Time-dependent recovery of brain hypometabolism in neuro-COVID-19 patients.

PURPOSE: We evaluated brain metabolic dysfunctions and associations with neurological and biological parameters in acute, subacute and chronic COVID-19 phases to provide deeper insights into the pathophysiology of the disease. METHODS: Twenty-six patients with neurological symptoms (neuro-COVID-19) and [18F]FDG-PET were included. Seven patients were acute (< 1 month (m) after onset), 12 subacute (4 ≥ 1-m, 4 ≥ 2-m and 4 ≥ 3-m) and 7 with neuro-post-COVID-19 (3 ≥ 5-m and 4 ≥ 7-9-m). One patient was evaluated longitudinally (acute and 5-m). Brain hypo- and hypermetabolism were analysed at single-subject and group levels. Correlations between severity/extent of brain hypo- and hypermetabolism and biological (oxygen saturation and C-reactive protein) and clinical variables (global cognition and Body Mass Index) were assessed. RESULTS: The "fronto-insular cortex" emerged as the hypometabolic hallmark of neuro-COVID-19. Acute patients showed the most severe hypometabolism affecting several cortical regions. Three-m and 5-m patients showed a progressive reduction of hypometabolism, with limited frontal clusters. After 7-9 months, no brain hypometabolism was detected. The patient evaluated longitudinally showed a diffuse brain hypometabolism in the acute phase, almost recovered after 5 months. Brain hypometabolism correlated with cognitive dysfunction, low blood saturation and high inflammatory status. Hypermetabolism in the brainstem, cerebellum, hippocampus and amygdala persisted over time and correlated with inflammation status. CONCLUSION: Synergistic effects of systemic virus-mediated inflammation and transient hypoxia yield a dysfunction of the fronto-insular cortex, a signature of CNS involvement in neuro-COVID-19. This brain dysfunction is likely to be transient and almost reversible. The long-lasting brain hypermetabolism seems to reflect persistent inflammation processes.

Impulsivity traits and awareness of motor intention in Parkinson's disease: a proof-of-concept study.

INTRODUCTION: In patients with Parkinson's disease (PD), impulsivity is still a matter of investigation. It has been hypothesized that impulsive personality traits may favour impulse control disorder (ICD) onset during dopaminergic therapy. In healthy subjects, a relationship between the awareness of motor intention and impulsive personality traits assessed by the Barratt impulsivity scale (BIS-11) has been reported. The aim of this study was to evaluate the relationship between the awareness of voluntary action and impulsivity traits in PD. METHODS: Twenty-eight PD patients (stages I-III on the Hoehn and Yahr scale) underwent an impulsivity trait assessment by the BIS-11 scale and a task based on the Libet's clock. Participants were requested to perform a self-initiated movement and report the time they first feel their intention to move (W-judgement) or the time of the actual movement (M-judgement). RESULTS: In patients with higher BIS-11 scores, the time lag between the W-judgement and the actual movement was significantly lower than in patients with lower BIS-11. No difference emerged in the M-judgement. CONCLUSION: Data suggest that also in PD patients, the impulsive personality trait is related to a "delayed" awareness of motor intention and therefore to a shorter interval to allow a conscious "veto" of the impending action. Characterization of the temporal profile of awareness of motor intention could prove useful in identifying PD patients at risk of developing ICDs during dopaminergic treatment.

Epilepsy and brain channelopathies from infancy to adulthood.

Genetic brain channelopathies result from inherited or de novo mutations of genes encoding ion channel subunits within the central nervous system. Most neurological channelopathies arise in childhood with paroxysmal or episodic symptoms, likely because of a transient impairment of homeostatic mechanisms regulating membrane excitability, and the prototypical expression of this impairment is epilepsy. Migraine, episodic ataxia and alternating hemiplegia can also occur, as well as chronic phenotypes, such as spinocerebellar ataxias, intellectual disability and autism spectrum disorder. Voltage-gated and ligand-gated channels may be involved. In most cases, a single gene may be associated with a phenotypical spectrum that shows variable expressivity. Different clinical features may arise at different ages and the adult phenotype may be remarkably modified from the syndrome onset in childhood or adolescence. Recognizing the prominent phenotypical traits of brain channelopathies is essential to perform appropriate diagnostic investigations and to provide the better care not only in the paediatric setting but also for adult patients and their caregivers. Herein, we provide an overview of genetic brain channelopathies associated with epilepsy, highlight the different molecular mechanisms and describe the different clinical characteristics which may prompt the clinician to suspect specific syndromes and to possibly establish tailored treatments.

Imaging in Glucocerebrosidase-Associated Parkinsonism: Current Status and Implications for Pathophysiology.

BACKGROUND: Glucocerebrosidase (GBA) mutations have been described as the most prevalent in Parkinson's disease (PD) and in Lewy body dementia, accounting for up to 7 and 13.8% of cases, respectively. To elucidate the pathophysiology of idiopathic Parkinson's disease (iPD), the pathogenic mechanisms leading to Lewy body accumulation in GBA-associated parkinsonism (GBA-PD) are a matter of current research. However, only few imaging studies, conducted on small GBA-PD patient cohorts, exist. METHODS: We provide an overview of current structural and functional imaging studies in patients with Gaucher's disease and parkinsonism and in GBA-PD patients, underlining the main differences compared to iPD. RESULTS: A limited number of PET studies have been conducted in GBA-PD, exploring brain metabolism and dopaminergic presynaptic and postsynaptic function. Moreover, structural MRI and spectroscopy studies recently evidenced the differences with iPD, aiding to understand of some peculiar aspects of iPD. Finally, new evidence from transcranial sonography confirms the technique's role in the study of GBA-PD and highlights the additional involvement of the raphe nucleus. CONCLUSIONS: Further imaging studies conducted in a broader population of early GBA-PD are warranted to characterize the disease and elucidate the pathophysiological mechanisms underlying GBA-PD and to understand GBA implications in iPD.

Neural response to visual sexual cues in dopamine treatment-linked hypersexuality in Parkinson's disease.

Hypersexuality with compulsive sexual behaviour is a significant source of morbidity for patients with Parkinson's disease receiving dopamine replacement therapies. We know relatively little about the pathophysiology of hypersexuality in Parkinson's disease, and it is unknown how visual sexual stimuli, similar to the portrayals of sexuality in the mainstream mass media may affect the brain and behaviour in such susceptible individuals. Here, we have studied a group of 12 patients with Parkinson's disease with hypersexuality using a functional magnetic resonance imaging block design exposing participants to both sexual, other reward-related and neutral visual cues. We hypothesized that exposure to visual sexual cues would trigger increased sexual desire in patients with Parkinson's disease with hypersexuality that would correspond to changes in brain activity in regions linked to dopaminergically stimulated sexual motivation. Patients with Parkinson's disease with hypersexuality were scanned ON and OFF dopamine drugs, and their results were compared with a group of 12 Parkinson's disease control patients without hypersexuality or other impulse control disorders. Exposure to sexual cues significantly increased sexual desire and hedonic responses in the Parkinson's disease hypersexuality group compared with the Parkinson's disease control patients. These behavioural changes corresponded to significant blood oxygen level-dependent signal changes in regions within limbic, paralimbic, temporal, occipital, somatosensory and prefrontal cortices that correspond to emotional, cognitive, autonomic, visual and motivational processes. The functional imaging data showed that the hypersexuality patients' increased sexual desire correlated with enhanced activations in the ventral striatum, and cingulate and orbitofrontal cortices. When the patients with Parkinson's disease with hypersexuality were OFF medication, the functional imaging data showed decreases in activation during the presentation of sexual cues relative to rest. These deactivations were not observed when the patients were ON medication, suggesting that dopamine drugs may release inhibition within local neuronal circuits in the cerebral cortex that may contribute to compulsive sexual behaviour. The findings of this study have implications with respect to the potential influence of cue exposure via exposure to mass media in enhancing libido, which in this group of vulnerable patients can lead to devastating social consequences and occasionally, custodial sentences. Stimulation through exposure to sexual visual cues in patients with Parkinson's disease with hypersexuality provides a motivational impetus for seeking this reward behaviour through activations and deactivations of cerebral cortex.

Microglial activation in regions related to cognitive function predicts disease onset in Huntington's disease: a multimodal imaging study.

Huntington's disease (HD) is an inherited neurodegenerative disorder associated with motor, cognitive and psychiatric deficits. This study, using a multimodal imaging approach, aims to assess in vivo the functional and structural integrity of regions and regional networks linked with motor, cognitive and psychiatric function. Predicting disease onset in at risk individuals is problematic and thus we sought to investigate this by computing the 5-year probability of HD onset (p5 HD) and relating it to imaging parameters. Using MRI, (11)C-PK11195 and (11)C-raclopride PET, we have investigated volumes, levels of microglial activation and D2/D3 receptor binding in CAG repeat-matched groups of premanifest and symptomatic HD gene carriers. Findings were correlated with disease-burden and UHDRS scores. Atrophy was detected in sensorimotor striatum (SMST), substantia nigra, orbitofrontal and anterior prefrontal cortex in the premanifest HD. D2/D3 receptor binding was reduced and microglial activation increased in SMST and associative striatum (AST), bed nucleus of the stria terminalis, the amygdala and the hypothalamus. In symptomatic HD cases this extended to involve atrophy in globus pallidus, limbic striatum, the red nuclei, anterior cingulate cortex, and insula. D2/D3 receptor binding was additionally reduced in substantia nigra, globus pallidus, limbic striatum, anterior cingulate cortex and insula, and microglial activation increased in globus pallidus, limbic striatum and anterior prefrontal cortex. In premanifest HD, increased levels of microglial activation in the AST and in the regional network associated with cognitive function correlated with p5 HD onset. These data suggest that pathologically activated microglia in AST and other areas related to cognitive function, maybe better predictors of clinical onset and stresses the importance of early cognitive assessment in HD.

Intravenous brivaracetam in status epilepticus: A multicentric retrospective study in Italy.

PURPOSE: to evaluate the use, effectiveness, and adverse events of intravenous brivaracetam (BRV) in status epilepticus (SE). METHODS: a retrospective multicentric study involving 24 Italian neurology units was performed from March 2018 to June 2020. A shared case report form was used across participating centres to limit biases of retrospective data collection. Diagnosis and classification of SE followed the 2015 ILAE proposal. We considered a trial with BRV a success when it was the last administered drug prior the clinical and/or EEG resolution of seizures, and the SE did not recur during hospital observation. In addition, we considered cases with early response, defined as SE resolved within 6 h after BRV administration. RESULTS: 56 patients were included (mean age 62 years; 57 % male). A previous diagnosis of epilepsy was present in 21 (38 %). Regarding SE etiology classification 46 % were acute symptomatic, 18 % remote and 16 % progressive symptomatic. SE episodes with prominent motor features were the majority (80 %). BRV was administered as first drug after benzodiazepine failure in 21 % episodes, while it was used as the second or the third (or more) drug in the 38 % and 38 % of episodes respectively. The median loading dose was 100 mg (range 50-300 mg). BRV was effective in 32 cases (57 %). An early response was documented in 22 patients (39 % of the whole sample). The use of the BRV within 6 h from SE onset was independently associated to an early SE resolution (OR 32; 95 % CI 3.39-202; p = 0.002). No severe treatment emergent adverse events were observed. CONCLUSION: BRV proved to be useful and safe for the treatment of SE. Time to seizures resolution appears shorter when it is administered in the early phases of SE.

Staging of serotonergic dysfunction in Parkinson's disease: an in vivo 11C-DASB PET study.

Thirty Parkinson's disease (PD) patients were divided into three equal groups according to their disease duration while 10 normal healthy volunteers matched for age and sex served as a control group. Striatal and extrastriatal serotonergic function was studied with (11)C-DASB PET, a marker of serotonin transporter availability. (11)C-DASB binding was correlated with disease disability and exposure to dopaminergic therapy. We found significant (11)C-DASB binding reductions in striatal, brainstem, and cortical regions in PD but no correlations were evident between (11)C-DASB binding and UPDRS scores, Hoehn &Yahr staging, disease duration and level of exposure to dopaminergic therapy. Our results suggest that progressive non-linear serotonergic dysfunction occurs in PD but it does not determine levels of disability. Additionally, chronic exposure to dopaminergic therapy does not appear to influence SERT binding.

Predictive value of nigrostriatal dysfunction in isolated tremor: a clinical and SPECT study.

The overlap among tremor disorders is wide and complex because essential tremor patients may present resting tremor coexisting with postural tremor, while postural may coexist with resting tremor in Parkinson's disease. We investigated dopamine transporter binding in 61 subjects presenting with isolated atypical tremors defined as unilateral either postural, resting, or mixed (i.e. resting and postural) tremor, without rigidity or bradykinesia, by means of 123I-FPCIT SPECT imaging at baseline. Patients were followed-up clinically for 28.4 +/- 7.2 months. Twenty-five patients with baseline normal SPECT continued to present only tremor at follow-up. Among 36 patients with abnormal SPECT, 23 (64%) developed PD, while the remaining 13 continued to present only tremor at follow-up. The value of 123I-FPCIT SPECT in predicting the evolution to PD was very high in a way independent from the first clinical presentation of tremor (Rest tremor, P = 0.015; Mixed tremor, P = 0.015; Postural tremor, P = 0.039; chi-square test). Our data suggest that the clinical presentation of isolated tremors is insufficient to allow a precise early-stage diagnosis, whereas the detection of presynaptic nigrostriatal dopaminergic dysfunction could lead to diagnosis of atypical tremor disorders at a very early stage. We suggest this disorder to be labeled as "isolated tremor with dopaminergic presynaptic dysfunction".

Mitochondrial DNA haplogroups do not influence the Huntington's disease phenotype.

Various lines of evidence demonstrate the involvement of mitochondrial dysfunction in the pathogenesis of Huntington's disease (HD). However, the precise role of mitochondria in the neurodegenerative cascade leading to HD is still unclear. Mitochondrial DNA (mtDNA) haplogroups-specific polymorphisms were previously related to several neurodegenerative diseases. The length of CAG repeat seems to be related to the clinical features of HD, such as age of onset and progression of motor impairment. The basis for the impaired cognitive functions and for the mood changes is less clear. Aim of this study was to determine whether mtDNA polymorphism(s) play the role of "modifier gene(s)" in this disease. In this work we have genotyped predefined European mtDNA haplogroups in 51 patients with HD and 181 matched controls. The frequency of the haplogroups and haplogroup clusters did not differ between the two groups, and no correlation with gender, age of onset and disease status was observed. No significant difference was observed between different haplogroups and haplogroup clusters in the cognitive or motor progression of the disease. Our study does not support any association between mtDNA haplogroups and HD.

Visual hallucinations in Parkinson's disease are not influenced by polymorphisms of serotonin 5-HT2A receptor and transporter genes.

Psychiatric disorders are common in Parkinson's disease (PD) and hallucinations are observed in nearly 40% of PD patients. The involvement of dopaminergic system in the pathogenesis of psychosis has been sustained by most of the authors even if several evidences indicate that multiple neurochemical substrates might underlie psychosis in PD. In PD there is an extensive loss of serotoninergic raphe neurons and serotonin dysfunction had been implicated in the pathogenesis of many psychiatric disorders such as depression, schizophrenia, and in psychosis of patients with Alzheimer disease. The association of a serotonin transporter gene-linked polymorphic region (5-HTTLPR) and the 5-HT2A receptor T102C polymorphism with psychosis in a group of patients with PD was investigated. No significant differences in the distribution of allele and genotype frequencies of the 5-HTTLPR (p>0.01) and 5-HT2A T102C (p>0.05) were found between patients and controls as well as between the patients' subgroups without and with psychosis. These data might suggest that 5-HTTLPR and 5-HT2A polymorphisms are not major susceptibility factors of psychotic symptoms in PD patients.

Cerebral perfusional effects of cholinesterase inhibitors in Alzheimer disease.

Cholinesterase (ChE) inhibitors improve or stabilize cognitive impairment in patients with Alzheimer disease (AD). However, the regional metabolic and perfusion correlates of treatment with ChE inhibitors are not fully known. Twenty-four patients with mild to moderate AD were evaluated with Tc-ethyl cysteinate dimer (ECD) single-photon-emission CT scanning (SPECT), before and after 4.3 +/- 1.1 months of treatment with ChE inhibitors (donepezil, rivastigmine). Clinical evaluations included the Mini-Mental State Examination (MMSE) as well as the Neuropsychiatric Inventory (NPI). Inclusion criterion was a clear favorable response to therapy with ChE inhibitors (MMSE improvement of at least 2 points; total NPI improvement of at least 4 points). SPECT data were analyzed by Statistical Parametric Mapping (SPM 99, Wellcome, Department of Cognitive Neurology, London, UK). SPM analysis showed a significant increase (P < 0.01) of regional cerebral perfusion (rCBF) after short-term ChE inhibitor therapy with respect to baseline in the right anterior cingulate, the dorsolateral prefrontal, and the temporoparietal areas bilaterally. These data suggest that cognitive or behavioral benefits after ChE inhibitor therapy are related to a clear increase of rCBF in crucial areas specifically involved in the attentional and limbic networks.

Caudate dopaminergic denervation and visual hallucinations: evidence from a ¹²³I-FP-CIT SPECT study.

OBJECTIVE: The pathogenesis of visual hallucinations (VHs) in Parkinson's disease (PD) has been considered multifactorial. In the pathophysiology of VHs a combination of impaired visual processing and attention has been reported. Imaging studies evidenced a role of the primary visual system and visual association areas as well as a dysfunctional activation of frontal areas in the occurrence of VHs. Due to the functional connections between basal ganglia and frontal areas, a role of basal ganglia and of the fronto-striatal circuits in the pathogenesis of VHs may be postulated. Aim of this study is to unveil whether a presynaptic dopamine deficiency at baseline may predict the development of VHs. METHODS: A group of 18 non demented PD patients with VHs was matched with 18 non demented PD patients without VHs as regards age of onset of disease, disease duration and severity and levodopa equivalent dose. We retrospectively analyzed the (123)I-FP CIT SPECT performed on the two groups at the onset of their disease. The striatal uptake values in the two groups were examined, in order to evaluate nigrostriatal differences between the groups with different behavioral phenotype. RESULTS: The group of patients with VHs had a significant reduction (p < 0.05) in right caudate uptake values at baseline when compared with patients without VHs. No significant differences were found between the groups regarding left caudate and putaminal uptake values. CONCLUSIONS: The frontal impairment reported in PD patients with VHs may be due to a right caudate dysfunction, as it is connected to the frontal brain areas via neuronal loops.

Serotonergic mechanisms responsible for levodopa-induced dyskinesias in Parkinson's disease patients.

Levodopa-induced dyskinesias (LIDs) are the most common and disabling adverse motor effect of therapy in Parkinson's disease (PD) patients. In this study, we investigated serotonergic mechanisms in LIDs development in PD patients using 11C-DASB PET to evaluate serotonin terminal function and 11C-raclopride PET to evaluate dopamine release. PD patients with LIDs showed relative preservation of serotonergic terminals throughout their disease. Identical levodopa doses induced markedly higher striatal synaptic dopamine concentrations in PD patients with LIDs compared with PD patients with stable responses to levodopa. Oral administration of the serotonin receptor type 1A agonist buspirone prior to levodopa reduced levodopa-evoked striatal synaptic dopamine increases and attenuated LIDs. PD patients with LIDs that exhibited greater decreases in synaptic dopamine after buspirone pretreatment had higher levels of serotonergic terminal functional integrity. Buspirone-associated modulation of dopamine levels was greater in PD patients with mild LIDs compared with those with more severe LIDs. These findings indicate that striatal serotonergic terminals contribute to LIDs pathophysiology via aberrant processing of exogenous levodopa and release of dopamine as false neurotransmitter in the denervated striatum of PD patients with LIDs. Our results also support the development of selective serotonin receptor type 1A agonists for use as antidyskinetic agents in PD.

Twinkle mutation in an Italian family with external progressive ophthalmoplegia and parkinsonism: a case report and an update on the state of art.

The objective is to describe the clinical phenotype and genetic basis of a family with autosomal dominant progressive external ophthalmoplegia and parkinsonism with a Twinkle mutation. The proband, an 82 years old female, reported since childhood bilateral eyelid ptosis, ophthalmoplegia, sensorineural hypoacusis, mild depression since she was 45, with a positive familiar anamnesis of eyelid ptosis (father, two sisters and a son). She developed mild bilateral parkinsonism with a moderate clinical response to levodopa. The (123)I-FP-CIT SCAN evidenced a marked bilateral putaminal reduction and moderate caudate uptake reduction. Her 79 years old sister reported eyelid ptosis since she was 45 with ophthalmoplegia and developed a mild bilateral rest and postural tremor with moderate right arm plastic hypertonia when she was 76. The parkinsonism was confirmed with (123)I-FP-CIT SCAN. One of the two sons presented eyelid ptosis since he was 30 years old, with peripheral neuropathy with biopsy evidence of myopathy. We identified a G1750A mutation in the c10orf2 gene in the three patients. Mitochondrial dysfunction has been implicated in the pathogenesis of sporadic, idiopathic Parkinson disease (PD). In some cases, mitochondrial DNA primary genetic abnormalities or more commonly secondary rearrangements due to polymerase gamma (POLG) gene mutation can directly cause parkinsonism. Parkinsonism has been reported as a rare symptom associated to Twinkle (c10orf2). Parkinsonism has to be investigated in patients with PEO with analysis of Twinkle mutation.

Nigral involvement and nigrostriatal dysfunction in Huntington's disease: evidences from an MRI and SPECT study.

BACKGROUND: Huntington disease (HD) is pathologically characterized by a selective neurodegeneration of vulnerable populations of neurons, with an early marked neuronal loss and atrophy in the neostriatum. Dopaminergic innervations of neostriatal neurons originate in the substantia nigra pars compacta. Few studies investigated the neuronal loss and the functional role of the substantia nigra in modulating clinical features in HD. METHODS: 12 patients and 12 age-matched controls underwent SPECT scans with (123)I-FP-CIT and a 1.5 T MRI scan with inversion recovery technique. The association between both clinical and neuropsychological features and striatal uptake and volume of substantia nigra was explored. RESULTS: Striatal (p < 0.05), caudate (p < 0.05), and putaminal (p < 0.01) uptake was significantly lower in patients with respect to controls. Further, the volume of substantia nigra was reduced in HD when compared to controls (p < 0.01). No relationship between the volume of SN and tracer striatal uptake was found as well as between clinical and neuropsychological features with the SPECT and MRI results. CONCLUSIONS: Our results confirm that the degeneration of nigrostriatal pathway may occur in symptomatic HD patients. If confirmed by larger studies, the lack of any kind of correlation between clinical and neuropsychological features with striatal uptake and volume of substantia nigra suggests that motor and cognitive aspects in HD are not directly related to nigrostriatal degeneration.

Metabolic changes induced by theta burst stimulation of the cerebellum in dyskinetic Parkinson's disease patients.

BACKGROUND: Cerebellar repetitive transcranial magnetic stimulation may be effective in reducing peak-dose levodopa induced dyskinesia in Parkinson's disease patients. It was proposed that the antidyskinetic effect could be due to modulation of cerebello-thalamo-cortical pathways. However the neural basis for these clinical effects have not yet been demonstrated. METHODS: We investigated the effects of repeated sessions of cerebellar continuous theta burst stimulation in Parkinson's disease patients with levodopa induced dyskinesia on brain metabolism by means of positron emission tomography scan with fluorodeoxyglucose ((18)F-FDG) to characterize the specific cerebral network activated by cerebellar stimulation in these patients. RESULTS: We found that five days of bilateral cerebellar continuous theta burst stimulation (cTBS) were effective in reducing levodopa induced dyskinesia. Clinical changes were paralleled by a reduction of (18)F-FDG metabolism in the cerebellum as revealed by positron emission tomography imaging. We found a global decrease in the metabolism of the bilateral cerebellar hemispheres, and a significant decrease in (18)F-FDG uptake in correspondence of bilateral dentate nucleus. CONCLUSIONS: Our study demonstrates the antidyskinetic effect of cerebellar cTBS in Parkinson's disease patients with levodopa induced dyskinesia, is paralleled by modulation of the activity of the pathways connecting the cerebellar cortex with the deep cerebellar nuclei, confirming the hypothesis that the motor cerebellar circuit is involved in the generations of levodopa induced dyskinesia.