RESUMO
BACKGROUND: Compared to conventional transcranial magnetic stimulation (TMS), the triple stimulation technique (TST) strongly decrease the effects of desynchronization of descending discharges and accompanying phase cancellation that follow TMS and offers a more sensitive method to quantify motor evoked potentials (MEPs). NEW METHOD: Using the TST, we explored as to whether sub-threshold TMS evokes peripheral motor neuron discharges (MNs). We compared the number of MEPs elicited by TMS and by TST in fifteen healthy participants. We used the subthreshold intensity of 80 % resting motor threshold. To control the TST assessment of the corticospinal tract, we included a peripheral stimulation control condition, which consisted of peripheral stimulation alone, in a subgroup of five volunteers. RESULTS: Compared to TMS, TST at sub-threshold intensities did not detect significantly more responses unequivocally attributable to the cortical stimulation. In contrast, the peripheral supra-maximal stimuli produced confounding effects in the TST condition that were, in part, indistinguishable from cortical responses. COMPARISON WITH EXISTING METHODS: At subthreshold TMS intensities, the TST does not detect more discharges of spinal MNs than conventional TMS and, in addition, it is confounded by effects from peripheral stimulation. CONCLUSION: The TST can be useful in assessing the integrity of the MN pool and of the corticospinal tract. However, if used at near threshold intensity, the confounding effects of peripheral stimulation need to be considered; for instance, in paired-pulse stimulation paradigms assessing the cortical physiology.
Assuntos
Potencial Evocado Motor , Tratos Piramidais , Humanos , Neurônios Motores , Descanso , Estimulação Magnética TranscranianaRESUMO
The paired-pulse (PP) transcranial magnetic stimulation (TMS) paradigms allow the exploration of the motor cortex physiology. The triple stimulation technique (TST) improves conventional TMS by reducing effects of desynchronization of motor neuron discharges allowing a precise evaluation of the corticospinal conduction. The objective of our study was to explore PP TMS paradigms combined with the TST to study whether the desynchronization contributes to these phenomena and whether the combined TMS-TST protocol could improve the consistency of responses. We investigated the PP paradigms of short intracortical inhibition (SICI) with 2 ms interstimulus interval (ISI) and of intracortical facilitation (ICF) with 10 ms ISI in 22 healthy subjects applying either conventional TMS alone or combined with the TST protocol. The results of the PP paradigms combined with the TST of SICI and ICF do not differ from those with conventional TMS. However, combining the PP paradigm with the TST reduces their variability. These results speak against a contribution of the desynchronization of motor neuron discharges to the PP paradigms of SICI and ICF. Combining the PP TMS paradigm with the TST may improve their consistency, but the interindividual variability remains such that it precludes their utility for clinical practice.NEW & NOTEWORTHY Combining the triple stimulation technique with the paired-pulse stimulation paradigm improves the consistency of short intracortical inhibition and facilitation and could be useful in research, but the interindividual variability precludes their utility for clinical practice. Our findings do not suggest that desynchronization of descending discharges following transcranial magnetic stimulation contributes to short intracortical inhibition or intracortical facilitation.
Assuntos
Córtex Motor/fisiologia , Inibição Neural , Estimulação Magnética Transcraniana/métodos , Adulto , Potencial Evocado Motor , Feminino , Humanos , Masculino , Adulto JovemRESUMO
OBJECTIVE: To investigate the safety and efficacy of intermittent theta-burst stimulation (iTBS) in the treatment of motor symptoms in Parkinson disease (PD). BACKGROUND: Progression of PD is characterized by the emergence of motor deficits, which eventually respond less to dopaminergic therapy and pose a therapeutic challenge. Repetitive transcranial magnetic stimulation (rTMS) has shown promising results in improving gait, a major cause of disability, and may provide a therapeutic alternative. iTBS is a novel type of rTMS that may be more efficacious than conventional rTMS. METHODS: In this randomized, double-blind, sham-controlled study, we investigated safety and efficacy of iTBS of the motor and dorsolateral prefrontal cortices in 8 sessions over 2 weeks (evidence Class I). Assessment of safety and clinical efficacy over a 1-month period included timed tests of gait and bradykinesia, Unified Parkinson's Disease Rating Scale (UPDRS), and additional clinical, neuropsychological, and neurophysiologic measures. RESULTS: We investigated 26 patients with mild to moderate PD: 13 received iTBS and 13 sham stimulation. We found beneficial effects of iTBS on mood, but no improvement of gait, bradykinesia, UPDRS, and other measures. EEG/EMG monitoring recorded no pathologic increase of cortical excitability or epileptic activity. Few reported discomfort or pain and one experienced tinnitus during real stimulation. CONCLUSION: iTBS of the motor and prefrontal cortices appears safe and improves mood, but failed to improve motor performance and functional status in PD. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that iTBS was not effective for gait, upper extremity bradykinesia, or other motor symptoms in PD.
Assuntos
Doença de Parkinson/fisiopatologia , Doença de Parkinson/terapia , Ritmo Teta/fisiologia , Estimulação Magnética Transcraniana/métodos , Idoso , Método Duplo-Cego , Eletroencefalografia , Eletromiografia , Potencial Evocado Motor/fisiologia , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Córtex Motor/fisiopatologia , Testes Neuropsicológicos , Escalas de Graduação PsiquiátricaRESUMO
BACKGROUND/AIMS: Excessive daytime sleepiness (EDS) is frequent in patients with Parkinson's disease (PD). Occasionally, EDS in PD exhibits narcolepsy-like features. We aimed to assess characteristics and determinants of EDS in consecutive patients with PD. METHODS: Thirty consecutive patients with PD underwent a detailed clinical examination. EDS was assessed using the Epworth Sleepiness Scale (ESS) and Multiple Sleep Latency Test (MSLT). Sleep was assessed using video-polysomnography. Cerebrospinal fluid (CSF) hypocretin-1 levels were obtained in 3 patients. RESULTS: ESS was >10 in 17 patients (57%). Mean sleep latency (MSL) on MSLT was <5 min in 11 patients (37%). There was a significant negative correlation between ESS and MSL. None of the 11 patients with MSL <5 min showed a sleep onset REM (SOREM) episode. Patients with EDS had higher dopamine agonists/levodopa equivalent doses, higher apnea/hypopnea index and exhibited wearing-off symptoms more often. Hypocretin-1 was normal in 3 patients tested. CONCLUSION: EDS, which can sometimes be severe, is common in PD patients even in the absence of SOREM and detectable CSF-hypocretin deficiency. In PD, EDS is a multifaceted phenomenon, the determinants of which include severity of PD, wearing-off symptoms, dosage of antiparkinsonian drugs and sleep-disordered breathing.
Assuntos
Distúrbios do Sono por Sonolência Excessiva/complicações , Distúrbios do Sono por Sonolência Excessiva/fisiopatologia , Doença de Parkinson/complicações , Idoso , Idoso de 80 Anos ou mais , Antiparkinsonianos/uso terapêutico , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/líquido cefalorraquidiano , Pessoa de Meia-Idade , Neuropeptídeos/líquido cefalorraquidiano , Orexinas , Doença de Parkinson/tratamento farmacológico , Doença de Parkinson/fisiopatologia , Polissonografia , TempoAssuntos
Dissecção Aórtica/etiologia , Dissecção Aórtica/terapia , Dissecação da Artéria Carótida Interna/complicações , Dissecação da Artéria Carótida Interna/terapia , Artéria Carótida Interna/patologia , Adulto , Idoso , Dissecção Aórtica/fisiopatologia , Aneurisma Roto/etiologia , Aneurisma Roto/fisiopatologia , Aneurisma Roto/terapia , Anticoagulantes/uso terapêutico , Aspirina/uso terapêutico , Artéria Carótida Interna/fisiopatologia , Dissecação da Artéria Carótida Interna/fisiopatologia , Protocolos Clínicos , Doenças dos Nervos Cranianos/etiologia , Doenças dos Nervos Cranianos/fisiopatologia , Doenças dos Nervos Cranianos/prevenção & controle , Progressão da Doença , Feminino , Cefaleia/etiologia , Cefaleia/fisiopatologia , Cefaleia/prevenção & controle , Síndrome de Horner/etiologia , Síndrome de Horner/fisiopatologia , Síndrome de Horner/prevenção & controle , Humanos , Masculino , Pessoa de Meia-Idade , Cervicalgia/etiologia , Cervicalgia/fisiopatologia , Cervicalgia/prevenção & controle , Inibidores da Agregação Plaquetária/uso terapêutico , Prognóstico , Estudos Prospectivos , Estudos Retrospectivos , Medição de Risco , Acidente Vascular Cerebral/etiologia , Acidente Vascular Cerebral/fisiopatologia , Acidente Vascular Cerebral/prevenção & controle , Fatores de TempoRESUMO
Ictal transient opercular syndrome is rarely observed in benign epilepsy with centro-temporal spikes in children, and even more rarely in epilepsia partialis continua and symptomatic focal status epilepticus in adults. Here we report the ictal and interictal neuroimaging and electrophysiological findings in an adult female suffering from discontinuous focal status epilepticus presenting as a transient opercular syndrome. This patient was unusual insofar as the discharges were strictly unilateral, i.e., that even with extensive neuroimaging no structural abnormalities could be found.
Assuntos
Eletroencefalografia , Epilepsia do Lobo Frontal/diagnóstico , Estado Epiléptico/patologia , Adulto , Circulação Cerebrovascular/fisiologia , Feminino , Humanos , Imageamento por Ressonância Magnética , Tomografia por Emissão de Pósitrons , Gravação em VídeoRESUMO
Ultrasound allows the reliable exclusion of spontaneous dissection of the cervical internal carotid artery (sICAD) in patients with carotid territory ischemia. The possibility of falsely positive ultrasound findings indicates that cervical magnetic resonance imaging (MRI) and angiography must confirm ultrasonic suspicion of sICAD. The sensitivity of ultrasound for assessing sICAD which causes no carotid territory ischemia, but headache, neck pain, Horner syndrome, or palsy of the cranial nerves on the side of dissection is about 70%, and for identifying spontaneous dissection of the vertebral artery (sVAD) the sensitivity is 75-86%. The negative predictive value and specificity for ultrasound diagnosis of the latter two types of cervical artery dissection is unknown. Consequently, all patients with clinical suspicion of sICAD causing no ischemic event or sVAD should undergo cervical MRI and angiography. Ultrasound is useful for noninvasive monitoring of vessel recanalization and for determining the duration of antithrombotic therapy.
Assuntos
Isquemia Encefálica/diagnóstico por imagem , Dissecação da Artéria Carótida Interna/diagnóstico por imagem , Ultrassonografia Doppler/métodos , Dissecação da Artéria Vertebral/diagnóstico por imagem , Isquemia Encefálica/etiologia , Isquemia Encefálica/fisiopatologia , Dissecação da Artéria Carótida Interna/fisiopatologia , Angiografia Cerebral/normas , Erros de Diagnóstico/prevenção & controle , Reações Falso-Negativas , Humanos , Imageamento por Ressonância Magnética/normas , Valor Preditivo dos Testes , Ultrassonografia Doppler/normas , Ultrassonografia Doppler/tendências , Dissecação da Artéria Vertebral/fisiopatologiaRESUMO
The purpose of this chapter is to present ultrasound and, in particular, color duplex sonography (CDS) assessment of spontaneous dissection of the cervical internal carotid (sICAD) and vertebral (sVAD) arteries. The examination, typical ultrasound findings and pitfalls in the acute sICAD and sVAD, detection of microembolic signals, and recanalization will be discussed.
Assuntos
Dissecação da Artéria Carótida Interna/diagnóstico por imagem , Artéria Carótida Interna/diagnóstico por imagem , Dissecação da Artéria Vertebral/diagnóstico por imagem , Artéria Vertebral/diagnóstico por imagem , Artéria Carótida Interna/patologia , Artéria Carótida Interna/fisiopatologia , Dissecação da Artéria Carótida Interna/fisiopatologia , Circulação Cerebrovascular/fisiologia , Humanos , Embolia Intracraniana/diagnóstico por imagem , Embolia Intracraniana/etiologia , Embolia Intracraniana/fisiopatologia , Valor Preditivo dos Testes , Recuperação de Função Fisiológica/fisiologia , Ultrassonografia Doppler em Cores/métodos , Ultrassonografia Doppler em Cores/tendências , Artéria Vertebral/patologia , Artéria Vertebral/fisiopatologia , Dissecação da Artéria Vertebral/fisiopatologiaRESUMO
BACKGROUND AND PURPOSE: It is unclear whether stroke in patients with spontaneous dissection of the cervical internal carotid artery (ICAD) is due to thromboembolism or impaired hemodynamics. This study investigated the mechanism of stroke in ICAD by examining brain imaging and cerebrovascular findings of such patients. METHODS: We retrospectively evaluated the prospectively collected brain CT, MR, and ultrasound findings of 141 consecutive patients with 143 ICADs causing ischemic stroke. Eleven patients were not included because they had an inappropriate temporal bone window (n=6) or were treated with thrombolysis (n=5). Thus, the data of 130 patients (76 men, 54 women) with 131 ICADs were analyzed. RESULTS: All patients had territorial infarcts; 6 patients (5%) also had border-zone infarct patterns. Territorial infarcts affected the middle cerebral artery (MCA) in 130 of 131 cases (99%) and the anterior cerebral artery (ACA) in 1 case (1%). Additional vascular territories were affected in 8 patients with MCA infarcts (ACA, n=5 [4%]; posterior cerebral artery, n=3 [2%]). The pattern (hemodynamic versus thromboembolic) and extent of infarction were not influenced by vascular findings (MCA stenosis or occlusion, ACA occlusion, degree of obstruction in the dissected ICA, pattern of cross-flow in 115 patients with >80% ICA stenosis or occlusion). CONCLUSIONS: This study suggests that thromboembolism, not hemodynamic infarction, is the essential stroke mechanism in ICAD.
Assuntos
Isquemia Encefálica/etiologia , Trombose das Artérias Carótidas/complicações , Dissecação da Artéria Carótida Interna/complicações , Infarto Cerebral/etiologia , Isquemia Encefálica/diagnóstico , Trombose das Artérias Carótidas/diagnóstico , Artéria Carótida Interna/diagnóstico por imagem , Dissecação da Artéria Carótida Interna/diagnóstico por imagem , Infarto Cerebral/classificação , Infarto Cerebral/diagnóstico , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Fatores de Risco , Tomografia Computadorizada por Raios X , UltrassonografiaRESUMO
OBJECTIVE: To compare the rate of ischemic events and intracranial hemorrhage in the long-term follow-up of patients with persistent and transient severe stenosis or occlusion of the internal carotid artery (ICA) due to spontaneous dissection (ICAD). METHODS: One hundred and sixty-one consecutive patients with unilateral ICAD causing severe stenosis or occlusion were examined clinically and by ultrasound 1 year after symptom onset. Forty-six cases with persistent and 46 age- and latency-matched cases with transient (recanalization complete or less than 50% stenosis) severe stenosis or occlusion of the ICA were enrolled. Nine patients with surgical, endovascular, or fibrinolytic therapy for ICAD or associated stroke were excluded. Antithrombotic therapy was given at the discretion of the treating physician. Clinical follow-ups were done annually. RESULTS: Antithrombotic therapy and follow-up were similar in patients with permanent (6.2 +/- 3.4 years) and transient (7.2 +/- 4.3 years) severe stenosis or occlusion of the ICA. Cases with permanent carotid stenosis or occlusion showed annual rates of 0.7% for ipsilateral carotid territory stroke and of 1.4% for any stroke. Cases with transient carotid stenosis or occlusion showed annual rates of 0.3% for ipsilateral carotid territory stroke and of 0.6% for any stroke. CONCLUSIONS: This study suggests that ICAD has a benign long-term prognosis with low rates of ipsilateral carotid territory and any stroke and that the stroke rate in ICAD is not related to the persistence of severe carotid stenosis or occlusion. These results question the rationale of surgical or catheter-based revascularization in patients with ICAD.