Peripheral neuropathies in Sjogren syndrome: a new reappraisal.

BACKGROUND: The prevalence of peripheral neuropathy in patients with Sjögren syndrome remains unclear owing to conflicting results in the published series, with numbers ranging from 2% to over 60% of Sjögren syndrome patients. Whether peripheral neuropathy is a feature of the systemic or glandular disease or whether it is related to a circulating antineuronal antibody remains also uncertain. METHODS: The authors reviewed the records of patients with primary Sjögren syndrome (pSS), fulfilling the Revised European-American Classification Criteria, seen in their department from 1992 to 2009. The patients with previously recorded neuropathic features were re-examined clinically and electrophysiologically. Other causes of polyneuropathy were excluded. The authors also searched for circulating antineural antibodies using immunofluorescence and western blot and for antibodies against muscarinic and nicotinic acetylcholine receptors as potential biomarkers. RESULTS: 509 cases met the diagnostic criteria for pSS. Among these, 44 patients were recorded as having neuropathic symptoms. After completing the evaluation, however, only nine (1.8%) had polyneuropathy with objective clinical signs and abnormal electrophysiological findings. The neuropathy was axonal in all, in five pure sensory and in four sensorimotor. The patients with peripheral neuropathy had extraglandular manifestations such as palpable purpura and vasculitis. No evidence of antineural autoimmunity was found, and no candidate biomarkers were identified. CONCLUSION: Polyneuropathy is a rare manifestation of pSS occurring in 1.8% of patients. In the majority of patients, it is a late event and frequently associated with systemic disease or risk factors for lymphoma development.

Reductions in plasma prolactin during acute erythropoietin administration.

OBJECTIVES: The presence of erythropoietin (EPO) and its receptors in several central nervous system regions indicates additional functions beside its hematopoietic role. Preclinical data suggest that it may slow down the process of neuronal loss, and that EPO may cause dopamine release, and thus influence hormone release, especially prolactin. This possibility has not yet been studied in humans. METHODS: During a clinical trial on possible protective effects in patients with amyotrophic lateral sclerosis (ALS), we studied the acute effects of EPO administration on prolactin, the release of which is under tonic inhibition of hypothalamic-pituitary dopaminergic activity. Prolactin as well as EPO levels were estimated in blood samples taken every 30 min over 2 hours after administration of 3000 IU EPO i.v. in seven male and four female patients with ALS. RESULTS: The baseline PRL levels of the 11 patients were all within normal range (4.5-10.5 ng/ml). EPO administration caused a significant reduction in prolactin levels, maximal at 60 min after administration. Reductions in PRL were not related to EPO dose (IU per kg body weight), or to duration of illness. CONCLUSIONS: The findings indicate that EPO promotes dopamine release in humans, and is consistent with preclinical data showing that EPO releases dopamine from rat striatal slices. Previous reports showed that dopaminergic neurons express EPO receptors, which exert a facilitating action on dopamine release, and the present data indicate that this may hold true in humans.