Inclusion criteria:
Diagnosis of chronic myofascial pain in the shoulder girdle.
A history of at least 3 months of pain due to shoulder girdle myofascial pain syndrome.
Spontaneous pain in at least one of the trigger points in the trapezius, supraspinatus, rhomboid, and levator scapulae muscles.
Use of stable dose of painkillers, at least 3 months prior to the study.
Pain intensity of 5 or greater with VAS criteria over the past week.
Age between 18 and 50 years old.
Exclusion criteria:
Previous diagnosis of shoulder pathology other than MPS that can help with pain, including partial dislocation, instability, fracture, frozen shoulder, infection and inflammation.
Cervical radiculopathy based on clinical examinations.
Diagnosis of neurological diseases such as Alzheimer's or Parkinson's.
Severe psychological conditions or symptoms such as schizophrenia, major depression or mania.
Current pregnancy or lactation.
History of seizures.
Defects in the skull bone.
Existence of skin scar at the electrode installation site.
Tumors in the tissue of the areas below the electrode.
Current use of herbal remedies or other alternative therapies such as recent topical injections for pain.