Neurological complications in patients with SARS-CoV-2 infection: a systematic review / Complicações neurológicas em pacientes infectados pelo SARS-CoV-2: uma revisão sistemática

ABSTRACT Background: As the COVID-19 pandemic unfolds worldwide, different forms of reports have described its neurologic manifestations. Objective: To review the literature on neurological complications of SARS-CoV-2 infection. Methods: Literature search performed following systematic reviews guidelines, using specific keywords based on the COVID-19 neurological complications described up to May 10th, 2020. Results: A total of 43 articles were selected, including data ranging from common, non-specific symptoms, such as hyposmia and myalgia, to more complex and life-threatening conditions, such as cerebrovascular diseases, encephalopathies, and Guillain-Barré syndrome. Conclusion: Recognition of neurological manifestations of SARS-CoV-2 should be emphasized despite the obvious challenges faced by clinicians caring for critical patients who are often sedated and presenting other concurrent systemic complications.

RESUMO Introdução: À medida que a pandemia da COVID-19 se desenvolve em todo o mundo, diferentes tipos de publicações descreveram suas manifestações neurológicas. Objetivo: Revisar a literatura sobre complicações neurológicas da infecção por SARS-CoV-2. Métodos: A pesquisa bibliográfica foi realizada seguindo diretrizes de revisões sistemáticas, usando palavras-chave específicas baseadas nas complicações neurológicas da COVID-19 descritas até 10 de maio de 2020. Resultados: Foram selecionados 43 artigos, incluindo descrições que variam de sintomas comuns e inespecíficos, como hiposmia e mialgia, a condições mais complexas e com risco de vida, como doenças cerebrovasculares, encefalopatias e síndrome de Guillain-Barré. Conclusão: O reconhecimento das manifestações neurológicas da SARS-CoV-2 deve ser enfatizado apesar dos óbvios desafios enfrentados pelos clínicos que cuidam de pacientes críticos, muitas vezes sedados e apresentando outras complicações sistêmicas concomitantes.

Analyzing the neuropsychological characteristics and changes in serum markers of patients with chronic cerebral circulation insufficiency

Summary Objective: To investigate the neuropsychological characteristics and changes in CRP, S100B, MBP, HSP-7, and NSE in serum. Method: Sixty-six (66) patients treated in our hospital as CCCI group were chosen for our study, and 90 patients with depression were selected as the depression group. The patients in both groups were examined with CT perfusion, depression, anxiety and cognition evaluation. Their serum CRP, S100B, MBP, HSP-70 and NSE levels were detected. Neuropsychological and serum markers characteristics were compared. Results: The CBF and CBV in bilateral basal ganglia, frontal lobes, greater oval center, brain stem, and left and right regions of occipital lobes of the patients in CCCI group were significantly lower than in the depression group. The HAMD and HAMA scores of CCCI group patients were significantly lower than in the depression group; CCCI group performed better regarding attention, memory, abstract terms and delayed recall. CCCI also had significantly higher total scores than the depression group. Serum CRP, S100B, MBP, HSP-70 and NSE levels in CCCI group were significantly higher than in the depression group. The differences reach statistical significance (p<0.05). Conclusion: CCCI patients who are accompanied by minor depressive disorder have different degrees of cognitive impairment and experience a significant rise in serum CRP, S100B, MBP, HSP-70 and NSE.

Associations of Cerebrovascular Metabolism Genotypes With Neuropsychiatric Symptoms and Age at Onset of Alzheimer's Disease Dementia

Objective: To study associations of cerebrovascular metabolism genotypes and haplotypes with age at Alzheimer’s disease dementia (AD) onset and with neuropsychiatric symptoms according to each dementia stage. Methods: Consecutive outpatients with late-onset AD were assessed for age at dementia onset and Neuropsychiatric Inventory scores according to Clinical Dementia Rating scores, apolipoprotein E gene (APOE) haplotypes, angiotensin-converting enzyme gene (ACE) variants rs1800764 and rs4291, low-density lipoprotein cholesterol receptor gene (LDLR) variants rs11669576 and rs5930, cholesteryl ester transfer protein gene (CETP) variants I422V and TaqIB, and liver X receptor beta gene (NR1H2) polymorphism rs2695121. Results: Considering 201 patients, only APOE-ɛ4 carriers had earlier dementia onset in multiple correlations, as well as less apathy, more delusions, and more aberrant motor behavior. Both ACE polymorphisms were associated with less intense frontally mediated behaviors. Regarding LDLR variants, carriers of the A allele of rs11669576 had less anxiety and more aberrant motor behavior, whereas carriers of the A allele of rs5930 had less delusions, less anxiety, more apathy, and more irritability. CETP variants that included G alleles of I422V and TaqIB were mostly associated with less intense frontally mediated behaviors, while severely impaired carriers of the T allele of rs2695121 had more anxiety and more aberrant motor behavior. Conclusion: Though only APOE haplotypes affected AD onset, cerebrovascular metabolism genotypes were associated with differences in several neuropsychiatric manifestations of AD.

The role of necroptosis in neurosurgical diseases

Programmed necrosis or necroptosis is an alternative form of cell death that is executed through a caspase-independent pathway. Necroptosis has been implicated in many pathological conditions. Genetic or pharmacological inhibition of necroptotic signaling has been shown to confer neuroprotection after traumatic and ischemic brain injury. Therefore, the necroptotic pathway represents a potential target for neurological diseases that are managed by neurosurgeons. In this review, we summarize recent advances in the understanding of necroptotic signaling pathways and explore the role of necroptotic cell death in craniocerebral trauma, brain tumors, and cerebrovascular diseases.

Vascular parkinsonism: a case series of 17 patients / Parkinsonismo vascular: uma serie de casos de 17 pacientes

Objective To report the clinical and neuroimaging findings in a case series of vascular parkinsonism (VP). Methods Seventeen patients with VP were evaluated with motor, cognitive, and neuroimaging standardized tests and scales. Results All patients had arterial hypertension. Ten patients were male and the mean age of the whole sample was 75.8±10.1 years. The mean age of parkinsonism onset was 72.2±10.0 years. Common clinical features were urinary incontinence (88.2%), lower limb parkinsonism with freezing of gait and falls (82.3%), and pyramidal signs (76.4%). The mean Unified Parkinson’s Disease Rating Scale (UPDRS) and Hoehn-Yahr scores were 72.5±21.6 points and 3.3±0.9 points, respectively. Sixteen (94.1%) patients had freezing of gait and executive dysfunction. Twelve (70.5%) patients had probable vascular dementia. The mean dose of levodopa was 530.9 mg/day. Unresponsiveness to the drug was confirmed by a 6.9 mean point reduction in the UPDRS score after the “practically defined off” test. Conclusion This series provides a profile of VP with predominant lower-limb involvement, freezing of gait and falls, pyramidal signs, executive dysfunction, concomitant vascular dementia, and poor levodopa response. .

Objetivo Relatar os achados clínicos e de neuroimagem em parkinsonismo vascular (PV). Métodos Foram avaliados 17 pacientes com PV do ponto de vista motor, cognitivo e de neuroimagem através de testes e escalas padronizados. Resultados Dos 17 pacientes, 10 (58,5%) eram homens; a média de idade média foi 75,8±10,1 anos. Todos os pacientes eram hipertensos; a média de idade do início do parkinsonismo foi 72,2±10,0 anos. Achados clínicos mais frequentes: incontinência urinária (88,2%); parkinsonismo de membros inferiores com bloqueio de marcha e quedas (82,3%); sinais piramidais (76,4%). A média dos escores UPDRS e Hoehn-Yahr foram, respectivamente, 72,5±21,6 e 3,3±0,9 pontos. Dezesseis pacientes (94,1%) apresentaram bloqueio de marcha e disfunção executiva. Doze pacientes (70,5%) preencheram critérios para demência vascular provável. A dose média de levodopa foi 530,9 mg/dia e os pacientes tiveram uma baixa resposta à droga, tendo havido redução de apenas 6,9 pontos em média no escore UPDRS após o teste “practically-defined off”. Conclusão O perfil de PV encontrado neste estudo foi caracterizado por: envolvimento predominante de membros inferiores, com bloqueio de marcha e quedas; sinais piramidais; disfunção executiva; demência vascular concomitante e resposta pobre à levodopa. .

Prognóstico da incompetência cronotrópica em idosos diabéticos à ecocardiografia sob estresse físico / Prognostic value of chronotropic incompetence in elderly patients undergoing exercise echocardiography

FUNDAMENTO: A incompetência cronotrópica (IC), definida como a incapacidade de atingir no esforço 80% da frequência de reserva esperada para a idade, é um fator preditor de mortalidade e eventos cardiovasculares e pode conferir pior prognóstico a grupos em expansão devido ao acelerado processo de envelhecimento populacional, como em idosos diabéticos. OBJETIVO: Avaliar o valor prognóstico da IC em idosos diabéticos considerando desfechos com infarto agudo do miocárdio (IAM), doença cerebrovascular (DCV) e óbito geral, e comparar características clínicas e ecocardiográficas entre os que têm IC e os que não têm. MÉTODO: Foram estudados 298 pacientes idosos e diabéticos submetidos a ecocardiografia de estresse sob esforço físico (EF), de janeiro de 2001 a dezembro de 2010. Destes, 109 eram incompetentes cronotrópicos, grupo G1, e foram comparados aos competentes, grupo G2, quanto à ocorrência de eventos cardiovasculares, características clínicas e ecocardiográficas. RESULTADOS: O grupo G1, em relação ao grupo controle, apresentou maior frequência de DCV (9,2% × 3,2; p = 0,027) e maior frequência de óbito para aqueles que sofreram DCV ou IAM. Angina típica e dispneia prévias à realização da EF e sexo masculino foram mais frequentes no G1. A análise das variáveis ecocardiográficas demonstrou que o índice do escore de motilidade do ventrículo esquerdo (IEMVE) de repouso e de esforço, o índice de massa do VE (ventrículo esquerdo) e o diâmetro do AE (átrio esquerdo) foram maiores entre os incompetentes cronotrópicos. CONCLUSÃO: A IC foi associada, de forma independente, à ocorrência de DCV em idosos diabéticos.

BACKGROUND: Chronotropic incompetence (CI), defined as failure to achieve less than 80% of age-expected heart rate, is a predictor of mortality and adverse cardiovascular events and may confer a worse prognosis in elderly diabetic individuals. OBJECTIVE: To evaluate the prognostic value of chronotropic incompetence (CI) in elderly diabetic patients considering endpoints with acute myocardial infarction (AMI), cerebrovascular disease (CVD) and overall mortality and compare clinical and echocardiographic characteristics between patients with and without CI. METHOD: A total of 298 elderly diabetic patients undergoing exercise echocardiography (EE) were studied from January 2001 to December 2010. Of these, 109 were chronotropic incompetent (group 1) and were compared with the chronotropic competent ones (group 2) regarding the occurrence of cardiovascular events, clinical and echocardiographic characteristics. RESULTS: Chronotropic incompetents patients showed a higher frequency of cerebrovascular disease (9.2% vs. 3.2, p = 0.027) and higher mortality was observed in those who had cerebrovascular disease or acute myocardial infarction. The presence of typical angina and dyspnea prior to the performance of EE and male gender were more frequent in group 1. Rest and exercise left ventricular wall motion score index, rate of left ventricle mass and left atrium diameter were higher in chronotropic incompetent individuals. CONCLUSION: Chronotropic incompetence was independently associated with the occurrence of cerebrovascular disease in elderly diabetic individuals.

Cerebral hemodynamics: concepts of clinical importance / Hemodinâmica encefálica: conceitos de importância clínica

Cerebral hemodynamics and metabolism are frequently impaired in a wide range of neurological diseases, including traumatic brain injury and stroke, with several pathophysiological mechanisms of injury. The resultant uncoupling of cerebral blood flow and metabolism can trigger secondary brain lesions, particularly in early phases, consequently worsening the patient's outcome. Cerebral blood flow regulation is influenced by blood gas content, blood viscosity, body temperature, cardiac output, altitude, cerebrovascular autoregulation, and neurovascular coupling, mediated by chemical agents such as nitric oxide (NO), carbon monoxide (CO), eicosanoid products, oxygen-derived free radicals, endothelins, K+, H+, and adenosine. A better understanding of these factors is valuable for the management of neurocritical care patients. The assessment of both cerebral hemodynamics and metabolism in the acute phase of neurocritical care conditions may contribute to a more effective planning of therapeutic strategies for reducing secondary brain lesions. In this review, the authors have discussed concepts of cerebral hemodynamics, considering aspects of clinical importance.

Alterações hemodinâmicas e metabólicas do encéfalo ocorrem frequentemente em diversas doenças neurológicas, principalmente em condições de traumatismo cranioencefálico e acidente vascular encefálico, com vários mecanismos patofisiológicos lesionais. O desacoplamento resultante do fluxo sanguíneo e do metabolismo encefálico pode resultar em lesões encefálicas secundárias, principalmente nas primeiras fases, e, consequentemente, no agravamento do desfecho neurológico dos pacientes. Diversos fatores influenciam o fluxo sanguíneo encefálico, entre eles, a concentração sanguínea de gases, viscosidade sanguínea, temperatura corpórea, débito cardíaco, altitude, autorregulação cerebrovascular e acoplamento neurovascular, que é mediado por óxido nítrico (ON), monóxido de carbono (CO), eicosanoides, radicais livres derivados do oxigênio, endotelinas, potássio, íons hidrogênio e adenosinas. Melhor compreensão destes fatores é fundamental para o manejo clínico dos pacientes neurológicos críticos. A avaliação hemodinâmica e metabólica do encéfalo nas lesões encefálicas agudas pode contribuir para o planejamento de estratégias de redução das lesões encefálicas secundárias. Nesta revisão, os autores discutiram princípios da hemodinâmica encefálica, considerando os aspectos de importância clínica.

Transcranial doppler in sickle cell anaemia: evaluation of brain blood flow parameters in children of Aracaju, Northeast - Brazil / Doppler transcraniano em portadores de anemia falciforme: estudo dos parâmetros de fluxo sangüíneo cerebral em crianças de Aracaju, Sergipe

BACKGROUND: Environmental factors interfere on sickle cell anaemia (SCA). Transcanial Doppler (TCD) is important to evaluate cerebrovascular disease. OBJECTIVE: To evaluate brain haemodynamic profile of children with SCA in Sergipe. METHODS: Cross sectional study (group1: SCA patients aged 3-18; group2: age and sex matched healthy individuals). Baseline brain flow was evaluated. RESULTS: Group1=34 patients; group 2=81 controls. SCA patients had mean velocity (MV)=125.69 cm/s±23.40; pulsatility index (PI)=0.66±0.10; middle cerebral artery ratio (MCAr)=14.53±15.23; right anterior cerebral artery/right middle cerebral artery=0.77±0.20; left anterior cerebral artery/left middle cerebral artery=0.78±0.20. Controls had MV=79.44±15.54; PI=0.82±0.11; MCAr=13.19±13.77; right anterior cerebral artery/right middle cerebral artery=0.80±0.16; left anterior cerebral artery/left middle cerebral artery=0.84±0.18. MV and PI differences were statistically significant between groups. MV was related to age but not to gender. CONCLUSION: MV evaluation using TCD was similar to international standards and possible to be used in our setting.

INTRODUÇÃO: Aspectos ambientais interferem na apresentação da anemia falciforme (AF). Doppler transcraniano (DTC) é útil na avaliação do risco para doença cerebrovascular em pacientes com AF. OBJETIVO: Avaliar o perfil hemodinâmico cerebral de crianças com AF em Sergipe. MÉTODO: Estudo transversal (grupo1: portadores de AF 3-18 anos; grupo2: indivíduos saudáveis, pareados por idade e gênero). Foram avaliadas medidas de fluxo sangüíneo cerebral basal. RESULTADOS: Grupo1 (n=34): velocidade média (Vm)=125,69 cm/s ±23,40; índice de pulsatilidade (Ip)=0,66±0,10; relação entre artéria cerebral média (ACMs)=14,53±15,23; artéria cerebral anterior (ACA)/ACM direita=0,77±0,20; ACA/ACM esquerda=0,78±0,20. Grupo 2 (n=81): Vm=79,44 cm/s ±15,54; Ip=0,82±0,11, relação entre ACMs=13,19±13,77, ACA/ACM direita=0,80±0,16; ACA/ACM esquerda=0,84± 0,18. Vm foi maior e Ip menor no grupo1. Vm se correlacionou com idade mas não com gênero. CONCLUSÃO: O perfil hemodinâmico cerebral de crianças com AF em Sergipe assemelha-se às referências internacionais. Não se observou interferência de fatores ambientais sobre os resultados.

Processamento auditivo em criança com doença cerebrovascular / Auditory processing in children with cerebrovascular disease

TEMA: na infância a doença cerebrovascular (DCV) constitui condição rara em que a evolução a curto, médio e longo prazo tem merecido esclarecimentos. Neste sentido, a aplicação de técnicas comportamentais pode possibilitar melhor caracterização clínica, visando o planejamento e controle terapêutico eficientes. OBJETIVO: descrever em uma criança com DCV as manifestações audiológicas em dois momentos distintos da evolução clínica. MÉTODO: a criança, com diagnóstico comprovado de episódio único e unilateral de DCV, apresentando habilidades de linguagem e cognição satisfatórias, foi submetida a conjunto de testes convencionais e de processamento auditivo, incluindo a avaliação simplificada e as categorias de testes monóticos, dicóticos e de processamento temporal. Os dados obtidos foram pareados com criança normal destra, de mesmo sexo, idade e nível sócio-cultural. RESULTADOS: foi constatado comprometimento nas habilidades de memória auditiva e atenção seletiva em tarefas de integração e separação binaural para estímulos verbais e não-verbais. CONCLUSÃO: a evolução, embora favorável, se mostrou abaixo do esperado para a idade, quando comparado com seu par. A avaliação prospectiva da criança acometida por DCV possibilitou caracterizar o comportamento auditivo, definir seus parâmetros e a evolução do quadro audiológico.

BACKGROUND: cerebrovascular disease (CVD) during childhood is a rare condition; its short, medium and long-term characteristics deserve further investigation. The application of behavioral techniques may improve clinical characterization, thus rendering more efficient therapeutic planning and control. AIM: to describe the audiological manifestations in a child with CVD in two distinct moments of clinical follow-up. METHOD: the child, with a confirmed diagnosis of a single and unilateral episode of CVD, presenting satisfactory cognition and language skills, was submitted to a battery of conventional and auditory processing tests, which included a simplified evaluation as well as monotic, dichotic, and temporal processing tests. The obtained data was paired with those of a normal right-handed child, of the same gender, age and socio-cultural level. RESULTS: results indicate impairments in auditory memory as well as in selective attention during binaural separation and integration tasks for verbal and non-verbal stimuli. CONCLUSION: clinical development, although favorable, was below the average expected for the same age when compared to the control. The prospective evaluation of a child with DCV permitted the characterization of the auditory behavior, the definition of its parameters as well as the development of the audiological characteristics.

Mortalidade por doenças isquêmicas do coração, doenças cerebrovascualres e causas mal definidas nas ergiões de saúde do estado do Rio de Janeiro, no perído de 1980 a 2000 / Ischemic heart diseases, cerebrovascular diseases and defined causes of death in health districts of Rio de Janeiro state from 1980 to 2000

Analisar a evolução da mortalidade por Doenças Isquêmicas do Coração (DIC), por Doenças Cerebrovasculares (DCBV) e por Causas Mal Definidas (CMD), em adultos, nas regiões do estado do Rio de Janeiero (RJ), no período de 1980 a 2000.Métodos: os dados referentes às populações foram obtidos por consulta aos dados do IBGE e os óbitos aos dados do DATASUS/MS. Demarcaram-se 10 regiões de saúde: Cinturão Metropolitano, Município do Rio de Janeiro, Niterói, Médio-Paraíba, Serrana, Norte, Baixada Litorânea, Noroeste, Centro-Sul e Baía da Ilha Grande. As taxas de mortalidade por DIC, DCBV e CMD foram ajustadas por sexo e idade pelo método direto, tendo como padrão a população de 20 anos ou acima do Estado do Rio de Janeiro, no censo de 2000. Como a mortalidade por CMD, no Estado do RJ, aumentou de forma relevante a partir de 1990, realizou-se uma manobra de compensação. Empregaram-se modelos de regressão linear para a análise das tendências das taxas de mortalidade.Resultados: as taxas de mortalidade por DCBV apresentaram tendência de queda durante todo o período em todas as regiões (decréscimo anual médio de 2,9 por cento para o Estado), enquanto que as taxas por DIC passaram a manifestar quedas masi relevantes, em quase todas as regiões, a partir do início da década de 1990, acompanhadas pelo aumento simultâneo das taxas de mortalidade por CMD na área metropolitana.Conclusão: As DCBV predominaram em todas as regiões, exceto em Niterói e no município do Rio de Janeiro. Houve supremacia na tendência de queda da mortalidade por DCBV em relação à DIC em todas as regiões

Transcranial Doppler ultrasound assessment of intracranial hemodynamics in patients with type 2 diabetes mellitus

Diabetics have a 3-fold risk for cardiovascular diseases compared with non-diabetics. This study was designed to evaluate cerebral hemodynamic changes related to type 2 diabetes mellitus [DM] with transcranial Doppler ultrasonography [TCD]. TCD is a highly sensitive and specific method of quick bedside assessment of cerebrovascular circulation hemodynamics. In a prospective study, we compared a group of 100 patients with the diagnosis of type 2 diabetes mellitus [aged 48 to 67 years] and an age- and sex-matched control group of 100 healthy subjects without diabetes mellitus. We measured flow velocities [Vm] and the Gosling pulsatility index [PI] of the middle cerebral artery [MCA]. The rate of TCD abnormalities was significantly higher in diabetic patients than in healthy control subjects [55% vs. 11%, P<0.05]. The PI was significantly higher in diabetic patients than in healthy controls [P<0.001]. Atherosclerotic changes were found in 34.0% and 71.4% of patients suffering from diabetes for <5 and >/= 5 years, respectively. This study suggests that TCD is a useful marker for the detection of diabetic cerebrovascular changes. The duration and type of diabetes were found to have an impact on the development of pathologic cerebrovascular changes

Wicket spikes: a case-control study of a benign eletroencephalografic variant pattern

Wicket spikes (WS) are a benign eletroencephalogram (EEG) variant, seen mainly in adults, during sommolence, in the temporal regions, in many clinical situation. WS can appear in trains or isolatedly, sometimes being difficult to differentiate from epileptiform activity. We reviewed 2.000 EEG's, foud 65 with WS (3.25 per cent) and compared them with 65 normal EEG without WS. There was statistically significant (SS) association between WS and age over 33; adolescent age was correlated to absence of WS and age over 65, to the presence of WS; there was an inverse correlation between WS and epilepsy, related to differences in age; a SS association with cerebrovascular disorders disapeared after controling for age; a SS correlation with headache was also related to age; female predominance was not SS. There was a great variety of clinical situation associated with WS. We conclude that WS are a inespecific normal variant of the EEG that is age-related.

Doença cerebrovascular na infância: II. Aspectos clínicos em 42 casos / Cerebrovascular disease in children: II. Clinical aspects in 42 cases

Entre 1990 e 1998 foram analisadas, do ponto de vista clínico, 42 crianças com diagnóstico de doença cerebrovascular, internadas no Hospital das Clínicas da FCM-UNICAMP. O distúrbio cerebrovascular mais frequente foi do tipo isquêmico com acometimento predominante da artéria cerebral média, sendo o quadro clínico agudo caracterizado por manifestações epilépticas e alterações motoras, principalmente em crianças de idade precoce. A avaliação do seguimento das crianças mostrou predomínio de sequelas motoras.

Posterior circulation abnormalities in moyamoya disease : a radiological study.

Moyamoya disease (MMD) is an uncommon entity outside Japan. Though the clinical and radiological features are well described, involvement of the posterior circulation has not been highlighted. Out of 10 patients of MMD studied, the posterior circulation was involved in 9 (3 bilateral, 6 unilateral). The P1 segment was most commonly affected. Interestingly, no infarcts were seen in the territory of the posterior circulation in any patient. Five patients showed recent haemorrhages on scan. It was thalamic haemorrhage in four and subarachnoid in one patient. The posterior circulation is frequently involved in MMD as evident on angiography. However, ischaemic events of the posterior circulation are not frequent, as the posterior circulation acts as collateral pathway for the diseased anterior circulation till later stages of the disease.

Estimulación magnética transcraneana en el hombre / Transcranial magnetic stimulation in man

La estimulación magnética constituye una herramienta de estudio de las vías motoras centrales de carácter no invasivo e indoloro. La ausencia de efectos colaterales y molestias para el paciente han permitido su rápido desarrollo y aceptación. Es posible la estimulación de la corteza motora mediante la estimulación transcraneana (EMT), así como de las raíces motoras a nivel de su pasaje por los agujeros de conjugación mediante la estimulación espinal. Esto permite conocer el tiempo de conducción motora central (TCMC), el parámetro más utilizado, aunque la morfología y la amplitud de las respuestas permite ampliar el espectro diagnóstico. Además del potencial evocado motor (PEM), obtenido como un efecto excitatorio de la EMT, también existe un efecto inhibitorio, conocido como período de silencio (PS). En la esclerosis múltiple es característico el aumento del TCMC debido al retardo en zonas de desmielinización. Pueden observarse también respuestas polifásicas, reducción en la amplitud, aumento en la duración de las respuestas y aun ausencia de éstas. En la mielopatía cervicoartrósica el aumento del TCMC es considerablemente menor que en la anterior, siendo más frecuentes los efectos sobre la amplitud. El estudio de diferentes grupos musculares permite un diagóstico topográfico del nivel de compresión. En el accidente muscular encefálico, la presencia o ausencia de respuestas en los primeros días de instalación permite un pronóstico de recuperación funcional. En la esclerosis lateral amiotrófica se encuentra una marcada reducción de la amplitud y frecuentemente ausencia de respuestas, con escaso o ningún efecto sobre el TCMC