Postmastectomy pain syndrome is a constellation of symptoms that includes pain in the anterior chest, breast, axilla, and medial upper extremity after surgical procedures on the breast. Postmastectomy pain is a misnomer because the clinical syndrome includes the pain mentioned here even if the patient has only a lumpectomy or if another, less extensive surgical procedure is performed on the breast.
The pain is often described as constricting, with a continuing dull ache. In addition to these symptoms, many patients with postmastectomy pain syndrome also report sudden paresthesia radiating into the breast, axilla, or both. In some patients, a burning, allodynic pain reminiscent of reflex sympathetic dystrophy may be the principal manifestation. The intensity of postmastectomy pain is moderate to severe. The onset of postmastectomy pain may be immediately after surgery and initially be confused with expected postsurgical pain, or the onset may be more insidious, occurring gradually 2 to 6 weeks after the inciting surgical procedure. If complete mastectomy is performed, phantom breast pain may confound the diagnosis further, as may associated lymphedema. Sleep disturbance is a common finding in patients with postmastectomy pain.
Signs and Symptoms
Evaluation of a patient with postmastectomy syndrome requires that the clinician take a careful history designed to delineate the various components that make up the patient’s pain to help guide the physical examination. The clinician should question the patient specifically about the presence of phantom breast pain, which may be quite distressing to the patient when superimposed on the pain of postmastectomy syndrome.
Typical physical findings in patients with postmastectomy syndrome include areas of decreased sensation, hyperpathia, and dysesthesia in the distribution of the intercostobrachial nerve, which is a branch of the second intercostal nerve. This nerve is frequently damaged during breast surgery.
Allodynia outside the distribution of the intercostobrachial nerve also is often present. Movement of the arm and axilla often exacerbates the pain, which leads to splinting and disuse of the affected shoulder and upper extremity. This disuse often worsens any lymphedema that is present. If disuse of the upper extremity continues, frozen shoulder may develop, further complicating the clinical picture.
The clinician should always be alert to the possibility of metastatic disease or direct extension of tumor into the chest wall, which may mimic the pain of postmastectomy syndrome.
The findings of the targeted history and physical examination assist the clinician in making an assessment of the sympathetic, neuropathic, and musculoskeletal components of the pain and designing a rational treatment plan.
How is this investigated?
Plain radiographs are indicated in all patients who present with pain thought to be due to postmastectomy syndrome to rule out occult bony pathology, including tumor.
Electromyography helps rule out damage to the intercostobrachial nerve or plexopathy that may be contributing to the patient’s pain. Radionucleotide bone scanning may be useful to rule out occult pathological fractures of the ribs, sternum, or both. Based on the patient’s clinical presentation, additional tests, including complete blood cell count, prostate-specific antigen level, erythrocyte sedimentation rate, and antinuclear antibody testing, may be indicated.
Computed tomography (CT) scan of the thoracic contents is indicated if occult mass is suspected. Magnetic resonance imaging (MRI) of the brachial plexus also should be considered if plexopathy secondary to tumor involvement is a consideration.
As mentioned earlier, the pain of postmastectomy syndrome is often mistaken for postoperative pain. If the breast surgery was performed for malignancy, a careful search for metastatic disease or tumor invasion of the chest wall is mandatory.
Postmastectomy syndrome may coexist with pathological rib fractures or pathological fractures of the sternum itself, which can be missed on plain radiographs and may require radionucleotide bone scanning for proper identification.
Neuropathic pain involving the chest wall also may be confused or coexist with postmastectomy syndrome. Examples of such neuropathic pain include diabetic polyneuropathies and acute herpes zoster involving the thoracic nerves.
The possibility of diseases of the structures of the mediastinum is ever present, and these diseases sometimes can be difficult to diagnose. Pathological processes that inflame the pleura, such as pulmonary embolus, infection, and Bornholm disease, also may mimic the pain of postmastectomy syndrome.
Initial treatment of postmastectomy syndrome should include a combination of simple analgesics and nonsteroidal antiinflammatory drugs (NSAIDs) or cyclooxygenase-2 (COX-2) inhibitors. If these medications do not control the patient’s symptoms adequately, a tricyclic antidepressant or gabapentin should be added.
Traditionally, tricyclic antidepressants have been a mainstay in the palliation of pain secondary to postmastectomy syndrome. Controlled studies have shown the efficacy of amitriptyline for this indication. Other tricyclic antidepressants, including nortriptyline and desipramine, also have been shown to be clinically useful. This class of drugs is associated with significant anticholinergic side effects, however, including dry mouth, constipation, sedation, and urinary retention. These drugs should be used with caution in patients with glaucoma, cardiac arrhythmia, and prostatism.
To minimize side effects and encourage compliance, the primary care physician should start amitriptyline or nortriptyline at a 10-mg dose at bedtime. The dose can be titrated to 25 mg at bedtime as side effects allow. Upward titration of dosage in 25-mg increments can be done each week as side effects allow. Even at lower doses, patients generally report a rapid improvement in sleep disturbance and begin to experience pain relief in 10 to 14 days.
If the patient does not experience any improvement in pain as the dose is being titrated upward, the addition of gabapentin alone or in combination with nerve blocks of the intercostal nerves with local anesthetics, steroid, or both is recommended. Selective serotonin reuptake inhibitors, such as fluoxetine, also have been used to treat the pain of diabetic neuropathy, and although better tolerated than tricyclic antidepressants, they seem to be less efficacious.
If the antidepressant compounds are ineffective or contraindicated, gabapentin represents a reasonable alternative. Gabapentin should be started with a 300-mg dose at bedtime for 2 nights.
The patient should be cautioned about potential side effects, including dizziness, sedation, confusion, and rash. The drug is increased in 300-mg increments, given in equally divided doses over 2 days, as side effects allow, until pain relief is obtained or a total dose of 2400 mg daily is reached.
At this point, if the patient has experienced partial pain relief, blood values are measured and the drug is carefully titrated upward using 100-mg tablets. Rarely is more than 3600 mg daily required. Pregabalin may be a consideration if gabapentin is ineffective.
Intravenous infusions of lidocaine and topical lidocaine patches have been reported to provide symptomatic relief of postmastectomy pain. Spinal cord stimulation may also provide symptomatic relief of postmastectomy pain.
Local application of heat and cold, as well as topical capsaicin, also may be beneficial to provide symptomatic relief of the pain of postmastectomy syndrome. The use of an elastic rib belt may help provide symptomatic relief.
Hypnosis may provide adjunctive relief of pain. For patients who do not respond to these treatment modalities, injection of the affected intercostal nerves or thoracic epidural nerve block using local anesthetic and steroid may be a reasonable next step.
The major problem in the care of patients thought to have postmastectomy syndrome is the failure to identify potentially serious pathological conditions of the thorax or upper abdomen secondary to metastatic disease or invasion of the chest wall and thorax by tumor.
Given the proximity of the pleural space, pneumothorax after intercostal nerve block is a distinct possibility. The incidence of the complication is less than 1%, but it occurs with greater frequency in patients with chronic obstructive pulmonary disease. Although uncommon, infection is an ever-present possibility, especially in an immunocompromised patient with cancer. Early detection of infection is crucial to avoid potentially life-threatening sequelae.
Postmastectomy syndrome is a cause of chest wall and thoracic pain that should not be overlooked in patients after breast surgery.
Correct diagnosis is necessary to treat this painful condition properly and to avoid overlooking serious intrathoracic or intra-abdominal pathological processes.
The use of the pharmacological agents mentioned, including gabapentin, allows the clinician to control the pain of postmastectomy syndrome adequately. Intercostal nerve block is a simple technique that can produce dramatic relief for patients with postmastectomy syndrome.
As mentioned, the proximity of the intercostal nerve to the pleural space makes careful attention to technique mandatory. Recent research has identified genetic and epigenetic factors that may predispose patients to the development of postmastectomy pain.