Neuroprotective effect of epidural hypothermia after spinal cord lesion in rats

OBJECTIVES : To evaluate the neuroprotective effect of epidural hypothermia in rats subjected to experimental spinal cord lesion. METHODS: Wistar rats (n = 30) weighing 320-360 g were randomized to two groups (hypothermia and control) of 15 rats per group. A spinal cord lesion was induced by the standardized drop of a 10-g weight from a height of 2.5 cm, using the New York University Impactor, after laminectomy at the T9-10 level. Rats in the hypothermia group underwent epidural hypothermia for 20 minutes immediately after spinal cord injury. Motor function was assessed for six weeks using the Basso, Beattie and Bresnahan motor scores and the inclined plane test. At the end of the final week, the rats' neurological status was monitored by the motor evoked potential test and the results for the two groups were compared. RESULTS: Analysis of the Basso, Beattie and Bresnahan scores obtained during the six-week period indicated that there were no significant differences between the two groups. There was no significant difference between the groups in the inclined plane test scores during the six-week period. Furthermore, at the end of the study, the latency and amplitude values of the motor evoked potential test were not significantly different between the two groups. CONCLUSION: Hypothermia did not produce a neuroprotective effect when applied at the injury level and in the epidural space immediately after induction of a spinal cord contusion in Wistar rats. .

Combined Muscle Motor and Somatosensory Evoked Potentials for Intramedullary Spinal Cord Tumour Surgery

PURPOSE: To evaluate whether intraoperative neurophysiologic monitoring (IONM) with combined muscle motor evoked potentials (mMEPs) and somatosensory evoked potentials is useful for more aggressive and safe resection in intramedullary spinal cord tumour (IMSCT) surgery. MATERIALS AND METHODS: We reviewed data from consecutive patients who underwent surgery for IMSCT between 1998 and April 2012. The patients were divided into two groups based on whether or not IONM was applied. In the monitored group, the procedures were performed under IONM using 75% muscle amplitude decline weaning criteria. The control group was comprised of patients who underwent IMSCT surgery without IONM. The primary outcome was the rate of gross total excision of the tumour on magnetic resonance imaging at one week after surgery. The secondary outcome was the neurologic outcome based on the McCormick Grade scale. RESULTS: The two groups had similar demographics. The total gross removal tended to increase when intraoperative neurophysiologic monitoring was used, but this tendency did not reach statistical significance (76% versus 58%; univariate analysis, p=0.049; multivariate regression model, p=0.119). The serial McCormick scale score was similar between the two groups (based on repeated measure ANOVA). CONCLUSION: Our study evaluated combined IONM of trans-cranial electrical (Tce)-mMEPs and SEPs for IMSCT. During IMSCT surgery, combined Tce-mMEPs and SEPs using 75% muscle amplitude weaning criteria did not result in significant improvement in the rate of gross total excision of the tumour or neurologic outcome.

The evaluation of SCI by TMS-MEP and its forensic significance / 法医学杂志

OBJECTIVE@#To find an objective and accurate examination for evaluation of spinal cord injury (SCI) in forensic clinical medicine.@*METHODS@#The onset latency of cortex, peak latency of N1, central motor conduction time (CMCT) and wave width of the abductor pollicis brevis and the anterior tibialis were calculated by transcranial magnetic stimulation-motor evoked potential (TMS-MEP). The data of 68 patients suffered from SCI including 23 cervical levels and 45 thoracolumbar levels were collected and compared with that of 30 normal controls.@*RESULTS@#In experimental group, when the muscle strength of the abductor pollicis brevis or the anterior tibialis decreased or disappeared, the onset latency of cortex, the peak latency of N1, and CMCT prolonged and the wave width broadened. And these indexes of grade 2 and 3 muscle strength in experimental group were higher than that in the control group (P < 0.05).@*CONCLUSION@#The TMS-MEP can determine directly and objectively the motor functional status of pyramidal tract of spinal cord in order to provide more accurate and objective evidences in forensic medicine.

Intraoperative Neurophysiologic Monitoring: Basic Principles and Recent Update

The recent developments of new devices and advances in anesthesiology have greatly improved the utility and accuracy of intraoperative neurophysiological monitoring (IOM). Herein, we review the basic principles of the electrophysiological methods employed under IOM in the operating room. These include motor evoked potentials, somatosensory evoked potentials, electroencephalography, electromyography, brainstem auditory evoked potentials, and visual evoked potentials. Most of these techniques have certain limitations and their utility is still being debated. In this review, we also discuss the optimal stimulation/recording method for each of these modalities during individual surgeries as well as the diverse criteria for alarm signs.

Does the longer application of anodal-transcranial direct current stimulation increase corticomotor excitability further? a pilot study

Anodal transcranial direct current stimulation [a-tDCS] of the primary motor cortex [M1] has been shown to be effective in increasing corticomotor excitability. We investigated whether longer applications of a-tDCS coincide with greater increases in corticomotor excitability compared to shorter application of a-tDCS. Ten right-handed healthy participants received one session of a-tDCS [1mA current] with shorter [10 min] and longer [10+10 min] stimulation durations applied to the left m1 of extensor carpi radialis muscle [ECR]. Corticomotor excitability following application of a-tDCS was assessed at rest with transcranial magnetic stimulation [TMS] elicited motor evoked potentials [MEP] and compared with baseline data for each participant. MEP amplitudes were increased following 10 min of a-tDCS by 67% [p=0.001] with a further increase [32%] after the second 10 min of a-tDCS [p =0.005]. MEP amplitudes remained elevated at 15 min post stimulation compared to baseline values by 65% [p=0.02]. The results demonstrate that longer application of a-tDCS within the recommended safety limits, increases corticomotor excitability with after effects of up to 15 minutes post stimulation

Cortical excitability in amyotrophic; lateral sclerosis

The primary purpose of this study was to provide insight into the central changes that occur in amyotrophic lateral sclerosis with a view to pointing out that these could contribute to symptoms, Seventeen patients with definite ALS and 17 control healthy volunteers were included in the study. Clinical examination, amyotrophic lateral sclerosis severity score [ALSSS] and transonic magnetic stimuli investigations including measurement of resting and active motor threshold [RMT, and AMT], motor evoked potential [MEP], input-output curve, contralateral silent period and transcallosal inhibition [CSP and TI] were measured for each participant. There were no significant differences in RMT or AMT in either hemisphere between patients and the control group. Despite this there was a significant negative correlation between ALSSS and RMT, and AMT meaning that increased seventy was associated with higher thresholds. MEPs were significantly smaller in ALS patients in comparison to the control group [P=0.03]. There was a significant decrease in the slope of the I/O relationship of MEP amplitude to TMS intensity in patients group in comparison to controls. ALS patients had a significant prolongation of CSP and TI for both hemispheres. There was a tendency for there to be a significant negative correlation between left TI and ALSSS [P= 0.051]. Measurements of cortical motor excitatory and inhibitory changes in ALS confirm the presence of hypoexcitability and GABAb dysfunction, that was correlated with the severity of ALS

Progress of transcranial magnetic stimulation-motor evoked potential and its forensic application / 法医学杂志

Transcranial magnetic stimulation-motor evoked potential (TMS-MEP) test is one of the electrophysiological examination methods to evaluate the function of central nervous system. The value of the TMS-MEP has been recognized by some clinical forensic workers recently. This article reviews the principle and advantages of TMS-MEP and its application in functional evaluation of central nervous system and clinical treatment. The value of TMS-MEP in forensic medicine, especially in objective assessment of muscle strength after injury of central nervous system is also discussed.

The motor evoked potential in aids and HAM/TSP State of the evidence / El potencial evocado motor en SIDA y HAM/PET

OBJECTIVE: We aimed to better understand the involvement of the corticospinal tract, assessed by non-invasive transcranial stimulation, in order to determine the actual involvement of the motor system in patients with HAM/TSP and AIDS. METHOD: An exhaustive MEDLINE search for the period of 1985 to 2008 for all articles cross-referenced for "HTLV-I, HTLV-II, HTLV-III and HIV, HIV1, HIV2, evoked potential, motor evoked potential, high voltage electrical stimulation, transcranial magnetic stimulation, magnetic stimulation, corticomotor physiology, motor pathways, acquired immunodeficiency syndrome, AIDS, SIDA, tropical spastic paraparesis, HTLV-I-associated myelopathy, HAM, TSP, and HAM/TSP" were selected and analysed. RESULTS: Eighteen papers published in English, Spanish, Portuguese, French and Japanese were identified. Only the central motor conduction time has been analyzed in seropositive patients to human retroviruses. The investigations done on HAM/TSP support the involvement of the pyramidal tract mainly at lower levels, following a centripetal pattern; in AIDS, such an involvement seems to be more prominent at brain levels following a centrifugal pattern. CONCLUSION: The central motor conduction time abnormalities and involvement differences of the corticospinal tract of patients with AIDS and HAM/TSP dissected here would allow to re-orient early neurorehabilitation measures in these retroviruses-associated neurodegenerative disorders. Besides this, more sophisticated and sensitive non-invasive corticospinal stimulation measures that detect early changes in thalamocortical-basal ganglia circuitry will be needed in both clinically established as well as asymptomatic patients at times when the fastest corticospinal fibers remain uninvolved.

OBJETIVO: Investigar el compromiso del tracto piramidal, evaluado por estimulación trascranial no invasiva, en pacientes afectados por SIDA y HAM/TSP. MÉTODO: Se realizó una búsqueda en la base de datos MEDLINE, que abarcó el período de 1985 a 2008; se incluyeron los términos "HTLV-I, HTLV-II, HTLV-III and HIV, HIV1, HIV2, evoked potential, motor evoked potential, high voltage electrical stimulation, transcranial magnetic stimulation, magnetic stimulation, corticomotor physiology, motor pathways, acquired immunodeficiency syndrome, AIDS, SIDA, tropical spastic paraparesis, HTLV-I-associated myelopathy, HAM, TSP, and HAM/TSP". RESULTADOS: Se obtuvieron 18 artículos publicados en inglés, español, portugués, francés y japonés. El tiempo de conducción central es el único parámetro que se ha estudiado en individuos seropositivos a retrovirus humanos. Las investigaciones hechas en HAM/PET apoyan el compromiso del tracto piramidal, principalmente a nivel dorso-lumbar, de manera centrípeta. En SIDA, el compromiso parece ser mas prominente a nivel cortical, siguiendo un patrón centrifugo. CONCLUSION: El conocer las diferencias en el compromiso y anormalidades del tracto corticoespinal de los pacientes con SIDA y HAM/TSP podrán ser útiles para reorientar la neurorehabilitación temprana en estos desórdenes neurodegenerativos asociados a retrovirus. De otro lado, evaluaciones mas sensibles y sofisticadas del sistema piramidal, que permitan detectar cambios tempranos en los circuitos talamocorticoganglionicos serán mandatarios de realizar a partir de la fecha, bien sea que los individuos estén asintomáticos o no, en estadios clínicos donde las fibras corticoespinales rápidas no estén aun comprometidas.

Hepatic myelopathy as a presenting neurological complication in patients with cirrhosis and spontaneous splenorenal shunt / 대한간학회지

Hepatic myelopathy is a rare complication of chronic liver disease that is associated with extensive portosystemic shunts. The main clinical feature of hepatic myelopathy is progressive spastic paraparesis in the absence of sensory or sphincter impairment. Early and accurate diagnosis of hepatic myelopathy is important because patients with early stages of the disease can fully recover following liver transplantation. Motor-evoked potential studies may be suitable for the early diagnosis of hepatic myelopathy, even in patients with preclinical stages of the disease. Here we describe two patients who presented with spastic paraparesis associated with a spontaneous splenorenal shunt and without any previous episode of hepatic encephalopathy. One patient experienced improved neurologic symptoms after liver transplantation, whereas the other patient only received medical treatment, which did not prevent the progression of spastic paraparesis.

Os efeitos da estimulação elétrica funcional na assimetria cortical inter-hemisférica / The effects of functional electrical stimulation on cortical interhemispheric asymmetry

O objetivo do presente estudo foi avaliar os efeitos da estimulação elétrica funcional na assimetria cortical inter-hemisférica. Para tal, simultaneamente ao registro da atividade eletroencefalográfica, realizou-se eletroestimulação no antebraço direito para estimulação da extensão do indicador. A amostra consistiu de 45 sujeitos randomizados em 3 grupos de 15 sujeitos cada: grupo controle (submetido a 24 blocos de estimulação com intensidade de corrente zero), grupo 1 (24 blocos) e grupo 2 (36 blocos). A assimetria entre os pares de eletrodos F3-F4, C3-C4 e P3-P4 foi analisada ao longo dos grupos através de uma Anova. Os resultados apontaram para uma interação grupo x eletrodo e uma tendência de diminuição da assimetria inter-hemisférica após a eletroestimulação.

The aim of the present study was to assess the effects of functional electrical stimulation (FES) on cortical interhemispheric asymmetry. Electrostimulation was performed on the right forearm to stimulate the extension of the index finger. EEG activity was recorded simultaneously. The sample included 45 subjects randomly divided into 3 groups of 15 subjects each: control group (submitted to 24 blocks of stimulation at a null intensity current), group 1 (24 blocks) and group 2 (36 blocks). Interhemispheric asymmetry between F3-F4, C3-C4 and P3-P4 was analyzed through an Anova. Results pointed out to a group x electrode interaction and a general tendency of asymmetry decrease after stimulation.

Relief of primary cervical dystonia symptoms by low frequency transcranial magnetic stimulation of the premotor cortex: case report

OBJECTIVE: To evaluate the effect of low-frequency repetitive transcranial magnetic stimulation (rTMS) on the symptoms of a patient with primary segmental dystonia (PSD). METHOD: 1200 TMS pulses at a frequency of 1Hz, over the premotor cortex, with an intensity of 90 percent of the motor threshold (MT), using an eight-shaped coil; a total of 5 sessions were carried out. RESULTS: A reduction of 50 percent in the neck subset of the Burke, Fahn and Marsden torsion dystonia scale (BFM) was observed in our patient. CONCLUSION: The reduction in the BFM scale supports the concept that rTMS of the premotor cortex may reduce specific motor symptoms in PSD.

OBJETIVO: Investigar o efeito da estimulação magnética transcraniana repetitiva (EMTr) de baixa freqüência nos sintomas de um paciente com distonia segmentar primária (DSP). MÉTODO: 1200 pulsos a uma freqüência de 1Hz, sobre o córtex pré-motor, a uma intensidade de 90 por cento do limiar motor (LM), usando uma bobina em forma de 8. Foram realizadas 5 sessões. RESULTADOS: Uma redução de 50 por cento no sub-item "pescoço" na escala de distonia de torção de Burke, Fahn e Marsden (BFM) foi observada no paciente em questão. CONCLUSÃO: A redução na escala BFM corrobora a idéia de que a EMTr sobre o córtex pré-motor pode reduzir sintomas motores específicos na DSP.

Different Modulation of the Cortical Silent Period by Two Phases of Short Interval Intracortical Inhibition

PURPOSE: To investigate the influence of 2 phases of short interval intracortical inhibition (SICI) on the cortical silent period (SP). MATERIALS AND METHODS: Single- and paired-pulse transcranial magnetic stimulations (TMSs) at 1 and 2.5ms interstimulus intervals (ISIs) were applied to the left motor cortex in 12 healthy subjects while their right hand muscles were moderately activated. Conditioning stimulation intensity was 90% of the active motor threshold (AMT). Test stimulation intensities were 120, 140, 160, 180, 200, 220, 240, 260% of the AMT and at 100% of the maximal stimulator output, the order of which was arranged randomly. The rectified electromyography area of motor evoked potential (MEP) and duration of the SP were measured off-line using a computerized program. RESULTS: At high-test stimulation intensities, MEP areas were saturated in both single- and paired-pulse stimulations, except that saturated MEPs were smaller for the paired-pulse TMS at 1ms ISI than for the other conditions. As the test stimulation intensity increased, SP was progressively prolonged in both single- and paired-pulse stimulations but was shorter in paired-pulse than single-pulse TMS. Overall, the ratio of SP duration/MEP area was comparable between single- and paired-pulse TMS except for the paired-pulse TMS at 1 ms ISI with a test stimulation intensity at 140-180% of the AMT, in which the ratio was significantly higher than in the single pulse TMS. CONCLUSION: These results suggest that 2 phases of SICI modulate MEP saturation and SP duration differently and provide additional evidence supporting the view that 2 phases of SICI are mediated by different inhibitory mechanisms.

Achados dos potenciais evocados somatossensitivos e motores na mielopatia associada oa HTLV-I / Somatosensitive and motor evoked potentials in HTLV-I associated mylopathy

Foram estudados 63 pacientes com diagnóstico de paraparesia espástica tropical/ mielopatia associada ao HTLV-I (PET/ MAH) através de potencial evocado somatossensitivo (PESS) e 42 destes pacientes através de potencial evocado motor (PEM). Todos os pacientes apresentaram história clínica típica de MAH e sorologia para HTLV-I confirmada por Western blot. Dos pacientes estudados por PESS 51/63 (81 por cento) alterados em membros inferiores e 11 (17,5 por cento) deles estavam também em membros superiores. Dos pacientes estudados por PEM 37/42 estavam alterados, 34/42 (81 por cento) em membros inferiores e 25/42 (59,5 por cento) em membros superiores. Um alto percentual da amostra apresentou alterações das vias corticoespinhais nos quatro membros ao PEM, e ausência de alterações em membros superiores ao PESS, evidenciando a correlação entre o tempo de condução motora central para membros superiores e a gravidade clínica da PET/ MAH (p<0,01). Não foi evidenciado correlação entre o tempo de historia clínica e os achados dos PESS e PEM (p=0,69).

Comparação entre diferentes metodologias de determinação do limiar motor para estimulação magnética transcraniana / Comparasion between different methods to determine motor threshold to transcranial magnetic stimulation

O objetivo deste estudo foi investigar diferentes aspectos técnicos relacionados à medida de limiar motor para estimulação magnética transcraniana e seu impacto sobre o desenho de protocolos experimentais Encontramos diferenças significativas entre limiares motores do músculo abdutor curto do polegar definidos com diversas metodologias. As amplitudes de potenciais evocados motores não foram significativamente diferentes com a estimulação de diferentes posições, quando as intensidades de estimulação foram ajustadas de acordo com o limiar medido em cada posição. Não houve diferenças significativas entre medidas de limiar realizadas com avaliação de diferentes números de potenciais evocados motores. Este estudo contribuiu para a padronização de técnicas de estimulação magnética transcraniana / The purpose of this study was to investigate different technical aspects related to the measure of motor threshold to transcranial magnetic stimulation and their impact on the design of experimental protocols. We have found significant differences between motor thresholds of the abductor pollicis brevis muscle defined with different methodologies. Amplitudes of mtor evoked potentials were not significantly different with stimulation of different positions, when intensities of stimulation were adjusted to thresholds measured at each position. There were no significant differences between threshold measurements performed with evaluation of different numbers of motor evoked potentials. This study has contributed to standardization of techniques of transcranial magnetic stimulation...

Value of motor and somatosensory evoked potentials in assessment of motor function in cerebral palsy

Cerebral palsy is a static non progressive motor disability that occurs at birth or early childhood. It results of injury to the neuromotor components of the central nervous system. Evoked potentials [EPs] are neurophysiological investigations used to demonstrate the existence of central nervous system lesions and were used as a screening method for neuropediatric diseases. Motor and somatosensory evoked potential [SEP] are the most sensitive methods of evoked potentials. They can provide a noninvasive objective method of evaluating the central and peripheral nervous system. The present study included 20 Egyptian children, 11 males and 9 females ranging in age from 3 to 6 years with a mean age of 3.9 years, presenting with spastic diplegia. All patients had mild to moderate motor disability and I.Q. above 50. Control group included 20 children, age and sex-matched with patients group. We studied motor and somatosensory evoked potentials in those patients and their correlation with motor functions. Transcranial magnetic stimulation [TMS] to the right upper limb [abductor pollicis brevis muscle] and somatosensory evoked potentials testing from the right median nerve and the left posterior tibial nerve were used to assess function of the corresponding systems. Motor evoked potentials from the right upper limb showed significant delay in cortical latencies and significant prolongation of central motor conduction time in CP patients compared to control group. However, the amplitude of cortical response showed no significant changes. Somato-sensory evoked potentials of right median nerve showed significantly prolonged cortical N[19]/ P[22] absolute latency, N[13] - N[20], Erb's - N[20], N[13] - N[20] inter peak latencies respectively, however, Erb's, N[13], Erb's - N[13] absolute latencies and inter peak latency showed non significant changes but N[20] amplitude was significantly decreased. Somatosensory evoked potentials of the left posterior tibial nerve showed significant prolonged cortical and lumber absolute latencies and inter peak latency. Also, significant decrease of amplitude of cortical wave. A statistically highly significant positive correlation was observed between the hand function and N[20] amplitude [P < 0.01] of SEPs of the right median nerve while all other variables showed no statistically significant correlation with each other. Also, a statistically significant positive correlation was observed between the foot function and cortical amplitude [P < 0.05] of SEPs of the left posterior tibial nerve while all other variables showed no statistically significant correlation with each other. A tendency towards positive correlation was observed between hand functions and cortical latency [P < 0.09] of motor evoked potentials to the right abductor pollicis brevis muscle. We concluded that somatosensory evoked potentials are sensitive, non-invasive techniques for detection of the severity of motor impairment. We recommend MEPs and SSEPs as a relatively fast and effective means of assessing the functional integrity of the central nervous system in cerebral palsy patients

Potenciales evocados motores. Evaluación no invasiva de la vía motora en sujetos normales y en pacientes con enfermedades neurológicas

Se presenta por primera vez en la comunidad médica nacional un estimulador eléctrico para la obtención de PEM, utilizando un aparato de diseño y fabricación local, siguiendo una línea investigativa iniciada en 1981 y mediante la cual se diseñan y construyen algunos equipos para la aplicación en neurofisiología clínica, derivada de proyectos de investigación que integran conocimientos de la instrumentación biomédica y la neurofisiología. El registro en 42 sujetos normales y la demostración de sus usos con algunos casos nos demuestran la validez y confiabilidad del instrumento fabricado. Se resalta la importancia de los PEM como método objetivo, reproducible, fácil de obtener y especialmente útil para la demostración anormalidades funcionales en la vía motora tanto central como periférica. Finalmente, se hace una revisión del tema en las que se corroboran los conocimientos sobre el estudio de la función y de las vías motoras.

Monitoreo medular intraoperatorio con potenciales motores

Spinal Cord Monitoring with Motor Action Potentials:The risk of cord damage during espinal surgery and specially in scoliosis correction and instrumentation is still high todoy. Many systems of medullary monitoring have been described, starting with trhe widely uses "wka-up" test and ending with the Somatosensory Evoked Potentials. This methodos have shown a lack of sensitivity for being cuantitative and specific for the sensitive spinal cord. In this paper we designed a system os Spinal Cord Monitoring using MOTOR ACTION POTENTIALS (M.A.P.s.) WITH TRANSVERTEBRAL STIMULATION AND DISTRAL MUSCULAR RECEPTION. This has been performed both in experimental animals and patients.In this first stage we present the results of the experiemental work on ten rabbits, on which we obtained a spinal cord section obtaining a to tal loss of the stimuli. Finally we studied the charges of the M.A.P.; on a second stage we induced distraction forces. The results showed that the M.A.P. is reproducible, that it disapear with the cord section and of the initial amplitude the espinal cord has irreversible damages. this experimental work is the first to present a spinal cord monitoring with transvertebral to distal muscular motor action potentials