Practice Essentials
Neoplastic brachial plexopathy (NBP) is an uncommon diagnosis in most physiatrists' offices, but the condition bears review as it can mimic symptoms of many common upper limb neuropathies. Approximately 10% of all peripheral nerve lesions involve some type of brachial plexus lesion. Neoplastic invasion of the brachial plexus is an uncommon, though not rare, cause of plexopathy. This article reviews the more common issues associated with physiatric treatment of patients with NBP. [1, 2, 3]
Signs and symptoms of neoplastic brachial plexopathy
Some historical findings suggestive of NBP include the following:
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Onset of limb pain less than 6 months following radiation
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Rapid progression
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Horner syndrome (in two thirds of patients with Pancoast syndrome)
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Severe pain predominant
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Other metastases
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Focal mass or neoplasm on biopsy
The most reliable feature of NBP (in 80% of patients) is early, severe, unrelenting pain.
Workup in neoplastic brachial plexopathy
Laboratory studies
A general lab survey, such as a complete metabolic panel, complete blood count, and urinalysis, usually has been obtained by the primary physician and can be used to screen for signs of neoplasm. If a patient is referred for what might be thought of as simple shoulder pain and turns out to have constitutional symptoms (eg, fevers, weight loss, malaise) and signs of brachial plexopathy, other lab tests, such as the following, certainly may be of value:
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A carcinoembryonic antigen (CEA) in a patient with prior colon cancer
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A prostate specific antigen (PSA) in a patient with prior prostate cancer
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Serum protein electrophoresis (SPEP) in a patient with back pain and pain at rest
Imaging studies
These include the following:
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Plain radiographs of the chest, shoulder, and cervical spine
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Magnetic resonance imaging (MRI) of the plexus
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Bone scan
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Myelography
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Positron emission tomography (PET) scanning
Other tests
Additional tests include the following:
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Nerve conduction and electromyographic studies
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Somatosensory evoked potentials (SSEP)
Management of neoplastic brachial plexopathy
Physical therapy
Interventions include the following:
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Early passive range of motion (PROM) - PROM of the upper limb is appropriate to prevent contracture
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Active-assistive range of motion (AAROM) and active range of motion (AROM) exercises - These may be instituted if there is preserved volitional motor function
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Progressive resistance exercises - When tolerated, these can help to maintain as much strength as possible
Surgical intervention
Points to consider include the following:
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Most solitary neurofibromas can be resected without producing or increasing deficit, but this procedure is more difficult than excision of encapsulated tumors and usually requires magnification, intraoperative nerve action potential (NAP) recording, and sometimes cable grafts
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Many benign tumors (including neurofibromas) can be removed without significant loss using surgical loupes or microscope and repetitive NAP recording
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Plexiform neuromas are more difficult to remove because of extensive segments of nerve fiber involvement
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In patients with severe intractable pain, dorsal rhizotomy, dorsal root entry zone surgery, or high contralateral percutaneous cordotomies can be considered
Pathophysiology
Lesions of the brachial plexus occur most often secondary to neoplasms that reach the plexus by direct extension (Pancoast syndrome) or, more commonly, by metastasis through lymphatics from the axilla. Pain in the shoulder, radiating down the limb, may be observed, as well as pain in the medial forearm and hand with lower trunk innervation (C8-T1 roots) in some series. The most common pathophysiology revealed on electrodiagnostic tests is axonal loss. Peripheral pain mechanisms may include lowering of the nociceptor threshold by prostaglandins and other noxious chemical substances and persistent nociceptor stimulation. Compression or infiltration of the nerves of the plexus by a tumor may produce neuralgia and inflammation.
Epidemiology
Frequency
United States
Approximately 14% of all upper limb neurologic lesions are due to brachial plexopathy of all types. Neoplastic plexopathies were responsible for 1.4 and 14.5% of symptoms in 2 series of patients who had undergone surgery. Insufficient data have been published to determine the frequency of NBP, but symptomatic NBP has been estimated to occur in 4% of patients with lung cancer and 2% of patients with breast cancer.
International
The international incidence of NBP is unknown.
In a single institution in Ireland, a 5-year retrospective study of 20 MRIs performed in patients with neoplasms, 6 (30%) confirmed a diagnosis of NBP. [4]
Mortality/Morbidity
Primary neoplasms of the brachial plexus generally are benign, while secondary neoplasms are malignant. Most secondary tumors are metastatic, contributing to higher mortality. [5]
Sex
Solitary neoplastic lesions of the brachial plexus are more common in females. Neurofibromas demonstrate a male-to-female ratio of 1:1.
Age
Incidence of metastatic neoplasm of the brachial plexus increases with age; thus, the condition is more common in elderly patients.
