Trigger Point Injections for Post-Mastectomy Pain Syndrome

Phase 2

Active, not recruiting

• Conditions: Breast Cancer; Myofascial Pain Syndrome; Trigger Point Pain, Myofascial; Post-mastectomy Pain Syndrome
• Interventions: Procedure: Subcutaneous saline injection; Procedure: Trigger point injection; Other: Comprehensive Rehabilitation program

• Registration Number: NCT04267315
• Lead Sponsor: Instituto do Cancer do Estado de São Paulo

Brief Summary

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.

Detailed 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%.

Study Timeline

• Study Start: 2020-01-03
• Study First Submitted: 2020-01-29
• Study First Submitted QC: 2020-02-11
• Study First Posted: 2020-02-12
• Status Verified: 2023-10
• Last Update Submitted: 2023-10-13
• Last Update Posted: 2023-10-16
• Primary Completion: 2023-11-30
• Study Completion: 2024-02-15

Recruitment & Eligibility

• Status: ACTIVE_NOT_RECRUITING
• Sex: All
• Target Recruitment: 72

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.

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Placebo	Subcutaneous saline injection	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.
Active	Trigger point injection	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.
Active	Comprehensive Rehabilitation program	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.
Placebo	Comprehensive Rehabilitation program	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.

Primary Outcome Measures

Name	Time	Method
Pressure Pain Threshold (PPT)	1 month	Pressure Pain Threshold (PPT) at bilateral latissimus dorsi, levator scapulae, trapezius superior, infraspinatus, pectoralis major, serratus anterior. Difference from baseline
Visual Numeric Scale (VNS) for pain in 3 months	3 months	Mean difference of Pain between groups from baseline to 3 months(T3m), assessed by the Visual Numeric Scale (VNS, 0-10), in which higher scores represent higher pain intensity.
Pressure Pain Threshold	3 months	Pressure Pain Threshold (PPT) at bilateral latissimus dorsi, levator scapulae, trapezius superior, infraspinatus, pectoralis major, serratus anterior. Difference from baseline
Trigger-points	3 months	Number of active trigger-points in the assessed muscles (latissimus dorsi, levator scapulae, trapezius superior, infraspinatus, pectoralis major, serratus anterior). Mean difference between groups.

Secondary Outcome Measures

Name	Time	Method
Percentage of patients with at least 50% improvement of pain as per VNS scores (VNS50%)	3 months	Percentage of patients with at least 50% improvement of pain as per VAS scores (VAS30%). Mean difference between groups.
Adverse events	3 months	Number of participants with adverse events. Mean difference between groups.
Visual Numeric Scale (VNS) for pain in 1 month	1 month	Mean difference of Pain between groups from baseline,assessed by the Visual Numeric Scale (VNS, 0-10), in which higher scores represent higher pain intensity.
Pain medication	3 months	Use of pain medication. Classified as "Increased", "Decreased", "Stable" or "Non-applicable" . Mean difference between groups.
Short-Form McGill Pain Questionnaire (SF-MPQ) - total score, sensorial and affective scale	3 months	Short-Form McGill Pain Questionnaire - total score, sensorial and affective scale. Mean difference between groups from baseline. Higher values represent higher pain intensity
Disabilities of the Arm, Shoulder and Hand Questionnaire (DASH)	3 months	Disabilities of the Arm, Shoulder and Hand Questionnaire (DASH). Mean difference between groups from baseline. Higher values represent lower functionality.
Shoulder range of motion (ROM)	3 months	Range of motion (ROM) of affected shoulder, for abduction and external rotation. Mean difference between groups from baseline.
Percentage of patients with at least 30% improvement of pain as per VNS scores (VNS30%)	3 months	Percentage of patients with at least 30% improvement of pain as per VAS scores (VAS30%). Mean difference between groups.
Neuropathic Pain Symptom Inventory (NPSI)	3 months	Neuropathic Pain Symptom Inventory . Mean difference between groups from baseline. Higher values represent more symptoms of neuropathic pain.

Trial Locations

Locations (2)

Hospital de Câncer de Barretos; 🇧🇷 Barretos, São Paulo, Brazil

Instituto do Câncer do Estado de São Paulo; 🇧🇷 São Paulo, Brazil