Cerebrospinal fluid protein in Guillain-Barré syndrome: Need for age-dependent interpretation.

BACKGROUND AND PURPOSE: Elevated cerebrospinal fluid (CSF) total protein in patients with acute ascending paresis is indicative of Guillain-Barré syndrome (GBS). Recent studies showed that the outdated, but still widely used upper reference limit (URL) for CSF total protein of 0.45 g/L leads to false-positive results, mainly as a result of lack of age-adjustment. The objective of this study was to assess the frequency of increased CSF total protein in adult GBS patients according to a new age-dependent URL. METHODS: Patients with GBS treated at the Medical University of Innsbruck between 2000 and 2018 were included in this study. Demographic, clinical, electrophysiological and CSF data were obtained from patients' medical charts. Frequency of increased CSF total protein depending on disease duration was compared using the conventional URL of 0.45 g/L and the age-dependent URL. RESULTS: Ninety-seven patients with GBS aged 57 ± 18 years, comprising 38% women, underwent CSF sampling within a median of 6 days after symptom onset. The median CSF total protein concentration was 0.65 g/L and correlated with disease duration. Overall, 74% of patients had elevated CSF total protein levels using the conventional URL, as opposed to 52% applying the age-dependent URL. At 0-3, 4-7, 8-14 and >14 days after disease onset, elevated CSF total protein was found in 46%, 84%, 78% and 100% of patients using the conventional URL, and in 32%, 53%, 65% and 64% of patients using the age-dependent URL. In multivariate analysis, significant predictors of elevated CSF total protein were disease duration and the demyelinating GBS variant. Similar results were obtained for CSF/serum albumin quotient (Qalb ). CONCLUSION: Fewer true-positives for CSF total protein and Qalb must be considered in suspected GBS, especially in the early disease course.

Peripapillary retinal nerve fibre layer as measured by optical coherence tomography is a prognostic biomarker not only for physical but also for cognitive disability progression in multiple sclerosis.

BACKGROUND: Peripapillary retinal nerve fibre layer (pRNFL) thickness is emerging as a marker of axonal degeneration in multiple sclerosis (MS). OBJECTIVE: We aimed to prospectively assess the predictive value of pRNFL for progression of physical and cognitive disability in relapsing-remitting MS (RRMS). METHODS: In this 3-year longitudinal study on 151 RRMS patients, pRNFL was measured by spectral-domain optical coherence tomography (OCT). We used proportional hazard models, correcting for age, sex, disease duration, Expanded Disability Status Scale (EDSS) and Symbol Digit Modalities Test (SDMT) at baseline, to test a pRNFL thickness ≤88 µm at baseline for prediction of EDSS progression and cognitive decline. We also evaluated the decrease in pRNFL thickness from baseline to year 3 in a multivariate linear regression model. RESULTS: pRNFL thickness ≤88 µm was independently associated with a threefold increased risk of EDSS progression ( p < 0.001) and a 2.7-fold increased risk of cognitive decline within the subsequent 3 years ( p < 0.001). Mean pRNFL delta was -5.3 µm (SD, 4.2). It was significantly negatively impacted by EDSS progression, cognitive decline, higher age and disease duration, while positively impacted by disease-modifying therapy (DMT). CONCLUSION: Cross-sectional and longitudinal monitoring of pRNFL is useful as a biomarker for prediction of physical and cognitive disability progression in patients with RRMS in everyday clinical practice.

Change of olfactory function as a marker of inflammatory activity and disability progression in MS.

BACKGROUND: Impaired olfactory threshold has been reported in early inflammatory phases of MS, while impaired odor identification was associated with more widespread disability. OBJECTIVE: To prospectively assess the development of olfactory function and its correlation with relapse and disability progression. METHODS: In this prospective, 3-year longitudinal study on 151 MS patients and 30 healthy controls, three different qualities of olfactory function (threshold, discrimination, and identification) were quantified using the Sniffin' Sticks test. The influence of relapses and disability on olfactory function was analyzed at different time points and in a multivariate model. RESULTS: Discrimination and identification capability significantly worsened over 3 years, while threshold did not. Threshold was markedly impaired in patients with relapse activity within 12 months, recovered in the absence of relapse, and was associated with a 2.5-fold increased risk of relapse. Deterioration of discrimination and identification was irreversible and both strongly associated with and predictive of EDSS progression. CONCLUSION: Olfactory function changes over time in MS. Threshold impairment is transient and predicts inflammatory disease activity, while odor identification and discrimination are associated with disability progression. Olfactory dysfunction might be a useful and easily obtainable parameter to monitor patients with regard to inflammation and neurodegeneration in MS.

Expanding the occupational health methodology: A concatenated artificial neural network approach to model the burnout process in Chinese nurses.

Artificial neural networks are sophisticated modelling and prediction tools capable of extracting complex, non-linear relationships between predictor (input) and predicted (output) variables. This study explores this capacity by modelling non-linearities in the hardiness-modulated burnout process with a neural network. Specifically, two multi-layer feed-forward artificial neural networks are concatenated in an attempt to model the composite non-linear burnout process. Sensitivity analysis, a Monte Carlo-based global simulation technique, is then utilised to examine the first-order effects of the predictor variables on the burnout sub-dimensions and consequences. Results show that (1) this concatenated artificial neural network approach is feasible to model the burnout process, (2) sensitivity analysis is a prolific method to study the relative importance of predictor variables and (3) the relationships among variables involved in the development of burnout and its consequences are to different degrees non-linear. PRACTITIONER SUMMARY: Many relationships among variables (e.g., stressors and strains) are not linear, yet researchers use linear methods such as Pearson correlation or linear regression to analyse these relationships. Artificial neural network analysis is an innovative method to analyse non-linear relationships and in combination with sensitivity analysis superior to linear methods.

Transient impairment of olfactory threshold in acute multiple sclerosis relapse.

BACKGROUND: Impairment of olfactory threshold is a feature of early and active relapsing remitting multiple sclerosis (RRMS). It predicts inflammatory disease activity and was reported to be transient. However, the timing of onset and resolve of olfactory threshold impairment remains unclear. OBJECTIVE: To prospectively assess the development of olfactory threshold in acute MS relapse over time in comparison to stable MS patients. METHODS: In a prospective observational design, we measured olfactory threshold by performing the Sniffin' Sticks test (minimum score 0, maximum score 16 reflecting optimal olfactory function) at baseline and after 4, 12 and 24 weeks. We included 30 RRMS patients with acute MS relapse and 30 clinically stable RRMS patients (defined as no relapse within the last 12 months) as a control group. RESULTS: Olfactory threshold was impaired in patients with acute MS relapse at baseline (median difference = -3.5; inter-quartile range [IQR] -4.5- - 2.5; p < 0.001), week 4 (-2.5; IQR -3.0 - -2.0; p < 0.001), week 12 (-1.5; IQR -2.0 - -0.5; p = 0.002) and week 24 (-0.5; IQR -1.0 - 0.0; p = 0.159) compared to stable MS patients. Of note, in relapsing patients in whom disease-modifying treatment was initiated or escalated after relapse, threshold did not differ anymore from stable patients at week 12 (-0.5; IQR -1.0 - 0.5; p = 0.247) and week 24 (0.0; IQR -1.0 - 1.0; p = 0.753). CONCLUSIONS: Olfactory threshold impairment seems to be a transient bystander feature of MS relapse. It may be correlated to the level of inflammation within the CNS and might be a useful biomarker in this regard.