Small fibre neuropathy in primary Sjögren syndrome

Purpose

About forty percent of the patients with primary Sjögren's syndrome (pSS) experience chronic neuropathic pain with normal electrodiagnostic studies. Two previous studies suggest that chronic neuropathic pain in pSS is due to small fiber neuropathy (SFN). Quantification of epidermal nerve fiber density after skin biopsy has been validated to diagnose small fiber neuropathy.

Methods

Skin biopsy was performed in 14 consecutive pSS patients (satisfying the american-european classification criteria) with chronic neuropathic pain and normal electrodiagnostic studies suggesting SFN.

Résults

Fourteen female pSS patients exhibited chronic neuropathic pain [burning sensation (n = 14), prickling (n = 4), dysesthesia (n = 8)] with paroxystic exacerbations (n = 10) and allodynia (n = 13), for a mean period of 18.4 ± 12.4 months. Neuropathic pain involved mostly hands and feet (n = 13), with a distal (n = 9) and leg (n = 4) predominant distribution. Neurological examination disclosed normal deep tendon responses and absence of motor weakness (n = 14). Small fiber neuropathy was confirmed by skin biopsy in 13 cases. Epidermal nerve fiber density was decreased in distal [(n = 12), mean 3.5 ± 1.7 fibers/mm (N > 6.9)] and proximal site of biopsy [(n = 9), mean 7.04 ± 2.63 fibers/mm (N > 9.3)].

Conclusion

Small fiber neuropathy is commonly responsible of chronic neuropathic pain in pSS. Prevalence, physiopathology and neurological evolution of such neuropathies still remain unknown.     

Growth, psychomotor development and morbidity up to 3 years of age in children born after IVF

BACKGROUND: To examine the long-term child outcome after IVF until the age of 3 years in Northern Finland, we conducted a population-based cohort study. METHODS: First, a cohort of 299 IVF children born in 1990-1995 was compared with a cohort of 558 controls representing the general population in terms of a multiple birth rate of 1.2%, randomly chosen from the Finnish Medical Birth Register (FMBR) and matched for sex, year of birth, area of residence, parity, maternal age and social class (full sample analyses). Second, IVF singletons (n = 150) were compared with singleton controls (n = 280). Third, a plurality matched control cohort (n = 100) for IVF twins (n = 100) was randomly chosen, matched as above, from the FMBR and analysed separately. Infant mortality rate was compared with the national rate from the FMBR. RESULTS: Infant mortality in the IVF group was >2-fold higher compared to the national rate in the general population. The risk (OR, 95% CI) of low weight and height, below the lowest quartile, at 1 year of age (1.6, 1.1-2.2; 1.6, 1.1-2.4) and 2 years of age (1.5, 1.1-2.4; 1.7, 1.2-2.5) was significantly higher in the IVF group when compared with the general population control group. No statistically significant differences were found in the psychomotor development between the cohorts. Cumulative incidence of different diseases up to 3 years of age was significantly higher among IVF children in the full sample and singleton analyses (OR, 95% CI: 2.3, 1.7-3.2; 2.1, 1.3-3.3 respectively) especially regarding respiratory diseases (3.5, 1.9-6.5; 3.1, 1.0-9.4) and diarrhoea (3.7, 2.2-6.2; 5.7, 2.6-12.7), but not in twin comparisons. CONCLUSIONS: The growth of IVF children was behind that of control children during the first 3 years of life, but their psychomotor development was similar. Their postnatal health was worse, probably reflecting the problems in the neonatal period.     

Influence of cognitive load on the dynamics of neurophysiological adjustments during fatiguing exercise

We aimed to determine the neurophysiological mechanisms associated with reduced endurance performance during cognitive‐motor dual task at different levels of cognitive load, compared to a motor task alone. Eighteen healthy men performed isometric quadriceps contractions at 15% of maximal voluntary contraction (blocks of 170 s interspaced by neuromuscular evaluations) until exhaustion. This task was performed on three separate days: (a) in the absence of concomitant cognitive task, (b) with concomitant 1‐back task, and (c) with concomitant 2‐back task. Autonomic nervous system activity, perceived exertion, and cognitive performance were continuously monitored. Peripheral and central determinants of neuromuscular function were assessed at rest, between each block, and at task failure using femoral nerve stimulation. Endurance time was shorter during 2‐back (982 ± 545 s) and 1‐back (1,128 ± 592 s) conditions, compared with control (1,306 ± 836 s). Voluntary activation level was lower in 2‐back (87.1%; p < 0.001) and 1‐back (88.6%; p = 0.04) conditions compared to control (91.2%) at isotime (100% of the shortest test duration). Sympathetic activity showed a greater increase in 2‐back condition compared to control. Perceived muscular exertion was higher during 2‐back than during control. Cognitive performance decreased similarly with time during both cognitive‐motor dual task but was always lower during 2‐back condition. Motor performance is reduced when adding a concomitant demanding memory task to a prolonged isometric exercise. This can be explained by the interaction of various psychological and neurophysiological factors including higher perceived exertion, greater perturbations of autonomic nervous system activity, and cerebral impairments leading to earlier onset of central fatigue.     

Defective regulation of phosphatidylinositol-3-kinase gene expression in skeletal muscle and adipose tissue of non-insulin-dependent diabetes mellitus patients

Summary We investigated the regulation of the mRNA expression of the insulin receptor, insulin receptor substrate-1 (IRS-1) and p85α-phosphatidylinositol-3-kinase (PI-3K), three major actors of insulin action, in skeletal muscle from 10 healthy lean volunteers, 13 obese patients with Type II (non-insulin-dependent) diabetes mellitus and 7 non-diabetic obese subjects. The in vivo regulation by insulin was studied using a 3-h euglycaemic, hyperinsulinaemic clamp. There were no differences in the basal concentrations of the three mRNAs in skeletal muscle between groups. Insulin infusion produced a twofold reduction in insulin receptor substrate-1 mRNA expression in the three groups (p < 0.02). In contrast, insulin increased p85α-phosphatidylinositol-3-kinase mRNA expression in muscle from non-diabetic subjects ( + 98 ± 22 % in lean and + 127 ± 16 % in obese, p < 0.02) but this effect was totally impaired in Type II diabetic patients ( + 5 ± 12 %, NS). A similar defect in insulin action on p85α-phosphatidylinositol-3-kinase mRNA expression was observed in abdominal subcutaneous adipose tissue ( + 138 ± 25 %, p < 0.01 in lean and + 46 ± 14 %, p < 0.02 in obese and + 29 ± 11 %, NS in Type II diabetic patients). The lack of action of insulin on p85α-phosphatidylinositol-3-kinase mRNA in diabetic subjects was probably not due to a deleterious effect of hyperglycaemia since improvement of the glycaemic control for 10 days did not restore the response in muscle or in adipose tissue. This study provides evidence for a defect in the regulation by insulin of PI-3K gene expression in Type II diabetic patients, thus reinforcing the concept that alterations at the gene expression might be involved in the pathogeny of Type II diabetes. [Diabetologia (1999) 42: 358–364] Received: 26 August 1998 and in revised form: 23 October 1998