Medial Prefrontal Transcranial Direct Current Stimulation Aimed to Improve Affective and Attentional Modulation of Pain in Chronic Low Back Pain Patients

Abstract

Chronic low back pain (CLBP) is often without clear underlying pathology. Affective disturbance and dysfunctional pain mechanisms, commonly observed in populations with CLBP, have, therefore, been suggested as potential contributors to CLBP development and maintenance. However, little consensus exists on how these features interact and if they can be targeted using non-invasive brain stimulation. In this pilot trial, 12 participants completed two phases (Active or Sham) of high-definition transcranial direct current stimulation (HD-tDCS) to the medial prefrontal cortex, applied for 20 min on three consecutive days. Clinical pain ratings, questionnaires, and sensitivity to painful cuff pressure were completed at baseline, then 4 trials of conditioned pain modulation (CPM; alone, with distraction using a Flanker task, with positive affect induction, and with negative affect induction using an image slideshow) were performed prior to HD-tDCS on Day 1 and Day 4 (24 h post-HD-tDCS). At baseline, attentional and affective manipulations were effective in inducing the desired state (p < 0.001) but did not significantly change the magnitude of CPM-effect. Active HD-tDCS was unable to significantly alter the magnitude of the shift in valence and arousal due to affective manipulations, nor did it alter the magnitude of CPM under any basal, attentional, or affective manipulation trial significantly on Day 4 compared to sham. The CPM-effect was greater across all manipulations on Day 1 than Day 4 (p < 0.02) but also showed poor reliability across days. Future work is needed to expand upon these findings and better understand how and if HD-tDCS can be used to enhance attentional and affective effects on pain modulation.

Efficacy of transcranial direct current stimulation on pain intensity and functionality in patients with knee osteoarthritis: a systematic review and meta-analysis

“…There has been a recent tendency for studies to report a lack of significant improvement in CPM despite the reduction or even resolution of pain. 42 Overall, tDCS can be considered a safe therapy, as few mild adverse effects were described (12.8%), and there was a minimal number of dropouts (1.5%) in the active tDCS group. The safety profile is an appealing characteristic of tDCS and has been previously evidenced in a systematic review and meta-analysis.…”

“…The lack of significant results regarding this outcome may be due to the small simple size and the differences in the CPM protocols followed. There has been a recent tendency for studies to report a lack of significant improvement in CPM despite the reduction or even resolution of pain 42 …”

Brain Circuits Involved in the Development of Chronic Musculoskeletal Pain: Evidence From Non-invasive Brain Stimulation

“…With respect to the non-invasive stimulation targets, only very recently additional targets such as the medial prefrontal cortex were investigated in chronic pain patients. In a study that attempted to modulate clinical pain manifestations via affective and attentional manipulations, chronic low back patients underwent active and sham HD-tDCS over the medial prefrontal cortex ( 123 ). Conditioned pain modulation was not altered by attentional and affective manipulations, and in addition HD-tDCS compared with sham did not show effects on the magnitude of the effects of these manipulations.…”

Is transcranial direct current stimulation beneficial for treating pain, depression, and anxiety symptoms in patients with chronic pain? A systematic review and meta-analysis

“…Thus, it can directly modulate a wide neural network involved in pain processing through the transcranial application of electrical field stimulation (Antal et al, 2017 ; O'Connell et al, 2018 ). In recent years, tDCS has been explored for the treatment of mental and neurological diseases (Meron et al, 2015 ) such as anxiety and depression (Palm et al, 2016 ; Vergallito et al, 2021 ) and has been employed in the treatment of a range of pathological chronic pain circumstances, such as chronic low back pain (CLBP) (Mariano et al, 2019 ; McPhee and Graven-Nielsen, 2021b ), fibromyalgia (Fagerlund et al, 2015 ; Khedr et al, 2017 ), and complex regional pain syndrome (Cruccu et al, 2016 ; Lagueux et al, 2018 ). However, these results of studies are mixed.…”