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.
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 Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Enrollment
72
1mL injections of 1% lidocaine in the muscles identified active trigger points at the day of intervention (pectoralis major, serratus anterior, levator scapulae, latissimus dorsi, infraspinatus).
0.2mL subcutaneous saline injections superficial to the muscles identified with active trigger points at the day of intervention (pectoralis major, serratus anterior, levator scapulae, latissimus dorsi, infraspinatus).
Patients in both groups will undergo standard of care rehabilitation delivered by a Physiatrist, which may include Physical Therapy, Occupational Therapy, Exercise Physiologist, Rehabilitation Nurse, Psychologist, as per Physiatrist's prescription. Both the comprehensive rehabilitation program and pain medications will continue to be managed by participant's Physiatrist, who will be blinded to patient's allocation. The researchers will be responsible for TPI and for data collection.
Hospital de Câncer de Barretos
Barretos, São Paulo, Brazil
Instituto do Câncer do Estado de São Paulo
São Paulo, Brazil
Visual Numeric Scale (VNS) for pain in 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.
Time frame: 3 months
Trigger-points
Number of active trigger-points in the assessed muscles (latissimus dorsi, levator scapulae, trapezius superior, infraspinatus, pectoralis major, serratus anterior). Mean difference between groups.
Time frame: 1 month
Trigger-points
Number of active trigger-points in the assessed muscles (latissimus dorsi, levator scapulae, trapezius superior, infraspinatus, pectoralis major, serratus anterior). Mean difference between groups.
Time frame: 3 months
Pressure Pain Threshold (PPT)
Pressure Pain Threshold (PPT) at bilateral latissimus dorsi, levator scapulae, trapezius superior, infraspinatus, pectoralis major, serratus anterior. Difference from baseline
Time frame: 1 month
Pressure Pain Threshold
Pressure Pain Threshold (PPT) at bilateral latissimus dorsi, levator scapulae, trapezius superior, infraspinatus, pectoralis major, serratus anterior. Difference from baseline
Time frame: 3 months
Visual Numeric Scale (VNS) for pain in 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.
Time frame: 1 month
Short-Form McGill Pain Questionnaire (SF-MPQ) - total score, sensorial and affective scale
Short-Form McGill Pain Questionnaire - total score, sensorial and affective scale. Mean difference between groups from baseline. Higher values represent higher pain intensity
Time frame: 1 month
Short-Form McGill Pain Questionnaire (SF-MPQ) - total score, sensorial and affective scale
Short-Form McGill Pain Questionnaire - total score, sensorial and affective scale. Mean difference between groups from baseline. Higher values represent higher pain intensity
Time frame: 3 months
Neuropathic Pain Symptom Inventory (NPSI)
Neuropathic Pain Symptom Inventory . Mean difference between groups from baseline. Higher values represent more symptoms of neuropathic pain.
Time frame: 1 month.
Neuropathic Pain Symptom Inventory (NPSI)
Neuropathic Pain Symptom Inventory . Mean difference between groups from baseline. Higher values represent more symptoms of neuropathic pain.
Time frame: 3 months
Disabilities of the Arm, Shoulder and Hand Questionnaire (DASH)
Disabilities of the Arm, Shoulder and Hand Questionnaire (DASH). Mean difference between groups from baseline. Higher values represent lower functionality.
Time frame: 1 month
Disabilities of the Arm, Shoulder and Hand Questionnaire (DASH)
Disabilities of the Arm, Shoulder and Hand Questionnaire (DASH). Mean difference between groups from baseline. Higher values represent lower functionality.
Time frame: 3 months
Shoulder range of motion (ROM)
Range of motion (ROM) of affected shoulder, for abduction and external rotation. Mean difference between groups from baseline.
Time frame: 1 month
Shoulder range of motion (ROM)
Range of motion (ROM) of affected shoulder, for abduction and external rotation. Mean difference between groups from baseline.
Time frame: 3 months
Percentage of patients with at least 30% improvement of pain as per VNS scores (VNS30%)
Percentage of patients with at least 30% improvement of pain as per VAS scores (VAS30%). Mean difference between groups.
Time frame: 1 month
Percentage of patients with at least 30% improvement of pain as per VNS scores (VNS30%)
Percentage of patients with at least 30% improvement of pain as per VAS scores (VAS30%). Mean difference between groups.
Time frame: 3 months
Percentage of patients with at least 50% improvement of pain as per VNS scores (VNS50%)
Percentage of patients with at least 50% improvement of pain as per VAS scores (VAS30%). Mean difference between groups.
Time frame: 1 month
Percentage of patients with at least 50% improvement of pain as per VNS scores (VNS50%)
Percentage of patients with at least 50% improvement of pain as per VAS scores (VAS30%). Mean difference between groups.
Time frame: 3 months
Adverse events
Number of participants with adverse events. Mean difference between groups.
Time frame: 1 month
Adverse events
Number of participants with adverse events. Mean difference between groups.
Time frame: 3 months
Pain medication
Use of pain medication. Classified as "Increased", "Decreased", "Stable" or "Non-applicable" . Mean difference between groups.
Time frame: 1 months
Pain medication
Use of pain medication. Classified as "Increased", "Decreased", "Stable" or "Non-applicable" . Mean difference between groups.
Time frame: 3 months
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