The Clinical Features of Painful Small-Fiber Neuropathy Suggesting an Origin Linked to Primary Sjögren's Syndrome.

OBJECTIVE: We attempted to determine whether clinical features could differentiate painful small-fiber neuropathy related to primary Sj€ogren's syndrome (pSS-SFN) from idiopathic SFN (idio-SFN). METHODS: Validated clinical questionnaires and neurophysiological investigations specific for pain and SFN assessment were performed in 25 patients with pSS-SFN and 25 patients with idio-SFN. RESULTS: Patients with idio-SFN had more frequent severe burning sensations and higher mean anxiety scores and daily pain intensity compared to patients with pSSSFN. Conversely, patients with pSS-SFN had reduced electrochemical skin conductance measured by Sudoscan_, and almost half of them had the sensation of walking on cotton wool. CONCLUSION: Our results suggest that idio-SFN more specifically involved small sensory fibers than pSS-SFN, in which subtle dysfunction of larger sensory fibers and damage of distal autonomic sudomotor innervation may occur. A practical algorithm is proposed to help to differentiate SFN associated with pSS from idio-SFN, based on information very easy to obtain by clinical interview.

Coaching of lifestyle recommendations improves sensory neurophysiological parameters in neuropathies related to glycemic disorder or metabolic syndrome. A pilot study.

OBJECTIVES: Metabolic abnormalities, such as, glycemic disorders and metabolic syndrome (GDMS) are one of the main causes of peripheral neuropathies. The objective of this study was to evaluate the impact of adding specific coaching care (CC) to standard care (SC) of therapeutic education based on lifestyle recommendations for neuropathies associated with GDMS. METHODS: This prospective randomized study included two groups of four patients (SC vs. CC) with examiners blinded to group allocation. The SC group had one day of therapeutic education on lifestyle measures (physical activity and diet recommendations) followed by only one phone call of reinforcement. The CC group received an additional weekly phone call of reinforcement for 3 months. Clinical, biological and neurophysiological variables were compared between the two groups at baseline and for the percentage of change at 3 months. RESULTS: All patients (4 men and 4 women) had diabetes or pre-diabetes, which was associated with metabolic syndrome in 5 cases. There was no difference on any variable at baseline, but at 3 months, Mann-Whitney test showed a difference (P=0.0008) between the two groups regarding the sensory neurophysiological variable, which deteriorated in the SC group (median: -6.0%) and improved in the CC group (median: +12.4%). No significant difference was observed between the two groups for the other variables at 3 months. CONCLUSION: The weekly coaching of recommendations for lifestyle measures over a period of three months allows an improvement of GDMS neuropathies, at least in terms of sensory aspects, as evidenced by neurophysiological assessments.

Characterization of Neuropathic Pain in Primary Sjögren's Syndrome with Respect to Neurophysiological Evidence of Small-Fiber Neuropathy.

OBJECTIVE: To determine whether clinical features of neuropathic pain differ with respect to the presence of small-fiber neuropathy (SFN) in patients with primary Sjögren's syndrome (pSS). METHODS: We compared the clinical presentation of neuropathic pain between 15 patients with pSS and SFN detected by neurophysiological tests (laser-evoked potentials, cold and warm detection thresholds, sympathetic skin responses, and electrochemical skin conductance) and 15 patients with pSS but no neurophysiological evidence of SFN. RESULTS: The patients with SFN had more intense squeezing and pressure sensations and more frequent dynamic mechanical allodynia (pain provoked by brushing) than the patients without SFN. Restless leg syndrome was also more frequently observed in patients with SFN, who had pain aggravated at rest that improved by moving. CONCLUSIONS: These findings are in favor of the sensitization of relatively spared large Aß-fibers and second-order nociceptive neurons in patients with SFN. On the other hand, burning sensations, which rather reveal sensitization of small nociceptive fibers, were observed whether SFN was present or not. Thus, some discriminating clinical features may help to suggest the presence of SFN in patients with pSS and chronic neuropathic pain.

Characterization of Pain in Familial Amyloid Polyneuropathy.

UNLABELLED: Familial amyloid polyneuropathy (FAP) caused by transthyretin (TTR) mutation is a small-fiber predominant polyneuropathy, exposing patients with TTR-FAP to development of neuropathic pain. However, the painful nature of TTR-FAP has never been specifically addressed. In this study, we compared 2 groups of 16 patients with either painless or painful TTR-FAP with regard to various clinical and neurophysiologic variables, including laser evoked potential (LEP) recording and quantitative sensory testing. The 2 groups of patients did not differ on any clinical or neurophysiologic variable. Patients with painful TTR-FAP complained of ongoing burning pain sensations, pain aggravation at rest, paroxysmal pain (electric shock and stabbing sensations), or provoked pain (mostly dynamic mechanical allodynia). However, the symptomatic presentation of painful TTR-FAP evolved with the course of the disease. The duration of the disease and the severity of small-fiber lesions (increase in thermal thresholds and reduction in LEP amplitude) correlated negatively with the intensity of ongoing burning sensations and positively with the intensity of paroxysmal pain. In addition, small-fiber preservation correlated positively with cold allodynia and pain aggravation at rest and negatively with dynamic mechanical allodynia. Peripheral sensitization of small-diameter nociceptive axons might occur in early TTR-FAP and be responsible for the burning sensation and cold allodynia. As polyneuropathy and small-fiber loss progress, paroxysmal pain and dynamic mechanical allodynia may develop as a result of central sensitization generated by abnormal activities affecting relatively spared large-diameter sensory fibers. PERSPECTIVE: Pain in TTR-FAP includes several mechanisms varying with the course of the disease and the involvement of the different types of nerve fibers.

Sensory correlates of pain in peripheral neuropathies.

OBJECTIVE: To characterize sensory threshold alterations in peripheral neuropathies and the relationship between these alterations and the presence of pain. METHODS: Seventy-four patients with length-dependent sensory axonal neuropathy were enrolled, including 38 patients with painful neuropathy (complaining of chronic, spontaneous neuropathic pain in the feet) and 36 patients with painless neuropathy. They were compared to 28 age-matched normal controls. A standardized quantitative sensory testing protocol was performed in all individuals to assess large and small fiber function at the foot. Large fibers were assessed by measuring mechanical (pressure and vibration) detection thresholds and small fibers by measuring pain and thermal detection thresholds. RESULTS: Between patients with neuropathy and controls, significant differences were found for mechanical and thermal detection thresholds but not for pain thresholds. Patients with painful neuropathy and those with painless neuropathy did not differ regarding mechanical or thermal thresholds, but only by a higher incidence of thermal or dynamic mechanical allodynia in case of painful neuropathy. Pain intensity correlated with the alteration of thermal detection and mechanical pain thresholds. CONCLUSIONS: Quantitative sensory testing can support the diagnosis of sensory neuropathy when considering detection threshold measurement. Thermal threshold deterioration was not associated with the occurrence of pain but with its intensity. SIGNIFICANCE: There is a complex relationship between the loss or functional deficit of large and especially small sensory nerve fibers and the development of pain in peripheral neuropathy.

Neurophysiological markers of small fibre neuropathy in TTR-FAP mutation carriers.

Individuals carrying the amyloidogenic transthyretin (TTR) mutation are predisposed to develop familial amyloid polyneuropathy (FAP). The first clinical manifestations are often subjective sensory symptoms and, therefore, objective markers are needed to confirm the onset of TTR-FAP. The purpose of this study was to evaluate the usefulness of a comprehensive battery of neurophysiological tests to provide early markers of FAP in TTR-mutation carriers. Twenty patients with documented pathogenic TTR mutation were enrolled, including eight clinically asymptomatic carriers and 12 paucisymptomatic carriers who had subjective sensory symptoms or doubtful sensory signs but no firm clinical deficit at clinical examination. Neurophysiological assessment of large fibres consisted of conventional nerve conduction studies. Small-fibre tests included laser evoked potentials, sympathetic skin responses and the measurement of cold and warm detection thresholds and heart-rate variability. Abnormalities in small-fibre tests were found in two of the eight asymptomatic carriers and nine of the 12 paucisymptomatic carriers. In contrast, conventional conduction studies did not show any sign of polyneuropathy. Early neuropathic involvement in TTR-mutation carriers can be detected or confirmed by neurophysiological tests specifically assessing small nerve fibres. These tests did not show any redundancy or difference in their sensitivity, emphasizing the value of combining them for TTR-FAP diagnosis.

Efficacy of vinblastine in central nervous system Langerhans cell histiocytosis: a nationwide retrospective study.

BACKGROUND: Vinblastine (VBL) is the standard treatment for systemic Langerhans cell histiocytosis (LCH), but little is known about its efficacy in central nervous system (CNS) mass lesions. METHODS: A retrospective chart review was conducted. Twenty patients from the French LCH Study Group register met the inclusion criteria. In brief, they had CNS mass lesions, had been treated with VBL, and were evaluable for radiologic response. RESULTS: The median age at diagnosis of LCH was 11.5 years (range: 1-50). Intravenous VBL 6 mg/m2 was given in a 6-week induction treatment, followed by a maintenance treatment. The median total duration was 12 months (range: 3-30). Eleven patients received steroids concomitantly. Fifteen patients achieved an objective response; five had a complete response (CR: 25%), ten had a partial response (PR: 50%), four had stable disease (SD: 20%) and one patient progressed (PD: 5%). Of interest, four out of the six patients who received VBL without concomitant steroids achieved an objective response. With a median follow-up of 6.8 years, the 5-year event-free and overall survival was 61% and 84%, respectively. VBL was well-tolerated and there were no patient withdrawals due to adverse events. CONCLUSION: VBL, with or without steroids, could potentially be a useful therapeutic option in LCH with CNS mass lesions, especially for those with inoperable lesions or multiple lesions. Prospective clinical trials are warranted for the evaluation of VBL in this indication.