The role of ultrasound imaging in the evaluation of peripheral nerve in systemic sclerosis (scleroderma)
Introduction
Systemic sclerosis (SSc) is a rare multisystem disorder of complex and not completely understood etiology, characterized by thickening of the skin, due to accumulation of connective tissue [1]. The diagnostic criteria adopted in 1980 by the American College of Rheumatology (ACR; formerly the American Rheumatism Association or ARA) received several modifications. Now at least three subsets of SSc are identified: diffuse form of SSc, when the major criterion is present, limited SSc (three minor criteria) divided in “SSc sine scleroderma” (without cutaneous involvement) and limited cutaneous SSc (with cutaneous involvement) [2], [3].
The prognosis of the disease largely depends on visceral involvement (particularly the lung and the kidney), musculoskeletal symptoms are a major cause of disability in SSc [4]. The earliest manifestations of the disease can be divided radiographically as soft tissue involvement, bone involvement, joint and tendon involvement, and vascular involvement [5].
Peripheral nerve involvement had been estimated to be present in up to 16% of patients and trigeminal neuropathy had been described as associated with SSc more rarely such as polyneuropathy, brachial plexopathy, and lumbosacral radiculopathy [4]. Only few cases of ulnar nerve entrapment at the level of the Guyon tunnel due to calcinosis have been described [6], [7].
High-resolution sonography is a suitable method for the diagnostic workup of different types of nerve lesions, such as nerve entrapments, nerve tumours, and traumatic nerve injuries. High-resolution sonography of nerves has also been used to characterize and evaluate hereditary neuropathies and metabolic disorders [8], [9], [10], [11].
On the basis of our knowledge, there are no reports describing the imaging features of nerves in SSc. Patients affected by SSc may complain of sensory disturbances especially in the hand.
The aim of the study was to study the imaging features of upper limb nerves in patients affected by SSc.
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Materials and methods
Between January 2007 and August 2008, 25 patients (22 women, 3 men) who did not complain of diseases other than SSc (American College Rheumatology classification criteria [2] and more recently proposed criteria for early SSc [3]) were recruited out of 120 consecutive patients with SSc at the outpatient division of clinical immunology of our institution. Duration of disease in the SSc population was calculated from the onset of first non-Raynaud's phenomenon. According to the values of the oral
Results
The presence of sensory disturbances was the main symptom and only two patients with severe cubital tunnel had motor involvement. The prevalence of sensory disturbances in our series was 40%.
In SSc patients, the imaging modalities used revealed an increased nerve cross-sectional area and features suggestive of entrapment neuropathies in 7 out of 10 patients consistent with carpal tunnel syndrome or cubital tunnel syndrome.
Subjective US evaluation revealed apparently normal nerves outside the
Discussion
The pathogenesis of peripheral nervous system involvement is not fully defined and the main hypothesis to explain the neuropathy are at least three: a vascular dependent mechanism, a compression dependent mechanism and an autoimmune-dependent neuropathy. The first considers the unique microvascular involvement in SSc and the involvement of vasa nervorum. Indeed, the axonal degeneration may indirectly favor the hypothesis of a vascular genesis of nerve involvement. The second is supposed by the
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