Abstract
Post-mastectomy pain syndrome is a constellation of symptoms that affect patients for longer than 6 months after treatment for breast cancer. It is believed to be of neuropathic etiology with many contributing variables. Epidemiology, diagnosis, and treatment are discussed. By understanding the nature of the syndrome, physicians are better equipped to identify and provide comprehensive management strategies.
Definition
Post-mastectomy pain syndrome (PMPS) is a chronic pain condition, typically neuropathic in nature, that can follow surgery to the breast. PMPS can occur with any surgery to the breast including mastectomy, lumpectomy, reconstruction, and augmentation, although symptoms of post-mastectomy pain are reduced with sentinel lymph node procedures as opposed to resection of multiple nodes. PMPS affects approximately 40% to 52% of patients after breast surgery. The definition of PMPS is variable and attempts have been made more recently to standardize the definition in order to promote more consistent research and discussion. More recent definitions specify that it is pain persisting for at least 6 months after surgery when all other causes of pain, such as recurrence or infection, have been eliminated. The risk factors for development of PMPS include younger age, more extensive surgery with axillary lymph node dissection, radiation therapy, neurotoxic chemotherapy, tumor location in the upper outer quadrant of the breast, immediate acute postoperative pain, pre-existing chronic pain, and psychosocial factors including stress, anxiety, and depression PMPS often manifests as phantom breast pain, incisional pain, or neuropathic pain in the anterior/lateral chest wall, axilla, and/or medial upper arm. Early management includes pain control, desensitization techniques, and shoulder range of motion. Chronic management includes neuropathic pain agents, interventional procedures, and rehabilitation. Primary objectives of management include sleep preservation, maintenance of shoulder function, and vocational rehabilitation.
Classification of PMPS can be divided into four categories: phantom breast pain, intercostobrachial neuralgia, myogenic pain, and neuroma pain. Phantom pain is identified in 23% of post-mastectomy patients and consists of painful sensations in the area of the removed breast. The intercostobrachial nerve is the lateral cutaneous nerve of the second thoracic root. It courses along the axillary vein and then provides sensation to the axilla and breast ( Fig. 110.1 ). The intercostobrachial nerve is frequently stretched or sacrificed during axillary lymph node dissections and is a common cause of PMPS. Myogenic pain is common after mastectomy and is associated with surgical irritation and immobilization. The scar from breast surgery can be a generator of pain. The pain has been attributed to underlying neuroma formation, axon impingement, and scar retraction.
Symptoms
The symptoms associated with PMPS include shooting, stabbing, burning, and pins and needles sensations in the breast, axilla, or medial arm. In addition, patients complain of symptoms of tightness and fullness in the axilla. Pain is aggravated by shoulder movement, stretching, straining, and direct contact with clothes. The symptoms of PMPS are usually nonprogressive and have been found to persist in half of patients observed for 9 years. PMPS results in functional loss and sleep disruption, and these may be common presenting complaints.
Physical Examination
The primary aspects of the physical examination include exclusion of other causes of the identified pain and classification of PMPS. General inspection should be performed to evaluate for muscle wasting, asymmetry, and gross masses. The musculoskeletal examination should focus on shoulder range and function; muscle restriction in the pectoralis major and minor; myofascial pain in the scapulothoracic region, and costovertebral, costochondral, and rib integrity. A careful skin examination should be performed to assess for scar adherence, fibrosis, scar tenderness, neuromas, infection, and recurrence of malignant disease. The lymphatic examination should be performed to assess for lymphadenopathy in lymphatic distributions not already dissected. The neurologic examination includes motor testing of the shoulder girdle, focusing on motor nerves potentially affected by breast surgery (thoracodorsal, long thoracic, medial and lateral pectoral). Sensory testing should include all breast dermatomes T1-T5. Particular attention should be paid to the posterior thoracic dermatomes, as these can be a clue to spinal disease. The sensory examination of the axilla should identify the distribution, severity, and type of sensory abnormality. The complete neurologic examination should include a full assessment of upper extremity motor, reflex, and sensory function.
Functional Limitations
The major functional limitations with PMPS include loss of shoulder range of motion, lifting restrictions, and sleep disruption. Loss of shoulder range of motion is attributed to maintenance of the more comfortable adducted position, resulting in restricted abduction and external rotation. Concurrently, restriction in the pectoralis minor and major results in decreased forward flexion and extension. Limitations with lifting result in diminished capacity to perform household duties (vacuuming, laundry), occupational duties (stocking shelves), and vocational pursuits. Sleep disruption affects 50% of patients with PMPS and can lead to global daytime dysfunction.
Diagnostic Studies
Diagnostic studies are used primarily to exclude other causes of pain. Recurrent malignant neoplasms can be excluded by mammography, ultrasound, magnetic resonance imaging, or positron emission tomography scans. Dedicated imaging of the thoracic spine is warranted to exclude other suspected causes of neuropathic pain in the breast dermatomes, such as radiculopathy. Electrodiagnosis can be useful to exclude motor nerve abnormalities and plexopathy.
Tumor recurrence
Rib fracture
Paraneoplastic neuropathy
Intraparenchymal lung disease
Chemotherapy neuropathy
Thoracic nerve root impingement
Radiation plexopathy
Intercostal neuralgia
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