Postmastectomy Pain Syndrome




Abstract


Context : Postmastectomy pain syndrome is a common and debilitating complication of surgery of the breast or axilla. It is important for the clinician to understand how to recognize this syndrome and how to treat the pain and dysfunction that it causes.


Evidence Acquisition : Studies were identified by searching PubMed for articles published from 1985 to 2017 using the terms “postmastectomy pain,” “complications of breast surgery,” “brachial plexopathy,” and “postoperative breast pain.” References from the relevant publications were searched. Articles were chosen based on relevance to the topic, quality of data, and publication in peer-reviewed journals.


Results : Postmastectomy pain syndrome is underrecognized and underdiagnosed. There is no standard definition, but most authors recognize a syndrome of pain and dysfunction in the operated arm or anterior thorax that lasts from 3 months after surgery to indefinitely. Differential diagnosis includes neuroma, complex regional pain syndrome, axillary hematoma, axillary web syndrome, compressive radiculopathy, and brachial plexopathy. Possible treatment modalities include psychological support, physical therapy, TENS units, myofascial release, autologous fat grafting, venlafaxine, gabapentin, and capsaicin.


Conclusions : Postmastectomy pain syndrome is a common entity that clinicians should recognize. Although there are multiple treatment options, more than one treatment may have to be tried to improve pain and dysfunction.




Keywords

Axilla, Breast surgery, Chest wall, Mastectomy, Postmastectomy pain syndrome

 


Postmastectomy pain syndrome (PMPS) is a common, undertreated condition that affects patients who have had surgery of the breast or axilla. It was hoped that PMPS would decrease in incidence with the movement away from mastectomy and toward lumpectomy and sentinel lymph node dissection. However, it has continued to be a major complication of any breast surgery. Its causes remain poorly understood, and most patients have uncontrolled symptoms despite treatment. PMPS can lead to substantial functional impairment. Pain, sensory loss, adhesive capsulitis, or rotator cuff tendonitis can cause loss of function of the shoulder. It has been estimated that PMPS results in a billion dollars annually of lost productivity.




Presentation


There is no universal definition of PMPS. PMPS is often diagnosed clinically by its location in the anterior thorax or upper arm that occurs on the same side of the body as the breast surgery. The pain lasts from weeks to indefinitely and can be accompanied by phantom breast sensations, sensory loss, paresthesia, or hyperesthesia. Others have defined PMPS more narrowly; Stevens defined the syndrome in 1995 as “paroxysms of sharp pain in a background of burning, aching, and constriction,” which are worsened by movement, do not improve, and are not relieved by narcotics. The International Association for the Study of Pain proposed a requirement that the pain has to be present at least 3 months after surgery, when normal healing presumably would have occurred. Most women report that it significantly worsened their quality of life. Brackstone et al. proposed a standard definition of PMPS as “pain after any type of surgery that is at least of moderate intensity and comprises neuropathic qualities, lasts longer than 6 months, is present in the ipsilateral breast/chest/arm, and is present at least half of the time.”




Epidemiology


PMPS was first described in the age of the Halstead radical mastectomy, in which the breast, skin, fat, and the major and minor pectoral muscles were removed. In the 1970s, the modified radical mastectomy surgery was developed, which leaves the pectoral muscles intact. More recently, lumpectomy (also known as partial mastectomy) became more widely used. These procedures are usually accompanied by either an axillary lymph node dissection, where multiple lymph nodes are removed and sampled, or a sentinel lymph node dissection, where one to four nodes are identified with blue dye or a radioactive tracer and removed, leaving the majority of lymph nodes intact.


It was hoped that the advent of less extensive surgeries for breast cancer would lead to a decrease in the incidence of PMPS. Unfortunately, this has not proven to be the case. Wallace et al. surveyed 282 women 1 year after breast surgery and found the highest rate of PMPS was after breast augmentation (55%), followed by mastectomy and reconstruction (49%), mastectomy alone (31%), and breast reduction (22%). Fabro conducted a survey of 174 women and found an incidence of PMPS of 52%. Age over 40 years or axillary lymph node dissection of more than 15 nodes conveyed a significantly higher risk. Other factors that predict for persistent postoperative pain include younger age, poorer social support, and greater preoperative anxiety.


PMPS is generally regarded as being caused by damage to the intercostobrachial nerves. Paredes et al. reported on a series of patients whose intercostobrachial nerves were either sectioned or preserved. The patients with sectioned nerves had anesthesia and hypoesthesia in the arm, whereas patients with intact nerves had less of both. A second study reported no difference but was limited by short follow-up and a small sample size. If we accept Brackstone’s proposed standard definition, then damage to a regional nerve would be implied. Damage can occur both by transection and contraction of scar tissue around the regional nerves.




Physical Examination


All patients with possible PMPS should have a thorough physical examination at baseline and periodically throughout the course of their treatment. Both arms should be measured at the widest part of the wrist, forearm, and bicep. Lymphedema is present if the measurements between the affected arm and the opposite arm differ by more than 110%. Upper body muscle strength should be assessed by testing the involved muscles against resistance. Grip strength should likewise be tested. Both arms should be tested for sensory response using pinprick and light touch. Finally, the entire arm should be palpated to assess for dysesthesia, allodynia, and hyperalgesia.




Course


Pain from PMPS can be long lasting or even permanent. MacDonald surveyed 138 patients with a mean time after surgery of 9 years. Approximately half of the patients still had pain. The majority of these patients had mastectomies, and a major risk factor was younger age. Their pain responded poorly to medical treatment.




Differential Diagnosis


The differential for thorax pain after breast surgery is limited. Intercostal neuroma is an underrecognized entity that is treatable. Wong reported a series of five patients who had complete relief of their pain after resection of neuroma. These patients had a positive Tinel sign at one of the intercostal nerves of the lateral chest wall. This pain was relieved when the site of the Tinel sign was injected with lidocaine. All of these patients were found to have transected nerves, which were embedded in scar tissue, directly below the Tinel sign. After the neuroma was resected, the cut end was allowed to retract into the intercostal muscles. All of these patients had pain relief from 18 to 36 months after surgery. Intercostal neuromas have also been known to cause pain after breast implant placement. Ultrasound-guided cryoablation is a possible treatment modality for this syndrome.


Some patients may develop complex regional pain syndrome after breast surgery. This can be distinguished from PMPS by its unique symptoms. These may include autonomic changes, skin atrophy, and contraction or fibrosis of joints in the hand and arm.


Another treatable cause of postoperative pain in the axilla is axillary hematoma. This entity presents with pain and swelling of the axilla and can be mistaken for a seroma. Fluid-filled lesions are best evaluated by ultrasound. Seromas are bland, homogenous collections on ultrasound imaging. In contrast, hematomas are more complex, often with visible blood and debris. Blunt et al. report a series of three cases where aspiration of axillary hematoma resulted in substantial, long-lasting relief of pain. One patient required complete resection of the hematoma cavity. They noted that pain from a hematoma may be much greater than that from a seroma of equivalent size. Aspiration of a seroma does not cure PMPS, as most seromas have resolved before the development of PMPS. The presence of a seroma is not associated with a higher risk of PMPS.


Another complication of mastectomy is the axillary web syndrome. This occurs 1–6 weeks after surgery and consists of visible, painful cords in the axilla, which restrict movement. These cords cause pain with shoulder abduction. These patients can often be significantly helped by physical therapy.


It is important to distinguish a compressive radiculopathy from PMPS, because the former is progressive and treatable. The pain in compressive radiculopathy is typically of gradual onset, often accompanied by numbness, severe pain, and variable weakness. The diagnostic test of choice is MRI of the cervical and thoracic spine. Radiculopathy can be benign or malignant; malignant radiculopathy can be diagnosed by a mass on MRI. Malignant lesions should be treated immediately with either radiation or surgery to preserve function. Benign radiculopathy may be treated with physical therapy, nonsteroidal antiinflammatory drugs, or gabapentin.


Brachial plexopathy is a rare, late sequela of radiation therapy that can occur years to decades after therapy. The mechanism is damage to blood vessels, fibrosis of connective tissue around the nerves, and direct damage to the nerves. It presents with pain, paresthesias, and inability to move the affected arm and can lead to muscular atrophy and paralysis. This entity presents late after treatment, with a median onset of 1–4 years after therapy, which helps distinguish it from PMPS.


Venous thrombosis and lymphedema are easily distinguished from PMPS by the presence of erythema and edema.

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Jun 17, 2019 | Posted by in NEUROLOGY | Comments Off on Postmastectomy Pain Syndrome

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