THE EFFECT OF tDCS IN THE TREATMENT OF CHRONIC PELVIC PAIN ASSOCIATED WITH ENDOMETRIOSIS

Study Overview
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Brief Summary
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The purpose of this study is to determine if transcranial direct current stimulation (tDCS) is effective in the treatment of chronic pelvic pain associated with endometriosis

Official Title
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THE EFFECT OF TRANSCRANIAL DIRECT CURRENT STIMULATION (tDCS) IN THE TREATMENT OF CHRONIC PELVIC PAIN ASSOCIATED WITH ENDOMETRIOSIS

Conditions
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Chronic Pain, Endometriosis

Intervention / Treatment
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* Device: transcranial direct current stimulation (tDCS)
* Device: Sham Transcranial Direct Current Stimulation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: age > 18 years old, non-menopausic, with the diagnosis of endometriosis by videolaparoscopy and biopsy, able to understand and write the Portuguese language, in treatment with isolated progestin for at least one month, that have worst daily pain in the analogue visual scale > 4 cm in most of the days in the last month Exclusion Criteria: left-handed women, endometriosis implantation in intestine, bladder or urether (surgical treatment indication), history of intense or frequent headache, chronic dermatologic disease, previous adverse effects to treatment with tDCS, seizures, severe cranial trauma with alteration of the cranial anatomy, metallic intracranial implants or pacemaker, history of pelvic inflammatory disease, non-compensated psychiatric disease, non-collaborative patients, history of neurologic, oncologic disease, heart, renal or hepatic failure.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 55 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Active tDCS<br>tDCS will be applied in the head of the patients in 20 minute sessions, daily from Monday to Friday for 2 weeks (10 sessions total). The stimulation will be administered with a pair of surface electrodes, sponge coated, soaked in saline. A battery-powered constant current stimulator will be used for this purpose (tDCS device Soterix 1X1). The stimulation is performed by placing the anodal electrode in the primary motor cortex (M1) and the cathodal one in the contralateral supraorbital area, and it will use a 2 mA current. | Device: transcranial direct current stimulation (tDCS)<br>* The stimulation will be administered with a pair of surface electrodes, sponge coated, soaked in saline. A battery-powered constant current stimulator will be used for this purpose (tDCS device Soterix 1X1). The stimulation is performed by placing the anodal electrode in the primary motor cortex (M1) and the cathodal one in the contralateral supraorbital area and it will use a 2 mA current.<br>* Other names: tDCS;|
| Sham Comparator: tDCS Sham<br>The sham tDCS consists of the same montage of the active tDCS, but the device is turned off 30 seconds after initiating stimulation (without letting the patient notice it). Rest of the montage is kept identical as the active one during the 20 minutes that the session lasts. | Device: Sham Transcranial Direct Current Stimulation<br>* The sham tDCS consists of the same montage of the active tDCS, but the device is turned off 30 seconds after initiating stimulation (without letting the patient notice it). Rest of the montage is kept identical as the active one during the 20 minutes that the session lasts.<br>* Other names: Sham tDCS;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in worst daily pain assessed with the visual analogue scale. | Patients will be asked to daily write down their worst pain level (assessed by the Visual Analogue Scale, self-administered) in a paper diary with different scores: global pain, pain during menses, pain during sexual intercourse, pain during urination, pain during defecation. They will also be asked to daily write the analgesic drug intake. Total evaluations: 35 days. | Once Daily. Start 7 days before treatment, everyday during treatment period and every day during follow-up period (total = 35 days) | 
| Changes in motor cortex blood flow assessed by near infrared spectroscopy | Motor cortex blood flow will be assessed before the first session of tDCS (on Treatment day 1), after the end of treatment period (Day 15) and after the follow-up period (Day 29). Total = 3 evaluations. | Treatment Day 1 (before receiving the 1st session of tDCS); Day 15 (at the end of treatment period) and Day 29 (at the end of follow-up period) | 
| Change in Functional Pain Scale | Functional Pain Scale will be assessed by the Brazilian Profile of Chronic Pain: Screen (B-PCP:S) once a week, as folow: On the Treatment Day 1 (before the first session of tDCS - considered baseline), on Treatment Day 8, Day 15, Day 22 and Day 29. Total = 5 evaluations. | Once a week - Treatment Day 1, Day 8, Day 15, Day 22, Day 29 | 
| Change in the temperature pain threshold | It will be assessed by the Quantitative Sensory Test (QST) in the dominant (right) forearm. The heat pain tolerance and pain threshold to the heat and the temperature defined as pain 6/10 by the participant. The temperature starts at 32°C, and it heat at a 1.0 °C/sec rate and cools down after a button is pressed or whenever it reaches the max temperature of 52°C. The participant will be asked to press the button at the first sensation of pain to determine the pain threshold; to press the button whenever she can not stand the heat anymore for the pain tolerance determination and, for last, to press the button at the temperature she fells pain equivalent to 6/10 in the numeric scale of pain. The pain threshold and the temperature of pain 6/10 will be determined by the arithmetic mean of 3 evaluations each. Total of 3 test days: Day 1 (before the first session of tDCS), after the end of the Treatment period (Day 15) and at the end of the follow-up period (Day 29). | up to Day 29 | 
| Change in effect of the descendent modulator system of pain | It will be assessed by the Conditioned Pain Modulation test (CPM). A nociceptive tonic conditioning stimulus - immersion of the non-dominant hand in cold water (0°C for 1 minute) - will be applied concomitant to the progressive thermal stimulus in the dominant forearm as applied in the QST pattern until it reaches the 6/10 pain temperature previously determined by the participant. It will be tested in Treatment Day 1 (before the first session of tDCS - considered baseline), after the end of the Treatment period (Day 15) and at the end of the follow-up period (Day 29) - Total = 3 evaluation. | up to Day 29 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in serum biomarkers level: The brain derived neurotrophic factor (BDNF) and interleukins | A blood sample will be colected to measure BDNF and interleukins on Treatment Day 1 (right before the first tDCS session - considered baseline), after the end of the treatment period (day 15) and after the end of the follow-up period (day 29). Total = 3 evaluations | up to Day 29 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Endometriosis, Transcranial Direct Current Stimulation, tDCS, Near Infrared Spectroscopy, NIRS, Chronic Pelvic Pain