patients with chronic low back pain.⁴

This case report shows the high frequency of rTMS’ effectiveness in treating patients with Chronic Low Back Pain (CLBP). rTMS has emerged as a potential therapeutic modality for pain management. The case report showed significant improvements in pain perception visual analog scale (VAS) to assess the effects of rTMS on pain, heart rate variability (HRV), cortical motor excitability autonomic function, and cognitive performance in a CLBP patient.

CASE REPORT

A 72-year-old male patient visited the Orthopedics OPD at AIIMS Bhopal with a four-year history of CLBP. An MRI finding revealed lumbar spine abnormalities, including disc protrusions, nerve root impingement, and degenerative changes. The patient was referred rTMS therapy to alleviate pain. Before initiating rTMS, consent was obtained, and safety guidelines were followed. Baseline measurements revealed a blood pressure of 160/89 mmHg, with a pulse rate of 70. The systolic/diastolic pressure fluctuated to 184/120 mmHg during a handgrip test, indicating increased autonomic stress responses.

RESULTS

After completing the rTMS therapy, case ‘A’ showed notable improvements. Pain levels significantly decreased as reflected in VAS scores. Cognitive performance also showed measurable enhancement, with reduced P300 latency and increased amplitude observed in testing. “Table 1: showing Autonomic function improved, indicated by enhanced HRV metrics and stabilized blood pressure.

Baseline measures: Motor Threshold, Latency, Amplitude, VAS Score, and Assessments of Autonomic Function and Pain Perception, Including the Modified Oswestry Low Back Pain Disability Index (MODI), Composite Autonomic Symptom Score (COMPASS), Self-Administered Gerocognitive Examination (SAGE), Deep Breathing Test (E: I Ratio), Valsalva Ratio, and Lying-to-Standing Test.”

Changes after pre- and post-rTMS therapy: The motor threshold remained unchanged, while latency decreased to 37.7 and 27.6 milliseconds, respectively, indicating faster neural responses. Amplitude increased to 28 and 83, suggesting enhanced neural responsiveness. The VAS pain score decreased from 6 to 4, reflecting reduced perceived pain levels. Assessments of autonomic function and pain perception showed improvements, indicating positive effects on pain perception, a reduction in disability index, and enhanced autonomic function in neuropathic pain due to radiculopathy.

P300 and rTMS: -P300 latency decreased at all electrode placements (A11, A21, A31), and amplitude increased after rTMS, indicating quicker cognitive processing. These changes in P300 parameters suggest that rTMS therapy positively impacted cognitive function by improving processing speed and resource allocation.

DISCUSSION

Our findings demonstrate that rTMS had a significant impact on our patient, reducing pain perception (VAS score from 6 to 4) and enhancing cognitive function (P300 amplitude). These results align with existing research on rTMS for chronic pain conditions.^6-8 rTMS alleviates pain by reducing activity in pain-processing regions (thalamus, somatosensory cortex) while enhancing pain-inhibiting areas (prefrontal cortex, periaqueductal grey). It modulates neurotransmitter release, boosts endogenous opioid production, and improves mood and stress, relieving pain.^6,7 Additionally, rTMS influences autonomic function and HRV through brain region stimulation and neurotransmitter modulation, leading to improved autonomic balance and cardiovascular health.^9,10 These mechanisms also enhance functional outcomes, as reflected in significant improvements in the MODI, reinforcing its efficacy in reducing pain and disability in chronic low back pain patients.¹⁰ Our 72-year-old patient represents a unique example of rTMS application in older adults, where pain perception, autonomic function, and cognition are often compromised due to age-related neurophysiological changes. The observed improvements post-rTMS suggest its efficacy in modulating pain pathways, enhancing autonomic balance, and potentially supporting cognitive function despite age-related neuroplastic decline.

Pre- and post-intervention measures showed reduced pain intensity, improved HRV, and cognitive benefits, reinforcing rTMS as a viable non-invasive treatment for geriatric patients with chronic radicular pain. While further studies are needed, this case highlights the broader neurophysiological benefits of rTMS in ageing populations.

CONCLUSION

This case report indicates that rTMS could be a potential treatment for CLBP, helping to reduce pain, improve autonomic function, and enhance cognitive abilities. However, more research is needed to confirm these results and establish the best rTMS protocols for different chronic pain conditions.