BackgroundCerebrospinal fluid (CSF) kappa free light chain (κFLC) measures gained increasing interest as diagnostic markers in multiple sclerosis (MS). However, the lack of studies comparing assay-dependent diagnostic cutoff values hinders their use in clinical practice. Additionally, the optimal κFLC parameter for identifying MS remains a subject of ongoing debate.ObjectivesThe aim of this study was to compare same-sample diagnostic accuracies of the κFLC index, κIgG index, CSF κFLC/IgG ratio, and isolated CSF κFLC (iCSF-κFLC) between two reference centers using different methods.MethodsPaired serum and CSF samples were analyzed for κFLC and albumin concentrations by Freelite®-Optilite (Sint-Jan Bruges hospital) and N Latex®-BNII (Ghent University hospital). Diagnostic performance to differentiate MS from controls was assessed using ROC curve analysis.ResultsA total of 263 participants were included (MS, n = 80). Optimal diagnostic cutoff values for the κFLC index (Freelite®-Optilite: 7.7; N Latex®-BNII: 4.71), κIgG index (Freelite®-Optilite: 14.15, N Latex®-BNII: 12.19), and CSF κFLC/IgG ratio (Freelite®-Optilite: 2.27; N Latex®-BNII: 1.44) differed between the two methods. Sensitivities related to optimal cutoff values were 89.9% (Freelite®-Optilite) versus 94.6% (N Latex®-BNII) for the κFLC index, 91% (Freelite®-Optilite) versus 92.2% (N Latex®-BNII) for the κIgG index, and 81.3% (Freelite®-Optilite) versus 91.4% (N Latex®-BNII) for the CSF κFLC/IgG ratio. However, for iCSF-κFLC, optimal diagnostic cutoff values (0.36 mg/L) and related specificities (81.8%) were identical with a related diagnostic sensitivity of 89.9% for Freelite®-Optilite and 90.5% for N Latex®-BNII. The diagnostic performance of the κFLC index [area under the curve (AUC) Freelite®-Optilite: 0.924; N Latex®-BNII: 0.962] and κIgG index (AUC Freelite®-Optilite: 0.929; N Latex®-BNII: 0.961) was superior compared to CSF oligoclonal bands (AUC: 0.898, sensitivity: 83.8%, specificity: 95.9%).ConclusionsThe κFLC index and the κIgG index seem to be excellent markers for identifying MS, irrespective of the method used for κFLC quantification. Based on the AUC, they appear to be the measures of choice. For all measures, optimal cutoff values differed between methods except for iCSF-κFLC. iCSF-κFLC might therefore serve as a method-independent, more cost-efficient, initial screening measure for MS. These findings are particularly relevant for clinical practice given the potential future implementation of intrathecal κFLC synthesis in MS diagnostic criteria and for future multicentre studies pooling data on κFLC measures.

Background Disability progression is a key milestone in the disease evolution of people with multiple sclerosis (PwMS). Prediction models of the probability of disability progression have not yet reached the level of trust needed to be adopted in the clinic. A common benchmark to assess model development in multiple sclerosis is also currently lacking. Methods Data of adult PwMS with a follow-up of at least three years from 146 MS centers, spread over 40 countries and collected by the MSBase consortium was used. With basic inclusion criteria for quality requirements, it represents a total of 15, 240 PwMS. External validation was performed and repeated five times to assess the significance of the results. Transparent Reporting for Individual Prognosis Or Diagnosis (TRIPOD) guidelines were followed. Confirmed disability progression after two years was predicted, with a confirmation window of six months. Only routinely collected variables were used such as the expanded disability status scale, treatment, relapse information, and MS course. To learn the probability of disability progression, state-of-the-art machine learning models were investigated. The discrimination performance of the models is evaluated with the area under the receiver operator curve (ROC-AUC) and under the precision recall curve (AUC-PR), and their calibration via the Brier score and the expected calibration error. All our preprocessing and model code are available at https://gitlab.com/edebrouwer/ms_benchmark, making this task an ideal benchmark for predicting disability progression in MS. Findings Machine learning models achieved a ROC-AUC of 0⋅71 ± 0⋅01, an AUC-PR of 0⋅26 ± 0⋅02, a Brier score of 0⋅1 ± 0⋅01 and an expected calibration error of 0⋅07 ± 0⋅04. The history of disability progression was identified as being more predictive for future disability progression than the treatment or relapses history. Conclusions Good discrimination and calibration performance on an external validation set is achieved, using only routinely collected variables. This suggests machine-learning models can reliably inform clinicians about the future occurrence of progression and are mature for a clinical impact study.

BackgroundIt remains unclear whether routine cerebrospinal fluid (CSF) parameters can serve as predictors of multiple sclerosis (MS) disease course.MethodsThis large-scale cohort study included persons with MS with CSF data documented in the MSBase registry. CSF parameters to predict time to reach confirmed Expanded Disability Status Scale (EDSS) scores 4, 6 and 7 and annualised relapse rate in the first 2 years after diagnosis (ARR2) were assessed using (cox) regression analysis.ResultsIn total, 11 245 participants were included of which 93.7% (n=10 533) were persons with relapsing-remitting MS (RRMS). In RRMS, the presence of CSF oligoclonal bands (OCBs) was associated with shorter time to disability milestones EDSS 4 (adjusted HR=1.272 (95% CI, 1.089 to 1.485), p=0.002), EDSS 6 (HR=1.314 (95% CI, 1.062 to 1.626), p=0.012) and EDSS 7 (HR=1.686 (95% CI, 1.111 to 2.558), p=0.014). On the other hand, the presence of CSF pleocytosis (≥5 cells/µL) increased time to moderate disability (EDSS 4) in RRMS (HR=0.774 (95% CI, 0.632 to 0.948), p=0.013). None of the CSF variables were associated with time to disability milestones in persons with primary progressive MS (PPMS). The presence of CSF pleocytosis increased ARR2 in RRMS (adjusted R2=0.036, p=0.015).ConclusionsIn RRMS, the presence of CSF OCBs predicts shorter time to disability milestones, whereas CSF pleocytosis could be protective. This could however not be found in PPMS. CSF pleocytosis is associated with short-term inflammatory disease activity in RRMS. CSF analysis provides prognostic information which could aid in clinical and therapeutic decision-making.

PurposeTo characterize vestibulocochlear involvement in patients with Susac syndrome (SuS), a rare immune-mediated endotheliopathy of cerebral, retinal and inner ear microvasculature causing a triad of encephalopathy, branch retinal artery occlusions and sensorineural hearing loss.MethodsThe electronic patient files of 21 patients with SuS are reviewed for data on demography, clinical presentation, disease course and audiovestibular testing.ResultsAll 21 patients experienced some form of audiovestibular complaints during the disease course, with vertigo and instability being most frequently reported, followed by hearing loss, tinnitus and aural fullness. These audiovestibular symptoms did not always coincide. Fifteen patients had objectified predominant low- to midfrequency sensorineural hearing loss and 8 out of 18 patients showed abnormalities on vestibular testing, most frequently vestibular evoked myogenic potential-abnormalities, indicating otolith dysfunction. Treatment protocols consisted of uniformly extensive immunosuppressive therapy and hearing loss remained mostly mild.ConclusionAudiovestibular involvement is very common in patients with SuS. Characteristic findings include a "reverse-slope" configuration on audiological testing and otolith dysfunction on vestibular testing. Aggressive immunosuppression may prevent severe audiovestibular dysfunction. Symptoms as aural fullness and otolith dysfunction may indicate an underlying hydrops. Further investigations are necessary to elucidate the histopathological mechanisms underlying these preferentially involved cochleovestibular areas. Early recognition and treatment of SuS are important to stabilize or decrease disease activity and might also have beneficial effects on inner ear outcome.The submitted manuscript reports data derived from clinical observations in humansConsent for the research was provided by the Ethics Committee of Ghent University hospital (application number 2019/1443, registration date 31/12/2021, principal investigator Guy Laureys).

BACKGROUND AND PURPOSE:Susac syndrome (SuS) is a rare, autoimmune, neurological disease characterized by a clinical triad of branch retinal artery occlusion, sensorineural hearing loss and encephalopathy. Neuropsychological functioning in SuS is little researched and the prevalence, nature, and evolution over time of cognitive deficits in SuS remain unclear. This study aimed to better understand the long-term neuropsychological outcomes of patients with SuS. METHODS:Thirteen patients with SuS (mean [SD] age 39.5 [11.1] years) were enrolled at the Ghent University Hospital by their treating neurologist. The cognitive functioning and emotional well-being of each patient was evaluated by means of a thorough neuropsychological test battery at baseline and after 2 years. Follow-up testing after 2 years was performed in 11 patients (mean [SD] age 42.2 [11.5] years). RESULTS:Patients showed normal neuropsychological test results at a group level, both at baseline and follow-up testing. Significant improvements over time were found for information processing speed, verbal recognition, and semantic and phonological fluency. Individual test results showed interindividual variability at baseline, with most impairments being in attention, executive functioning and language, which improved after a 2-year period. In addition, patients reported significantly lower mental and physical well-being, both at baseline and follow-up testing. CONCLUSIONS:Our results suggest that neuropsychological dysfunction in SuS is limited at a group level and improves over time. Nonetheless, individual test results reveal interindividual variability, making cognitive screening essential. Furthermore, a high psycho-emotional burden of the disease was reported, for which screening and follow-up are necessary.

Susac syndrome (SuS) is a rare immune-mediated endotheliopathy that affects the brain, retina and inner ear and is characterised by the variable clinical triad of encephalopathy, visual and vestibulocochlear dysfunction. Here, we present clinical and paraclinical data of 19 SuS patients followed at Ghent University Hospital and highlight some atypical clinical and novel radiological findings. Our findings suggest that spinal involvement expands the clinical phenotype of SuS. We further introduce dark blood sequences as a more sensitive technique to detect radiological disease activity in SuS. Our data add to the current understanding of the diagnosis, monitoring and treatment of SuS.

A 49-year-old patient with a history of lymphoproliferation and autoimmune cytopenias presented with unexplained longitudinal extensive transverse myelitis. Flow cytometry on peripheral blood showed an elevated level of double negative T lymphocytes, a finding typical for autoimmune lymphoproliferative syndrome (ALPS). Inborn error of immunity (IEI) gene panel demonstrated a heterozygous variant in the FAS gene (c.857G > A, p. (Gly286Glu)), formally confirming the diagnosis. Autoimmune neurological conditions in a context of predisposition for infection and lymphoproliferation should raise suspicion of IEI. Specific testing for ALPS should be considered in patients with a history of non-malignant lymphoproliferation, multilineage cytopenias and unexplained autoimmune (neurological) manifestations.

BACKGROUND:Many natalizumab treated patients experience end of dose interval (EDI) symptoms towards the end of the administration cycle. Natalizumab has previously shown to influence cytokine profiles in relapsing remitting MS patients. We hypothesize that EDI symptoms might be explained by variability in serum cytokine levels during natalizumab treatment.METHODS:42 relapsing remitting MS patients were included. Participants were evaluated before natalizumab administration (day 0) and 7 days afterwards (day 7). At both time points fatigue, depressed mood and cognition were evaluated using the fatigue severity scale (FSS), the visual analogue scale for fatigue (VAS-F), the symbol digit modality test (SDMT) and the inventory for depressive symptomatology (IDS-SR). Serum samples were tested for concentrations of IL-6, IFN-γ and TNF-α at both timepoints. On day 7 an additional EDI questionnaire was completed. Data were analyzed with SPSS by means of non-parametric tests.RESULTS:EDI symptoms were reported by 59.5%. Although fatigue was most frequently reported, fatigue scales did not significantly change from day 0 to 7 in (fatigued) EDI patients. Mood and cognition significantly ameliorated in both EDI and non-EDI patients. Cytokines remained stable at day 0 vs 7 except for a significant increase in IFN-γ. On day 0, IFN-γ concentration was positively correlated with a depressed mood in the whole cohort, and with mood and fatigue in the EDI group. Depressed mood positively whilst cognition negatively correlated with IFN-γ concentration on day 0 in the EDI subgroup reporting fatigue. No significant correlations between IL-6 nor TNF-α and symptom scores could be found.CONCLUSION:In our study EDI symptoms could not be objectified since EDI and non-EDI groups did not differ in terms of change in mood, cognition and fatigue between day 0 and 7 suggesting that symptom recrudescence could be a subjective experience. Although our results need to be interpreted cautiously, we found no clear correlation between studied serum cytokines concentrations and the occurrence of EDI symptoms.

Introduction: Repetitive transcranial magnetic stimulation (rTMS) is an established non-invasive neurostimulation technique that is able to induce neuromodulatory effects outlasting the duration of the stimulation train. The cortical excitability disturbance in epilepsy provides a rationale for investigating the efficacy of low-frequency rTMS as a treatment for epilepsy patients. Sofar clinical trials in epilepsy patients have shown conflicting results ranging from ineffective to very effective.Areas covered: This manuscript provides an overview of the performed studies, retrieved from a PubMed search, and a critical appraisal of their results. A number of conclusions are drawn and potential optimization strategies are discussed.Expert commentary: Although the therapeutic efficacy of rTMS in refractory epilepsy has not yet been established, the non-invasiveness of the technique warrants further investigation of rTMS as a treatment for epilepsy.