Correlation between blink reflex abnormalities and magnetic resonance imaging findings in patients with multiple sclerosis

Machine learning for exploring neurophysiological functionality in multiple sclerosis based on trigeminal and hand blink reflexes

Brainstem dysfunctions are very common in Multiple Sclerosis (MS) and are a critical predictive factor for future disability. Brainstem functionality can be explored with blink reflexes, subcortical responses consisting in a blink following a peripheral stimulation. Some reflexes are already employed in clinical practice, such as Trigeminal Blink Reflex (TBR). Here we propose for the first time in MS the exploration of Hand Blink Reflex (HBR), which size is modulated by the proximity of the stimulated hand to the face, reflecting the extension of the peripersonal space. The aim of this work is to test whether Machine Learning (ML) techniques could be used in combination with neurophysiological measurements such as TBR and HBR to improve their clinical information and potentially favour the early detection of brainstem dysfunctionality. HBR and TBR were recorded from a group of People with MS (PwMS) with Relapsing-Remitting form and from a healthy control group. Two AdaBoost classifiers were trained with TBR and HBR features each, for a binary classification task between PwMS and Controls. Both classifiers were able to identify PwMS with an accuracy comparable and even higher than clinicians. Our results indicate that ML techniques could represent a tool for clinicians for investigating brainstem functionality in MS. Also, HBR could be promising when applied in clinical practice, providing additional information about the integrity of brainstem circuits potentially favouring early diagnosis.

Nasolacrimal transition time in patients with multiple sclerosis

PURPOSE

To measure the duration of nasolacrimal transition in patients with Multiple Sclerosis (MS), to compare the findings with the healthy population and to investigate the relationship between MS-related disability and nasolacrimal transition time.

METHODS

A total of 73 individuals including 37 patients with relapsing-remitting MS and 36 healthy volunteers were included in the study. In both groups the nasolacrimal transition time was measured using flurosein drops. The degree of disability of MS patients was calculated according to the Expanded Disability Status Scale (EDSS).

RESULTS

There was a significant difference between MS patients and control group in terms of the median value of nasolacrimal transition time in (240 s (min: 85, max: 724) and 58.5 s (min: 21, max: 428), respectively) (p < 0.001). A positive correlation was found between EDSS scores and nasolacrimal transition time of MS patients (r = 0.384, p = 0.019).

CONCLUSION

This study showed that nasolacrimal transition time is prolonged in MS patients and there is a relationship between the degree of MS-related disability and the nasolacrimal transition time. This is the first study in the literature on this subject and the results of our study have the potential to shed light on the causes of common infections in MS patients. Long-term prospective studies are needed to further investigate the relationship between prolonged nasolacrimal transition and infections in MS patients.

Early diagnosis of secondary progressive multiple sclerosis: focus on fluid and neurophysiological biomarkers

BACKGROUND AND AIMS

Most patients with multiple sclerosis presenting with a relapsing-remitting disease course at diagnosis transition to secondary progressive multiple sclerosis (SPMS) 1-2 decades after onset. SPMS is characterized by predominant neurodegeneration and atrophy. These pathogenic hallmarks result in unsatisfactory treatment response in SPMS patients. Therefore, early diagnosis of SPMS is necessary for prompt treatment decisions. The aim of this review was to assess neurophysiological and fluid biomarkers that have the potential to monitor disease progression and support early SPMS diagnosis.

METHODS

We performed a systematic review of studies that analyzed the role of neurophysiological techniques and fluid biomarkers in supporting SPMS diagnosis using the preferred reporting items for systematic reviews and meta-analyses statement.

RESULTS

From our initial search, we selected 24 relevant articles on neurophysiological biomarkers and 55 articles on fluid biomarkers.

CONCLUSION

To date, no neurophysiological or fluid biomarker is sufficiently validated to support the early diagnosis of SPMS. Neurophysiological measurements, including short interval intracortical inhibition and somatosensory temporal discrimination threshold, and the neurofilament light chain fluid biomarker seem to be the most promising. Cross-sectional studies on an adequate number of patients followed by longitudinal studies are needed to confirm the diagnostic and prognostic value of these biomarkers. A combination of neurophysiological and fluid biomarkers may be more sensitive in detecting SPMS conversion.

There is still a role for the blink reflex in the diagnosis and follow-up of multiple sclerosis

OBJECTIVE

The evolution of the diagnostic criteria for multiple sclerosis (MS) has essentially evolved to clinical manifestations and magnetic resonance imaging. Inexpensive, quick to apply, non-invasive, quantitative and reliable neurophysiological tests are rare in daily practice and absent in clinical trials.

METHOD

The blink reflex was assessed in 50 patients with remitting-relapsing MS (RRMS) and 100 matched controls.

RESULTS

Patients with RRMS had abnormalities in the blink reflex waves in relation to controls. If only RRMS patients were considered, these abnormalities were more pronounced in patients with longer disease duration, higher disability and for those with clinical or image lesions in the brainstem.

CONCLUSION

Neurophysiological tests, such as the blink reflex, can be used for helping the diagnosis and follow-up of patients with RRMS, since the reflex can identify dissemination in time and in space in a clear and quantitative manner.

SIGNIFICANCE

Potential good methods for diagnosis and follow-up of MS should be considered for clinical trials and daily practice.

Abnormal control of orbicularis oculi reflex excitability in multiple sclerosis

Brain lesions in patients with multiple sclerosis may lead to abnormal excitability of brainstem reflex circuits because of impairment of descending control pathways. We hypothesized that such abnormality should show in the analysis of blink reflex responses in the form of asymmetries in response size. The study was done in 20 patients with relapsing-remitting multiple sclerosis and 12 matched healthy subjects. We identified first patients with latency abnormalities (AbLat). Then, we analyzed response size by calculating the R2c/R2 ratio to stimulation of either side and the mean area of the R2 responses obtained in the same side. Patients with significantly larger response size with respect to healthy subjects in at least one side were considered to have abnormal response excitability (AbEx). We also examined the blink reflex excitability recovery (BRER) and prepulse inhibition (BRIP) of either side in search for additional indices of asymmetry in response excitability. Neurophysiological data were correlated with MRI-determined brain lesion-load and volume. Eight patients were identified as AbLat (median Expanded Disability Status Scale–EDSS = 2.75) and 7 of them had ponto-medullary lesions. Nine patients were identified as AbEx (EDSS = 1.5) and only 2 of them, who also were AbLat, had ponto-medullary lesions. In AbEx patients, the abnormalities in response size were confined to one side, with a similar tendency in most variables (significantly asymmetric R1 amplitude, BRER index and BRIP percentage). AbEx patients had asymmetric distribution of hemispheral lesions, in contrast with the symmetric pattern observed in AbLat. The brainstem lesion load was significantly lower in AbEx than in AbLat patients (p = 0.04). Asymmetric abnormalities in blink reflex response excitability in patients with multiple sclerosis are associated with lesser disability and lower tissue loss than abnormalities in response latency. Testing response excitability could provide a reliable neurophysiological index of dysfunction in early stages of multiple sclerosis.