Trigger Point Injections for Post-Mastectomy Pain Syndrome

Instituto do Cancer do Estado de São Paulo

Status and phase: Active, not recruiting; Phase 2

Conditions: Breast Cancer; Trigger Point Pain, Myofascial; Myofascial Pain Syndrome; Post-mastectomy Pain Syndrome

Treatments: Other: Comprehensive Rehabilitation program; Procedure: Trigger point injection; Procedure: Subcutaneous saline injection

Study type: Interventional

Funder types: Other

Identifiers

NCT04267315

1474/19

Details and patient eligibility

About

Post-Mastectomy Pain Syndrome (PMPS) is a chronic pain that persists for more than three months after a surgical breast procedure. It has 11-70% incidence in patients that underwent a breast surgery. It consists of mixed pain, frequently associated with myofascial pain, an specific type of muscular pain. Trigger point injections (TPI) are classically used for the treatment of myofascial pain in other painful conditions. However, there are no controlled trials assessing the efficacy of TPI in the treatment of PMPS. The intervention objective is to assess the efficacy of TPI in patients with PMPS, when associated with a comprehensive rehabilitation program and pain management.

Full description

INTRODUCTION: Post-Mastectomy Pain Syndrome (PMPS) is a chronic pain that persists for more than three months after a surgical breast procedure. It has 11-70% incidence in patients that underwent a breast surgery. It consists of mixed pain, frequently associated with myofascial pain. Trigger point injections (TPI) are classically used for the treatment of myofascial pain in other etiologies. However, there are no controlled trials assessing the efficacy of TPI in the treatment of PMPS

OBJECTIVE: Assess the efficacy of TPI in patients with PMPS, when associated with a comprehensive rehabilitation program and pain management.

METHODS: Double-blind randomized controlled trial with intention-to-treat analysis. Both groups will undergo standard of care delivered by Physiatrist blinded to group allocation. Active group will undergo TPI with 1% lidocaine in each identified trigger-point, weekly, for three consecutive weeks. Control group will undergo subcutaneous saline injection superficial to the same trigger points, with the same frequency and number of sessions. Primary outcome is the mean difference between groups for pain levels, as assessed by Visual Numeric Scale (VNS), from baseline to 3 months after the procedure.

STATISTICAL ANALYSIS: Difference between groups at baseline, one and three months after injection, using Analysis of Covariance (ANCOVA) for the following outcomes: VNS; Presence of active trigger points, Pressure pain threshold (PPT); Short-Form McGill Pain Questionnaire (SF-MPQ); Neuropathic Pain Symptom Inventory (NPSI); Disabilities of the Arm, Shoulder and Hand Questionnaire (DASH); Range of motion (ROM) of affected shoulder, for abduction and external rotation; adverse events; use of pain medication.

Total sample size is 120. Alpha=5%, power=80%.

Enrollment: 72 patients

Sex: All

Volunteers: No Healthy Volunteers

Inclusion criteria

• Breast cancer patients.

• PMPS diagnosis, as per Wisotzky et col.

  • Pain > 3 months over breast, chest wall or shoulder ipsilateral to surgery.

• Pain Visual analog Scale (VAS) ≥4.

• At least one active trigger point in the following muscles: pectoralis major, superior trapezius, serratus anterior, levator scapularis, latissimus dorsi, infraspinatus

Exclusion criteria

• Current radiation therapy or time since completion < 3months.
• Allergy to lidocaine or other local anesthetics
• Active infection over injection sites
• Unavailability to be at the hospital during study intervention.

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Triple Blind

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72 participants in 2 patient groups

Active

Active Comparator group

Description:

3 weekly sessions of TPI. Participants will undergo 1mL injections of 1% lidocaine in the muscles identified with either active or latent trigger points at the initial assessment. The same muscles will be injected at all procedures.

Treatment:

Other: Comprehensive Rehabilitation program

Procedure: Trigger point injection

Placebo

Sham Comparator group

Description:

3 weekly sessions of subcutaneous saline injections. Participants will undergo 0.2mL subcutaneous saline injections superficial to the trigger points identified at initial assessment. The same superficial sites will be injected in all procedures.

Treatment:

Procedure: Subcutaneous saline injection

Other: Comprehensive Rehabilitation program