Understanding progressive multifocal leukoencephalopathy: links between milky-way appearance and mismatch T2/FLAIR.

BACKGROUND: Magnetic resonance imaging is essential to diagnose progressive multifocal leukoencephalopathy. The broad radiological spectrum may partially be explained by genetic viral mutations and their differential neurotropism. Recent pharmacovigilance-magnetic resonance imaging studies have provided new insight into pathophysiology and radiological markers of early stages. However, how lesions evolve and why certain anatomical locations are more frequently affected remains unknown. We aim to describe a new sign - T2/fluid-attenutated inversion recovery mismatch - as a complementary marker of cavitated lesions and propose a link with the milky-way appearance, a key early sign. Furthermore, we hypothesise viral dissemination routes. METHODS: We conducted a retrospective longitudinal study from January 2010 to January 2020, to analyse clinical and magnetic resonance imaging features of 13 progressive multifocal leukoencephalopathy individuals at the symptomatic stage (mean age 58.3 years (SD ± 16.8) - 61.5% were women). RESULTS: The most prevalent pathology was HIV (61.5%) and motor deficit prevailed regarding other symptoms (76.9%). Frontal lobes (76.9%), middle cerebellar peduncle (61.5%), cerebellum (61.5%), and pons (53.8%) were most commonly affected, and the cortico-ponto-cerebellar pathway seemed involved in these patients. Five patients had a pure radiological pattern. Milky-way appearance was the most frequent radiological sign (58.3%). Five patients with milky-way appearance had concomitantly T2/fluid-attenuated inversion recovery mismatch (P = 0.02). This sign showed high sensitivity and specificity (100-71%, P = 0.02) to assess evolved lesions besides diffusion. CONCLUSION: The possible tract-dependent spread, as well as clinical and genetic, have implications on the MRI variability of progressive multifocal leukoencephalopathy. The milky-way appearance could reflect a transitional phase towards evolved lesions, the latter demonstrated by T2/fluid-attenuated inversion recovery mismatch. Both could be key magnetic resonance imaging signs to diagnose progressive multifocal leukoencephalopathy at the symptomatic stage.

Access and unmet needs to multiple sclerosis care in a cohort of Argentinean patients.

BACKGROUND: Multiple sclerosis (MS) has a low prevalence in Argentina. However, MS has a high burden of disease, which implies frequent neurological visits, magnetic resonance images (MRI) use and chronic MS medication during follow-up, with a high impact on the healthcare system. Therefore, MS care is essential to optimize disease management and improve patients' outcome. We aimed to evaluate the access and barriers to MS care and identified differences in treatment and management of MS patients over a period of 12 months in an Argentinean cohort. METHODS: A cross-sectional study based on a self-administered survey was carried out from August to December 2017 in 13 provinces from Argentina. MS patients (n = 219) were divided into three groups as follows: prepaid health insurance (PHI), social health insurance (SHI) and state-run health insurance (SRHI, Public Health Ministry) and they were assessed in order to detect differences in employment, access and barriers to MS care (neurological visit, MRI use and MS medication). RESULTS: A total of 185 (84.5%) MS patients were employed (full-time: 59%), 34 (15.5%) were currently unemployed and 15 (6.8%) retired by MS. In addition, 132 had SHI, 45 PHI and 40 SRHI. No statistical differences were found in disease severity, frequency of neurological visit, waiting time for neurological visit as well as frequency and waiting time for MRI use. MS patients with SRHI experienced a longer waiting time (first prescription and during follow-up) and inappropriate delivery of MS medication during follow-up compared to MS patients with PHI and SHI. A total of 8/45 (17.7%) in PHI, 17/40 (42.5%) in SRHI and 25/132 (18.9%) in SHI did not receive the MS medication as properly as prescribed for their neurologists. PHI was independently associated with appropriate delivery of MS medication (OR = 0.81, p = 0.01). CONCLUSION: This study showed that MS patients had access barriers to receive MS medication properly, especially those with SRHI (public sector).

Migraine triggers and habituation of visual evoked potentials.

Background Identifying specific subsets of patients within the clinical spectrum of migraine could help in personalizing migraine treatment. Profiling patients by combining clinical characteristics and neurophysiological biomarkers is largely unexplored. We studied the association between migraine attack triggers and habituation of visual evoked potentials. Methods We personally interviewed 25 patients about their migraine triggers following a structured list, and measured the N1-P1 habituation slope over six blocks of 100 averaged pattern-reversal VEP afterwards. Results The mean number of triggers per patient was 4.52 ± 1.42. Habituation slopes differed significantly between subjects who reported stress as a migraine trigger (deficient VEP habituation) and subjects who did not (preserved VEP habituation). For the remaining categories, the mean amplitude slope was always positive, indicating deficient habituation, and was not significantly different between subgroups. Conclusions Migraine patients not reporting perceived stress as a trigger for their attacks might constitute a distinct clinic-physiological subset within the migraine spectrum.

Familial history of migraine influences habituation of visual evoked potentials.

Background Lack of habituation of visual evoked potentials (VEP) is a common finding in migraine patients between attacks. Previous studies have suggested an electrophysiological familial aggregation pattern associated with migraine. The aim of this study was to evaluate the influence of a positive familial history of migraine on VEP amplitude and habituation. Methods We recorded six blocks of 100 VEP during continuous pattern-reversal stimulation in 30 patients with migraine between attacks (MO) and in 30 healthy volunteers, of whom 15 had a first-degree relative suffering from migraine (HVm) and 15 had not (HV). Results Both MO and HVm had a significant deficit of VEP habituation and similarly reduced N1-P1 first block amplitudes, compared to HV (habituation slope: MO = 0.033, HVm = 0.021, HV = -0.025, HV vs. MO p = 0.002, HV vs. HVm p = 0.036; mean N1-P1 amplitude in the first block: MO = 9.08 µV, HVm = 9.29 µV, HV = 12.19 µV. HV vs. MO p = 0.041, HV vs. HVm p = 0.076). The first block N1-P1 amplitude was negatively correlated with the habituation slope for both MO (ρ = -.44, p = 0.015) and HVm (ρ = -.56, p = 0.031) while no significant correlation was found in HV (ρ = .17, p = 0.53). There were no differences in VEP latencies between the groups. Conclusions Our study suggests that lack of habituation of visual evoked potentials is probably a genetically determined endophenotypic trait that is associated with both migraine and migraine susceptibility. We hypothesize that genetic diversity of populations could account for some of the discrepancies between electrophysiological studies performed in migraine and for interindividual variations among the subgroups.