Clinical and neuroimaging evidence of interictal cerebellar dysfunction in FHM2

A study on the correlation of the asymmetric regulation between the periaqueductal gray and the bilateral trigeminal nucleus caudalis in migraine male rats

BACKGROUND

The study was designed to explore the correlation of the asymmetric regulation between periaqueductal gray (PAG) and bilateral trigeminal nucleus caudalis (TNC) in migraine rats through studying the changes of metabolites in pain regulatory pathway of acute migraine attack.

METHODS

Thirty male Sprague-Dawley (SD) rats were randomly divided into three groups: blank, control, model groups. Then, blank group was intraperitoneally injected with ultrapure water, while control group injected with saline and model group injected with Glyceryl Trinitrate (GTN). Two hours later, PAG and bilateral TNC were removed respectively, and metabolite concentrations of PAG, Left-TNC, Right-TNC were obtained. Lastly, the differences of metabolite among three brain tissues were compared.

RESULTS

The relative concentrations of rNAA, rGlu, rGln, rTau, rMI in PAG or bilateral TNC had interaction effects between groups and sites. The concentration of rLac of three brain tissues increased in migraine rats, however, the rLac of LTNC and RTNC increased more than that of PAG. Besides, the concentrations of rNAA and rGln increased in RTNC, while rGABA decreased in RTNC.

CONCLUSIONS

There is correlation between PAG, LTNC and RTNC in regulation of pain during acute migraine attack, and the regulation of LTNC and RTNC on pain is asymmetric.

Alterations in metabolic flux in migraine and the translational relevance

BACKGROUND

Migraine is a highly prevalent disorder with significant economical and personal burden. Despite the development of effective therapeutics, the causes which precipitate migraine attacks remain elusive. Clinical studies have highlighted altered metabolic flux and mitochondrial function in patients. In vivo animal experiments can allude to the metabolic mechanisms which may underlie migraine susceptibility. Understanding the translational relevance of these studies are important to identifying triggers, biomarkers and therapeutic targets in migraine.

MAIN BODY

Functional imaging studies have suggested that migraineurs feature metabolic syndrome, exhibiting hallmark features including upregulated oxidative phosphorylation yet depleted available free energy. Glucose hypometabolism is also evident in migraine patients and can lead to altered neuronal hyperexcitability such as the incidence of cortical spreading depression (CSD). The association between obesity and increased risk, frequency and worse prognosis of migraine also highlights lipid dysregulation in migraine pathology. Calcitonin gene related peptide (CGRP) has demonstrated an important role in sensitisation and nociception in headache, however its role in metabolic regulation in connection with migraine has not been thoroughly explored. Whether impaired metabolic function leads to increased release of peptides such as CGRP or excessive nociception leads to altered flux is yet unknown.

CONCLUSION

Migraine susceptibility may be underpinned by impaired metabolism resulting in depleted energy stores and altered neuronal function. This review discusses both clinical and in vivo studies which provide evidence of altered metabolic flux which contribute toward pathophysiology. It also reviews the translational relevance of animal studies in identifying targets of biomarker or therapeutic development.

The Role of Metabolism in Migraine Pathophysiology and Susceptibility

Migraine is a highly prevalent and disabling primary headache disorder, however its pathophysiology remains unclear, hindering successful treatment. A number of key secondary headache disorders have headaches that mimic migraine. Evidence has suggested a role of mitochondrial dysfunction and an imbalance between energetic supply and demand that may contribute towards migraine susceptibility. Targeting these deficits with nutraceutical supplementation may provide an additional adjunctive therapy. Neuroimaging techniques have demonstrated a metabolic phenotype in migraine similar to mitochondrial cytopathies, featuring reduced free energy availability and increased metabolic rate. This is reciprocated in vivo when modelling a fundamental mechanism of migraine aura, cortical spreading depression. Trials assessing nutraceuticals successful in the treatment of mitochondrial cytopathies including magnesium, coenzyme q10 and riboflavin have also been conducted in migraine. Although promising results have emerged from nutraceutical trials in patients with levels of minerals or vitamins below a critical threshold, they are confounded by lacking control groups or cohorts that are not large enough to be representative. Energetic imbalance in migraine may be relevant in driving the tissue towards maximum metabolic capacity, leaving the brain lacking in free energy. Personalised medicine considering an individual's deficiencies may provide an approach to ameliorate migraine.

Functional and structural alterations in the migraine cerebellum

The cerebellum plays an important role in pain processing but its function in headache and specifically in migraine is not known. We therefore compared 54 migraineurs with pairwise matched healthy controls in a magnetic resonance imaging study on neuronal cerebellar activity in response to nociceptive trigeminal sensation and also investigated possible structural alterations. Headache frequency, disease duration, and the proximity to a migraine attack were used as co-factors. Migraine patients showed functional and structural alterations in the posterior part of the cerebellum, namely crus I and crus II. Gray matter volume changes were seen on the right side whereas functional changes were ipsilateral to the stimulation, on the left side. Neuronal activity in the crus in response to trigeminal pain was modulated by migraine severity and the migraine phase. As the crus is strongly interconnected to higher cognitive areas in the temporal, frontal, and parietal part of the cortex our results suggest an specific cerebellar involvement in migraine. This is further supported by our finding of decreased connectivity from the crus to the thalamus and higher cortical areas in the patients. We therefore suggest an abnormally decreased inhibitory involvement of the migraine cerebellum on gating and nociceptive evaluation.

Metabolic assessment of a migraine model using relaxation-enhanced 1 H spectroscopy at ultrahigh field

PURPOSE

This study evaluates biochemical imbalances in a rat model that reflects dysfunctional pathways in migraine. The high sensitivity and spectral dispersion available to 1 H MRS at 21.1 T expands metabolic profiling in this migraine model to include lactate (Lac), taurine (Tau), aspartate, and Gly-a mixture of glycine, glutamine, and glutamate.

METHODS

Sprague-Dawley male rats were administered in situ an intraperitoneal injection of nitroglycerin (NTG) to induce the migraine analogue or saline as a control. A selective relaxation-enhanced MR spectroscopy sequence was used to target upfield metabolites from a 4-mm3 voxel for 2.5 h after injection.

RESULTS

Significant increases were evident for Lac as early as 10 min after NTG injection, peaking over 50% compared with baseline and control (normalized Lac/N-acetyl aspartate with NTG = 1.54 ± 0.65 versus with saline = 0.99 ± 0.08). Tau decreased progressively in controls over 2 h after injection, but remained elevated with NTG, peaking at 105 min after injection (normalized Tau/N-acetyl aspartate with NTG = 1.10 ± 0.18 versus with saline = 0.85 ± 0.14). Total creatine under NTG showed significant decreases with time and compared with saline; Gly demonstrated temporal increases for NTG.

CONCLUSIONS

These changes indicate an altered metabolic profile in the migraine analogue consistent with early changes in neural activity and/or vasodilation consistent with progressively enhanced neuroprotection and osmoregulation. Magn Reson Med 79:1266-1275, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Mitochondrial dysfunction in myotonic dystrophy type 1

The pathophysiological mechanism linking the nucleotide expansion in the DMPK gene to the clinical manifestations of myotonic dystrophy type 1 (DM1) is still unclear. In vitro studies demonstrate DMPK involvement in the redox homeostasis of cells and the mitochondrial dysfunction in DM1, but in vivo investigations of oxidative metabolism in skeletal muscle have provided ambiguous results and have never been performed in the brain. Twenty-five DM1 patients (14M, 39 ± 11years) underwent brain proton MR spectroscopy (¹H-MRS), and sixteen cases (9M, 40 ± 13 years old) also calf muscle phosphorus MRS (³¹P-MRS). Findings were compared to those of sex- and age-matched controls. Eight DM1 patients showed pathological increase of brain lactate and, compared to those without, had larger lateral ventricles (p < 0.01), smaller gray matter volumes (p < 0.05) and higher white matter lesion load (p < 0.05). A reduction of phosphocreatine/inorganic phosphate (p < 0.001) at rest and, at first minute of exercise, a lower [phosphocreatine] (p = 0.003) and greater [ADP] (p = 0.004) were found in DM1 patients compared to controls. The post-exercise indices of muscle oxidative metabolism were all impaired in DM1, including the increase of time constant of phosphocreatine resynthesis (TC PCr, p = 0.038) and the reduction of the maximum rate of mitochondrial ATP synthesis (p = 0.033). TC PCr values correlated with the myotonic area score (ρ = 0.74, p = 0.01) indicating higher impairment of muscle oxidative metabolism in clinically more affected patients. Our findings provide clear in vivo evidence of multisystem impairment of oxidative metabolism in DM1 patients, providing a rationale for targeted treatment enhancing energy metabolism.

Amplitude of low-frequency fluctuation (ALFF) and fractional ALFF in migraine patients: a resting-state functional MRI study

AIM

To evaluate the amplitude of low-frequency oscillations (LFOs) of the brain in migraine patients using amplitude of low-frequency fluctuation (ALFF) and fractional ALFF in the interictal period, in comparison to healthy controls (HCs).

MATERIALS AND METHODS

A total of 54 subjects, including 30 migraineurs and 24 gender- and age-matched HCs completed the fMRI. All the data and ALFF, fALFF analyses were preprocessed with the Data Processing Assistant for Resting-State fMRI (DPARSF). All of the statistical analyses were performed using the REST software to explore the differences in ALFF and fALFF between migraine patients and HCs.

RESULTS

In contrast to HCs, migraine patients showed significant ALFF increase in the left medulla and pons, the bilateral cerebellum posterior lobe and right insula. The regions showing decreased ALFF in migraine patients included the bilateral cerebellum posterior lobe, left cerebellum anterior lobe, bilateral orbital cortex, right middle frontal gyrus, bilateral occipital lobe, right fusiform gyrus, and bilateral postcentral gyrus. The fALFFs in migraine patients were significantly increased in the bilateral insular and left orbital cortex, but were decreased in the left occipital lobe and bilateral cerebellum posterior lobe.

CONCLUSION

These ALFF and fALFF alterations in the brain regions of migraineurs are in keeping with the domains associated with pain and cognition. Such brain functional alteration may contribute to further understanding of migraine-related network imbalances demonstrated in previous studies.

Brain magnetic resonance metabolic and microstructural changes in adult-onset autosomal dominant leukodystrophy

INTRODUCTION

adult-onset autosomal dominant leukodystrophy (ADLD) is a rare inherited disorder due to a duplication of lamin-B1 (LMNB1) gene. The aim of this study was to investigate brain metabolic and microstructural alterations by using advanced MR techniques.

METHODS

we performed brain MR scans including single-voxel proton-MR Spectroscopy ((1)H-MRS) of the lateral ventricles and parietal white matter and diffusion tensor imaging (DTI) in 4 subjects with LMNB1 gene duplication, 6 non-mutated relatives and 7 unrelated healthy controls. Cervical and thoracic spinal cord MR was performed in three symptomatic subjects with LMNB1 mutation. All participants underwent clinical and neuropsychological evaluation.

RESULTS

all subjects with LMNB1 gene duplication presented pathological accumulation of lactate in lateral ventricles CSF and no alterations of brain white matter absolute metabolites concentrations or metabolites/Cr ratios. We found increased white matter intra- and extracellular water transverse relaxation times. Tract-based spatial statistics analysis detected a significantly reduced fractional anisotropy in the genu of the corpus callosum in mutated cases compared to unrelated healthy controls and non-mutated relatives. Moreover, we detected different degrees of the typical white matter signal intensity alterations and brain and spinal atrophy at conventional MRI in symptomatic subjects with LMNB1 mutation. A mild impairment of executive functions was found in subjects with LMNB1 gene mutation.

CONCLUSION

in subjects with LMNB1 gene duplication, we found a pathological increase in CSF lactate, likely due to active demyelination along with glial activation, and microstructural changes in the genu of the corpus callosum possibly underpinning the mild neuropsychological deficits.

Biochemical changes in the brain of hemiplegic migraine patients measured with 7 tesla 1H-MRS

AIM

The aim of this study was to assess biochemical changes in the brain of patients with hemiplegic migraine in between attacks.

METHODS

Eighteen patients with hemiplegic migraine (M:F, 7:11; age 38 ± 14 years) of whom eight had a known familial hemiplegic migraine (FHM) mutation (five in the CACNA1A gene (FHM1), three in the ATP1A2 gene (FHM2)) and 19 age- and sex-matched healthy controls (M:F, 7:12; mean age 38 ± 12 years) were studied. We used single-voxel 7 tesla (1)H-MRS (STEAM, TR/TM/TE = 2000/19/21 ms) to investigate four brain regions in between attacks: cerebellum, hypothalamus, occipital lobe, and pons.

RESULTS

Patients with hemiplegic migraine showed a significantly lower total N-acetylaspartate/total creatine ratio (tNAA/tCre) in the cerebellum (median 0.73, range 0.59-1.03) than healthy controls (median 0.79, range (0.67-0.95); p = 0.02). In FHM1 patients with a CACNA1A mutation, the tNAA/tCre was lowest.

DISCUSSION

We found a decreased cerebellar tNAA/tCre ratio that might serve as an early biomarker for neuronal dysfunction and/or loss. This is the first high-spectral resolution 7 tesla (1)H-MRS study of interictal biochemical brain changes in hemiplegic migraine patients.

Cybrid studies establish the causal link between the mtDNA m.3890G>A/MT-ND1 mutation and optic atrophy with bilateral brainstem lesions

Complex I (CI) deficiency is a frequent cause of mitochondrial disorders and, in most cases, is due to mutations in CI subunit genes encoded by mitochondrial DNA (mtDNA). In this study, we establish the pathogenic role of the heteroplasmic mtDNA m.3890G>A/MT-ND1 (p.R195Q) mutation, which affects an extremely conserved amino acid position in ND1 subunit of CI. This mutation was found in a young-adult male with optic atrophy resembling Leber's hereditary optic neuropathy (LHON) and bilateral brainstem lesions. The only previously reported case with this mutation was a girl with fatal infantile Leigh syndrome with bilateral brainstem lesions. Transfer of the mutant mtDNA in the cybrid cell system resulted in a marked reduction of CI activity and CI-dependent ATP synthesis in the presence of a normally assembled enzyme.

These findings establish the pathogenicity of the m.3890G>A/MT-ND1 mutation and remark the link between CI mutations affecting the mtDNA-encoded ND subunits and LHON-like optic atrophy, which may be complicated by bilateral and symmetric lesions affecting the central nervous system. Peculiar to this mutation is the distribution of the brainstem lesions, with sparing of the striatum in both patients.

Magnetic resonance spectroscopy in migraine: what have we learned so far?

OBJECTIVE

To summarize and evaluate proton ((1)H) and phosphorus ((31)P) magnetic resonance spectroscopy (MRS) findings in migraine.

METHODS

A thorough review of (1)H and/or (31)P-MRS studies in any form of migraine published up to September 2011.

RESULTS

Some findings were consistent in all studies, such as a lack of ictal/interictal brain pH change and a disturbed energy metabolism, the latter of which is reflected in a drop in phosphocreatine content, both in the resting brain and in muscle following exercise. In a recent interictal study ATP was found to be significantly decreased in the occipital lobe of migraine with aura patients, reinforcing the concept of a mitochondrial component to the migraine threshold, at least in a subgroup of patients. In several studies a correlation between the extent of the energy disturbance and the clinical phenotype severity was apparent. Less consistent but still congruent with a disturbed energy metabolism is an observed lactate increase in the occipital cortex of several migraine subtypes (MwA, migraine with prolonged aura). No increases in brain glutamate levels were found.

CONCLUSION

The combined abnormalities found in MRS studies imply a mitochondrial component in migraine neurobiology. This could be due to a primary mitochondrial dysfunction or be secondary to, for example, alterations in brain excitability. The extent of variation in the data can be attributed to both the variable clinical inclusion criteria used and the variation in applied methodology. Therefore it is necessary to continue to optimize MRS methodology to gain further insights, especially concerning lactate and glutamate.

Migraine- and dystonia-related disease-mutations of Na+/K+-ATPases: relevance of behavioral studies in mice to disease symptoms and neurological manifestations in humans

The two autosomal dominantly inherited neurological diseases: familial hemiplegic migraine type 2 (FHM2) and familial rapid-onset of dystonia-parkinsonism (Familial RDP) are caused by in vivo mutations of specific alpha subunits of the sodium-potassium pump (Na(+)/K(+)-ATPase). Intriguingly, patients with classical FHM2 and RDP symptoms additionally suffer from other manifestations, such as epilepsy/seizures and developmental disabilities. Recent studies of FHM2 and RDP mouse models provide valuable tools for dissecting the vital roles of the Na(+)/K(+)-ATPases, and we discuss their relevance to the complex patient symptoms and manifestations. Thus, it is interesting that mouse models targeting a specific α-isoform cause different, although still comparable, phenotypes consistent with classical symptoms and other manifestations observed in FHM2 and RDP patients. This review highlights that use of mouse models have broad potentials for future research concerning migraine and dystonia-related diseases, which will contribute towards understanding the, yet unknown, pathophysiologies.

Does visual cortex lactate increase following photic stimulation in migraine without aura patients? A functional (1)H-MRS study

Proton magnetic resonance spectroscopy ((1)H-MRS) has been used in a number of studies to assess noninvasively the temporal changes of lactate (Lac) in the activated human brain. Migraine neurobiology involves lack of cortical habituation to repetitive stimuli and a mitochondrial component has been put forward. Our group has recently demonstrated a reduction in the high-energy phosphates adenosine triphosphate (ATP) and phosphocreatine (PCr) in the occipital lobe of migraine without aura (MwoA) patients, at least in a subgroup, in a phosphorus MRS ((31)P-MRS) study. In previous studies, basal Lac levels or photic stimulation (PS)-induced Lac levels were found to be increased in patients with migraine with aura (MwA) and migraine patients with visual symptoms and paraesthesia, paresia and/or dysphasia, respectively. The aim of this study was to perform functional (1)H-MRS at 3 T in 20 MwoA patients and 20 control subjects. Repetitive visual stimulation was applied using MR-compatible goggles with 8 Hz checkerboard stimulation during 12 min. We did not observe any significant differences in signal integrals, ratios and absolute metabolite concentrations, including Lac, between MwoA patients and controls before PS. Lac also did not increase significantly during and following PS, both for MwoA patients and controls. Subtle Lac changes, smaller than the sensitivity threshold (i.e. estimated at 0.1-0.2 μmol/g at 3 T), cannot be detected by MRS. Our study does, however, argue against a significant switch to non-aerobic glucose metabolism during long-lasting PS of the visual cortex in MwoA patients.

A new Italian FHM2 family: clinical aspects and functional analysis of the disease-associated mutation

OBJECTIVE

To describe a new FHM kindred, and to analyse the functional consequences of the disease-associated ATP1A2 p.G301R mutation in human cellular models grown at 37°C.

PATIENTS AND METHODS

Seven patients were clinically evaluated and gave informed consent for molecular analysis. Extra-pyramidal rigidity of the limbs was present in four subjects and in three of them tongue apraxia was also observed. ATP1A2 and CACNA1A were analysed by direct sequencing. Functional consequences of the mutation were investigated by cell viability assays, Western blots, and immunocytochemistry. Three-dimensional models of the human Na(+)/K(+)-ATPase α2 subunit were generated by homology modelling using SWISS-MODEL.

FINDINGS

Analysis of ATP1A2 showed a heterozygous mutation, c.901G>A predicting the replacement of arginine for glycine at residue 301 (p.G301R). Functional analysis suggested that the mutation completely abolished Na(+)/K(+)-ATPase function.

CONCLUSIONS

The phenotypic spectrum of our FHM2 family includes some peculiar features. Functional data confirm that Na(+)/K(+)-ATPase haploinsufficiency caused by the ATP1A2 p.G301R mutation is responsible for FHM in the described family.

(1)H-MRS of brain metabolites in migraine without aura: absolute quantification using the phantom replacement technique

OBJECTIVE

Several studies have demonstrated differences in migraine patients when performing (1)H-MRS; however, no studies have performed (1)H-MRS in migraine without aura (MwoA), the most common migraine subtype. The aim of this (1)H-MRS study was to elucidate whether any differences could be found between MwoA patients and controls by performing absolute quantification.

MATERIALS AND METHODS

(1)H-MRS was performed in 22 MwoA patients and 25 control subjects. Absolute quantification was based on the phantom replacement technique. Corrections were made for T (1) and T (2) relaxation effects, CSF content, coil loading and temperature. The method was validated by phantom measurements and in vivo measurements in the occipital visual cortex.

RESULTS

After calibration of the quantification procedure and the implementation of the required correction factors, measured absolute concentrations in the visual cortex of MwoA patients showed no significant differences compared to controls, in contrast to relative results obtained in earlier studies.

CONCLUSION

In this study, we demonstrate the implementation of quantitative in vivo (1)H-MRS spectroscopy in migraine patients. Despite rigorous quantification, no spectroscopic abnormalities could be found in patients with migraine without aura.