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OBJECTIVES: To characterize direct and reflex hand muscle responses to cervical root magnetic stimulation (CRMS) in healthy volunteers during sustained voluntary contraction. METHODS: In 18 healthy volunteers, we recorded from the first dorsal interosseous (FDI) muscle the responses to CRMS of progressively increasing intensity and level of muscle contraction. The compound muscle action potential (CMAP) and the silent period (SP) were compared to those obtained with plexus, midarm and wrist stimulation. Additionally, in a smaller number of subjects, we obtained the peristimulus time histogram (psth) of single motor unit firing in the FDI, examined the effects of vibration and recorded the modulation of sustained EMG activity in muscles of the lower limbs. RESULTS: Increasing CRMS intensity led to larger CMAP with no relevant changes in SP1 or SP2, except for lower amplitude of the burst interrupting the silent period (BISP). Increasing the level of muscle contraction led to reduced CMAP, shorter SP duration and increased BISP amplitude. The psth analysis showed the underlying changes in the motor unit firing frequency that corresponded to the changes seen in the CMAP and the SP with surface recordings. Progressively distal stimulation led to CMAPs of shorter latency and increased amplitude, SPs of longer latency and shorter duration, and a BISP of longer latency. Vibration led to reduction of the SP. CRMS induced SPs in muscles of the lower limb. CONCLUSIONS: CRMS induces excitatory and inhibitory responses in hand muscles, fitting with the expected behavior of mixed nerve stimulation at very proximal sites. SIGNIFICANCE: Characterization of the effects of CRMS on hand muscles is of physiological and potentially clinical applicability, as it is a painless and reliable procedure.
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BACKGROUND: Prepulse inhibition (PPI) is a neurophysiological phenomenon whereby a weak stimulus modulates the reflex response to a subsequent strong stimulus. Its physiological purpose is to avoid interruption of sensory processing by subsequent disturbing stimuli at the subcortical level, thereby preventing undesired motor reactions. An important hub in the PPI circuit is the pedunculopontine nucleus, which is also involved in the control of posture and sleep/wakefulness. OBJECTIVE: To study the effect of posture (supine versus standing) on PPI, induced by somatosensory prepulses to either upper or lower limb. PPI was measured as the percentage inhibition of the blink reflex response to electrical supraorbital nerve (SON) stimulation. METHODS: Sixteen healthy volunteers underwent bilateral blink reflex recordings following SON stimulation either alone (baseline) or preceded by an electrical prepulse to the median nerve (MN) or sural nerve (SN), both in supine and standing. Stimulus intensity was 8 times sensory threshold for SON, and 2 times sensory threshold for MN and SN, respectively. Eight stimuli were applied in each condition. RESULTS: Baseline blink reflex parameters did not differ significantly between the two postures. Prepulse stimulation to MN and SN caused significant inhibition of R2. In supine but not in standing, R2 was significantly more inhibited by MN than by SN prepulses. In standing, SN stimulation caused significantly more inhibition of R2 than in supine, while the inhibition caused by MN prepulses did not differ significantly between postures. SIGNIFICANCE: PPI induced by lower limb afferent input may contribute to postural control while standing.
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Piscadela/fisiologia , Extremidade Inferior/fisiologia , Equilíbrio Postural/fisiologia , Postura/fisiologia , Inibição Pré-Pulso/fisiologia , Sensação/fisiologia , Extremidade Superior/fisiologia , Adulto , Feminino , Humanos , Masculino , Núcleo Tegmental Pedunculopontino , Limiar Sensorial/fisiologia , Adulto JovemRESUMO
The pedunculopontine nucleus (PPN) is located in the mesopontine tegmentum and is best delimited by a group of large cholinergic neurons adjacent to the decussation of the superior cerebellar peduncle. This part of the brain, populated by many other neuronal groups, is a crossroads for many important functions. Good evidence relates the PPN to control of reflex reactions, sleep-wake cycles, posture and gait. However, the precise role of the PPN in all these functions has been controversial and there still are uncertainties in the functional anatomy and physiology of the nucleus. It is difficult to grasp the extent of the influence of the PPN, not only because of its varied functions and projections, but also because of the controversies arising from them. One controversy is its relationship to the mesencephalic locomotor region (MLR). In this regard, the PPN has become a new target for deep brain stimulation (DBS) for the treatment of parkinsonian gait disorders, including freezing of gait. This review is intended to indicate what is currently known, shed some light on the controversies that have arisen, and to provide a framework for future research.
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Tronco Encefálico/fisiologia , Congressos como Assunto , Consenso , Núcleo Tegmental Pedunculopontino/fisiologia , Sociedades Médicas , Estimulação Encefálica Profunda/métodos , District of Columbia/epidemiologia , Humanos , Doença de Parkinson/fisiopatologia , Doença de Parkinson/terapia , Inibição Pré-Pulso/fisiologia , Fases do Sono/fisiologiaRESUMO
A combined assessment tool for the perceptual-motor aspects of pain processing will be valuable to clinicians. Fifteen healthy subjects were exposed to contact-heat stimulation (Pathway, Medoc, Israel) to assess perception through a simple task (motor response or conscious appraisal of the time the stimulus was felt) or with a dual task (both responses). The outcome measure was the temporal relationship between contact heat evoked potentials (CHEPS), reaction time (RT) and conscious awareness (AW). There were different temporal profiles for CHEPs, RT and AW to changes in stimulus intensity, AW being the least affected. Performing the dual task led to a significantly more pronounced effect on RT than on AW, while CHEPS were not influenced by task performance. Our results support the dissociation between physiological, behavioral and cognitive events elicited by nociceptive stimuli. The time of conscious appraisal of stimulus occurrence is a complementary information to other responses such as evoked potentials or behavioral tasks. The combined assessment of physiological and behavioral aspects of pain processing may provide clinicians with information on the different paths followed by nociceptive afferent inputs in the central nervous system.
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Cognição , Temperatura Alta/efeitos adversos , Percepção da Dor , Dor/fisiopatologia , Tempo de Reação , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
STUDY DESIGN: A cross-sectional study in chronic spinal cord injury with cervical lesions (cSCI). OBJECTIVE: To determine the corticomotor projection and motor cortex organization of paralyzed forearm muscles that presented only liminal voluntary activation. SETTING: Burke Medical Research Institute, White Plains, NY, USA. METHODS: We identified ten people with chronic SCI who had a wrist flexor or extensor muscle with a motor power (MP) of 1 over 5. We recorded motor evoked potentials (MEPs) to transcranial magnetic stimulation (TMS) over the primary motor cortex of the hemisphere contralateral to the target muscle. We measured resting motor threshold (RMT), corticomotor latency (LTY), MEP amplitude (AMP) and performed cortical motor mapping to determine the optimal site (OPT) and map area (AREA). Results were compared with the data from 18 controls. RESULTS: A MEP in the target muscle was observed for all cSCI cases. LTY was normal, while corticomotor excitability (as determined by RMT and AMP) was reduced in about half of the group. The OPT site of the motor maps was within control range for all cSCI cases, while AREA was reduced in three cases. CONCLUSIONS: Corticomotor conduction and cortical topography were appreciably normal despite only liminal activation of the target muscle with voluntary effort. Muscles with these characteristics may benefit from a targeted rehabilitation program even in the chronic phase after SCI.
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Antebraço/fisiopatologia , Córtex Motor/fisiopatologia , Músculo Esquelético/fisiopatologia , Traumatismos da Medula Espinal/fisiopatologia , Adulto , Mapeamento Encefálico/métodos , Doença Crônica , Estudos Transversais , Eletromiografia , Potencial Evocado Motor , Feminino , Antebraço/inervação , Lateralidade Funcional , Humanos , Masculino , Pessoa de Meia-Idade , Atividade Motora/fisiologia , Músculo Esquelético/inervação , Condução Nervosa , Vias Neurais/fisiopatologia , Estimulação Magnética Transcraniana/métodos , Adulto JovemRESUMO
OBJECTIVE: Although the diagnosis of inherited ataxias is ultimately genetic, this usually means an extensive and expensive process. This justifies the search for distinct clinical signs that may potentially help orient molecular diagnosis. METHODS: We explored the vestibulo-ocular reflex (VOR) with the video Head Impulse Test in patients diagnosed with spinocerebellar ataxia (SCA) type 3 (nâ=â15), type 1 (nâ=â4) and type 2 (nâ=â4), Friedreich's ataxia (FA) (nâ=â9) and healthy controls (nâ=â40). We estimated the latency, regression (VORr) and instantaneous VOR gain at 40, 60 and 80âms (VOR40, VOR60 and VOR80), and determined the latency, peak-velocity and occurrence rate of catch-up saccades triggered with head-impulses. RESULTS: VOR latency was higher in FA (pâ<â0.001) and SCA3 (pâ=â0.02) as compared to controls, discriminating FA from other ataxic patients with an overall diagnostic accuracy of 88%. VORr, VOR40 and VOR60 were significantly lower in FA and SCA3 (pâ<â0.01). VOR80 was only significantly lower than controls in SCA3 (pâ<â0.01), discriminating these from other ataxic patients with an overall diagnostic accuracy of 78%. Covert saccades were only triggered in SCA3 but with low occurrence rate and peak velocity (11.1 ± 28.5% and 77.50 ± 15.30°/s) whereas overt saccades were present in all groups. VORr gain showed a negative correlation with disease severity evaluated with SARA (Spearman râ=â-0.46, pâ=â0.01). CONCLUSIONS: vHIT provides phenotypic information that differentiates these autosomal ataxias and can serve as a strategy to orient genetic diagnosis. A correlation between VOR and SARA raises the possibility of using VOR gain as a neurophysiologic biomarker for disease severity.
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Ataxia de Friedreich/diagnóstico , Teste do Impulso da Cabeça , Reflexo Vestíbulo-Ocular , Ataxias Espinocerebelares/diagnóstico , Adulto , Diagnóstico Diferencial , Feminino , Humanos , Doença de Machado-Joseph/diagnóstico , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Movimentos Sacádicos , Testes de Função VestibularRESUMO
BACKGROUND: Differentiating central from peripheral origins of spontaneous nystagmus (SN) is challenging. Looking for a simple sign of peripheral disease with the video Head Impulsive Test we noticed anti-compensatory eye movements (AQEM) in patients with peripheral etiologies of spontaneous nystagmus (SN). Here we assess the diagnostic accuracy of AQEM in differentiating peripheral from central vestibular disorders. METHODS: We recorded the eye movements in response to horizontal head impulses in a group of 43 consecutive patients with acute vestibular syndrome (12 with central, 31 with peripheral disorders), 5 patients after acute vestibular neurectomy (positive controls) and 39 healthy subjects (negative controls). AQEM were defined as quick eye movements (peak velocity above 50°/s) in the direction of the head movement. RESULTS: All patients with peripheral disorders and positive controls had AQEM (latency 231 ± 53 ms, amplitude 3.4 ± 1.4°, velocity 166 ± 55°/s) when their head was moved to the opposite side of the lesion. Central patients did not have AQEM. AQEM occurrence rate was higher in peripheral patients with contralesional (74 ± 4%, mean ± SD) in comparison to ipsilesional (1 ± 4%) impulses (p< 0.001). Overall diagnostic accuracy for differentiating central from peripheral patients was 96% (95% CI for AUC ROC curve: 0.90 to 1.0) for VOR gain and 100% (95% CI: 1.0 to 1.0) for AQEM occurrence rate. CONCLUSIONS: These results suggest that AQEM are a sign of vestibular imbalance in a peripheral deficit. In addition to VOR gain they should be added to the evaluation of the head impulse test.
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Movimentos Oculares , Nistagmo Patológico/diagnóstico , Testes de Função Vestibular/métodos , Adulto , Idoso , Diagnóstico Diferencial , Feminino , Lateralidade Funcional , Cabeça , Humanos , Masculino , Pessoa de Meia-Idade , Nistagmo Patológico/fisiopatologia , Estimulação Física , Reflexo Vestíbulo-Ocular , Doenças Vestibulares/fisiopatologia , Nervo Vestibular/cirurgiaRESUMO
The neural substrates of fatigue induced by muscular activity have been addressed in depth in relation to isometric tasks. For these activities, when fatigue develops, it has been noted that the duration of the silent periods (SPs) increases in response to both transcranial magnetic stimulation (TMS) of primary motor cortex or electric cervicomedullary stimulation (CMS). However, fatigue is known to be task-dependent and the mechanisms giving rise to a decrease in motor performance during brief, fast repetitive tasks have been less studied. We hypothesized that fatigue induced by repetitive fast finger tapping may have physiological mechanisms different from those accounting for fatigue during an isometric contraction, even in cases of matched effort durations. In these tasks, we examined the contribution of spinal and supraspinal motor circuits to the production of fatigue. The tapping rate and maximal voluntary contractions (MVC), and TMS- and CMS-evoked SPs were obtained at the time of fatigue, and while subjects maintained maximal muscle activation after fast finger-tapping (or isometric activity) of different durations (10 or 30s). Results showed different mechanisms of fatigue triggered by isometric contraction and repetitive movements, even of short duration. Short-lasting repetitive movements induce fatigue within intracortical inhibitory circuits. They increased TMS-SPs, but not CMS-SPs. On the other hand, isometric contraction had a clear impact on spinal circuits. The consideration of these differences might help to optimize the study of fatigue in physiological conditions and neurological disorders.
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Potenciais Evocados Auditivos do Tronco Encefálico/fisiologia , Fadiga/etiologia , Fadiga/patologia , Contração Isométrica/fisiologia , Músculo Esquelético/fisiopatologia , Desempenho Psicomotor/fisiologia , Adulto , Análise de Variância , Eletromiografia , Feminino , Dedos/fisiopatologia , Humanos , Masculino , Córtex Motor/fisiologia , Psicofísica , Estimulação Magnética Transcraniana , Adulto JovemRESUMO
Highly repetitive submaximal intermittent contractions of the forearm muscles during periods of 30-50 min partially explain why motorcycle races are so demanding for the neuromuscular system. This study investigated the contribution of central and peripheral mechanisms of fatigue on the exerted and contralateral extensor digitorum communis following an intermittent fatigue protocol (IFP) designed for motorcycle riders. 12 riders performed an IFP, which simulates the braking and throttle handle gesture. We examined the time course of recovery of maximal voluntary contraction (MVC), M-wave, motor evoked potential (MEP) to transcranial magnetic stimuli in relaxed and facilitated condition, and the cortical silent period (CSP) at time windows of 1, 3, 5, 10 and 20 min after the IFP. Whereas MVC, M-wave and MEP decreased, CSP lengthened significantly in the fatigued limb after completion of the IFP. Nevertheless, no differences were observed in the contralateral limb. All neurophysiological parameters reverted to baseline values in less than 20 min, while MVC remained lower in the exercised limb. No cross-over effects were observed in the contralateral non-exercised limb. Our results suggest that local factors are those mainly responsible for the incomplete MVC recovery after an intermittent muscle contraction protocol.
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Antebraço/fisiologia , Motocicletas , Contração Muscular/fisiologia , Fadiga Muscular/fisiologia , Adulto , Eletromiografia , Potencial Evocado Motor , Força da Mão/fisiologia , Humanos , Masculino , Dinamômetro de Força Muscular , Estimulação Magnética TranscranianaRESUMO
OBJECTIVE: Fast and accurate movements are often performed in response to a sensory signal. In reaction time tasks, execution of open loop movements is speeded up when a startling auditory stimulus (SAS) is applied together with the imperative signal (IS). In this study, we examined the effects of a SAS on the performance of a task that demands accuracy. METHODS: Nine subjects were asked to move a monitored pen to a target point located in a table at a fixed angular distance of 30 degrees from a start point. The target was a spot of three possible diameters: 5, 10, and 20mm. Finger force for pen holding, pen tip pressure against the table and kinematic variables of the forearm movement were measured for three conditions: control, SAS delivered at IS (SAS-IS trials) and SAS delivered during movement execution (SAS-MOV trials). RESULTS: Two movement phases could be identified in the movement trajectory and force profile. The first phase, ballistic, was significantly shortened in SAS-MOV trials, with earlier and larger peak velocity and peak force with respect to control trials. The second phase, slow approach to target, was longer in SAS-IS trials but not in SAS-MOV trials. Accuracy was maintained throughout all conditions and stimulation modes. CONCLUSIONS: A SAS speeds up only the first (ballistic) part of the movement in an accuracy task. Slower target approach compensates for the accelerated initial movement. No changes in the last part of the movement are seen when a SAS is delivered after movement onset. SIGNIFICANCE: The StartReact effect is restricted to the onset of a complex movement, when muscles are activated in a ballistic mode, without feedback.
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Estimulação Acústica/métodos , Movimento/fisiologia , Desempenho Psicomotor/fisiologia , Tempo de Reação/fisiologia , Reflexo de Sobressalto/fisiologia , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Distribuição AleatóriaRESUMO
INTRODUCTION: This article is part of the Focus Theme of Methods of Information in Medicine on "Biosignal Interpretation: Advanced Methods for Neural Signals and Images". OBJECTIVES: An efficient way to investigate the neural basis of nociceptive responses is the analysis of the event-related brain potentials (ERPs). The main objective of this work was to study how adaptation and fatigue affect the ERPs to stimuli of different modalities, by characterizing the responses to infrequent and frequent stimulation in different recording periods. METHODS: In this work, series of averaged EEG epochs recorded after thermal, electrical and auditory stimulation were analyzed with time-frequency representation and non-linear measures as spectral entropy and auto-mutual information function. The study was performed by considering the traditional EEG frequency bands. RESULTS: The defined measures presented a statistical significance p-value <â 0.01 and accuracy higher than 60% by differentiating windows of response to infrequent (I) and frequent (F) stimuli between the start and end of the EEG recording. CONCLUSIONS: These measures permitted to observe some aspects of the subject's adaptation and the nociceptive response.
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Estimulação Acústica , Eletroencefalografia/métodos , Potenciais Evocados , Algoritmos , Fadiga/psicologia , Humanos , Fatores de TempoRESUMO
During the last decade, many studies have been carried out to understand the effects of focal vibratory stimuli at various levels of the central nervous system and to study pathophysiological mechanisms of neurological disorders as well as the therapeutic effects of focal vibration in neurorehabilitation. This review aimed to describe the effects of focal vibratory stimuli in neurorehabilitation including the neurological diseases or disorders like stroke, spinal cord injury, multiple sclerosis, Parkinson's' disease and dystonia. In conclusion, focal vibration stimulation is well tolerated, effective and easy to use, and it could be used to reduce spasticity, to promote motor activity and motor learning within a functional activity, even in gait training, independent from etiology of neurological pathology. Further studies are needed in the future well-designed trials with bigger sample size to determine the most effective frequency, amplitude and duration of vibration application in the neurorehabilitation.
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Terapia por Exercício/métodos , Terapia por Exercício/enfermagem , Doenças do Sistema Nervoso/reabilitação , Vibração/uso terapêutico , HumanosRESUMO
Preparation of the motor system for movement execution involves an increase in excitability of motor pathways. In a reaction time task paradigm, a startling auditory stimulus (SAS) delivered together with the imperative signal (IS) shortens reaction time significantly. In self-generated tasks we considered that an appropriately timed SAS would have similar effects. Eight subjects performed a ballistic wrist extension in two blocks: reaction, in which they responded to a visual IS, and action, in which they moved when they wished within a predetermined time window. In 20-25% of the trials, a SAS was applied. We recorded electromyographic activity of wrist extension and wrist movement kinematic variables. No effects of SAS were observed in action trials when movement was performed before or long after SAS application. However, a cluster of action trials was observed within 200 ms after SAS. These trials showed larger EMG bursts, shorter movement time, shorter time to peak velocity, and higher peak velocity than other action trials (P < 0.001 for all), with no difference from Reaction trials containing SAS. The results show that SAS influences the execution of self-generated human actions as it does with preprogrammed reaction time tasks during the assumed building up of preparatory activity before execution of the willed motor action.
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Movimento/fisiologia , Desempenho Psicomotor/fisiologia , Tempo de Reação/fisiologia , Punho/fisiologia , Adulto , Fenômenos Biomecânicos , Eletromiografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Córtex Motor/fisiologiaRESUMO
BACKGROUND: Neuropathic pain (NP) is common in spinal cord injury (SCI) patients. One of its manifestations is a lowering of pain perception threshold in quantitative thermal testing (QTT) in dermatomes rostral to the injury level. Transcranial direct current stimulation (tDCS) combined with visual illusion (VI) improves pain in SCI patients. We studied whether pain relief with tDCS + VI intervention is accompanied by a change in contact heat- evoked potentials (CHEPs) or in QTT. METHODS: We examined 18 patients with SCI and NP before and after 2 weeks of daily tDCS + VI intervention. Twenty SCI patients without NP and 14 healthy subjects served as controls. We assessed NP intensity using a numerical rating scale (NRS) and determined heat and pain thresholds with thermal probes. CHEPs were recorded to stimuli applied at C4 level, and subjects rated their perception of evoked pain using NRS during CHEPs. RESULTS: Thirteen patients reported a mean decrease of 50% in the NRS for NP after tDCS + VI. Evoked pain perception was significantly higher than in the other two groups, and reduced significantly together with CHEPs amplitude after tDCS + VI with respect to baseline. Pain perception threshold was significantly lower than in the other two groups before tDCS + VI intervention, and increased significantly afterwards. CONCLUSION: Two weeks of tDCS + VI induced significant changes in CHEPs, evoked pain and heat pain threshold in SCI patients with NP. These neurophysiological tests might be objective biomarkers of treatment effects for NP in patients with SCI.
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Ilusões/fisiologia , Neuralgia/fisiopatologia , Neuralgia/terapia , Estimulação Luminosa/métodos , Traumatismos da Medula Espinal/fisiopatologia , Estimulação Magnética Transcraniana/métodos , Adulto , Idoso , Potenciais Somatossensoriais Evocados/fisiologia , Feminino , Habituação Psicofisiológica/fisiologia , Temperatura Alta/efeitos adversos , Humanos , Masculino , Pessoa de Meia-Idade , Neuralgia/etiologia , Limiar da Dor/fisiologia , Limiar Sensorial/fisiologia , Traumatismos da Medula Espinal/complicaçõesRESUMO
OBJECTIVE: To establish clinical guidelines for the clinical use and interpretation of motor evoked potentials (MEP) in diagnosing and monitoring patients with multiple sclerosis (MS). Recommendations for MEP use and interpretation will help us rationalise and optimise resources used in MS patient diagnosis and follow up. METHOD: We completed an extensive literature review and pooled our own data to produce a consensus statement with recommendations for the clinical use of MEPs in the study of MS. RESULTS: MEPs, in addition to spinal and cranial magnetic resonance imaging (MRI), help us diagnose and assess MS patients whose disease initially presents as spinal cord syndrome and those with non-specific brain MRI findings, or a normal brain MRI and clinical signs of MS. CONCLUSIONS: Whenever possible, a multimodal evoked potential study should be performed on patients with suspected MS in order to demonstrate involvement of the motor pathway which supports a diagnosis of dissemination in space.
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Potencial Evocado Motor/fisiologia , Esclerose Múltipla/diagnóstico , Consenso , Doenças Desmielinizantes/patologia , Estimulação Elétrica , Campos Eletromagnéticos , Humanos , Imageamento por Ressonância Magnética , Esclerose Múltipla/fisiopatologia , Condução Nervosa , Exame NeurológicoRESUMO
Transcranial magnetic stimulation (TMS) is an established neurophysiological tool to examine the integrity of the fast-conducting corticomotor pathways in a wide range of diseases associated with motor dysfunction. This includes but is not limited to patients with multiple sclerosis, amyotrophic lateral sclerosis, stroke, movement disorders, disorders affecting the spinal cord, facial and other cranial nerves. These guidelines cover practical aspects of TMS in a clinical setting. We first discuss the technical and physiological aspects of TMS that are relevant for the diagnostic use of TMS. We then lay out the general principles that apply to a standardized clinical examination of the fast-conducting corticomotor pathways with single-pulse TMS. This is followed by a detailed description of how to examine corticomotor conduction to the hand, leg, trunk and facial muscles in patients. Additional sections cover safety issues, the triple stimulation technique, and neuropediatric aspects of TMS.
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Estimulação Elétrica/métodos , Guias como Assunto/normas , Doenças do Sistema Nervoso/diagnóstico , Estimulação Magnética Transcraniana/métodos , Estimulação Magnética Transcraniana/normas , Biofísica , Depressão Alastrante da Atividade Elétrica Cortical , Eletromiografia , Potencial Evocado Motor , Lateralidade Funcional , Humanos , Músculo Esquelético/inervação , Músculo Esquelético/fisiopatologia , Condução NervosaRESUMO
OBJECTIVES: to provide a revised version of earlier guidelines published in 2006. BACKGROUND: primary dystonias are chronic and often disabling conditions with a widespread spectrum mainly in young people. DIAGNOSIS: primary dystonias are classified as pure dystonia, dystonia plus or paroxysmal dystonia syndromes. Assessment should be performed using a validated rating scale for dystonia. Genetic testing may be performed after establishing the clinical diagnosis. DYT1 testing is recommended for patients with primary dystonia with limb onset before age 30, and in those with an affected relative with early-onset dystonia. DYT6 testing is recommended in early-onset or familial cases with cranio-cervical dystonia or after exclusion of DYT1. Individuals with early-onset myoclonus should be tested for mutations in the DYT11 gene. If direct sequencing of the DYT11 gene is negative, additional gene dosage is required to improve the proportion of mutations detected. A levodopa trial is warranted in every patient with early-onset primary dystonia without an alternative diagnosis. In patients with idiopathic dystonia, neurophysiological tests can help with describing the pathophysiological mechanisms underlying the disorder. TREATMENT: botulinum toxin (BoNT) type A is the first-line treatment for primary cranial (excluding oromandibular) or cervical dystonia; it is also effective on writing dystonia. BoNT/B is not inferior to BoNT/A in cervical dystonia. Pallidal deep brain stimulation (DBS) is considered a good option, particularly for primary generalized or cervical dystonia, after medication or BoNT have failed. DBS is less effective in secondary dystonia. This treatment requires a specialized expertise and a multidisciplinary team.
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Toxinas Botulínicas/uso terapêutico , Estimulação Encefálica Profunda , Distonia/diagnóstico , Distonia/terapia , Distúrbios Distônicos/diagnóstico , Distúrbios Distônicos/terapia , Distonia/genética , Distonia/fisiopatologia , Distúrbios Distônicos/genética , Distúrbios Distônicos/fisiopatologia , Globo Pálido/fisiopatologia , Globo Pálido/cirurgia , Humanos , Chaperonas Moleculares/genéticaRESUMO
BACKGROUND: Revision of the guidelines on the use of skin biopsy in the diagnosis of peripheral neuropathy, published in 2005, has become appropriate owing to publication of more relevant articles. Most of the new studies focused on small fiber neuropathy (SFN), a subtype of neuropathy for which the diagnosis was first developed through skin biopsy examination. This revision focuses on the use of this technique to diagnose SFN. METHODS: Task force members searched the Medline database from 2005, the year of the publication of the first EFNS guideline, to June 30th, 2009. All pertinent articles were rated according to the EFNS and PNS guidance. After a consensus meeting, the task force members created a manuscript that was subsequently revised by two experts (JML and JVS) in the field of peripheral neuropathy and clinical neurophysiology, who were not previously involved in the use of skin biopsy. RESULTS AND CONCLUSIONS: Distal leg skin biopsy with quantification of the linear density of intraepidermal nerve fibers (IENF), using generally agreed upon counting rules, is a reliable and efficient technique to assess the diagnosis of SFN (Recommendation Level A). Normative reference values are available for bright-field immunohistochemistry (Recommendation Level A) but not yet for confocal immunofluorescence or the blister technique. The morphometric analysis of IENF density, either performed with bright-field or immunofluorescence microscopy, should always refer to normative values matched for age (Recommendation Level A). Newly established laboratories should undergo adequate training in a well-established skin biopsy laboratory and provide their own stratified for age and gender normative values, intra- and interobserver reliability, and interlaboratory agreement. Quality control of the procedure at all levels is mandatory (Good Practice Point). Procedures to quantify subepidermal nerve fibers and autonomic innervated structures, including erector pili muscles, and skin vessels, are under development but need to be confirmed by further studies. Sweat gland innervation can be examined using an unbiased stereologic technique recently proposed (Recommendation Level B). A reduced IENF density is associated with the risk of developing neuropathic pain (Recommendation Level B), but it does not correlate with its intensity. Serial skin biopsies might be useful for detecting early changes of IENF density, which predict the progression of neuropathy, and to assess degeneration and regeneration of IENF (Recommendation Level C). However, further studies are warranted to confirm its potential usefulness as an outcome measure in clinical practice and research. Skin biopsy has not so far been useful for identifying the etiology of SFN. Finally, we emphasize that 3-mm skin biopsy at the ankle is a safe procedure based on the experience of 10 laboratories reporting absence of serious side effects in approximately 35,000 biopsies and a mere 0.19% incidence of non-serious side effects in about 15 years of practice (Good Practice Point).
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Comitês Consultivos , Fibras Nervosas Mielinizadas/patologia , Doenças do Sistema Nervoso Periférico/diagnóstico , Doenças do Sistema Nervoso Periférico/patologia , Células Receptoras Sensoriais/patologia , Pele/inervação , Biópsia/métodos , Biópsia/normas , Biópsia/tendências , Europa (Continente) , Humanos , Sociedades MédicasRESUMO
OBJECTIVE: To describe a novel mutation (K239N) in the PSEN1 associated with familial Alzheimer's disease (AD). METHODS AND RESULTS: The proband was a man who developed cognitive decline with marked behavioural abnormalities at age 57. At age 70, he was admitted into a psychiatric facility because of aggressiveness and a suicide attempt. Family history was consistent with autosomal dominant AD. One of the two other family members studied presented also with prominent behavioural symptoms at age 42 and has also been forced into a psychiatric facility because of aggressiveness at age 56. The remainder patient has presented a prototypical AD, but starting at age 71. Direct sequencing of PSEN1 in the three living affected members disclosed a heterozygous G to C transition in exon 7 of PSEN1 leading to the K239N mutation. CONCLUSION: The K239N mutation is associated with autosomal dominant AD with a wide range of age of onset and incomplete penetrance at the age of 65, prominent behavioural features and slow progression.