Prefrontal tDCS Decreases Pain in Patients with Multiple Sclerosis.
BACKGROUND
In the last few years, transcranial direct current stimulation (tDCS) has emerged as an appealing therapeutic option to improve brain functions. Promising data support the role of prefrontal tDCS in augmenting cognitive performance and ameliorating several neuropsychiatric symptoms, namely pain, fatigue, mood disturbances, and attentional impairment. Such symptoms are commonly encountered in patients with multiple sclerosis (MS).


OBJECTIVE
The main objective of the current work was to evaluate the tDCS effects over the left dorsolateral prefrontal cortex (DLPFC) on pain in MS patients.Our secondary outcomes were to study its influence on attention, fatigue, and mood.


METHODS
Sixteen MS patients with chronic neuropathic pain were enrolled in a randomized, sham-controlled, and cross-over study.Patients randomly received two anodal tDCS blocks (active or sham), each consisting of three consecutive daily tDCS sessions, and held apart by 3 weeks. Evaluations took place before and after each block. To evaluate pain, we used the Brief Pain Inventory (BPI) and the Visual Analog Scale (VAS). Attention was assessed using neurophysiological parameters and the Attention Network Test (ANT). Changes in mood and fatigue were measured using various scales.


RESULTS
Compared to sham, active tDCS yielded significant analgesic effects according to VAS and BPI global scales.There were no effects of any block on mood, fatigue, or attention.


CONCLUSIONS
Based on our results, anodal tDCS over the left DLPFC appears to act in a selective manner and would ameliorate specific symptoms, particularly neuropathic pain. Analgesia might have occurred through the modulation of the emotional pain network. Attention, mood, and fatigue were not improved in this work. This could be partly attributed to the short protocol duration, the small sample size, and the heterogeneity of our MS cohort. Future large-scale studies can benefit from comparing the tDCS effects over different cortical sites, changing the stimulation montage, prolonging the duration of protocol, and coupling tDCS with neuroimaging techniques for a better understanding of its possible mechanism of action.
EA 4391, Excitabilité Nerveuse et Thérapeutique, Université Paris-Est-CréteilCréteil, France; Service de Physiologie - Explorations Fonctionnelles, Hôpital Henri Mondor, Assistance Publique - Hôpitaux de ParisCréteil, France; Neurology Division, Lebanese American University Medical Center - Rizk HospitalBeirut, Lebanon.
Samar S
SS
Ayache
EA 4391, Excitabilité Nerveuse et Thérapeutique, Université Paris-Est-CréteilCréteil, France; Department of Psychiatry and Psychotherapy, Ludwig-Maximilian-UniversityMunich, Germany.
Ulrich
U
Palm
EA 4391, Excitabilité Nerveuse et Thérapeutique, Université Paris-Est-CréteilCréteil, France; Service de Physiologie - Explorations Fonctionnelles, Hôpital Henri Mondor, Assistance Publique - Hôpitaux de ParisCréteil, France.
Moussa A
MA
Chalah
EA 4391, Excitabilité Nerveuse et Thérapeutique, Université Paris-Est-Créteil Créteil, France.
Tarik
T
Al-Ani
Département d'Informatique et de Recherche Opérationnelle, Université de Montréal Montréal, QC, Canada.
Arnaud
A
Brignol
Service de Neurologie, Hôpital Henri Mondor, Assistance Publique - Hôpitaux de Paris Créteil, France.
Mohamed
M
Abdellaoui
Service de Neurologie, Hôpital Henri Mondor, Assistance Publique - Hôpitaux de Paris Créteil, France.
Dalia
D
Dimitri
EA 4391, Excitabilité Nerveuse et Thérapeutique, Université Paris-Est-Créteil Créteil, France.
Marc
M
Sorel
EA 4391, Excitabilité Nerveuse et Thérapeutique, Université Paris-Est-CréteilCréteil, France; Service de Neurologie, Hôpital Henri Mondor, Assistance Publique - Hôpitaux de ParisCréteil, France.
Alain
A
Créange
EA 4391, Excitabilité Nerveuse et Thérapeutique, Université Paris-Est-CréteilCréteil, France; Service de Physiologie - Explorations Fonctionnelles, Hôpital Henri Mondor, Assistance Publique - Hôpitaux de ParisCréteil, France.
Jean-Pascal
JP
Lefaucheur
attention; dorsolateral prefrontal cortex; multiple sclerosis; pain; transcranial direct current stimulation