SUNCT syndrome secondary to multiple sclerosis: Not only trigeminal neuralgia.

BACKGROUND: Facial pain in multiple sclerosis is often due to trigeminal neuralgia but atypical pictures can be observed. CASE PRESENTATION: A man with primary progressive multiple sclerosis developed severe unilateral facial pain in the right orbital region. Spontaneous and triggered attacks were associated with ipsilateral conjunctival injection and lacrimation. A diagnosis of short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing was made, and symptoms significantly improved with lamotrigine. CONCLUSION: Pain is poorly investigated in multiple sclerosis, with a dramatic impact on patients' life quality. In this light, standardized evaluation of pain is needed to improve patient management.

Neurophysiological investigations in a case of primary paroxysmal hemicrania-tic syndrome.

BACKGROUND: The association between paroxysmal hemicrania (PH) and trigeminal neuralgia-the so-called PH-tic syndrome-has rarely been described. However, a correct diagnosis is crucial since both disorders require specific treatments. Little is known about pathophysiological mechanisms, and, to date, there are no electrophysiological studies in patients with PH-tic syndrome. CASE: We describe the case of a 52-year-old man with a PH-tic syndrome successfully treated with an association of carbamazepine (1200 mg/day) and indomethacin (150 mg/die). Patient underwent trigeminal reflex testing, including blink and masseter inhibitory reflex, and laser-evoked potential (LEP) recording after supraorbital region stimulation in the affected and unaffected side. Both neurophysiological investigations resulted normal; LEPs failed to detect any latency asymmetry between both sides. CONCLUSIONS: Neurophysiological findings demonstrate for the first time the integrity of somatosensory system in a primary PH-tic syndrome case. Central pathophysiological mechanisms and hypothalamic dysregulation may contribute to the development of this rare syndrome.

The objective assessment of sleep in cluster headache: State of the art and future directions.

Several lines of evidence suggest that cluster headache is related to chronobiology and sleep. Nevertheless, the nature of such a relationship is unclear. In this view, the objective evaluation of sleep in cluster headache has strong theoretical and clinical relevance. Here, we provide an in-depth narrative review of the literature on objective sleep assessment in cluster headache. We found that only a small number of studies (N = 12) focused on this topic. The key research aims were directed to assess: (a) the relationship between cluster headache and sleep breathing disorders; (b) the temporal relationship between sleep stages/events and cluster headache attacks; (c) sleep macrostructure in patients with cluster headache. No studies considered sleep microstructure. The reviewed studies are heterogeneous, conducted by a few research groups, and often characterised by relevant methodological flaws. Results are substantially inconclusive considering the main hypothesis. We outline several methodological points that should be considered for future research, and suggest that evaluating sleep microstructure, local sleep electrophysiology and actigraphic measures may strongly increase knowledge on the relationship between sleep and cluster headache.

Maintenance of response and predictive factors of 1-year GalcanezumAb treatment in real-life migraine patients in Italy: The multicenter prospective cohort GARLIT study.

BACKGROUND AND PURPOSE: To evaluate the 1-year effectiveness and tolerability of galcanezumab in real life and the prognostic indicators of persistent response. METHODS: High-frequency episodic migraine (HFEM) and chronic migraine (CM) patients treated with galcanezumab who completed a 1-year observation were enrolled. The primary outcomes assessed during the 12 months (V1-V12) were the change in monthly migraine days (MMDs) from baseline and the response rates ≥50% in MMDs (MMD ≥50% RR). The secondary outcomes were changes in pain intensity (numerical rating scale [NRS]) and in monthly acute medication intake (MAMI). RESULTS: We enrolled 191 patients (77.5% CM). Twenty-three patients (12%) dropped out, two for nonserious adverse events. At least 40% of patients took add-on standard preventives from baseline to V12. At V12, MMDs were reduced by 6.0 days in HFEM and by 11.9 days in CM patients (both p < 0.00001); NRS and MAMI were also decreased in both groups (p < 0.00001). One-hundred eight (56.5%) patients presented MMD ≥50% RR for 9 cumulative months (interquartile range=8): we defined this value as the cutoff for a persistent response. Persistent responders were less likely to have a higher body mass index (BMI) (p = 0.007) but more frequently had a good response to triptans (p = 0.005) and MMD ≥50% RR at V1 (p < 0.0000001). Patients without a persistent response were on add-on therapy for longer periods of time (p < 0.001). CONCLUSIONS: Galcanezumab was effective and well-tolerated in the 1-year term, with most patients presenting MMD ≥50% RR for at least 9 months. Triptan response, lower BMI, and MMD ≥50% RR in the first month emerged as predictive factors for a persistent response.

Functional connectivity alterations in migraineurs with Alice in Wonderland syndrome.

BACKGROUND AND PURPOSE: Alice in Wonderland syndrome (AIWS) is a neurological disorder characterized by erroneous perception of the body schema or surrounding space. Migraine is the primary cause of AIWS in adults. The pathophysiology of AIWS is largely unknown, especially regarding functional abnormalities. In this study, we compared resting-state functional connectivity (FC) of migraine patients experiencing AIWS, migraine patients with typical aura (MA) and healthy controls (HCs). METHODS: Twelve AIWS, 12 MA, and 24 HCs were enrolled and underwent 3 T MRI scanning. Independent component analysis was used to identify RSNs thought to be relevant for AIWS: visual, salience, basal ganglia, default mode, and executive control networks. Dual regression technique was used to detect between-group differences in RSNs. Finally, AIWS-specific FC alterations were correlated with clinical measures. RESULTS: With respect to HCs, AIWS and MA patients both showed significantly lower (p < 0.05, FDR corrected) FC in lateral and medial visual networks and higher FC in salience and default mode networks. AIWS patients alone showed higher FC in basal ganglia and executive control networks than HCs. When directly compared, AIWS patients showed lower FC in visual networks and higher FC in all other investigated RSNs than MA patients. Lastly, AIWS-specific FC alterations in the executive control network positively correlated with migraine frequency. CONCLUSIONS: AIWS and MA patients showed similar FC alterations in several RSNs, although to a different extent, suggesting common pathophysiological underpinnings. However, AIWS patients showed additional FC alterations, likely due to the complexity of AIWS symptoms involving high-order associative cortical areas.

Alice in Wonderland syndrome: a lesion mapping study.

BACKGROUND AND PURPOSE: Alice in Wonderland syndrome (AIWS) is a rare neurological disorder, characterized by an erroneous perception of the body schema or surrounding space. It may be caused by a variety of neurological disorders, but to date, there is no agreement on which brain areas are affected. The aim of this study was to identify brain areas involved in AIWS. METHODS: We conducted a literature search for AIWS cases following brain lesions. Patients were classified according to their symptoms as type A (somesthetic), type B (visual), or type C (somesthetic and visual). Using a lesion mapping approach, lesions were mapped onto a standard brain template and sites of overlap were identified. RESULTS: Of 30 lesions, maximum spatial overlap was present in six cases. Local maxima were identified in the right occipital lobe, specifically in the extrastriate visual cortices and white matter tracts, including the ventral occipital fasciculus, optic tract, and inferior fronto-occipital fasciculus. Overlap was primarily due to type B patients (the most prevalent type, n = 22), who shared an occipital site of brain damage. Type A (n = 5) and C patients (n = 3) were rarer, with lesions disparately located in the right hemisphere (thalamus, insula, frontal lobe, hippocampal/parahippocampal cortex). CONCLUSIONS: Lesion-associated AIWS in type B patients could be related to brain damage in visual pathways located preferentially, but not exclusively, in the right hemisphere. Conversely, the lesion location disparity in cases with somesthetic symptoms suggests underlying structural/functional disconnections requiring further evaluation.

A Propensity Score Matching Study on the Effect of OnabotulinumtoxinA Alone versus Short-Term Psychodynamic Psychotherapy Plus Drug-of-Choice as Preventive Therapy in Chronic Migraine: Effects and Predictive Factors.

OBJECTIVE: The objective of this study was to test the superiority of multidisciplinary approach, that is, Short-Term Psychodynamic Psychotherapy (STPP) plus drug of choice, versus monotherapy, that is, OnabotulinumtoxinA (OnaBoNT-A). METHOD: We consecutively recorded data from chronic migraine (CM) patients, with or without medication overuse headache (MOH), who underwent STPP or OnaBoNT-A, with a 3-month follow-up schedule. Headache days and analgesics intake were monitored as primary outcome measures. Propensity score matching (PSM) was used to eliminate discrepancies between groups. Discriminant function analysis (DFA) was used to pinpoint predictive factors associated with the clinical response. RESULTS: 96 patients with CM (64% with MOH) were treated with STPP and 54 (59% with MOH) with OnaBoNT-A. At baseline, OnaBoNT-A patients had more failed preventive therapies, more years of illness and chronicity, and were older; STPP patients were more depressed and had a higher HIT-6. Both STPP and OnaBoNT-A patients showed a significant reduction of headache days (STPP: -14 vs. OnaBoNT-A:-14.3) and analgesics intake (STPP: -12,3 vs. OnaBoNT-A -13.5 pills/month), respectively. MOH diminished more in STPP, adherence was higher in OnaBoNT-A. Results were confirmed after PSM balancing of the groups for those variables that resulted as different (but age). CONCLUSION: OnaBoNT-A monotherapy produced similar results to psychotherapy plus medication, after correcting for baseline differences.

A Hypothalamic Mechanism Regulates the Duration of a Migraine Attack: Insights from Microstructural and Temporal Complexity of Cortical Functional Networks Analysis.

The role of the hypothalamus and the limbic system at the onset of a migraine attack has recently received significant interest. We analyzed diffusion tensor imaging (DTI) parameters of the entire hypothalamus and its subregions in 15 patients during a spontaneous migraine attack and in 20 control subjects. We also estimated the non-linear measure resting-state functional MRI BOLD signal's complexity using Higuchi fractal dimension (FD) and correlated DTI/fMRI findings with patients' clinical characteristics. In comparison with healthy controls, patients had significantly altered diffusivity metrics within the hypothalamus, mainly in posterior ROIs, and higher FD values in the salience network (SN). We observed a positive correlation of the hypothalamic axial diffusivity with migraine severity and FD of SN. DTI metrics of bilateral anterior hypothalamus positively correlated with the mean attack duration. Our results show plastic structural changes in the hypothalamus related to the attacks severity and the functional connectivity of the SN involved in the multidimensional neurocognitive processing of pain. Plastic changes to the hypothalamus may play a role in modulating the duration of the attack.

Prevalence and characteristics of Alice in Wonderland Syndrome in adult migraineurs: Perspectives from a tertiary referral headache unit.

BACKGROUND: Migraine affects how the brain processes sensory information at multiple levels. The aberrant integration of visual and somatosensory stimuli is thought to underlie Alice in Wonderland Syndrome, a disorder often reported as being associated with migraine. However, there is still a lack of knowledge about the epidemiology of this syndrome in migraineurs and the association between Alice in Wonderland Syndrome episodes and migraine attacks. Therefore, we conducted a prospective cohort study to systematically evaluate the prevalence and the clinical features of Alice in Wonderland Syndrome in a large sample of patients with migraine. METHODS: All the patients attending for the first time a tertiary-level headache clinic were consecutively screened for Alice in Wonderland Syndrome symptoms by means of an ad hoc questionnaire and detailed clinical interview, over a period of 1.5 years. Patients experiencing Alice in Wonderland Syndrome symptoms were contacted for a follow-up after 8-12 months. RESULTS: Two hundred and ten patients were recruited: 40 patients (19%) reported lifetime occurrence of Alice in Wonderland Syndrome, 90% of whom (38/40) had migraine with aura. Thirty-one patients experienced episodes of Alice in Wonderland Syndrome within 1 h from the start of migraine headache. Patients reported either visual or visual and somatosensory symptoms (i.e. somatosensory symptoms never presented alone). We collected the follow-up details of 30 patients with Alice in Wonderland Syndrome, 18 of whom had been prescribed a preventive treatment for migraine. After 8-12 months, 5 of the treated patients reported a decrease, while 13 reported no episodes of Alice in Wonderland Syndrome. CONCLUSION: Alice in Wonderland Syndrome prevalence in migraineurs was found to be higher than expected. Alice in Wonderland Syndrome was mostly associated with migraine with aura and tended to occur close to the migraine attack, suggesting the existence of a common pathophysiological mechanism. Patients treated with migraine preventive treatments had a higher chance of decreasing or even resolving Alice in Wonderland Syndrome episodes.

Thalamo-cortical networks in subtypes of migraine with aura patients.

BACKGROUND: We searched for differences in resting-state functional connectivity (FC) between brain networks and its relationship with the microstructure of the thalamus between migraine with pure visual auras (MA), and migraine with complex neurological auras (MA+), i.e. with the addition of at least one of sensory or language symptom. METHODS: 3T MRI data were obtained from 20 patients with MA and 15 with MA + and compared with those from 19 healthy controls (HCs). We collected resting state data among independent component networks. Diffusivity metrics of bilateral thalami were calculated and correlated with resting state ICs-Z-scores. RESULTS: As compared to HCs, both patients with MA and MA + disclosed disrupted FC between the default mode network (DMN) and the right dorsal attention system (DAS). The MA + subgroup had lower microstructural metrics than both HCs and the MA subgroup, which correlated negatively with the strength of DMN connectivity. Although the microstructural metrics of MA patients did not differ from those of HCs, these patients lacked the correlation with the strength of DAS connectivity found in HCs. CONCLUSIONS: The present findings suggest that, as far as MRI profiles are concerned, the two clinical phenotypes of migraine with aura have both common and distinct morpho-functional features of nodes in the thalamo-cortical network.

Cognitive Performance in Relapsing-Remitting Multiple Sclerosis: At Risk or Impaired?

INTRODUCTION: Since cognitive impairment (CI) occurs on average in 45% of multiple sclerosis (MS) patients, the early detection of patients "at risk" of CI is important in order to promptly apply preventive strategies. The aim of the present study was to investigate the prevalence and risk factors for CI in MS patients using the Brief International Cognitive Assessment for Multiple Sclerosis (BICAMS) as a screening test. METHODS: During the 1-year period, CI was evaluated in 82 consecutives mild relapsing-remitting MS (EDSS ≤ 3.5) patients. Patients with 1 altered BICAMS test were defined "at risk." Both "at risk" and CI patients underwent an extensive neuropsychological battery. RESULTS: We found that: (i) 23% had CI, (ii), 25% were "at risk" of CI, and (iii) 76% of the "at risk" patients were already impaired at the NP assessment. In particular, the Symbol Digit Modalities Test was the most compromised (70% of "at risk" and 79% of CI patients). Patients with CI had more frequently an EDSS ≥ 2.5 (p = 0.05), lower education (p = 0.05), and relapses in the last 12 months (p = 0.03). CONCLUSIONS: CI is a significant issue in MS and integration of a screening test, such as the SDMT, into routine clinical practice could be of worth to identify "at risk" patients and to promote an early therapeutic intervention.

Promoting post-stroke recovery through focal or whole body vibration: criticisms and prospects from a narrative review.

OBJECTIVE: Several focal muscle vibration (fMV) and whole body vibration (WBV) protocols have been designed to promote brain reorganization processes in patients with stroke. However, whether fMV and WBV should be considered helpful tools to promote post-stroke recovery remains still largely unclear. METHODS: We here achieve a comprehensive review of the application of fMV and WBV to promote brain reorganization processes in patients with stroke. By first discussing the putative physiological basis of fMV and WBV and then examining previous observations achieved in recent randomized controlled trials (RCT) in patients with stroke, we critically discuss possible strength and limitations of the currently available data. RESULTS: We provide the first systematic assessment of fMV studies demonstrating some improvement in upper and lower limb functions, in patients with chronic stroke. We also confirm and expand previous considerations about the rather limited rationale for the application of current WBV protocols in patients with chronic stroke. CONCLUSION: Based on available information, we propose new recommendations for optimal stimulation parameters and strategies for recruitment of specific stroke populations that would more likely benefit from future fMV or WBV application, in terms of speed and amount of post-stroke functional recovery.

A Study of Clinical Features and Risk Factors of Self-Referring Emergency Department Headache Patients: A Comparison with Headache Center Outpatients.

BACKGROUND: Nonlife-threatening headaches account for 3% of emergency department (ED) admissions, with social and economic negative consequences. We aim to investigate clinical features and risk factors of nonlife-threatening headache patients referring to ED versus those referring to headache outpatient clinics. METHODS: During 6 months, we promptly reevaluated in our headache unit (HU) patients discharged from ED. We compared the clinical characteristics of patients who referred to ED with those of HU outpatients visited in the same time interval. Discriminant Function Analysis and Correspondence Analysis were used to determine risk factors for ED referral. RESULTS: We recruited 49 post-ED patients and 126 outpatients. The main reasons for ED admission were poor response to acute treatment and aura-related symptoms. Headache diagnoses made in ED were generally not confirmed later (overall concordance of 47%), except for cluster headache (CH) and migraine with aura (MA). ED patients complained higher headache intensity, longer duration, and prolonged aura compared to outpatients. Aura was the main risk factor associated with ED admission on statistical models, while less prominent risk factors were sex, age, and years from migraine onset. CONCLUSIONS: ED patients presented a more severe headache clinical phenotype compared with outpatients. Headache diagnosis remains difficult in the emergency setting and is more easily achieved for the headache forms with standout features, such as MA or CH. According to statistical models, the aura is the most important risk factor for ED admissions.

Haemodynamic activity characterization of resting state networks by fractal analysis and thalamocortical morphofunctional integrity in chronic migraine.

BACKGROUND: Chronic migraine (CM) can be associated with aberrant long-range connectivity of MRI-derived resting-state networks (RSNs). Here, we investigated how the fractal dimension (FD) of blood oxygenation level dependent (BOLD) activity may be used to estimate the complexity of RSNs, reflecting flexibility and/or efficiency in information processing in CM patients respect to healthy controls (HC). METHODS: Resting-state MRI data were collected from 20 untreated CM without history of medication overuse and 20 HC. On both groups, we estimated the Higuchi's FD. On the same subjects, fractional anisotropy (FA) and mean diffusivity (MD) values of bilateral thalami were retrieved from diffusion tensor imaging and correlated with the FD values. RESULTS: CM showed higher FD values within dorsal attention system (DAS) and the anterior part of default-mode network (DMN), and lower FD values within the posterior DMN compared to HC. Although FA and MD were within the range of normality, both correlated with the FD values of DAS. CONCLUSIONS: FD of DAS and DMN may reflect disruption of cognitive control of pain in CM. Since the normal microstructure of the thalamus and its positive connectivity with the cortical networking found in our CM patients reminds similar results obtained assessing the same structures but with the methods of neurophysiology, in episodic migraine during an attack, this may be yet another evidence in supporting CM as a never-ending migraine attack.

Patients with chronic migraine without history of medication overuse are characterized by a peculiar white matter fiber bundle profile.

BACKGROUND: We investigated intracerebral fiber bundles using a tract-based spatial statistics (TBSS) analysis of diffusion tensor imaging (DTI) data to verify microstructural integrity in patients with episodic (MO) and chronic migraine (CM). METHODS: We performed DTI in 19 patients with MO within interictal periods, 18 patients with CM without any history of drug abuse, and 18 healthy controls (HCs) using a 3 T magnetic resonance imaging scanner. We calculated diffusion metrics, including fractional anisotropy (FA), axial diffusion (AD), radial diffusion (RD), and mean diffusion (MD). RESULTS: TBSS revealed no significant differences in the FA, MD, RD, and AD maps between the MO and HC groups. In comparison to the HC group, the CM group exhibited widespread increased RD (bilateral superior [SCR] and posterior corona radiata [PCR], bilateral genu of the corpus callosum [CC], bilateral posterior limb of internal capsule [IC], bilateral superior longitudinal fasciculus [LF]) and MD values (tracts of the right SCR and PCR, right superior LF, and right splenium of the CC). In comparison to the MO group, the CM group showed decreased FA (bilateral SCR and PCR, bilateral body of CC, right superior LF, right forceps minor) and increased MD values (bilateral SCR and right PCR, right body of CC, right superior LF, right splenium of CC, and right posterior limb of IC). CONCLUSION: Our results suggest that chronic migraine can be associated with the widespread disruption of normal white matter integrity in the brain.

Did Going North Give Us Migraine? An Evolutionary Approach on Understanding Latitudinal Differences in Migraine Epidemiology.

This commentary discusses a recent publication by evolutionary biologists with strong implications for migraine experts. The Authors showed that a gene polymorphism associated with migraine gave our ancestors an evolutionary advantage when colonizing northern, and thus colder, territories. They then highlight that the prevalence of migraine may differ among countries because of climatic adaptation. These results may prove useful in planning both epidemiological and physiological studies in the field of migraine.

Migrainous Infarction in a Patient With Sporadic Hemiplegic Migraine and Cystic Fibrosis: A 99mTc-HMPAO Brain SPECT Study.

Genetic mutations of sporadic hemiplegic migraine (SHM) are mostly unknown. SHM pathophysiology relies on cortical spreading depression (CSD), which might be responsible for ischemic brain infarction. Cystic fibrosis (CF) is caused by a monogenic mutation of the chlorine transmembrane conductance regulator (CFTR), possibly altering brain excitability. We describe the case of a patient with CF, who had a migrainous stroke during an SHM attack. A 32-year-old Caucasian male was diagnosed with CF, with heterozygotic delta F508/unknown CFTR mutation. The patient experiences bouts of coughing sometimes triggering SHM attacks with visual phosphenes, aphasia, right-sided paresthesia, and hemiparesis. He had a 48-hour hemiparesis triggered by a bout of coughing with hemoptysis, loss of consciousness, and severe hypoxia-hypercapnia. MRI demonstrated transient diffusion hyperintensity in the left frontal-parietal-occipital regions resulting in a permanent infarction in the primary motor area. Later, a brain perfusion SPECT showed persistent diffuse hypoperfusion in the territories involved in diffusion-weighted imaging alteration. Migrainous infarction, depending on the co-occurrence of 2 strictly related phenomena, CSD and hypoxia, appears to be the most plausible explanation. Brain SPECT hypoperfusion suggests a more extensive permanent neuronal loss in territories affected by aura. CF may be then a risk factor for hemiplegic migraine and stroke since bouts of coughing can facilitate brain hypoxia, triggering auras.

GEN-O-MA project: an Italian network studying clinical course and pathogenic pathways of moyamoya disease-study protocol and preliminary results.

BACKGROUND: GENetics of mOyaMoyA (GEN-O-MA) project is a multicenter observational study implemented in Italy aimed at creating a network of centers involved in moyamoya angiopathy (MA) care and research and at collecting a large series and bio-repository of MA patients, finally aimed at describing the disease phenotype and clinical course as well as at identifying biological or cellular markers for disease progression. The present paper resumes the most important study methodological issues and preliminary results. METHODS: Nineteen centers are participating to the study. Patients with both bilateral and unilateral radiologically defined MA are included in the study. For each patient, detailed demographic and clinical as well as neuroimaging data are being collected. When available, biological samples (blood, DNA, CSF, middle cerebral artery samples) are being also collected for biological and cellular studies. RESULTS: Ninety-eight patients (age of onset mean ± SD 35.5 ± 19.6 years; 68.4% females) have been collected so far. 65.3% of patients presented ischemic (50%) and haemorrhagic (15.3%) stroke. A higher female predominance concomitantly with a similar age of onset and clinical features to what was reported in previous studies on Western patients has been confirmed. CONCLUSION: An accurate and detailed clinical and neuroimaging classification represents the best strategy to provide the characterization of the disease phenotype and clinical course. The collection of a large number of biological samples will permit the identification of biological markers and genetic factors associated with the disease susceptibility in Italy.

Temporal-occipital glioblastoma presenting with Alice in Wonderland Syndrome in a patient with a long-time history of migraine without aura.

Alice in Wonderland Syndrome (AIWS) is a rare perceptual disorder characterized by an erroneous perception of the body or the surrounding space. AIWS may be caused by different pathologies, ranging from infections to migraine. We present the case of a 54-year-old man, with a long-time history of migraine without aura, diagnosed with AIWS due to a glioblastoma located in the left temporal-occipital junction. To date, this is the first case of AIWS caused by glioblastoma. This case suggests that to exclude aura-mimic phenomena, a careful diagnostic workup should always be performed even in patients with a long-time history of migraine.

Neurophysiological correlates of clinical improvement after greater occipital nerve (GON) block in chronic migraine: relevance for chronic migraine pathophysiology.

BACKGROUND: Therapeutic management of Chronic Migraine (CM), often associated with Medication Overuse Headache (MOH), is chiefly empirical, as no biomarker predicting or correlating with clinical efficacy is available to address therapeutic choices. The present study searched for neurophysiological correlates of Greater Occipital Nerve Block (GON-B) effects in CM. METHODS: We recruited 17 CM women, of whom 12 with MOH, and 19 healthy volunteers (HV). Patients had no preventive treatment since at least 3 months. After a 30-day baseline, they received a bilateral betamethasone-lidocaine GON-B of which the therapeutic effect was assessed 1 month later. Habituation of visual evoked potentials (VEP) and intensity dependence of auditory evoked potentials (IDAP) were recorded before and 1 week after the GON-B. RESULTS: At baseline, CM patients had a VEP habituation not different from HV, but a steeper IDAP value than HV (p = 0.01), suggestive of a lower serotonergic tone. GON-B significantly reduced the number of total headache days per month (- 34.9%; p = 0.003). Eight out 17CM patients reversed to episodic migraine and medication overuse resolved in 11 out of 12 patients. One week after the GON-B VEP habituation became lacking respect to baseline (p = 0.01) and to that of HV (p = 0.02) like in episodic migraine, while the IDAP slope significantly flattened (p < 0.0001). GON-B-induced reduction in headache days positively correlated with IDAP slope decrease (rho = 0.51, p = 0.03). CONCLUSIONS: GON-B may be effective in the treatment of CM, with or without MOH. The pre-treatment IDAP increase is compatible with a weak central serotonergic tone, which is strengthened after GON-B, suggesting that serotonergic mechanisms may play a role in CM and its reversion to episodic migraine. Since the degree of post-treatment IDAP decrease is correlated with clinical improvement, IDAP might be potentially useful as an early predictor of GON-B efficacy.