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Postgraduate Education Corner: PULMONARY AND CRITICAL CARE PEARLS |

A 56-Year-Old Woman With Arm Pain, Dyspnea, and an Elevated Diaphragm* FREE TO VIEW

Meena Kalluri, MD; John T. Huggins, MD; Charlie Strange, MD, FCCP
Author and Funding Information

*From Medical University of South Carolina, Charleston, SC.

Correspondence to: Meena Kalluri, MD, Division of Pulmonary and Critical Care, Medical University of South Carolina, 96 Jonathan Lucas St, 812CSB, Charleston, SC 29425; e-mail: kalluri@musc.edu



Chest. 2008;133(1):296-299. doi:10.1378/chest.07-0721
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Published online

A 56-year-old woman presented with 4 months of progressive dyspnea. Six months before presentation, she recalled an episode of upper respiratory infection. Over the next 2 months, bilateral arm pain and weakness of proximal muscles developed in all four extremities. As the pain improved, she noted the onset of dyspnea.

The patient was afebrile with room air oxygen saturation of 96%. The thorax appeared normal on inspection. She had reduced motor strength 4/5 bilaterally in the biceps, triceps, and deltoid muscles without atrophy. The chest was clear to auscultation. An admission chest radiograph is shown in Figure 1 . Pulmonary function tests showed FVC of 1.79 L (55% of predicted); FEV1, 1.48 L (60% of predicted); FEV1/FVC, 83%; total lung capacity, 3.07 L (60% of predicted), Expiratory reserve volume, 0.39 L (36% of predicted); and functional residual capacity, 1.76 L (76% of predicted). Maximum inspiratory pressure and maximum expiratory pressure were 14 cm H2O (19% of predicted) and 24 cm H2O (15% of predicted), respectively. Basic metabolic panel, CBC count, thyroid, and hepatic function test results were normal. An autoimmune panel including antinuclear antibody, Westergren sedimentation rate, rheumatoid factor, creatine kinase, and aldolase was negative. Serum protein electrophoresis was normal. Acetylcholine receptor and calcium-channel antibodies were not detected. Phrenic nerve conduction studies showed bilateral phrenic axonopathy with severely diminished action potential amplitude of 30 mV on the right and 100 mV on the left (normal, 160 to 500 mV). Electromyography of shoulder muscles was normal. Nerve conduction studies of the median, ulnar, and radial nerves were normal. A brain MRI was normal.

What is the diagnosis?
Diagnosis: Neuralgic amyotrophy with bilateral phrenic nerve palsy

Neuralgic amyotrophy (NA) is an idiopathic neuropathy characterized by the acute onset of neuropathic pain followed by weakness and atrophy of the involved musculature. Sensory loss may also be seen. It commonly affects the brachial, lumbar, or cervical plexus but has also been reported to affect several peripheral nerves. Parsonage Turner syndrome, first described in 1948, is a “shoulder girdle syndrome” that involves only the brachial plexus. This is also known as brachial neuritis, brachial plexus neuropathy, and acute brachial radiculitis. Subsequently, it was increasingly recognized that extra brachial nerves such as the phrenic nerves, lumbosacral plexus, and other peripheral nerves may also be involved in this syndrome. From the anatomic perspective, NA should not be limited to brachial plexus disease; it should be considered a form of mononeuropathic multiplexa with preferential involvement of the cervical roots, plexuses, or nerves.

The annual incidence is 2 to 3 per 100,000 persons per year. The disorder has a peak incidence between the third and fifth decades and is male predominant, 2–4:1. NA can occur as a sporadic disorder (idiopathic) or as an autosomal dominant hereditary trait, known as hereditary NA, which predisposes to recurrent attacks of peripheral neuropathy.

The precise location (axon, dendrites, or neuromuscular junction) of neuronal injury and etiology of this neuropathy are unknown; but autoimmune injury leading to focal demyelination or axonal degeneration has been suggested as a pathogenic mechanism. A triggering antecedent event has been reported in majority of the cases. In descending order of frequency, the triggers include upper respiratory infections, exercise, surgery, peripartum state, trauma unrelated to the shoulder, and vaccinations (diptheria, polio, and tetanus).

The syndrome onset is usually heralded by sharp, severe neuropathic pain in the C4–C5 dermatomes, most commonly lateralizing to the right arm (when involving the brachial plexus). The average duration of pain is approximately 30 days, and approximately 10% of patients have pain lasting > 2 months. Chronic, therapy-resistant, continuous pain in the same region eventually develops in one third of patients. Within 1 week of pain onset, motor weakness commonly affecting the muscles innervated by C5–C7 nerve roots develops in most patients. Involvement of the long thoracic and suprascapular nerves arising from the upper part of the brachial plexus may result in “winging of the scapula.” In most of the patients, recovery of motor function begins between the first and sixth months. Sensory deficits with paraesthesias and/or hypoesthesias may also occur.

Although this syndrome mainly affects the brachial plexus, concomitant or isolated phrenic neuropathy also has been reported. The incidence of extrabrachial involvement (including the phrenic nerve) is higher (56%) in the hereditary subtype compared to the idiopathic subtype (17%). NA causes more than half of cases with isolated idiopathic phrenic nerve paresis.

The diagnosis of nonphrenic NA is made in the appropriate clinical setting with routine laboratory tests to rule out common causes of peripheral neuropathy. These include infections, autoimmune diseases, diabetes, and vasculitis. Electromyography and nerve conduction studies may show patchy conduction blocks and also serve to exclude a monoradiculopathy or entrapment neuropathy. These tests can also be used to determine disease severity and to follow progression. Chest radiography is performed to exclude a Pancoast tumor but may be more useful to document diaphragmatic palsy. Brachial plexus MRI is typically normal except for rare T2 hyperintensities. Phrenic nerve involvement can also be suggested by lung function tests that show restriction, decreased inspiratory pressures with preserved functional residual capacity. Expiratory reserve volume (ERV) and maximum expiratory mouth pressure are generally preserved in isolated phrenic palsy. In patients with isolated phrenic nerve involvement due to NA, obtaining an accurate history about preceding pain, weakness, and other sensory symptoms will lead to correct diagnosis and avoid unnecessary investigations.

Treatment of nonphrenic NA is mainly supportive, including analgesics, physiotherapy, and reassurance. Corticosteroids have been administered to reduce pain, but they have not been shown to influence the course of the illness. Anecdotal reports of success with plasma exchange and IV Ig have been recorded. Recovery is sporadic, and some patients are left with pain and/or paresis after ≥ 3 years. Full recovery of sensory deficits is seen in one third of patients.

In patients with associated or isolated phrenic nerve involvement, the clinical outcome is variable. Some degree of recovery is usual but may be slow or incomplete. Recovery may not commence for up to 3 years after diagnosis. The delay may be due to the long length over which the phrenic nerve must regenerate. In patients with severe dyspnea, plication of the diaphragm may result in improved ventilation and gas exchange. It is suggested that plication be delayed for at least 2 years after diagnosis because delayed spontaneous recovery may be seen.

This patient presented with the characteristic clinical features of NA, radiographic evidence of right phrenic palsy (admission radiograph showed an elevated right hemidiaphragm and atelectasis), and electromyograhic evidence of bilateral axonopathy. We also suspect that she had intercostal nerve involvement leading to chest wall muscle weakness. Her pulmonary function tests reveal a restrictive physiology and normal functional residual capacity with both a decreased ERV and maximum expiratory mouth pressures. ERV remains relatively preserved in cases of isolated bilateral phrenic nerve palsies. Decreased ERV and maximal expiratory pressure suggests that the nerves supplying the accessory muscles were also involved in this syndrome. This explains the profound dyspnea that is unusual for isolated phrenic palsies. Our patient underwent right diaphragmatic plication after 1 year of observation because of severe dyspnea. Her exercise tolerance improved remarkably, but pulmonary function test results did not change significantly.

  1. Consider the diagnosis of NA in patients with diaphragmatic paresis who present with pain, weakness, and sensory deficits of the upper extremities.

  2. Common triggers include upper respiratory viral infections and preceding surgery.

  3. NA is a clinical diagnosis supported by normal laboratory evaluation for other causes of neuropathy. Electromyography and radiologic imaging are essential to exclude other causes of neuropathy.

  4. Isolated phrenic nerve involvement has been known to occur.

  5. Phrenic nerve recovery may take > 3 years from diagnosis. It is seldom complete in most cases.

The authors have no conflicts of interest in the subject matter discussed.

Hughes, PD, Polkey, MI, Moxham, J, et al (1999) Long term recovery of diaphragmatic strength in neuralgic amyotrophy.Eur Respir J13,379-384. [PubMed] [CrossRef]
 
Parsonage, MJ, Turner, JW Neuralgic amyotrophy, the shoulder girdle syndrome.Lancet1948;i,973-978
 
Stolk, J, Versteegh, MI Long-term effect of bilateral plication of the diaphragm.Chest2000;117,786-789. [PubMed]
 
Tsairis, P, Dyck, PJ, Mulder, DW Natural history of brachial plexus neuropathy.Arch Neurol1972;27,109-117. [PubMed]
 
Tsao, BE, Ostroskiy, DA, Wilbourn, AJ, et al Phrenic neuropathy due to neuralgic amyotrophy.Neurology2006;66,1582-1584. [PubMed]
 
Van Alfen, N The trouble with neuralgic amyotrophy.Practical Neurol2006;6,298-307
 
Van Alfen, N, Van Engelen, BG The clinical spectrum of neuralgic amyotrophy in 246 cases.Brain2006;129,438-450. [PubMed]
 

Figures

Tables

Suggested Readings

Hughes, PD, Polkey, MI, Moxham, J, et al (1999) Long term recovery of diaphragmatic strength in neuralgic amyotrophy.Eur Respir J13,379-384. [PubMed] [CrossRef]
 
Parsonage, MJ, Turner, JW Neuralgic amyotrophy, the shoulder girdle syndrome.Lancet1948;i,973-978
 
Stolk, J, Versteegh, MI Long-term effect of bilateral plication of the diaphragm.Chest2000;117,786-789. [PubMed]
 
Tsairis, P, Dyck, PJ, Mulder, DW Natural history of brachial plexus neuropathy.Arch Neurol1972;27,109-117. [PubMed]
 
Tsao, BE, Ostroskiy, DA, Wilbourn, AJ, et al Phrenic neuropathy due to neuralgic amyotrophy.Neurology2006;66,1582-1584. [PubMed]
 
Van Alfen, N The trouble with neuralgic amyotrophy.Practical Neurol2006;6,298-307
 
Van Alfen, N, Van Engelen, BG The clinical spectrum of neuralgic amyotrophy in 246 cases.Brain2006;129,438-450. [PubMed]
 
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