Transcranial direct current stimulation in the neuromodulation of pain in fibromyalgia: A case study

Fibromyalgia is a prevalent chronic pain syndrome that can occur in women with widespread pain, fatigue, muscle stiffness, depression, poor quality of life and anxiety. It might also be associated with exacerbated psychological factors such as somatization, helplessness and catastrophic thinking related to pain .

The accurate pathophysiology of this syndrome is not completely known; however, some evidence shows that both peripheral and central sensitization may affect the functioning of descending inhibitory mechanisms and facilitatory pathways. These impairments, in turn, can modify the pain perception and sensory processing in the neurosystem and lead to emotional behavior in a person experiencing pain . We lack effective approaches to the management of long-lasting pain symptoms, and the pain experiences might affect sleep quality, physical functioning and quality of life, which can maintain a continuous cycle and sustain the experience of a chronic condition .

Brain neuromodulation therapies such as transcranial direct current stimulation (tDCS) can decrease pain in fibromyalgia. tDCS might induce significant analgesic effects when applied to the primary motor cortex (M1) and also a significant antidepressant effect when applied over the dorsolateral prefrontal cortex (DLPFC) , but its benefit for alleviating catastrophic thinking related to pain in fibromyalgia has never been investigated.

A decrease in pain might have a considerable impact on the functional physical rehabilitation of patients with fibromyalgia. We describe our study in a female patient with fibromyalgia for 21 years, diagnosed according to 1990 American College of Rheumatology criteria, which was refractory to various therapeutic interventions. Our application of active stimulation of the M1 and DLPFC was associated with a decrease in pain, anxiety and level of catastrophic thinking related to pain.

Our 52-year-old patient had postpartum depression associated with a severe and long-lasting cold after her first child was born 22 years ago, 10 months after she was married. She experienced multiple muscle spasms and felt intense and diffuse pain progressing over time. She also reported that household tasks (household chores plus care for her son and husband), associated with professional commitments, became troublesome. She considered that these burdens resulted from her perfectionist psychological profile. The patient began to experience sleep disorders, together with uncomfortable morning stiffness. She consulted a rheumatologist and the clinical diagnosis was fibromyalgia.

At this time, she started using antidepressants and received psychological therapy and rheumatology monitoring for a long period. She experienced periods of decreased pain but periodically began to feel widespread and intense pain symptoms, even without plausible external triggers. She reported that when her first child was 2 years old, her mother died, and then her painful condition worsened considerably. At that time, she was receiving an anxiolytic associated with an antidepressant and started shiatsu therapy associated with psychotherapy, together with rheumatologist monitoring. She confirmed that the pain decreased after this therapeutic approach, but in situations of emotional instability, the pain symptoms returned and were intense. She replaced the shiatsu therapy with global posture re-education, with good results in controlling pain, but manifestations of painful crises became a constant in her life.

Five years before the study, the patient began to feel an intense pain in the right shoulder, cervical spine, right and left hips and right knee, with multiple diagnoses after MRI and CT. Continuous medication prescription was revised (i.e., the anxiolytic was replaced by an anticonvulsant plus antidepressant); in addition, she received an anti-inflammatory agent for 1 month. Symptoms were relieved after this approach, but 1 year later, at menopause onset, she had a very sharp worsening of pain, together with emotional instability.

After signing informed consent, the patient was randomized to receive 3 treatments (10 sessions of 20 min each for each treatment, 30 sessions total, with an interval of 1 week between treatment types: (1) active tDCS (2 mA) over M1, (2) sham tDCS stimulation and (3) active tDCS (2 mA) over DLPFC. Adverse effects were minor and not common (skin redness and tingling). With DLPFC stimulation, pain score decreased 50%, trait-anxiety score 20% and ruminative catastrophism score related to pain 28.6% ( Table 1 ). With M1 stimulation, pain score decreased 46.7%, state-anxiety score 33.3%, and depressive symptom score 11.8%. With sham stimulation, pain score decreased 6.3% and state-anxiety score 4% and ruminative catastrophism score increased 6.7%.

Table 1

Scores for pain, disease, sleep and psychological scales before and after each transcranial direct current stimulation (tDCS) protocol.

Scales	tDCS over M1		Sham tDCS		tDCS over DLPFC
	Before	After	Before	After	Before	After
Pain, visual analogue scale (0–10)	7.5	4 (−46.7%)	8	7.5 (−6.3%)	7	3.5 (−50%)
Fibromyalgia impact questionnaire (0–80)	69	65 (−5.8%)	68	67 (−1.5%)	66	61 (−7.6%)
Brazilian state-trait anxiety inventory (0–100)
State-anxiety (0–52)	30	20 (−33.3%)	25	24 (−4%)	21	22 (4.8%)
Trait-anxiety (0–48)	31	32 (3.2%)	30	30 (0%)	30	24 (−20%)
Beck depression inventory (0–63)	17	15 (−11.8%)	19	19 (0%)	11	11 (0%)
Pain catastrophizing scale for the Brazilian population (0–52)
Rumination (0–16)	14	15 (7.4%)	15	16 (6.7%)	14	10 (−28.6%)
Magnification (0–12)	9	9 (0%)	11	11 (0%)	10	9 (0%)
Helplessness (0–24)	18	19 (5.6%)	19	19 (0%)	17	17 (0%)