Optimized tDCS for the Treatment of Migraine

Optimizing the Effect of Transcranial Direct Current Stimulation (tDCS) for the Treatment of Migraine

The aim of this study is to establish an optimized protocol of tDCS that normalize the lack of habituation and efficiency of inhibitory cortical circuits in migraine patients and determine tDCS polarity and the best cortical areas to stimulate which could normalize the lack of habituation and efficiency of inhibitory cortical circuits. For this, migraineurs volunteers will undergo to some tDCS protocols or sham tDCS.

A crossover trial to establish an optimized tDCS protocol will be accomplished. Anodal and cathodal tDCS will be applied over the primary motor cortex (C3 - active and contralateral supra-orbital region - reference) and visual cortex (Oz - active and Cz - reference). Dual tDCS (anodal and cathodal - optimized protocol) will be applied on C3 - active and Oz - active. Electrical cortical activity will be assessed on 14 migraineurs through: (i) MEP; (ii) MT; (iii) SICI; (iv) ICF; (v) PT and (vi) visual evoked-potential (VEP-habituation). An interval of 48hs between sessions will be taken. The order of the sessions will be randomized and counterbalanced among volunteers by site www.randomization.com.

migraine disorders, transcranial direct current stimulation, electric stimulation therapy, pain, rehabilitation

The direct electric current will be applied by surface electrodes with 35cm² and composed of rubbers conductive electricity and surrounded by sponges soaked in saline solution. The electrodes position will be performed according the 10-20 international system of marking and the different montages will be realized by distinct applications sites. To stimuli the primary motor cortex the active electrode will be positioned on C3 point and the reference electrode on the contralateral supraorbital region. To visual cortex stimulation, the active electrode will be positioned on the Oz point and the reference on Cz. To duo stimulation, the two electrodes will be considerate actives, stimulating the visual and motor cortex simultaneously. The sham tDCS has already been used in several studies to assess the effect active tDCS and the duration of the current is only 30 seconds.

The direct electric current will be applied by surface electrodes with 35cm² and composed of rubbers conductive electricity and surrounded by sponges soaked in saline solution. The electrodes position will be performed according the 10-20 international system of marking and the different montages will be realized by distinct applications sites. To stimuli the primary motor cortex the active electrode will be positioned on C3 point and the reference electrode on the contralateral supraorbital region. To visual cortex stimulation, the active electrode will be positioned on the Oz point and the reference on Cz. To duo stimulation, the two electrodes will be considerate actives, stimulating the visual and motor cortex simultaneously. The sham tDCS has already been used in several studies to assess the effect active tDCS and the duration of the current is only 30 seconds.

The direct electric current will be applied by surface electrodes with 35cm² and composed of rubbers conductive electricity and surrounded by sponges soaked in saline solution. The electrodes position will be performed according the 10-20 international system of marking and the different montages will be realized by distinct applications sites. To stimuli the primary motor cortex the active electrode will be positioned on C3 point and the reference electrode on the contralateral supraorbital region. To visual cortex stimulation, the active electrode will be positioned on the Oz point and the reference on Cz. To duo stimulation, the two electrodes will be considerate actives, stimulating the visual and motor cortex simultaneously. The sham tDCS has already been used in several studies to assess the effect active tDCS and the duration of the current is only 30 seconds.

The direct electric current will be applied by surface electrodes with 35cm² and composed of rubbers conductive electricity and surrounded by sponges soaked in saline solution. The electrodes position will be performed according the 10-20 international system of marking and the different montages will be realized by distinct applications sites. To stimuli the primary motor cortex the active electrode will be positioned on C3 point and the reference electrode on the contralateral supraorbital region. To visual cortex stimulation, the active electrode will be positioned on the Oz point and the reference on Cz. To duo stimulation, the two electrodes will be considerate actives, stimulating the visual and motor cortex simultaneously. The sham tDCS has already been used in several studies to assess the effect active tDCS and the duration of the current is only 30 seconds.

The direct electric current will be applied by surface electrodes with 35cm² and composed of rubbers conductive electricity and surrounded by sponges soaked in saline solution. The electrodes position will be performed according the 10-20 international system of marking and the different montages will be realized by distinct applications sites. To stimuli the primary motor cortex the active electrode will be positioned on C3 point and the reference electrode on the contralateral supraorbital region. To visual cortex stimulation, the active electrode will be positioned on the Oz point and the reference on Cz. To duo stimulation, the two electrodes will be considerate actives, stimulating the visual and motor cortex simultaneously. The sham tDCS has already been used in several studies to assess the effect active tDCS and the duration of the current is only 30 seconds.

The direct electric current will be applied by surface electrodes with 35cm² and composed of rubbers conductive electricity and surrounded by sponges soaked in saline solution. The electrodes position will be performed according the 10-20 international system of marking and the different montages will be realized by distinct applications sites. To stimuli the primary motor cortex the active electrode will be positioned on C3 point and the reference electrode on the contralateral supraorbital region. To visual cortex stimulation, the active electrode will be positioned on the Oz point and the reference on Cz. To duo stimulation, the two electrodes will be considerate actives, stimulating the visual and motor cortex simultaneously. The sham tDCS has already been used in several studies to assess the effect active tDCS and the duration of the current is only 30 seconds.

The direct electric current will be applied by surface electrodes with 35cm² and composed of rubbers conductive electricity and surrounded by sponges soaked in saline solution. The electrodes position will be performed according the 10-20 international system of marking and the different montages will be realized by distinct applications sites. To stimuli the primary motor cortex the active electrode will be positioned on C3 point and the reference electrode on the contralateral supraorbital region. To visual cortex stimulation, the active electrode will be positioned on the Oz point and the reference on Cz. To duo stimulation, the two electrodes will be considerate actives, stimulating the visual and motor cortex simultaneously. The sham tDCS has already been used in several studies to assess the effect active tDCS and the duration of the current is only 30 seconds.

this scale will be used to measure the patients' pain intensity. VAS is an important instrument to verify, reliably, the patient's evolution during treatment. This scale will be used at beginning and end of each period (observation and treatment), before and after each tDCS session. For the VAS use, pain intensity will be asked to the patient. 0 cm means total pain absence and 10 cm is the level of maximum pain bearable by the patient.

volunteers will be invited to sit in a comfortable chair, in a calm and dark room, at 90 cm of distance from computer screen. It will be asked to fix his right eye visual field on a red point at the center of the screen (the left one will be blindfolded). Visual stimuli will be a black and White grid pattern, alternating at a frequency of 3.1 Hz. Electrodes used to record data will be localized on Oz and Fz points according International 10-20 system. During the test, 600 cortical answers will be recorded. Data will be collected and recorded in a personal computer, and after, converted to the ".txt" format to futures analysis with MATLAB.

to measure MEP, the intensity of the magnetic stimulator will be adjusted to 120% of rest motor threshold and 10 stimuli will be registered. For evaluation volunteers will be instructed to sit in a chair and get into a comfortable position. Initially, single-pulse TMS will be administered over the motor cortex to determine the cortical representation area of the first dorsal interosseous muscle (FDI). For all evaluations the same figure-eight coil is used, in order to avoid measurement bias. Amplitude means of evoked potentials will determine the MEP.

to evaluate these variables, subthreshold conditioning stimuli (80% of RMT) and suprathreshold test stimuli (120% of RMT) will be delivered at an inter stimulus intervals (ISI) of 2 milliseconds, to determine the short interval cortical inhibition (SICI). The Intracortical facilitation (ICF) will be evaluated by the MEP average at an ISI of 10 milliseconds. Ten stimulus will be applied in each condition (unconditioned pulse, and pairs of stimuli with ISI of 2 and 10 milliseconds). The order of stimulus delivered will be pseudorandomized and SICI and ICF will be expressed as a percentage of a conditioned stimuli in regarding an unconditioned stimuli.

to evaluate these variables, subthreshold conditioning stimuli (80% of RMT) and suprathreshold test stimuli (120% of RMT) will be delivered at an inter stimulus intervals (ISI) of 2 milliseconds, to determine the short interval cortical inhibition (SICI). The Intracortical facilitation (ICF) will be evaluated by the MEP average at an ISI of 10 milliseconds. Ten stimulus will be applied in each condition (unconditioned pulse, and pairs of stimuli with ISI of 2 and 10 milliseconds). The order of stimulus delivered will be pseudorandomized and SICI and ICF will be expressed as a percentage of a conditioned stimuli in regarding an unconditioned stimuli.

a 10-cm circular coil was used that has giving a peak magnetic field strength of 2 tesla. Subjects were asked to wear a blindfold, sit comfortably in a chair and to close their eyes to diminish ambient light.In sagittal line, three points were scored: 2, 3 and 4 cm above the inion. The single pulse TMS was applied to one of the points scored and the subject was asked to report the presence or absence of a phosphene immediately after stimulation. The stimulation was repeated ten times at each intensity with a maximum frequency of 0.2 Hz, stimulation was initially applied to 60% of the maximum intensity of the stimulator. The intensity of stimulation was changed into blocks of 5% to minimum intensity that the subject can perceive the phosphene certainly, five times ten, then this value was set as the PT.

Inclusion Criteria: Ages: 18-55 years Gender: Both Presented diagnostic of episodic migraine with or without aura or probably migraine with or without aura according to the criteria for diagnosis of ICHD-III Disease duration of at least 12 months Without preventive medication for at least 6 months prior to initiation of treatment Exclusion Criteria: Pregnant women; Pacemaker; History of seizures; Metallic implants in the head; Patients with clinical evidence of brain injuries; Chronic pain associated to others diseases; Use of neuroleptic medications