The latest medical research on Neurology

Misfolded α-synuclein can be detected in blood samples of Parkinson's disease (PD) patients by a seed amplification assay (SAA), but the association with disease duration is not clear, yet.

In the present study we aimed to elucidate whether seeding activity of misfolded α-synuclein derived from neuronal exosomes in blood is associated with PD diagnosis and disease duration.

Cross-sectional samples of PD patients were analyzed and compared to samples of age- and gender-matched healthy controls using a blood-based SAA. Presence of α-synuclein seeding activity and differences in seeding parameters, including fluorescence response (in arbitrary units) at the end of the amplification assay (F60) were analyzed. Additionally, available PD samples collected longitudinally over 5-9 years were included.

In the cross-sectional dataset, 79 of 80 PD patients (mean age 69 years, SD = 8; 56% male) and none of the healthy controls (n = 20, mean age 70 years, SD = 10; 55% male) showed seeding activity (sensitivity 98.8%). When comparing subgroups divided by disease duration, longer disease duration was associated with lower α-synuclein seeding activity (F60: p <  0.001). In the longitudinal analysis 10/11 patients showed a gradual decrease of α-synuclein seeding activity over time.

This study confirms the high sensitivity of the blood-based α-synuclein SAA applied here. The negative association of α-synuclein seeding activity in blood with disease duration makes this parameter potentially interesting as biomarker for future studies on the pathophysiology of disease progression in PD, and for biologically oriented trials in this field.

We developed repetitive ocular vestibular-evoked myogenic potentials (roVEMP) as an electrophysiologic test that allows us to elicit the characteristic decrement of extraocular muscles in patients with ocular myasthenia gravis (OMG). Case-control studies demonstrated that roVEMP reliably differentiates patients with OMG from healthy controls. We now aimed to evaluate the diagnostic accuracy of roVEMP for OMG diagnosis in patients with ptosis and/or diplopia.

This study provides Class I evidence that in patients with diplopia and ptosis, roVEMP alone does not accurately distinguish MG from non-MG disorders.

Following a complete diagnostic work-up, 39 patients (44%) were diagnosed with ocular MG, while 50 patients (56%) had various other neuro-ophthalmologic conditions, but not MG (non-MG). roVEMP yielded 88.2% sensitivity, 30.2% specificity, 50% positive predictive value (PPV), and 76.5% negative predictive value (NPV). For comparison, SFEMG resulted in 75% sensitivity, 56% specificity, 55.1% PPV, and 75.7% NPV. All other diagnostic tests (except for the ice pack test) also yielded significantly higher positive results in patients with MG compared with non-MG.

The study revealed a high sensitivity of 88.2% for roVEMP in OMG, but specificity and PPV were too low to allow for the OMG diagnosis as a single test. Thus, differentiating ocular MG from other neuro-ophthalmologic conditions remains challenging, and the highest diagnostic accuracy is still obtained by a multimodal approach. In this study, roVEMP can complement the diagnostic armamentarium for the diagnosis of MG.

ClinicalTrials.gov: NCT03049956.

The LIBERTY study assessed the efficacy and safety of erenumab in participants with episodic migraine (EM) and 2-4 prior preventive treatment failures. The results have been presented after 3 years of erenumab exposure in its open-label extension phase (OLEP).

Participants completing the 12-week double-blind treatment phase (DBTP) of the LIBERTY study could enter the OLEP and receive 140 mg of erenumab once monthly for 3 years. The main outcomes included the proportion of participants achieving ≥50% reduction in monthly migraine days (MMDs), the mean MMD change from baseline, and tolerability and safety.

Overall, 240/246 (97.6%) participants entered the OLEP and 168/240 (70.0%) completed the study (85/118 continuing erenumab [n = 1 lost during follow-up]; 83/122 switching from placebo [n = 2 lost during follow-up]). In the overall population, 79/151 participants (52.3%) with valid data points achieved ≥50% reduction in MMDs at week 168 (i.e., responders). In the continuous erenumab group, 35/117 participants (29.9%) were ≥50% responders at week 12 of the DBTP and 26/35 (74.3%) remained ≥50% responders in at least half of OLEP visits. Of the 82/117 participants (70.1%) not achieving responder status at week 12 in the continuous erenumab group, 17/82 (20.7%) converted to ≥50% responders in at least half of OLEP visits. Of 103/120 participants (85.8%) not achieving responder status at week 12 in the placebo-erenumab group, 42/103 (40.8%) converted to ≥50% responders in at least half of OLEP visits after switching to erenumab. Overall, the mean (SD) MMD change from baseline showed sustained improvement over 3 years (-4.4 [3.9] days at week 168). The most common treatment-emergent AEs (per 100 person-years) were nasopharyngitis (28.8), influenza (7.5), and back pain (5.8). Overall, 9.6% (3.9 per 100 person-years) and 6.7% (2.7 per 100 person-years) of participants reported events of treatment-emergent hypertension and constipation, respectively. The safety and tolerability profile remained consistent with earlier studies.

Erenumab (140 mg) showed sustained efficacy over 3 years in participants with EM and 2-4 prior preventive treatment failures. No new safety signals were observed.

ClinicalTrials.gov Identifier: NCT03096834.