Neuroaxonal damage in natalizumab-treated MS patients: The role of JCV antibody titres.

BACKGROUND: While John Cunningham virus (JCV) is known to cause neuronal damage in progressive multifocal leukoencephalopathy (PML) among natalizumab-treated MS patients, its association with axonal loss in non-PML conditions remains unclear. METHODS: In a cohort of 128 natalizumab-treated MS patients, serum neurofilament (sNfL) levels and JCV antibody titres were measured. RESULTS: Among 128 patients (mean age = 38.4 years, 71.9% female), 51 (40%) were JCV positive. NfL levels increased by 15.3% for JCV index <0.7 (95% confidence interval [CI] = 0.963-1.381), by 18.6% for index 0.7-1.5 (95% CI = 1.009-1.394) and by 21.1% for index >1.5 (95% CI = 1.040-1.409) compared to JCV negative patients. CONCLUSION: These findings indicate a potential link between JCV burden and neuroaxonal degeneration in natalizumab-treated MS patients.

A wearable device perspective on the standard definitions of disability progression in multiple sclerosis.

INTRODUCTION: Multiple sclerosis (MS) is a leading cause of disability among young adults, but standard clinical scales may not accurately detect subtle changes in disability occurring between visits. This study aims to explore whether wearable device data provides more granular and objective measures of disability progression in MS. METHODS: Remote Assessment of Disease and Relapse in Central Nervous System Disorders (RADAR-CNS) is a longitudinal multicenter observational study in which 400 MS patients have been recruited since June 2018 and prospectively followed up for 24 months. Monitoring of patients included standard clinical visits with assessment of disability through use of the Expanded Disability Status Scale (EDSS), 6-minute walking test (6MWT) and timed 25-foot walk (T25FW), as well as remote monitoring through the use of a Fitbit. RESULTS: Among the 306 patients who completed the study (mean age, 45.6 years; females 67%), confirmed disability progression defined by the EDSS was observed in 74 patients, who had approximately 1392 fewer daily steps than patients without disability progression. However, the decrease in the number of steps experienced over time by patients with EDSS progression and stable patients was not significantly different. Similar results were obtained with disability progression defined by the 6MWT and the T25FW. CONCLUSION: The use of continuous activity monitoring holds great promise as a sensitive and ecologically valid measure of disability progression in MS.

Subclinical anterior optic pathway involvement in early multiple sclerosis and clinically isolated syndromes.

Optical coherence tomography (OCT) is gaining increasing relevance in the assessment of patients with multiple sclerosis. Converging evidence point to the view that neuro-retinal changes, in eyes without acute optic neuritis, reflect inflammatory and neurodegenerative processes taking place throughout the CNS. The present study aims at exploring the usefulness of OCT as a marker of inflammation and disease burden in the earliest phases of the disease. Thus, a cohort of 150 consecutive patients underwent clinical, neurophysiological and brain MRI assessment as well as lumbar puncture as part of their diagnostic workup for a neurological episode suggestive of inflammatory CNS disorder; among those 32 patients had another previous misdiagnosed episode. For the present study, patients also received a visual pathway assessment (OCT, visual evoked potentials, visual acuity), measurement of CSF inflammatory markers (17 cytokines-chemokines, extracellular vesicles of myeloid origin), and dosage of plasma neurofilaments. Subclinical optic nerve involvement is frequently found in clinically isolated syndromes by visual evoked potentials (19.2%). OCT reveals ganglion cell layer asymmetries in 6.8% of patients; retinal fibre layer asymmetries, despite being more frequent (17.8%), display poor specificity. The presence of subclinical involvement is associated with a greater disease burden. Second, ganglion cell layer thinning reflects the severity of disease involvement even beyond the anterior optic pathway. In fact, the ganglion cell layer in eyes without evidence of subclinical optic involvement is correlated with Expanded Disability Status Scale, low contrast visual acuity, disease duration, brain lesion load, presence of gadolinium enhancing lesions, abnormalities along motor and somatosensory evoked potentials, and frequency of CSF-specific oligoclonal bands. Third, the inner nuclear layer thickens in a post-acute (1.1-3.7 months) phase after a relapse, and this phenomenon is counteracted by steroid treatment. Likewise, a longitudinal analysis on 65 patients shows that this swelling is transient and returns to normal values after 1 year follow-up. Notwithstanding, the clinical, MRI, serological and CSF markers of disease activity considered in the study are strictly associated with one another, but none of them are associated with the inner nuclear layer. Our findings challenge the current hypothesis that the inner nuclear layer is an acute phase marker of inflammatory activity. The present study suggests that instrumental evidence of subclinical optic nerve involvement is associated with a greater disease burden in clinically isolated syndrome. Neuro-retinal changes are present since the earliest phases of the disease and yield important information regarding the neurodegenerative and inflammatory processes occurring in the CNS.

CSF extracellular vesicles and risk of disease activity after a first demyelinating event.

BACKGROUND: Extracellular vesicles (EVs), a recently described mechanism of cell communication, are released from activated microglial cells and macrophages and are a candidate biomarker in diseases characterized by chronic inflammatory process such as multiple sclerosis (MS). METHODS: We explored cerebrospinal fluid extracellular vesicle (CSF EV) of myeloid origin (MEVs), cytokine and chemokine levels in patients with clinically isolated syndrome (CIS). RESULTS: We found that CSF MEVs were significantly higher in CIS patients than in controls and were inversely correlated to CSF CCL2 levels. MEVs level were significantly associated with an shorter time to evidence of disease activity (hazard ratio: 1.01, 95% confidence interval: 1.00-1.02, p < 0.01) independently from other known prognostic markers. CONCLUSION: After a first demyelinating event, CSF EVs may improve risk stratification of these patients and allow more targeted intervention strategies.

Intracortical motor conduction is associated with hand dexterity in progressive multiple sclerosis.

BACKGROUND: Hand dexterity dysfunction is a key feature of disability in people with progressive multiple sclerosis (PMS). It underlies corticospinal tract (CST) and cerebellar integrity, as well as disruption of cortical networks, which are hardly assessed by standard techniques. Transcranial magnetic stimulation is a promising tool for evaluating the integrity of intracortical motor pathways. OBJECTIVE: To investigate neurophysiological correlates of motor hand impairment in PMS. METHODS: Antero-posterior (AP) stimulation of the primary motor cortex activates the CST indirectly through polysynaptic pathways, while a direct CST activation occurs with latero-medial (LM) directed current. Thirty PMS and 15 healthy controls underwent dominant hand motor evoked potentials (MEP) using AP and LM-directed stimulation, and a clinical assessment of dexterity (nine-hole peg test) and strength (MRC scale, grip and pinch). RESULTS: PMS with AP-LM latency difference 2.5 standard deviation above the mean of controls (33%) showed worse dexterity but no difference in upper limb strength. Accordingly, AP-LM latency shortening predicted dexterity (R2 = 0.538, p < 0.001), but not strength impairment. On the contrary, absolute MEP latencies only correlated with strength (grip: R2 = 0.381, p = 0.014; MRC: R2 = 0.184, p = 0.041). CONCLUSION: AP-LM latency shortening may be used to assess the integrity polysynaptic intracortical networks implicated in dexterity impairment.

Serum neurofilaments increase at progressive multifocal leukoencephalopathy onset in natalizumab-treated multiple sclerosis patients.

This study analyzed serum neurofilament light chains (NfL) in 2 European cohorts of 312 multiple sclerosis (MS) patients to investigate whether NfL are biomarkers of progressive multifocal leukoencephalopathy (PML) during natalizumab treatment. The cohort comprised 25 PML, 136 natalizumab-treated, and 151 untreated MS patients. Patients subsequently developing PML had similar NfL to other natalizumab-treated MS patients. At PML onset, NfL were 10-fold higher than in the pre-PML condition and in natalizumab-treated or untreated MS patients, and NfL continued to increase until onset of immune reconstitution inflammatory syndrome. The results suggest that in natalizumab-treated patients, NfL may represent an early and accessible marker of PML. Ann Neurol 2019;85:606-610.

Real-time assessment of COVID-19 prevalence among multiple sclerosis patients: a multicenter European study.

We assessed the prevalence and impact of COVID-19 among multiple sclerosis (MS) patients across Europe by leveraging participant data collected as part of the ongoing EU IMI2 RADAR-CNS major programme aimed at finding new ways of monitoring neurological disorders using wearable devices and smartphone technology. In the present study, 399 patients of RADAR-MS have been included (mean age 43.9 years, 60.7% females) with 87/399 patients (21.8%) reporting major symptoms suggestive of COVID-19. A trend for an increased risk of COVID-19 symptoms under alemtuzumab and cladribine treatments in comparison to injectables was observed. Remote monitoring technologies may support health authorities in monitoring and containing the ongoing pandemic.

Using Smartphones and Wearable Devices to Monitor Behavioral Changes During COVID-19.

BACKGROUND: In the absence of a vaccine or effective treatment for COVID-19, countries have adopted nonpharmaceutical interventions (NPIs) such as social distancing and full lockdown. An objective and quantitative means of passively monitoring the impact and response of these interventions at a local level is needed. OBJECTIVE: We aim to explore the utility of the recently developed open-source mobile health platform Remote Assessment of Disease and Relapse (RADAR)-base as a toolbox to rapidly test the effect and response to NPIs intended to limit the spread of COVID-19. METHODS: We analyzed data extracted from smartphone and wearable devices, and managed by the RADAR-base from 1062 participants recruited in Italy, Spain, Denmark, the United Kingdom, and the Netherlands. We derived nine features on a daily basis including time spent at home, maximum distance travelled from home, the maximum number of Bluetooth-enabled nearby devices (as a proxy for physical distancing), step count, average heart rate, sleep duration, bedtime, phone unlock duration, and social app use duration. We performed Kruskal-Wallis tests followed by post hoc Dunn tests to assess differences in these features among baseline, prelockdown, and during lockdown periods. We also studied behavioral differences by age, gender, BMI, and educational background. RESULTS: We were able to quantify expected changes in time spent at home, distance travelled, and the number of nearby Bluetooth-enabled devices between prelockdown and during lockdown periods (P<.001 for all five countries). We saw reduced sociality as measured through mobility features and increased virtual sociality through phone use. People were more active on their phones (P<.001 for Italy, Spain, and the United Kingdom), spending more time using social media apps (P<.001 for Italy, Spain, the United Kingdom, and the Netherlands), particularly around major news events. Furthermore, participants had a lower heart rate (P<.001 for Italy and Spain; P=.02 for Denmark), went to bed later (P<.001 for Italy, Spain, the United Kingdom, and the Netherlands), and slept more (P<.001 for Italy, Spain, and the United Kingdom). We also found that young people had longer homestay than older people during the lockdown and fewer daily steps. Although there was no significant difference between the high and low BMI groups in time spent at home, the low BMI group walked more. CONCLUSIONS: RADAR-base, a freely deployable data collection platform leveraging data from wearables and mobile technologies, can be used to rapidly quantify and provide a holistic view of behavioral changes in response to public health interventions as a result of infectious outbreaks such as COVID-19. RADAR-base may be a viable approach to implementing an early warning system for passively assessing the local compliance to interventions in epidemics and pandemics, and could help countries ease out of lockdown.

The Danger of Walking with Socks: Evidence from Kinematic Analysis in People with Progressive Multiple Sclerosis.

Multiple sclerosis (MS) is characterized by gait impairments and severely impacts the quality of life. Technological advances in biomechanics offer objective assessments of gait disabilities in clinical settings. Here we employed wearable sensors to measure electromyography (EMG) and body acceleration during walking and to quantify the altered gait pattern between people with progressive MS (PwPMS) and healthy controls (HCs). Forty consecutive patients attending our department as in-patients were examined together with fifteen healthy controls. All subjects performed the timed 10 min walking test (T10MW) using a wearable accelerator and 8 electrodes attached to bilateral thighs and legs so that body acceleration and EMG activity were recorded. The T10MWs were recorded under three conditions: standard (wearing shoes), reduced grip (wearing socks) and increased cognitive load (backward-counting dual-task). PwPMS showed worse kinematics of gait and increased muscle coactivation than controls at both the thigh and leg levels. Both reduced grip and increased cognitive load caused a reduction in the cadence and velocity of the T10MW, which were correlated with one another. A higher coactivation index at the thigh level of the more affected side was positively correlated with the time of the T10MW (r = 0.5, p < 0.01), Expanded Disability Status Scale (EDSS) (r = 0.4, p < 0.05), and negatively correlated with the cadence (r = -0.6, p < 0.001). Our results suggest that excessive coactivation at the thigh level is the major determinant of the gait performance as the disease progresses. Moreover, demanding walking conditions do not influence gait in controls but deteriorate walking performances in PwPMS, thus those conditions should be prevented during hospital examinations as well as in homecare environments.

Fifteen Years of Wireless Sensors for Balance Assessment in Neurological Disorders.

Balance impairment is a major mechanism behind falling along with environmental hazards. Under physiological conditions, ageing leads to a progressive decline in balance control per se. Moreover, various neurological disorders further increase the risk of falls by deteriorating specific nervous system functions contributing to balance. Over the last 15 years, significant advancements in technology have provided wearable solutions for balance evaluation and the management of postural instability in patients with neurological disorders. This narrative review aims to address the topic of balance and wireless sensors in several neurological disorders, including Alzheimer's disease, Parkinson's disease, multiple sclerosis, stroke, and other neurodegenerative and acute clinical syndromes. The review discusses the physiological and pathophysiological bases of balance in neurological disorders as well as the traditional and innovative instruments currently available for balance assessment. The technical and clinical perspectives of wearable technologies, as well as current challenges in the field of teleneurology, are also examined.

Assessing seasonal dynamics of Guillain-Barré syndrome with search engine query data.

BACKGROUND AND OBJECTIVE: In previous studies, data deriving from Google Trends showed promising correlation with disease incidence trends assessed with public health control systems. The aim of this work is to use search engine query data to investigate seasonal dynamics in Guillain-Barré syndrome (GBS) in the USA. METHODS: Average Google monthly search volumes for GBS from 2008 to 2017 were analysed for the USA overall and on regional base with generalized estimating equation models. Association with monthly historical temperature variations was tested. RESULTS: Monthly search volume for GBS displayed the greatest positive anomaly for October, clustering with September and November. Region-wide analysis confirmed this pattern and showed secondary spring (Feb/Apr) subpeaks in Pacific and Midwest. Association of GBS search volume with month-to-month temperature variations showed J-shaped relationship, with the highest peak occurring in months with greatest temperature falls, and subpeak in months with sharpest temperature rises. CONCLUSIONS: This study represents the first approach in investigating digital epidemiology of GBS and establishing possible links with traditional epidemiology. Cold season GBS peak has been observed by some traditional studies; hypothetical pathogenic relationship with infectious antecedents is supported from finding GBS peaks clustering with greatest temperature change. Further studies are needed to compare these findings to traditional public health approaches.

Assessing the role of innovative therapeutic paradigm on multiple sclerosis treatment response.

OBJECTIVE: Within the last decade, many changes have been made to the management of patients with multiple sclerosis (MS). The aim of our study was to investigate the global impact of all these changes on the disease's course. MATERIALS AND METHODS: This single-centre study was carried out on patients with multiple sclerosis (pwMS) who started treatment with first-line disease-modifying therapies. We have compared three large cohorts of patients with MS diagnosis, for three consecutive periods within July 2001, August 2001-December 2005, and January 2006-September 2011. RESULTS: A total of 1068 relapsing-remitting pwMS cases were included. Patients in the last cohort began treatment earlier (P < 0.0001), started more frequent treatment with high-dose interferon beta or glatiramer acetate (P < 0.0001), and had experienced a more frequent treatment escalation strategy (P = 0.004) than patients in other cohorts. The multivariate analysis adjusted for baseline characteristics showed that pwMS of the last cohort had a high probability of showing no evidence of disease activity (NEDA3) at 4 years (OR 3.22, 95% CIs 1.89-5.47; P < 0.0001). These results were confirmed in a propensity score analysis. CONCLUSIONS: Our study showed an improvement over the last 15 years in the treatment response; this observation can be associated to a paradigm shift in MS treatment strategies.

Disease-modifying treatments modulate myeloid cells in multiple sclerosis patients.

The role of myeloid cells in the pathogenesis of MS is determined by the polarization they acquire after activation, and mediated by release of extracellular vesicles (MVs). We assessed the effects of treatments for MS on activation and polarization of myeloid cells. MVs levels and markers of polarization of myeloid cells have been assessed at baseline and up to 6 months after the start of a MS treatment. Patients had higher levels of MVs than controls, and these increased significantly over 6 months under natalizumab. Interferon ß-1a significantly decreased M1 pro-inflammatory marker IL1ß and upregulated Trem2, a receptor important for debris clearance; both interferon ß-1a and fingolimod decreased pro-inflammatory marker IL6. Current treatments for MS significantly modulate myeloid cells activity.

Serum neurofilament light chain levels are increased in patients with a clinically isolated syndrome.

BACKGROUND: Neurofilament light chain (NfL) represents a promising biomarker for axonal injury. We present the first exploratory study on serum NfL in patients with a clinically isolated syndrome (CIS) and healthy controls. METHODS: We investigated serum NfL levels in 100 patients with CIS with a short conversion interval to clinically definite multiple sclerosis (MS) (fast converters (FC), median (IQR) conversion time: 110 days (79-139)); 98 patients with non-converting CIS (non-converters (NC), follow-up: 6.5 years (5.3-7.9)); and 92 healthy controls. RESULTS: NfL levels were higher in FC (24.1 pg/mL (13.5-51.8)) and NC (19.3 pg/mL (13.6-35.2)) than in healthy controls (7.9 pg/mL (5.6-17.2)) (OR=5.85; 95% CI 2.63 to 13.02; p = 1.5 × 10(-5) and OR = 7.03; 95% CI 2.85 to 17.34; p = 2.3 × 10(-5), respectively). When grouping FC and NC, increased serum NfL concentration was also associated with increasing numbers of T2 hyperintense MRI lesions (OR = 2.36; 95% CI 1.21 to 4.59; p = 0.011), gadolinium-enhancing lesions (OR = 2.69; 95% CI 1.13 to 6.41; p=0.026) and higher disability scores (OR = 2.54; 95% CI 1.21 to 5.31; p = 0.013) at CIS diagnosis. CONCLUSIONS: If replicated in future studies, serum NfL may represent a reliable and easily accessible biomarker of early axonal damage in CIS and MS.

Vitamin D levels and risk of multiple sclerosis in patients with clinically isolated syndromes.

BACKGROUND: Growing evidence suggests that vitamin D deficiency may be one of the most important environmental factors for the development of multiple sclerosis (MS). OBJECTIVES: The objectives of this paper are to evaluate serum 25-hydroxyvitamin D (25(OH)D) levels in patients with clinically isolated syndromes (CIS) and to examine whether they are related to MS risk. METHODS: This is a retrospective study of 100 CIS patients hospitalized from 2000 to 2009 at San Raffaele Hospital, Milan, Italy. We evaluated baseline 25(OH)D level as well as clinical, brain magnetic resonance imaging (MRI) and cerebrospinal fluid (CSF) data. RESULTS: A total of 52% of CIS patients had vitamin D deficiency (25(OH)D < 50 nmol/l). During follow-up (median: 7.17 years), 55 patients developed clinically definite MS (CDMS). Patients with very low (< 10th percentile) and low (< 25th percentile) 25(OH)D levels were particularly at risk of CDMS (HRs (95% CIs): 2.12 (0.91-4.96) and 1.61 (0.85-3.03), respectively), while no further reduction in the HRs of disease was observed at high levels of 25(OH)D. This association was even stronger after adjustment for additional risk factors for CDMS development (HRs (95% CIs) for 25(OH)D levels < 10th and 25th percentiles: 3.34 (1.32-8.45) and 2.04 (0.96-4.36), respectively). CONCLUSION: Low serum vitamin D is associated with increased MS risk in patients with CIS.

Overcoming recruitment challenges in patients with multiple sclerosis: Results from an Italian survey.

BACKGROUND: Recruiting patients for randomized clinical trials is still extremely difficult. While there has been much research in oncology patients, no previous studies have consistently addressed specific factors affecting the willingness to enroll in multiple sclerosis trials from the patient's perspective. To this end, we conducted an exploratory study to assess the related factors and to find ways to improve recruitment. METHODS: This is a single-center, observational study involving 352 consecutive outpatients followed at one site in Italy. Patients completed the Enrollment Problems Questionnaire and Beck Depression Inventory. RESULTS: Over 50% of the patients would consider participating in a randomized trial. Willing patients are frequently older, with no children, have a diagnosis of secondary progressive multiple sclerosis, and have already participated in clinical trials. Patients' choices were positively influenced by expectations of having (a) a greater chance of cure, (b) an unavailable drug, (c) a specialist's care, and (d) the chance to contribute to medical research. Willingness was significantly increased by the use of optimistic language and practical/psychological assistance during the decision-making process. CONCLUSION: Multiple sclerosis patients' willingness to participate in a randomized trial is mainly related to both altruistic and individual considerations, as well as to a greater chance of specialist/improved care. More effective information flow and an effective, long-standing patient-physician relationship may improve recruitment overall.

Optical coherence tomography with voxel-based morphometry: a new tool to unveil focal retinal neurodegeneration in multiple sclerosis.

Neurodegeneration is the main contributor to disability accumulation in multiple sclerosis. Previous studies in neuro-ophthalmology have revealed that neurodegeneration in multiple sclerosis also affects the neuro-retina. Optical coherence tomography has been used to measure thinning of retinal layers, which correlates with several other markers for axonal/neuronal loss in multiple sclerosis. However, the existing analytical tools have limitations in terms of sensitivity and do not provide topographical information. In this study, we aim to evaluate whether voxel-based morphometry can increase sensitivity in detecting neuroaxonal degeneration in the retina and offer topographical information. A total of 131 people with multiple sclerosis (41 clinically isolated syndrome, 53 relapsing-remitting and 37 progressive multiple sclerosis) and 50 healthy subjects were included. Only eyes with normal global peripapillary retinal nerve fibre layer thickness and no history of optic neuritis were considered. Voxel-based morphometry and voxel-wise statistical comparisons were performed on the following: (i) patients at different disease stages and 2) patients who experienced the first demyelination attack without subclinical optic neuritis, assessed by visual evoked potentials. Standard parameters failed to discern any differences; however, voxel-based morphometry-optical coherence tomography successfully detected focal macular atrophy of retinal nerve fibre layer and ganglion cell/inner plexiform layer, along with thickening of inner nuclear layer in patients who experienced the first demyelination attack (disease duration = 4.2 months). Notably, the atrophy pattern of the ganglion cell/inner plexiform layer was comparable across disease phenotypes. In contrast, the retinal nerve fibre layer atrophy spread from the optic nerve head to the fovea as the disease evolved towards the progressive phase. Furthermore, for patients who experienced the first neurological episode, the severity of retinal nerve fibre layer atrophy at entry could predict a second attack. Our results demonstrate that voxel-based morphometry-optical coherence tomography exhibits greater sensitivity than standard parameters in detecting focal retinal atrophy, even at clinical presentation, in eyes with no history of optic neuritis and with normal latency of visual evoked potentials. Thinning of the ganglion cell/inner plexiform layer primarily concentrated in nasal perifovea in all disease phenotypes, indicating selective vulnerability of retinal ganglion cells and their perifoveal axons. Conversely, the degree of retinal nerve fibre layer thinning seems to be related to the clinical course of multiple sclerosis. The findings suggest bidirectional neurodegeneration in the visual pathway. Voxel-based morphometry-optical coherence tomography shows potential as a valuable tool for monitoring neurodegeneration on a patient level and evaluating the efficacy of novel neuroprotective treatments.

Refractory migraine: the role of the physician in assessment and treatment of a problematic disease.

Patients affected by chronic forms of headache are often very difficult to treat. Refractory patients are so defined when adequate trials of specific drugs (for acute or prophylactic treatment) failed both to reduce the burden of disease and to improve headache-related quality of life. An escalating approach is suggested to test different kinds of therapies. All comorbid factors should be addressed. More invasive modalities (such as neurostimulation) or promising approaches such as repetitive transcranial magnetic stimulation (rTMS) could be a future major step as third line therapies.

From neuroimaging to clinical setting: what have we learned from migraine pain?

In the last 15 years, the neuroimaging of patients suffering from migraine with or without aura has improved our understanding of the mechanisms underlying the pathophysiology of the disease. A great number of studies based on modern imaging techniques, such as structural imaging and functional imaging emphasize that in migraine patients suffering from repetitive pain attacks, both significant abnormalities of function and diffuse structural changes of brain white and gray matter become striking features of the disease. The hypothesis that migraine pain is due to a global brain disorder with substantial brainstem involvement leading to secondary blood flow changes in the posterior circulation is reinforced by several elegant studies. Clinical application of functional imaging findings in migraine is yet to be considered, since the specificity of some results has to be determined. Nevertheless, functional MRI techniques have a vast potential for exploring the pathophysiology of pain in migraine patients.