Investigating cortical excitability and inhibition in patients with schizophrenia: A TMS-EEG study

BACKGROUND

Transcranial magnetic stimulation (TMS) combined with electromyography (EMG) has widely been used as a non-invasive brain stimulation tool to assess excitation/inhibition (E/I) balance. E/I imbalance is a putative mechanism underlying symptoms in patients with schizophrenia. Combined TMS-electroencephalography (TMS-EEG) provides a detailed examination of cortical excitability to assess the pathophysiology of schizophrenia. This study aimed to investigate differences in TMS-evoked potentials (TEPs), TMS-related spectral perturbations (TRSP) and intertrial coherence (ITC) between patients with schizophrenia and healthy controls.

MATERIALS AND METHODS

TMS was applied over the motor cortex during EEG recording. Differences in TEPs, TRSP and ITC between the patient and healthy subjects were analysed for all electrodes at each time point, by applying multiple independent sample t-tests with a cluster-based permutation analysis to correct for multiple comparisons.

RESULTS

Patients demonstrated significantly reduced amplitudes of early and late TEP components compared to healthy controls. Patients also showed a significant reduction of early delta (50-160 ms) and theta TRSP (30-250ms),followed by a reduction in alpha and beta suppression (220-560 ms; 190-420 ms). Patients showed a reduction of both early (50-110 ms) gamma increase and later (180-230 ms) gamma suppression. Finally, the ITC was significantly lower in patients in the alpha band, from 30 to 260 ms.

CONCLUSION

Our findings support the putative role of impaired GABA-receptor mediated inhibition in schizophrenia impacting excitatory neurotransmission. Further studies can usefully elucidate mechanisms underlying specific symptoms clusters using TMS-EEG biometrics.

CGRP-targeted medication in chronic migraine - systematic review

BACKGROUND

Chronic migraine is a highly debilitating condition that is often difficult to manage, particularly in the presence of medication overuse headache. Drugs targeting the calcitonin gene-related peptide (CGRP), or its receptor have shown promising results in treating this disorder.

METHODS

We searched Pubmed and Embase to identify randomized clinical trials and real-world studies reporting on the use of medication targeting the calcitonin gene-related peptide in patients with chronic migraine.

RESULTS

A total of 270 records were identified. Nineteen studies qualified for the qualitative analysis. Most studies reported on monoclonal antibodies targeting CGRP (anti-CGRP mAbs), that overall prove to be effective in decreasing monthly migraine days by half in about 27.6-61.4% of the patients. Conversion from chronic to episodic migraine was seen in 40.88% of the cases, and 29-88% of the patients stopped medication overuse. Obesity seems to be the main negative predictor of response to anti-CGRP mAbs. There is no evidence to suggest the superiority of one anti-CGRP mAb. Despite the lack of strong evidence, the combination of anti-CGRP medication with onabotulinumtoxinA in chronic migraine is likely to bring benefits for resistant cases. Atogepant is the first gepant to demonstrate a significant decrease in monthly migraine days compared to placebo in a recent trial. Further, anti-CGRP mAb and gepants have a good safety profile.

CONCLUSION

There is strong evidence from randomized trials and real-world data to suggest that drugs targeting CGRP are a safe and effective treatment for chronic migraine.

Health equity, care access and quality in headache - part 2

BACKGROUND

Headache disorders are a global public health concern affecting diverse populations. This review examines headache service organizations in low-, middle-, and high-income countries. It addresses global challenges in pharmacological headache treatment, with a focus on safety, tolerability, reproductive and child health, and outlines disparities in accessing innovative treatments worldwide.

MAIN BODY

Organized headache services are essential due to the wide prevalence and varying severity of headache disorders. The tiered headache service model is globally recognized, although its implementation varies based on financial and workforce considerations. Headache burden affects well-being, causing disability, economic challenges, and work limitations, irrespective of location or income. All nations still require improved diagnosis and treatment, and the majority of countries face obstacles including limited access, awareness, economic barriers, and inadequate health policies. Provided adequate internet availability, telemedicine could help improve health equity by expanding access to headache care, since it can offer patients access to services without lengthy waiting times or extensive travel and can provide healthcare unavailable in underserved areas due to staff shortages. Numerous health disparities restrict global access to many headache medications, especially impacting individuals historically excluded from randomized controlled trials, such as those with cardiovascular and cerebrovascular conditions, as well as pregnant women. Furthermore, despite advancements in researching migraine treatments for young patients, the options for treatment remain limited. Access to headache treatment relies on factors like medication availability, approval, financial coverage, and healthcare provider expertise. Inadequate public awareness leads to neglect by policymakers and undertreatment by patients and healthcare providers. Global access discrepancies are exacerbated by the introduction of novel disease-specific medications, particularly impacting Asian, African, and Latin American nations excluded from clinical trials. While North America and Europe experience broad availability of migraine treatments, the majority of countries worldwide lack access to these therapies.

CONCLUSIONS

Healthcare disparities, treatment access, and medication availability are concerning issues in headache medicine. Variations in national healthcare systems impact headache management, and costly innovative drugs are widening these gaps. Healthcare practitioners and experts should acknowledge these challenges and work towards minimizing access barriers for equitable global headache care in the future.

Placebo and nocebo in the treatment of migraine: How much does real world effectiveness depend on contextual effects?

PURPOSE

Treatments in medicine impact individuals beyond their intended effects, due to phenomena such as the placebo and nocebo effects. The placebo effect arises from the positive expectation of a treatment being beneficial, while the nocebo effect stems from the negative expectation of a treatment causing harm. Both in real-world practice and clinical trials, treatments can lead to outcomes unrelated to their intended mechanism of action, which we categorize as placebo and nocebo responses. These responses, combined with the inherent fluctuation in a condition's natural progression, regression to the mean, and random comorbidities, make up a significant part of the therapeutic experience. Particularly in pain management, placebo and nocebo effects play a substantial role. By addressing modifiable contextual factors such as patient expectations, lifestyle choices, and the therapeutic relationship, healthcare providers can enhance the effectiveness of migraine treatments, paving the way for a more comprehensive, individualized approach to patient care. We must also consider non-modifiable factors like personal experiences, beliefs, and information from social media and the internet.

CONCLUSION

This review offers a summary of our current understanding of the placebo and nocebo effects in migraine management.

Abnormal Glutamatergic and Serotonergic Connectivity in Visual Snow Syndrome and Migraine with Aura

OBJECTIVE

Neuropharmacological changes in visual snow syndrome (VSS) are poorly understood. We aimed to use receptor target maps combined with resting functional magnetic resonance imaging (fMRI) data to identify which neurotransmitters might modulate brain circuits involved in VSS.

METHODS

We used Receptor-Enriched Analysis of Functional Connectivity by Targets (REACT) to estimate and compare the molecular-enriched functional networks related to 5 neurotransmitter systems of patients with VSS (n = 24), healthy controls (HCs; n = 24), and migraine patients ([MIG], n = 25, 15 of whom had migraine with aura [MwA]). For REACT we used receptor density templates for the transporters of noradrenaline, dopamine, and serotonin, GABA-A and NMDA receptors, as well as 5HT1B and 5HT2A receptors, and estimated the subject-specific voxel-wise maps of functional connectivity (FC). We then performed voxel-wise comparisons of these maps among HCs, MIG, and VSS.

RESULTS

Patients with VSS had reduced FC in glutamatergic networks localized in the anterior cingulate cortex (ACC) compared to HCs and patients with migraine, and reduced FC in serotoninergic networks localized in the insula, temporal pole, and orbitofrontal cortex compared to controls, similar to patients with migraine with aura. Patients with VSS also showed reduced FC in 5HT2A -enriched networks, largely localized in occipito-temporo-parietal association cortices. As revealed by subgroup analyses, these changes were independent of, and analogous to, those found in patients with migraine with aura.

INTERPRETATION

Our results show that glutamate and serotonin are involved in brain connectivity alterations in areas of the visual, salience, and limbic systems in VSS. Importantly, altered serotonergic connectivity is independent of migraine in VSS, and simultaneously comparable to that of migraine with aura, highlighting a shared biology between the disorders. ANN NEUROL 2023;94:873-884.

Electrophysiological findings in migraine may reflect abnormal synaptic plasticity mechanisms: A narrative review

BACKGROUND

The cyclical brain disorder of sensory processing accompanying migraine phases lacks an explanatory unified theory.

METHODS

We searched Pubmed for non-invasive neurophysiological studies on migraine and related conditions using transcranial magnetic stimulation, electroencephalography, visual and somatosensory evoked potentials. We summarized the literature, reviewed methods, and proposed a unified theory for the pathophysiology of electrophysiological abnormalities underlying migraine recurrence.

RESULTS

All electrophysiological modalities have determined specific changes in brain dynamics across the different phases of the migraine cycle. Transcranial magnetic stimulation studies show unbalanced recruitment of inhibitory and excitatory circuits, more consistently in aura, which ultimately results in a substantially distorted response to neuromodulation protocols. Electroencephalography investigations highlight a steady pattern of reduced alpha and increased slow rhythms, largely located in posterior brain regions, which tends to normalize closer to the attacks. Finally, non-painful evoked potentials suggest dysfunctions in habituation mechanisms of sensory cortices that revert during ictal phases.

CONCLUSION

Electrophysiology shows dynamic and recurrent functional alterations within the brainstem-thalamus-cortex loop varies continuously and recurrently in migraineurs. Given the central role of these structures in the selection, elaboration, and learning of sensory information, these functional alterations suggest chronic, probably genetically determined dysfunctions of the synaptic short- and long-term learning mechanisms.

Visual snow syndrome and migraine: a review

Visual snow syndrome is a neurological condition characterized by ongoing prominent phenomena described consistently as tiny dots moving across the entire visual field, often associated with complex visual symptoms. These can take the form of afterimages, entoptic phenomena, nyctalopia and light sensitivity. Although some of these symptoms can be benign, they can nonetheless become significantly impactful for many who experience them, particularly in cases that have a sudden and abrupt start. As visual snow syndrome becomes increasingly recognized in clinical practice we begin to learn about its typical presentation and underlying pathophysiology. Treatment of visual snow, however, still proves quite challenging, and efforts need to be focused on unravelling the biological mechanisms of the syndrome. This endeavour has characterized the most recent research on visual snow, mostly involving neuroimaging, neurophysiological and neurobehavioral studies aimed at understanding its underlying neural signature. Another important aspect of the syndrome, which will likely prove critical in deepening our understanding of visual snow, is represented by the intricate biological and historical connexion with migraine. This narrative review focused on visual snow syndrome will explore its clinical, pathophysiological and treatment aspects in detail.

Migraine: from pathophysiology to treatment

Migraine is an extremely disabling, common neurological disorder characterized by a complex neurobiology, involving a series of central and peripheral nervous system areas and networks. A growing increase in the understanding of migraine pathophysiology in recent years has facilitated translation of that knowledge into novel treatments, which are currently becoming available to patients in many parts of the world and are substantially changing the clinical approach to the disease. In the first part of this review, we will provide an up to date overview of migraine pathophysiology by analyzing the anatomy and function of the main regions involved in the disease, focusing on how these give rise to the plethora of symptoms characterizing the attacks and overall disease. The second part of the paper will discuss the novel therapeutic agents that have emerged for the treatment of migraine, including molecules targeting calcitonin gene-related peptide (gepants and monoclonal antibodies), serotonin 5-HT_1F receptor agonists (ditans) and non-invasive neuromodulation, as well as providing a brief overview of new evidence for classic migraine treatments.

Evaluating the efficacy of CGRP mAbs and gepants for the preventive treatment of migraine: A systematic review and network meta-analysis of phase 3 randomised controlled trials

BACKGROUND

Several novel treatments targeting the calcitonin gene-related peptide pathway have been developed for migraine. We evaluated the efficacy of these medications, including atogepant, rimegepant, erenumab, eptinezumab, fremanezumab, and galcanezumab, for the prevention of migraine via network meta-analysis.

METHODS

Databases, including MEDLINE via PubMed, EMBASE, and Cochrane central, were systematically reviewed, and all eligible phase 3 randomised controlled trials were included.

RESULTS

Nineteen studies (n = 14,584 participants) were included. Studies included episodic (n = 11) and chronic (n = 4) migraine or both (n = 4). All interventions, except for eptinzumab 30 mg, significantly reduced mean monthly migraine days compared to placebo. All medications had a higher ≥50% responder rate than placebo and results were statistically significant in those with the subcutaneous or intravenous route of administrations, but not with the oral one. All medications significantly reduced mean monthly headache days, although no data for this outcome was available for rimegepant, and mean monthly acute medication days, with no data for eptinezumab.

CONCLUSION

The results show that medications targeting calcitonin gene-related peptide were effective in preventing migraine compared to placebo. Considering limitations of single studies, different populations such as episodic and chronic migraine, and the absence of head-to-head trials, all novel treatments decreased mean monthly migraine and headache days, and showed higher 50%, 75% and 100% responder rates than placebo.Trial registration: PROSPERO registration: CRD42022310579.

Habituation deficit of visual evoked potentials in migraine patients with hypermobile Ehlers-Danlos syndrome

Objectives

Migraine is one of the most frequent clinical manifestations of hypermobile Ehlers-Danlos syndrome (hEDS). The comorbidity between these two diseases has been only partially investigated. We aimed to observe whether neurophysiological alterations described in migraineurs in visual evoked potentials (VEPs) were present in hEDS patients with migraine.

Methods

We enrolled 22 hEDS patients with migraine (hEDS) and 22 non-hEDS patients with migraine (MIG), with and without aura (according to ICHD-3), as well as 22 healthy controls (HC). Repetitive pattern reversal (PR)-VEPs were recorded in basal conditions in all participants. During uninterrupted stimulation, 250 cortical responses were recorded (4,000 Hz sample rate) and divided into epochs of 300 ms after the stimulus. Cerebral responses were divided into five blocks. The habituation was calculated as the slope interpolating the amplitudes in each block, for both the N75-P100 and P100-N145 components of PR-VEP.

Results

We observed a significant habituation deficit of the P100-N145 component of PR-VEP in hEDS compared to HC (p = 0.002), unexpectedly more pronounced than in MIG. We observed only a slight habituation deficit of N75-P100 in hEDS, with a slope degree that was intermediate between MIG and HC.

Discussion

hEDS patients with migraine presented an interictal habituation deficit of both VEPs components like MIG. Pathophysiological aspects underlying the pathology could account for the peculiar pattern of habituation in hEDS patients with migraine characterized by a pronounced habituation deficit in the P100-N145 component and a less clear-cut habituation deficit in the N75-P100 component with respect to MIG.

Efficacy, safety and indirect comparisons of lasmiditan, rimegepant, and ubrogepant for the acute treatment of migraine: A systematic review and network meta-analysis of the literature

BACKGROUND

We performed a random-effects network meta-analysis to study the efficacy and safety of newly developed drugs for the acute treatment of migraine attacks.

METHODS

MEDLINE via PubMed, Embase and The Cochrane Register of Controlled Trials were searched from inception to 11 February 2022. Phase 3 randomized controlled trials examining all formulations of lasmiditan, rimegepant and ubrogepant for the acute treatment of adults with migraine, were included. Data were extracted following the PRISMA guidelines.

RESULTS

Seven studies (SAMURAI, SPARTAN, CENTURION, Study 302, Study 303, ACHIEVE I and II) involving n = 12,859 patients were included. All treatments were superior in efficacy to placebo. Lasmiditan 200 mg showed the highest two-hour pain freedom, while two-hour freedom from most bothersome symptom was equally achieved by the higher doses of lasmiditan (100 and 200 mg), rimegepant and the higher doses of ubrogepant (50 and 100 mg). The odds of treatment-emergent adverse events were greatest with all doses of lasmiditan.

CONCLUSION

Lasmiditan 200 mg was the most effective intervention in the treatment of migraine attacks, although it was associated with high degrees of dizziness, nausea and somnolence. Rimegepant showed slightly lower, but similar efficacy rates to lasmiditan. Ubrogepant had overall the best tolerability profile. These conclusions are limited by the absence of head-to-head comparisons, limitations of individual trials and of the meta-analysis methodology itself.PROSPERO trial registration: CRD42022308224.

Safety and tolerability of monoclonal antibodies targeting the CGRP pathway and gepants in migraine prevention: A systematic review and network meta-analysis

BACKGROUND

Direct comparisons of the tolerability and safety of migraine preventive treatments targeting the calcitonin gene-related peptide pathway are lacking. This study aimed to compare the safety and tolerability of anti-calcitonin gene-related peptide monoclonal antibodies and gepants in migraine prevention.

METHODS

A network meta-analysis of phase 3 randomized controlled trials assessing the safety and tolerability of anti-calcitonin gene-related peptide monoclonal antibodies (erenumab, eptinezumab, fremanezumab, or galcanezumab) and gepants (atogepant, rimegepant) in migraine prevention was performed. Primary outcomes were treatment-emergent adverse events and serious adverse events. Secondary outcomes included any adverse events, adverse events leading to treatment discontinuation and individual adverse events.

RESULTS

We included 19 randomized controlled trials, comprising 14,584 patients. Atogepant 120 mg (OR 2.22, 95% CI [1.26, 3.91]) and galcanezumab 240 mg (OR 1.63, 95% CI [1.33, 2.00]) showed the largest odds of treatment-emergent adverse events compared to placebo. While eptinezumab 30 mg had greater odds of adverse events leading to treatment discontinuation (OR 2.62, 95% CI [1.03,6.66]). No significant differences in serious adverse events were found between active treatments and placebo. Eptinezumab was associated with the lowest odds of treatment-emergent adverse events and serious adverse events compared to placebo, whereas erenumab was associated with the lowest odds of any adverse events and quarterly fremanezumab with the lowest odds of treatment discontinuation due to adverse events.

CONCLUSION

Monoclonal antibodies targeting the calcitonin gene-related peptide pathway and gepants are a safe and well tolerated option for migraine prevention.

Natural course of visual snow syndrome: a long-term follow-up study

Visual snow syndrome is characterized by a continuous visual disturbance resembling a badly tuned analogue television and additional visual and non-visual symptoms causing significant disability. The natural course of visual snow syndrome has not hitherto been studied. In this prospective longitudinal study, 78 patients with the diagnosis of visual snow syndrome made in 2011 were re-contacted in 2019 to assess symptom evolution using a semi-structured questionnaire. Forty patients (51% of 78) were interviewed after 84 ± 5 months (mean ± SD). In all patients, symptoms had persisted. Visual snow itself was less frequently rated as the most disturbing symptom (72 versus 42%, P = 0.007), whereas a higher proportion of patients suffered primarily from entopic phenomena (2 versus 17%, P = 0.024). New treatment was commenced in 14 (35%) patients, of whom in seven, visual snow syndrome was ameliorated somewhat. Three (7%) experienced new visual migraine aura without headache, and one (2%) had new migraine headache. There were no differences in the levels of anxiety and depression measured by the Patient Health Questionnaire 8 and the Generalized Anxiety Disorder Scale 7. Thirty-eight patients (49%) were lost to follow-up. In visual snow syndrome, symptoms can persist over 8 years without spontaneous resolution, although visual snow itself might become less bothersome.

Comparison and predictors of chronic migraine vs. new daily persistent headache presenting with a chronic migraine phenotype

Objective

To compare the clinical phenotype of patients with chronic migraine (CM) to patients with new daily persistent headache of the chronic migraine subtype (NDPH‐CM).

Methods

A study was conducted of CM (n = 257) and NDPH‐CM (n = 76) from a tertiary headache center in the UK, and in the US of patients with daily CM (n = 60) and NDPH‐CM (n = 22).

Results

From the UK cohort, the age of first headache onset was lower in CM (mean ± SD: 16 ± 12 years) than in NDPH‐CM (mean ± SD: 23 ± 14 years; p < 0.001). There was a greater number of associated migrainous symptoms in CM compared to NDPH‐CM (median and interquartile range: 6, 5–8 vs. 5, 4–7; p < 0.001). A family history of headache was more common in CM compared to NDPH‐CM (82%, 202/248, vs. 53%, 31/59; p < 0.001). In the US cohort there were no differences. Osmophobia (B = −1.08; p = 0.002) and older age at presentation to the clinic (B = −0.06; p = 0.001) were negative predictors of NDPH‐CM.

Conclusion

NDPH‐CM is relatively less migrainous than CM in the UK cohort. Family history of headache is less common in NDPH‐CM, with negative predictors for NDPH‐CM including osmophobia and older age of presentation to the clinic. More work is required to understand the chronic migraine phenotype of new daily persistent headache.

A history of International Headache Society grants and their impact on headache careers

Background

The International Headache Society has been offering multiple award opportunities for young researchers and clinicians for many years, with the aim of supporting the development of careers in headache science and medicine.

Methods

In order to assess the outcomes of the International Headache Society award grants, a questionnaire was sent to all previous recipients, investigating a series of aspects related to their work, both during and after award completion.

Results

Of 44 total questionnaires sent, 36 were returned. Eighty-one percent of the recipients reported to have remained in the headache field since the award, half of them held a current academic position and over three-quarters had stayed in contact with the host institution. The totality of questionnaire responders stated that the grant had had a significantly positive impact on their careers.

Conclusions

The International Headache Society grants have assisted many young researchers in building an academic and clinical career in the field of headache, throughout the years.

Case Report: Transformation of Visual Snow Syndrome From Episodic to Chronic Associated With Acute Cerebellar Infarct

Visual snow syndrome is a novel neurological condition characterized by a panfield visual disturbance associated with several additional symptoms. Although it is usually a continuous and primary disorder, cases of intermittent visual snow have been described in the literature, as well as rare secondary forms. This report is the first description of a case of intermittent visual snow syndrome, which transformed into a persistent form following a posterior circulation stroke due to vertebral artery dissection. At 1 and 2 years after experiencing the acute cerebellar infarct, the patient's only neurological sequalae was visual snow. This case provides a description of how visual snow syndrome may be caused by an underlying brain disorder, and highlights the importance of the cerebellum in the pathophysiology of this relatively unknown condition. It further shows evidence of how existing predispositions might be relevant to the development of visual snow, in certain subjects and following specific circumstances.

Evaluation of treatment response and symptom progression in 400 patients with visual snow syndrome

AIMS

To gather information on useful medications to treat visual snow syndrome (VSS) as well as to validate an instrument to assess its clinical severity and the course of the disorder over time.

METHODS

Four hundred patients with VSS were included in this web-based prospective questionnaire study. All subjects completed a treatment questionnaire and a clinical diary. The first allowed evaluation of the effects of previous medications on visual snow, while the second measured VSS symptoms daily over the course of 30 days.

RESULTS

Patients commonly reported previous use of medications such as antidepressants, antiepileptics, antibiotics and benzodiazepines. However, none of these drug classes was beneficial for the majority of patients. Recreational drugs and alcohol worsened visual snow symptoms in several reports. Vitamins and benzodiazepines had high therapeutic ratios, although in most cases they did not change the course of VSS.The monthly diary confirmed that the static in VSS is a consistent symptom over time. It also showed that indoor and fluorescent lights have a worse effect on symptoms when compared with natural outdoor lighting.

CONCLUSIONS

The study confirms clinical experience that medications are generally ineffective in VSS, with the exception of vitamins and perhaps benzodiazepines, which could be beneficial in some patients. The 30-day diary represents a useful tool to measure symptom progression over time, which could be used in future trials on VSS.

Localised increase in regional cerebral perfusion in patients with visual snow syndrome: a pseudo-continuous arterial spin labelling study

OBJECTIVES

We aimed to investigate changes in regional cerebral blood flow (rCBF) using arterial spin labelling (ASL) in patients with visual snow syndrome (VSS), in order to understand more about the underlying neurobiology of the condition, which remains mostly unknown.

METHODS

We performed an MRI study in which whole-brain maps of rCBF were obtained using pseudo-continuous ASL. Twenty-four patients with VSS and an equal number of gender and age-matched healthy volunteers took part in the study. All subjects were examined with both a visual paradigm consisting of a visual-snow like stimulus, simulating key features of the snow, and a blank screen at rest, randomly presented.

RESULTS

Patients with VSS had higher rCBF than controls over an extensive brain network, including the bilateral cuneus, precuneus, supplementary motor cortex, premotor cortex and posterior cingulate cortex, as well as the left primary auditory cortex, fusiform gyrus and cerebellum. These areas were largely analogous comparing patients either at rest, or when looking at a 'snow-like' visual stimulus. This widespread, similar pattern of perfusion differences in either condition suggests a neurophysiological signature of visual snow. Furthermore, right insula rCBF was increased in VSS subjects compared with controls during visual stimulation, reflecting a greater task-related change and suggesting a difference in interoceptive processing with constant perception of altered visual input.

CONCLUSION

The data suggest VSS patients have marked differences in brain processing of visual stimuli, validating its neurobiological basis.

Exploding head syndrome (a.k.a. episodic cranial sensory shock) responds to single-pulse transcranial magnetic stimulation

We present the case of a patient with a sleep disturbance attributed to the exploding head syndrome, recently redefined as episodic cranial sensory shock. The patient, who suffered with concomitant migraine, was treated for headache prevention with daily single-pulse transcranial magnetic stimulation (sTMS). Following treatment, he reported a significant reduction in the episodes of exploding head syndrome, albeit not of his migraine. Neurologists could consider sTMS in the management of patients troubled by episodic cranial sensory shock, as it is a safe and noninvasive treatment that might provide benefit for this benign but occasionally bothersome parasomnia.

Neuronal nitric oxide synthase regulates regional brain perfusion in healthy humans

Aims

Neuronal nitric oxide synthase (nNOS) is highly expressed within the cardiovascular and nervous systems. Studies in genetically modified mice suggest roles in brain blood flow regulation while dysfunctional nNOS signalling is implicated in cerebrovascular ischaemia and migraine. Previous human studies have investigated the effects of non-selective NOS inhibition but there has been no direct investigation of the role of nNOS in human cerebrovascular regulation. We hypothesized that inhibition of the tonic effects of nNOS would result in global or localized changes in cerebral blood flow (CBF), as well as changes in functional brain connectivity.

Methods and results

We investigated the acute effects of a selective nNOS inhibitor, S-methyl-L-thiocitrulline (SMTC), on CBF and brain functional connectivity in healthy human volunteers (n = 19). We performed a randomized, placebo-controlled, crossover study with either intravenous SMTC or placebo, using magnetic resonance imaging protocols with arterial spin labelling and functional resting state neuroimaging. SMTC infusion induced an ∼4% decrease in resting global CBF [−2.3 (−0.3, −4.2) mL/100g/min, mean (95% confidence interval, CI), P = 0.02]. In a whole-brain voxel-wise factorial-design comparison of CBF maps, we identified a localized decrease in regional blood flow in the right hippocampus and parahippocampal gyrus following SMTC vs. placebo (2921 voxels; T = 7.0; x = 36; y = −32; z = −12; P < 0.001). This was accompanied by a decrease in functional connectivity to the left superior parietal lobule vs. placebo (484 voxels; T = 5.02; x = −14; y = −56; z = 74; P = 0.009). These analyses adjusted for the modest changes in mean arterial blood pressure induced by SMTC as compared to placebo [+8.7 mmHg (+1.8, +15.6), mean (95% CI), P = 0.009].

Conclusions

These data suggest a fundamental physiological role of nNOS in regulating regional CBF and functional connectivity in the human hippocampus. Our findings have relevance to the role of nNOS in the regulation of cerebral perfusion in health and disease.

Disrupted connectivity within visual, attentional and salience networks in the visual snow syndrome

Here we investigate brain functional connectivity in patients with visual snow syndrome (VSS). Our main objective was to understand more about the underlying pathophysiology of this neurological syndrome. Twenty‐four patients with VSS and an equal number of gender and age‐matched healthy volunteers attended MRI sessions in which whole‐brain maps of functional connectivity were acquired under two conditions: at rest while watching a blank screen and during a visual paradigm consisting of a visual‐snow like stimulus. Eight unilateral seed regions were selected a priori based on previous observations and hypotheses; four seeds were placed in key anatomical areas of the visual pathways and the remaining were derived from a pre‐existing functional analysis. The between‐group analysis showed that patients with VSS had hyper and hypoconnectivity between key visual areas and the rest of the brain, both in the resting state and during a visual stimulation, compared with controls. We found altered connectivity internally within the visual network; between the thalamus/basal ganglia and the lingual gyrus; between the visual motion network and both the default mode and attentional networks. Further, patients with VSS presented decreased connectivity during external sensory input within the salience network, and between V5 and precuneus. Our results suggest that VSS is characterised by a widespread disturbance in the functional connectivity of several brain systems. This dysfunction involves the pre‐cortical and cortical visual pathways, the visual motion network, the attentional networks and finally the salience network; further, it represents evidence of ongoing alterations both at rest and during visual stimulus processing.

Occipital cortex and cerebellum gray matter changes in visual snow syndrome

Objective

To determine whether regional gray and white matter differences characterize the brain of patients with visual snow syndrome, a newly defined neurologic condition, we used a voxel-based morphometry approach.

Methods

In order to investigate whole brain morphology directly, we performed an MRI study on patients with visual snow syndrome (n = 24) and on age- and sex-matched healthy volunteers (n = 24). Voxel-based morphometry was used to determine volumetric differences in patients with visual snow. We further analyzed cerebellar anatomy directly using the high-resolution spatially unbiased atlas template of the cerebellum.

Results

Compared to healthy controls, patients with visual snow syndrome had increased gray matter volume in the left primary and secondary visual cortices, the left visual motion area V5, and the left cerebellar crus I/lobule VI area. These anatomical alterations could not be explained by clinical features of the condition.

Conclusion

Patients with visual snow syndrome have subtle, significant neuroanatomical differences in key visual and lateral cerebellar areas, which may in part explain the pathophysiologic basis of the disorder.

Visual snow syndrome: a comparison between an Italian and British population

BACKGROUND AND PURPOSE

Visual snow manifests as a pan-field, dynamic visual disturbance described as continuous television static-like tiny flickering dots. Current diagnostic criteria further require at least two additional symptoms for visual snow syndrome (VSS) from: palinopsia (afterimages and trailing); entoptic phenomena (floaters, blue field entoptic phenomenon, photopsia, self-light of the eye); photophobia and nyctalopia. Our objective was to compare the phenotype of VSS in an Italian and British population.

METHODS

Patients with VSS were characterized clinically using the current criteria. An online survey was prepared in collaboration with the patient group Eye-on-Vision. Patients were directed to the site if they contacted us by email asking to be involved in research. After data collection, we compared the phenotypic characteristics of a subgroup of British versus Italian patients taking part in the survey. As we expected more responses from the UK, we matched 100 UK patients for gender and age with our Italian cohort.

RESULTS

Patients were enrolled from the UK (n = 100) and Italy (n = 100). The populations had similar demography. After multiple correction testing there were no differences in VSS features between the two groups. The same was true for the prevalence of migraine and previous use of recreational drugs.

CONCLUSION

This is the first study comparing the phenotype of VSS between two distinct populations. Our findings suggest that the visual snow phenotype, as well as migraine comorbidity, is similar across the two groups.

Insular and occipital changes in visual snow syndrome: a BOLD fMRI and MRS study

Objective

To investigate the pathophysiology of visual snow (VS), through a combined functional neuroimaging and magnetic resonance spectroscopy (¹H‐MRS) approach.

Methods

We applied a functional MRI block‐design protocol studying the responses to a visual stimulation mimicking VS, in combination with ¹H‐MRS over the right lingual gyrus, in 24 patients with VS compared to an equal number of age‐ and gender‐matched healthy controls.

Results

We found reduced BOLD responses to the visual stimulus with respect to baseline in VS patients compared to controls, in the left (k = 291; P = 0.025; peak MNI coordinate [‐34 12 ‐6]) and right (k = 100; P = 0.003; peak MNI coordinate [44 14 ‐2]) anterior insula. Our spectroscopy analysis revealed a significant increase in lactate concentrations in patients with respect to controls (0.66 ± 0.9 mmol/L vs. 0.07 ± 0.2 mmol/L; P < 0.001) in the right lingual gyrus. In this area, there was a significant negative correlation between lactate concentrations and BOLD responses to visual stimulation (P = 0.004; r = −0.42), which was dependent on belonging to the patient group.

Interpretation

As shown by our BOLD analysis, VS is characterized by a difference in bilateral insular responses to a visual stimulus mimicking VS itself, which could be due to disruptions within the salience network. Our results also suggest that patients with VS have a localized disturbance in extrastriate anaerobic metabolism, which may in turn cause a decreased metabolic reserve for the regular processing of visual stimuli.

Visual snow syndrome: A clinical and phenotypical description of 1,100 cases

Objective

To validate the current criteria of visual snow and to describe its common phenotype using a substantial clinical database.

Methods

We performed a web-based survey of patients with self-assessed visual snow (n = 1,104), with either the complete visual snow syndrome (n = 1,061) or visual snow without the syndrome (n = 43). We also describe a population of patients (n = 70) with possible hallucinogen persisting perception disorder who presented clinically with visual snow syndrome.

Results

The visual snow population had an average age of 29 years and had no sex prevalence. The disorder usually started in early life, and ≈40% of patients had symptoms for as long as they could remember. The most commonly experienced static was black and white. Floaters, afterimages, and photophobia were the most reported additional visual symptoms. A latent class analysis showed that visual snow does not present with specific clinical endophenotypes. Severity can be classified by the amount of visual symptoms experienced. Migraine and tinnitus had a very high prevalence and were independently associated with a more severe presentation of the syndrome.

Conclusions

Clinical characteristics of visual snow did not differ from the previous cohort in the literature, supporting validity of the current criteria. Visual snow likely represents a clinical continuum, with different degrees of severity. On the severe end of the spectrum, it is more likely to present with its common comorbid conditions, migraine and tinnitus. Visual snow does not depend on the effect of psychotropic substances on the brain.

Imaging the Visual Network in the Migraine Spectrum

The involvement of the visual network in migraine pathophysiology has been well-known for more than a century. Not only is the aura phenomenon linked to cortical alterations primarily localized in the visual cortex; but also migraine without aura has shown distinct dysfunction of visual processing in several studies in the past. Further, the study of photophobia, a hallmark migraine symptom, has allowed unraveling of distinct connections that link retinal pathways to the trigeminovascular system. Finally, visual snow, a recently recognized neurological disorder characterized by a continuous visual disturbance, is highly comorbid with migraine and possibly shares with it some common pathophysiological mechanisms. Here, we review the most relevant neuroimaging literature to date, considering studies that have either attempted to investigate the visual network or have indirectly shown visual processing dysfunctions in migraine. We do this by taking into account the broader spectrum of migrainous biology, thus analyzing migraine both with and without aura, focusing on light sensitivity as the most relevant visual symptom in migraine, and finally analyzing the visual snow syndrome. We also present possible hypotheses on the underlying pathophysiology of visual snow, for which very little is currently known.

Treating Chronic Migraine With Neuromodulation: The Role of Neurophysiological Abnormalities and Maladaptive Plasticity

Chronic migraine (CM) is the most disabling form of migraine, because pharmacological treatments have low efficacy and cumbersome side effects. New evidence has shown that migraine is primarily a disorder of brain plasticity and migraine chronification depends on a maladaptive process favoring the development of a brain state of hyperexcitability. Due to the ability to induce plastic changes in the brain, researchers started to look at Non-Invasive Brain Stimulation (NIBS) as a possible therapeutic option in migraine field. On one side, NIBS techniques induce changes of neural plasticity that outlast the period of the stimulation (a fundamental prerequisite of a prophylactic migraine treatment, concurrently they allow targeting neurophysiological abnormalities that contribute to the transition from episodic to CM. The action may thus influence not only the cortex but also brainstem and diencephalic structures. Plus, NIBS is not burdened by serious medication side effects and drug–drug interactions. Although the majority of the studies reported somewhat beneficial effects in migraine patients, no standard intervention has been defined. This may be due to methodological differences regarding the used techniques (e.g., transcranial magnetic stimulation, transcranial direct current stimulation), the brain regions chosen as targets, and the stimulation types (e.g., the use of inhibitory and excitatory stimulations on the basis of opposite rationales), and an intrinsic variability of stimulation effect. Hence, it is difficult to draw a conclusion on the real effect of neuromodulation in migraine. In this article, we first will review the definition and mechanisms of brain plasticity, some neurophysiological hallmarks of migraine, and migraine chronification-related (dys)plasticity. Secondly, we will review available results from therapeutic and physiological studies using neuromodulation in CM. Lastly we will discuss the results obtained in these preventive trials in the light of a possible effect on brain plasticity.

Sapienza Global Bedside Evaluation of Swallowing after Stroke: the GLOBE-3S study

BACKGROUND AND PURPOSE

Dysphagia occurs in up to 50% of all patients with acute stroke. There is debate regarding which is the most effective screening tool in identifying aspiration in patients with acute stroke. We assessed the accuracy of the Sapienza Global Bedside Evaluation of Swallowing after Stroke (GLOBE-3S), which combines the Toronto Bedside Swallowing Screening Test (TOR-BSST©) with oxygen desaturation and laryngeal elevation measurement during swallowing.

METHODS

We prospectively enrolled consecutive patients with stroke within 72 h of symptom onset. All patients with stroke firstly underwent a standard neurological examination, then the GLOBE-3S evaluation and finally the fiberoptic endoscopic evaluation of swallowing (FEES). Two different assessors, a neurologist and a speech pathologist, blind to both the clinical data and each other's evaluation, administered the GLOBE-3S and FEES examination. We assessed the accuracy of the GLOBE-3S in detecting post-stroke swallow impairment with aspiration using the FEES as the standard.

RESULTS

We enrolled 50 patients with acute stroke, 28 of whom (56%) had swallowing impairment with aspiration at FEES evaluation. A total of 33 patients (66%) failed the GLOBE-3S evaluation. The GLOBE-3S reached a sensitivity of 100% and a specificity of 77.3% (negative predictive value, 100%; positive likelihood ratio, 4.34). The median time required for the GLOBE-3S to be performed was 297 s.

CONCLUSIONS

GLOBE-3S is quick to perform at the bedside and can accurately identify aspiration in patients with acute stroke. By including the measurement of laryngeal elevation and monitoring of oxygen desaturation, it could represent a highly sensitive instrument to avoid the misdiagnosis of silent aspirators.

Non-Pharmacological Approaches for Migraine

Migraine is one of the most common and debilitating neurological disorders. However, the efficacy of pharmacological therapies may have unsatisfactory efficacy and can be poorly tolerated. There is a strong need in clinical practice for alternative approaches for both acute and preventive treatment. Occasionally, this need might arise in the context of low-frequency migraneurs who are not keen to use medication or fear the potential side effects. At the opposite end of the spectrum, clinicians might be faced with patients who have proven refractory to numerous medications. These patients may benefit from invasive treatment strategies. In recent years, promising strategies for migraine therapy have emerged alongside a progressively better understanding of the complex pathophysiology underlying this disease. This review discusses the most recent and evidence-based advances in non-pharmacological therapeutic approaches for migraine, offering alternatives to drug treatment for both the commonly encountered episodic cases as well as the more complex migraine phenotypes, which are capable of challenging even the headache specialist.

Treatment of disabling headache with greater occipital nerve injections in a large population of childhood and adolescent patients: a service evaluation

Background

Pediatric headache disorders can be extremely disabling, with marked reduction in the quality of life of children and their carers. Evidenced-based options for the treatment of primary headache disorders with preventive medication is limited and clinical outcomes are often unsatisfactory. Greater occipital nerve injections represent a rapid and well-tolerated therapeutic option, which is widely used in clinical practice in adults, and has previously shown a good outcome in a pediatric population.

Methods

This service evaluation reviewed greater occipital nerve injections performed unilaterally with 30 mg 1% lidocaine and 40 mg methylprednisolone, to treat disabling headache disorders in children and adolescents.

Results

We analyzed a total of 159 patients who received 380 injections. Of the population, 79% had chronic migraine, 14% new daily persistent headache, 4% a trigeminal autonomic cephalalgia, 3% secondary headache and one patient had chronic tension-type headache. An improvement after injection was seen in 66% (n = 105) of subjects, lasting on average 9 ± 4 weeks. Improvement was seen in 68% of patients with chronic migraine, 67% with a trigeminal autonomic cephalalgia and 59% with new daily persistent headache. Side effects were reported in 8% and were mild and transient.

Older age, female gender, chronic migraine, increased number of past preventive use, medication overuse and developing side effects were all associated with an increased likelihood of positive treatment outcome.

Conclusions

This large single centre service evaluation confirms that unilateral injection of the greater occipital nerve is a safe, rapid-onset and effective treatment strategy in disabling headache disorders in children, with a range of diagnoses and severity of the condition, and with minimal side effects.

An update on migraine: current understanding and future directions

Migraine is a common brain disorder with high disability rates which involves a series of abnormal neuronal networks, interacting at different levels of the central and peripheral nervous system. An increase in the interest around migraine pathophysiology has allowed researchers to unravel certain neurophysiological mechanisms and neurotransmitter involvement culminating in the recent development of novel therapies, which might substantially change the clinical approach to migraine patients. The present review will highlight the current aspects of migraine pathophysiology, covering an understanding of the complex workings of the migraine state and the brain regions responsible for them. We will further discuss the therapeutic agents which have appeared in the most recent years for migraine care, from calcitonin gene-related peptide (CGRP) receptor antagonists, gepants; through serotonin 5-HT1F receptor agonists, ditans, and CGRP or CGRP receptor monoclonal antibodies to invasive and non-invasive neuromodulation techniques.

Right-to-left shunt detection sensitivity with air-saline and air-succinil gelatin transcranial Doppler

BACKGROUND

Air-saline transcranial Doppler is nowadays the first-choice examination to identify right-to-left shunt. To increase right-to-left shunt detection in echocardiography, cardiologists also use air-gelatin mixtures, which are more stable, more echogenic, and easier to be prepared.

AIM

We assessed the sensitivity of air-gelatin compared with air-saline for transcranial Doppler right-to-left shunt detection.

METHODS

Air-saline transcranial Doppler, during unilateral middle cerebral artery monitoring at rest and after Valsalva maneuver, was performed in patients referred to our neurosonology laboratory for right-to-left shunt detection. The same transcranial Doppler protocol was repeated with air-gelatin. To consider transcranial Doppler positive for cardiac right-to-left shunt, at least one embolic signal had to be detected within 20″ from contrast injection. Later signals were interpreted of pulmonary origin. Trans-thoracic echocardiography was repeated with both air-saline and air-gelatin.

RESULTS

A total of 97 patients were enrolled; 46 had negative transcranial Doppler for cardiac right-to-left shunt with both air-saline and air-gelatin; out of these, four patients with air-saline plus two more patients with air-gelatin presented late, isolated microemboli, slightly more numerous with air-gelatin: these were interpreted as pulmonary shunts and confirmed with trans-thoracic echocardiography. In 28 patients with already early positive air-saline transcranial Doppler at rest, air-gelatin induced a marked right-to-left shunt increase, facilitating its visualization at trans-thoracic echocardiography. In 23 patients in whom air-saline transcranial Doppler was negative at rest and positive for cardiac right-to-left shunt only after Valsalva maneuver, air-gelatin was able to reveal shunt also at rest.

CONCLUSIONS

Air-gelatin increases right-to-left shunt detection sensitivity with transcranial Doppler in particular at rest, even in patients in whom air-saline mixture fails to identify the shunt. The choice of air-gelatin mixture should be considered for multicentric, clinical, and research trials.

An Update on Non-Pharmacological Neuromodulation for the Acute and Preventive Treatment of Migraine

OBJECTIVE

To review current neuromodulation treatments available for migraine therapy, both in the acute and preventive setting.

METHODS

The published literature was reviewed for studies reporting the effects of different neuromodulation strategies in migraine with and without aura. The use of non-invasive: single pulse transcranial magnetic stimulation, non-invasive vagal nerve stimulation, supraorbital nerve stimulation, and transcranial direct current stimulation, as well as invasive methods such as occipital nerve stimulation and sphenopalatine ganglion stimulation, are assessed.

RESULTS

The available evidence shows that non-invasive techniques represent promising treatment strategies, whereas an invasive approach should only be used where patients are refractory to other preventives, including non-invasive methods.

CONCLUSIONS

Neuromodulation is emerging as an exciting approach to migraine therapy, especially in the context of failure of commonly used medicines or for patients who do not tolerate common side effects. More studies with appropriate blinding strategies are needed to confirm the results of these new treatment opportunities.

Current Approaches to Neuromodulation in Primary Headaches: Focus on Vagal Nerve and Sphenopalatine Ganglion Stimulation

Neuromodulation is a promising, novel approach for the treatment of primary headache disorders. Neuromodulation offers a new dimension in the treatment that is both easily reversible and tends to be very well tolerated. The autonomic nervous system is a logical target given the neurobiology of common primary headache disorders, such as migraine and the trigeminal autonomic cephalalgias (TACs). This article will review new encouraging results of studies from the most recent literature on neuromodulation as acute and preventive treatment in primary headache disorders, and cover some possible underlying mechanisms. We will especially focus on vagus nerve stimulation (VNS) and sphenopalatine ganglion (SPG) since they have targeted autonomic pathways that are cranial and can modulate relevant pathophysiological mechanisms. The initial data suggests these approaches will find an important role in headache disorder management going forward.

The Role of Noninvasive Neuromodulation in Migraine Management

Neuromodulation represents an exciting new approach that is being increasingly used as both acute and preventative treatment for migraine, providing a valid alternative option for patients for whom traditional drugs have failed, or for those who do not tolerate their side effects. This brief review aims at describing noninvasive neuromodulation techniques, which are currently the most used in clinical practice, specifically focusing on transcranial magnetic stimulation, vagus nerve stimulation and supraorbital nerve stimulation.

Cardioembolic stroke: Protective effect of a severe internal carotid artery stenosis in a patient with cardiac embolism

Cardioembolic stroke is generally caused by intracranial artery occlusion. Clots may be identified in the intracranial vessels by means of conventional neuroimaging in the acute phase. High-resolution ultrasonography may show some features suggestive of cardiac emboli when occluding extracranial carotid arteries. We describe a patient with cardioembolic ischemic stroke in the right hemisphere in whom a left internal carotid artery stenosis paradoxically protected the ipsilateral hemisphere from distal intracranial embolism. The patient also presented multiple acute ischemic embolic lesions in the right middle cerebral artery territory and in the right occipital lobe, which was fed by the posterior cerebral artery, anomally originating from the right carotid siphon. Interestingly, the left internal carotid artery--which showed a severe preexisting stenosis--was occluded by the cardiac clot, whereas the right internal carotid artery only presented a moderate stenosis that had probably allowed the clots to pass. Therefore, the severe left internal carotid artery stenosis may have blocked the cardiac embolus, preventing it from reaching the ipsilateral hemisphere.

Topiramate modulates habituation in migraine: evidences from nociceptive responses elicited by laser evoked potentials

BACKGROUND

Lack of habituation during repetitive stimulation is the most consistent interictal abnormality of cortical information processing observed in migraine. Preventive migraine treatments might act by stabilizing cortical excitability level and thus the habituation to external stimuli.

METHODS

We examined the effects of preventive treatment with topiramate on migraineur's habituation to nociceptive stimulation. Scalp potentials were evoked by Nd-YAP Laser stimulation of the hand dorsum and supraorbital region in 13 patients with migraine without aura (MO) and 15 healthy volunteers (HV). The exam was repeated in MO before and after treatment.

RESULTS

We observed a lack of habituation and lower initial amplitudes in MO compared to HV. These abnormalities reached statistical significance for N1 LEPs component, generated in the secondary somatosensory cortex (SII), but not for N2/P2 complex, generated in the insula and anterior cingulated cortex (ACC). Topiramate normalized the N1 habituation pattern in MO, with a significant correlation between clinical effects and normalization of neurophysiological responses.

CONCLUSIONS

Our results indicate a modulating action of topiramate on cortical processing of sensorial stimuli, mainly regarding the sensory-discriminative component of pain, elaborated by SII, without a significant effect on the affective dimension of pain, in which the ACC has an important role.