1,721,489 research outputs found
Tremor and myoclonus: clinical, neurophysiological and neuroimaging phenotypes in children and adolescents
No full textTremor, defined as an involuntary rhythmic oscillatory movement, and myoclonus, characterized by brief, jerk-like movements, are distinct hyperkinetic movement disorders. Despite differences in their pathophysiology and clinical management, tremor and myoclonus are often confused due to their potentially similar presentations.
Tremor and myoclonus are considered uncommon in children and adolescents, and few studies have investigated their causes and clinical features in the pediatric population. Therefore, the spectrum of clinical features and underlying causes of tremor and myoclonus in young patients remains only partially understood. Additionally, classification systems for tremor and myoclonus are largely based on adult-onset conditions, and their clinical applicability in children and adolescents has not yet been tested.
The aim of this thesis is to dissect the phenotype of tremor and myoclonus in children and adolescents.
By assessing a large cohort of patients with childhood-onset tremor and myoclonus, including the collection of clinical, neurophysiological and neuroimaging data, this project aims to address currently unanswered questions about these disorders in children.
First, through a deep analysis of a large pediatric cohort, we tested whether the latest classification of tremor syndromes is applicable to childhood-onset tremor, analyzing specific peculiarities and diagnostic uncertainties. Second, we investigated the clinical phenotype of essential tremor in children, examining its neurophysiological features. Third, we explored whether co-occurring subtle neurological abnormalities in patients with essential tremor ("essential tremor plus") are associated with identifiable anatomical differences in brain volumetry. Fourth, we assessed the role of combined EEG-polymyography in the diagnosis of tremor and myoclonus, evaluating its utility in refining clinical diagnoses. Finally, we investigated the neurophysiological features of myoclonus in a cohort of affected children, focusing on the accuracy of polymyographic recordings in differentiating myoclonus subtypes
Assessing somatosensory evoked potential (SEP) generators by human intracranial recordings
No full textCerebellar damage impairs detection of somatosensory input changes. A somatosensory mismatch-negativity study
Full text linkseveral recent studies support the view that the cerebellum's contribution to sensory processing is not limited to movement regulation. In a previous paper (restuccia d, valeriani m, barba c, le pera d, capecci m, filippini v, molinari m. functional changes of the primary somatosensory cortex in patients with unilateral cerebellar lesions. brain 2001; 124: 757-68) we showed that the cerebellum influences somatosensory input processing at very early stages. the present study was aimed at verifying whether an analogous influence is also exerted at higher levels. for some time it has been known that in the auditory modality a specific event-related potential (ERP), that is, mismatch negativity (MMN), reflects preattentive detection of changes in the incoming stimulus by comparing the new stimulus with sensory memory traces. to test the cerebellar influence on the processing of incoming somatosensory stimuli we first verified whether the electrical stimulation of fingers, according to an 'oddball' paradigm within a stimulus-ignored condition, was able to elicit event-related components specifically linked to the preattentive detection of change. we analysed scalp responses obtained from eight healthy volunteers during frequent and rare electrical stimulation of the first and fifth finger of the left hand, respectively. to ensure that responses to deviant stimuli were due to changes in detection mechanisms, rather than to activation of new afferents, we also analysed responses to rare stimulation alone ('standard-omitted' condition). the 'oddball' stimulation was able to elicit a parieto-occipital extra negativity that was different in scalp distribution and latency from the N140 response to the 'standard-omitted' stimulation. we considered that this response was related to changes in detection mechanisms and labelled it somatosensory mismatch negativity (S-MMN). When the same procedure was applied to six patients with unilateral cerebellar lesions we found that the S-MMN was clearly abnormal after stimulation of the affected hand (ipsilateral to the affected cerebellar hemisphere). Earlier ERPs, as well as ERPs elicited during the 'standard-omitted' condition, were fully normal. present data indicate that cerebellar processing is involved in preattentive detection of somatosensory input changes. In conclusion, this study demonstrates the reliability of S-MMN recordings and indicates that subjects with cerebellar damage may be impaired in the cortical processing of incoming somatosensory inputs
Increased habituation to painful stimuli:a self-protective mechanism during prolonged wakefulness?
No full textAntiepileptic drugs in the preventive treatment of migraine in children and adolescents
No full textMigraine prevalence in childhood ranges from 2.7 to 10% causing a significant impact on quality of life. No drugs are currently approved for use in the prevention of pediatric migraine. Antiepileptic drugs such as valproate and topiramate have been approved for the preventive treatment of migraine in adults. The present study aimed at reviewing evidence on the efficacy and safety of antiepileptic drugs in the preventive treatment of migraine in children and adolescents. We searched PubMed from 1988 to May 2007 and reviewed, abstracted, and classified relevant literature. Thirteen studies were reviewed. Data from randomized controlled trials are available only for valproate and topiramate. They show that both topiramate and valproate are effective in reducing headache frequency, intensity, and duration. As for safety and tolerability, topiramate is well tolerated, while there are insufficient data regarding the tolerability of valproate. Open-label or retrospective studies suggest that levetiracetam, zonisamide, and gabapentin are effective, but further evidence is warranted to confirm these data
Characterizing somatosensory evoked potential sources with dipole models: advantages and limitations
No full textSeveral methods have been developed to investigate the cerebral generators of scalp somatosensory evoked potentials (SEPs), because simple visual inspection of the electroencephalographic signal does not allow for immediate identification of the active brain regions. When the neurons fired by the afferent inputs are closely grouped, as usually occurs in SEP generation, they can be represented as a dipole, that is, as a linear source with two opposite poles. Several techniques for dipolar source modeling, which use different algorithms, have been employed to build source models of early, middle-latency, and late cognitive SEPs. Modifications of SEP dipolar activities after experimental maneuvers or in pathological conditions have also been observed. Although the effectiveness of dipolar source analysis should not be overestimated due to the intrinsic limitations of the approach, dipole modeling provides a means to assess SEPs in terms of cerebral sources and voltage fields that they produce over the head
Neuropathic pain
No full textNeuropathic pain is one of the most frequent symptoms in neurological clinical practice. It is caused by a lesion or disease of the somatosensory system and encompasses a broad spectrum of pathologies ranging from peripheral polyneuropathies to central nervous system disorders. The diagnosis of neuropathic pain requires clinical and instrumental assessment, as a single symptom or diagnostic test is not always sufficient to identify neuropathic pain. Neuropathic pain is extremely disabling and difficult to treat, and patients often have to try several pharmacological agents alone or in combination before a significant level of pain relief is achieved. Gabapentinoids, serotonin reuptake norephrine, and tricyclic antidepressants are the first-line therapy for neuropathic pain
Brain excitability in migraine: Hyperexcitability or inhibited inhibition?
No full textWhile migraine has been considered for a long time
a disease of the head vascular structures, it has been
more and more evident that the involvement of the
cerebral cortex has a primary role in the cascade of
events which trigger the migraine attacks. Neurophysiological
studies gave an important contribution to our
knowledge of the mechanisms underlying the migraine
diseas
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