tDCS for Reducing the Incidence of OEI After Cesarean Section

Official title

Study on the Preventive and Therapeutic Effects and Mechanism of Transcranial Direct Current Stimulation on Morphine-Induced Itching After Cesarean Section: A Randomized Clinical Controlled Trial

Overview

Cesarean section is the most common obstetric surgery worldwide. Epidural anesthesia has become the preferred anesthesia method for cesarean sections due to its definite analgesic effect and minimal impact on mother and baby. To ensure postoperative analgesia, intrathecal administration of morphine (the preferred opioid for obstetric intrathecal analgesia) is a routine clinical protocol, but morphine-induced postoperative pruritus is a common adverse reaction. A study targeting the cesarean section population confirmed that the incidence of pruritus after epidural morphine administration is as high as 40%-75%.Transcranial direct current stimulation (tDCS) can enhance the activity of GABAergic inhibitory interneurons in the spinal dorsal horn through the cortical-spinal descending pathway, reverse the inhibitory effect of morphine on them, and restore negative feedback regulation of itch-specific GRPR⁺ neurons; at the same time, it downregulates the phosphorylation level and membrane expression of μ-opioid receptors in the spinal dorsal horn, weakening the receptor activation efficiency of morphine. On the other hand, tDCS can reduce peripheral nerve excitability, decrease mast cell degranulation in the skin, and reduce the release of histamine and tryptase; simultaneously, it inhibits the activation of glial cells in the spinal cord/cortex, decreases the secretion of pro-inflammatory factors such as TNF-α and IL-6, and blocks the vicious cycle of 'inflammation-receptor upregulation-itch exacerbation,' thereby reducing the occurrence of itch.This study aims to explore the effect of transcranial direct current stimulation (tDCS) on the incidence of morphine-induced itching after cesarean section by inhibiting the central itch perception circuits in cesarean section patients and antagonizing the disinhibitory effects mediated by μ-opioid receptors in the spinal dorsal horn.

Interventions

• Device Transcranial direct current stimulation
  Patients in the transcranial direct current stimulation (tDCS) group had the anode of the tDCS device placed on the left dorsolateral prefrontal cortex (F3 area) and the cathode on the right mastoid. The tDCS was administered on the day of surgery (starting within 5 minutes after delivery of the fetus and ending upon transfer to the PACU after surgery). The current intensity was 1.5 mA.
• Device Transcranial direct current stimulation (placebo stimulation)
  Sham stimulation group (control group): The anode of the electrical stimulator is placed on the left dorsolateral prefrontal cortex (F3 region) and the cathode on the right mastoid area. A current of 1.5 mA is applied only during the first 30 seconds after the start of stimulation, after which the current is reduced to 0 mA. All other procedures (electrode placement, stimulation duration, intervention frequency) are the same as those in the experimental group.

Primary outcome measures

• Incidence of itching within 24 hours after surgery (defined as VAS itching score ≥1) [Time frame: 24 hours after surgery]

Secondary outcome measures (9)

• Incidence of itching at 12 and 48 hours postoperatively; VAS scores for itching at each time point; duration of itching and time of peak appearance [Time frame: 12 hours post-operation and 48 hours post-operation]
• Number of times the analgesic pump was pressed and the doses of additional morphine within 48 hours postoperatively; VAS pain scores at 12, 24, and 48 hours postoperatively [Time frame: 12 hours, 24 hours, and 48 hours after surgery]
• Maternal adverse reactions (nausea and vomiting, drowsiness, dizziness, ear pain, skin erythema) incidence; neonatal 1-minute and 5-minute Apgar scores, birth weight, complications within 72 hours (jaundice, shortness of breath, feeding difficulties) [Time frame: Within 72 hours after surgery]
• Preoperative and postoperative 24h serum histaminelevels [Time frame: 24 hours before surgery and 24 hours after surgery]
• Preoperative and postoperative 24h trypsin-like enzymelevels [Time frame: 24 hours before surgery and 24 hours after surgery]
• Preoperative and postoperative 24h TNF-α levels [Time frame: 24 hours before surgery and 24 hours after surgery]
• Preoperative and postoperative 24h IL-6 levels [Time frame: 24 hours before surgery and 24 hours after surgery]
• Preoperative and postoperative 24h β-endorphin levels [Time frame: 24 hours before surgery and 24 hours after surgery]
• Preoperative and postoperative 24h gastrin-releasing peptide precursor (ProGRP) levels [Time frame: 24 hours before surgery and 24 hours after surgery]

Eligibility criteria

Inclusion criteria

• Age 18-40 years, gestational age 37-41 weeks, singleton full-term pregnancy;
• Planned elective or emergency cesarean section, using epidural anesthesia (0.1\~0.2 mg/kg of morphine administered intrathecally during surgery);
• American Society of Anesthesiologists (ASA) classification I-III;
• Conscious and able to cooperate to complete scale assessments, serum sample collection, and postoperative follow-up;
• Voluntarily participate in the study and sign the informed consent form.

Exclusion criteria

• Presence of contraindications for tDCS (such as skull defects, intracranial metal implants, history of epilepsy, coagulation disorders);
• Allergy to opioids or a history of severe OEI;
• Presence of skin diseases (such as eczema, urticaria), liver diseases (cholestasis), mental disorders, or cognitive impairments;
• Coexisting pregnancy complications (preeclampsia, gestational diabetes, autoimmune diseases);
• Use of medications within the past week that may affect itch assessment, such as antihistamines, 5-HT3 receptor antagonists, or anti-inflammatory drugs.

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Triple blind

Primary purpose

Prevention

Study locations

Center list to be confirmed — check the primary protocol.

Identifiers

NCT: NCT07569783 · 2026-K102-01

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗