Objectives To assess prevalence, possible causes and clinical correlates of neuropathic pain (NP) in patients with systemic sclerosis (SSc).
Methods In 42 patients with SSc, presence of NP was assessed using the PainDetect questionnaire and subsequently confirmed by neurological evaluation. Patients with previously diagnosed neurological disorders and diabetes were excluded. Relationship between NP and disease status, symptoms of depression and quality of life was estimated. Index of disease status (IDS) was assessed using the Scleroderma Assessment Questionnaire (SAQ), occurrence of depressive symptoms by the Beck's Depression Inventory (BDI), whilst quality of life was evaluated using the EQ-5D index. In order to evaluate possible causes of NP in SSc, all patients with NP, except one (who did not agree with further assessments) underwent detailed neurological and electroneurography (ENG) examination, as well as HgbA1C and vitamin B12 level testing.
Results 12/42 (28.6%) of patients were found to have NP. Patients with and without NP were similar in age and disease duration. NP was found more frequently in patients with lcSSc (32.3%), than in dcSSc (18.2%), as well as in patients with ACA (46.7%) compared to patients with ATA (17.6%) and both ACA and ATA negative patients (20%), but the differences were not statistically significant. Patients with NP had significantly higher mean values of IDS (1.28 vs 0.66) and BDI (18.3 vs 9.9) than patients without NP (p<0.01). Mean value of the EQ-5D index was significantly lower in patients with NP (0.39 vs 0.79, p<0.01). Patients with NP had significantly higher mean value of Index of vascular status, then patients without NP (2.26 vs 1.36, p=0.02). HgbA1C and vitamin B12 levels were normal in all SSc patients with NP. Clinical signs of polyneuropathy were noticed in 10 patients by neurological evaluation. Typical symmetric glove-and-stocking hyperesthesia was found in 10/11 (90.9%) of SSc patients with NP, along with symmetric hyporeflexia in 6/11 (54.5%) patients on lower, and 7/11 (63.6%) on upper extremities. None of patients had allodynia, but impaired vibratory sensibility was found in all patients with NP. Clinical signs of radiculopathy were present in 6 patients. Hypoesthesia was registered in typical dermatomes in 6/11 (54.5%) of patients, with asymmetric hyporeflexia in 2/11 (18.1%) patients on lower, and none of patients on upper extremities. Despite the fact that almost every patient had symptoms and signs suggesting polyneuropathy, in only four of them demyelinating polyneuropathy was detected by ENG.
Conclusions NP is common in patients with SSc. Presence of NP is associated with more severe SSc, symptoms of depression and worse quality of life. Almost all SSc patients (90.9%) with NP have typical symptoms and signs for polyneuropathy. However, in only few of them polyneuropathy could be detected by ENG. This finding suggests that pure small-fiber polyneuropathy, which is not detectable by ENG, may be the cause of NP in most of patients.
Disclosure of Interest None declared
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