Non-invasive Personalized Transcranial Cortical Neurostimulation for Pain Relief

Condition(s) studied

Investigational drug(s) / intervention(s)

tDCS (Transcranial Direct Current Stimulation): The tDCS group will be treated with non-invasive motor cortex stimulation. A two-minute EEG recording will be made before each session, using the same electrodes as for stimulation. Anodal stimulation of 2,0 mA will be delivered over the motor area contralateral to the painful region (C4 or C3 according to the international 10-20 system). The return electrode will be placed over the fronto-polar region (FP1 or FP2) ipsilateral to the painful region. If pain is bilateral, the most painful region will be chosen to be treated.

tACS (Transcranial Alternating Current Stimulation): The tACS group will be treated with non-invasive motor cortex stimulation. The stimulation series comprises six sessions spaced 2 weeks apart, the first session being placebo. A two-minute EEG recording will be made before each session, using the same electrodes as for stimulation. Stimulation frequency will be set according to the dominant frequency recorded over the motor area. Anodal stimulation of 2,0 mA will be delivered over the motor area contralateral to the painful region (C4 or C3 according to the international 10-20 system). The return electrode will be placed over the fronto-polar region (FP1 or FP2) ipsilateral to the painful region.

Study summary

Neuropathic pain is a public health problem with less than 50% of patients being relieved by drug treatments.

Surgically implanted motor cortex stimulation represents an invasive therapeutic solution capable of relieving a significant proportion of drug-resistant patients (1 in 2); it cannot, however, be offered to all patients, and is not morbidity-free.

Non-invasive motor cortex stimulation techniques have been refined over the last decade, in particular transcranial repetitive magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), which provide pain relief among almost half of drug-resistant patients with few or no side effects.

To be efficient, cortical stimulation requires the activation of multiple distant networks involved in the cognitive and motivational response to pain; stimulation frequency is a crucial parameter for activating these mechanisms. The match between cortical stimulation frequency and the intrinsic neuronal frequency of the stimulated cortex has recently been suggested as a key determinant of clinical effect. Indeed, the transmission efficiency of an oscillatory network increases when its intrinsic frequency matches that of the stimulus applied to it. Given that human sensorimotor networks spontaneously oscillate at frequencies around 10 and 20 Hertz (Hz), this match could underlie the superior efficacy of transcranial stimulation at these frequencies.

The hypothesis of the study is that the analgesic effect of cortical stimulation will be enhanced if the stimulation frequency resonates with the spontaneous oscillations of the underlying cortex, thus facilitating its connectivity with the remote structures involved in pain control. The investigators propose to test this hypothesis in a population of patients with drug-resistant neuropathic pain, referred to the Pain Evaluation and Treatment Center (CETD) of the Neurological hospital, at the Hospices Civils de Lyon. The overall aim of the project is to compare the efficacy of stimulation at each individual's own rate of oscillation of the motor cortex, against a "classic" stimulation protocol, and against placebo stimulation.

Eligibility

Primary outcome measure(s)

• Pain intensity measure — daily from the beginning until the end of the protocol (15 months)
  Comparison of weekly standardized averages of the Numerical rating scale (NRS) values at the end of tACS versus tDCS versus placebo stimulation sessions. Pain scale measurement: pain scale : 1 the minimum and 10 maximum value, 10 the higher score mean a worse outcome.

Trial sites (1)

More Hospices Civils de Lyon trials in France