Transcranial Electrocortical Stimulation to Monitor the Facial Nerve Motor Function During Cerebellopontine Angle Surgery

OBJECTIVE: This study was conducted to investigate the success rate of using the facial motor evoked potential (FMEP) of orbicularis oculi and oris muscles for facial nerve function monitoring with use of a stepwise protocol, and its usefulness in predicting facial nerve outcome during cerebellopontine angle (CPA) surgeries. METHODS: FMEPs were recorded intraoperatively from 60 patients undergoing CPA surgeries. Transcranial electrocortical stimulation (TES) was performed using corkscrew electrodes positioned at hemispheric montage (C3/C4 and CZ). The contralateral abductor pollicis brevis muscle was used as the control response. Stimulation was always applied contralaterally to the affected side using 1, 3, or 5 rectangular pulses ranging from 200 to 600 V with 50 mu s of pulse duration and an interstimulus interval of 2 ms. Facial potentials were recorded from needles placed in the orbicularis oculi and oris muscles. RESULTS: FMEP from the orbicularis oris and oculi muscles could be reliably monitored in 86.7% and 85% of the patients, respectively. The immediate postoperative facial function correlated significantly with the FMEP ratio in the orbicularis oculi muscle at 80% amplitude ratio (P =.037) and orbicularis oris muscle at 35% ratio (P =.000). FMEP loss was always related to postoperative facial paresis, although in different degrees. CONCLUSION: FMEPs can be obtained reliably by using TES with 3 to 5 train pulses. Stable intraoperative FMEPs can predict a good postoperative outcome of facial function. However, further refinements of this technique are necessary to minimize artifacts and to make this method more reliable.

Non-pharmacological approach to neuropathic pain: the use of repetitive transcranial magnetic stimulation

Neuromodulation is the branch of neurophysiology related to the therapeutic effects of electrical stimulations of the nervous system. There are currently different practical applications of neuromodulation techniques for the treatment of various neurological disorders, such as deep brain stimulation for Parkinson`s disease and repetitive transcranial magnetic stimulation (rTMS) for major depression. An increasing number of studies have been devoted to the analgesic effects of rTMS in chronic pain patients. RTMS has been used either as a therapeutic tool per se, or as a preoperative test in patients undergoing epidural precentral gyrus stimulation. High-frequency rTMS (a parts per thousand yen5 Hz) is considered to be excitatory, while low-frequency stimulation (a parts per thousand currency sign1 Hz) is considered to exert an inhibitory effect over neuronal populations of the primary motor cortex. However, other parameters of stimulation may play a central role on its clinical effects such as the type of coil, its orientation over the scalp, and the total number of rTMS sessions performed. Experimental data from animals, healthy volunteers, and neuropathic pain patients have suggested that stimulation of the primary motor cortex by rTMS is able to activate brain regions implicated in the processing of the different aspects of chronic pain, and influence brain regions involved in the endogenous opioid system. Over twenty prospective randomized sham-controlled trials have studied the analgesic effects of rTMS on chronic pain. Most of the patients included in these trials had central or peripheral neuropathic pain. Although most studies used a single session of stimulation, recent studies have shown that the analgesic effects of rTMS may outlast the stimulation period for many days when repetitive sessions are performed. This opens the possibility to use rTMS as a therapeutic tool of its own in the armamentarium against neuropathic pain.

Changes of somatomotor and parietal regions produced by different amounts of electrical stimulation

Our study aims to investigate changes in electrocortical activity by observing the variations in absolute theta power in the primary somatomotor and parietal regions of the brain under three different electrical stimulation conditions: control group (without stimulation), group 24 (24 trials of stimulation) and group 36 (36 trials of stimulation). Thus, our hypothesis is that the application of different patterns of electrical stimulation will promote different states of habituation in these regions. The sample was composed of 24 healthy (absence of mental and physical impairments) students (14 male and 10 female), with ages varying from 25 to 40 years old (32.5 +/- 7.5), who are right-handed (Edinburgh Inventory). The subjects were randomly distributed into three groups: control (n = 8), G24 (n = 8) and G36 (n = 8). We use the Functional electrical stimulation (FES) equipment (NeuroCompact-2462) to stimulate the right index finger extensor muscle, while the electroencephalographic signal was simultaneously recorded. We found an interaction between condition and block factors for the C3 and P3 electrode, a condition and block main effects for the C4 electrode, and a condition main effect for the P4 electrode. Our results support the hypothesis that electrical stimulation promotes neurophysiological changes. It appears that stimulus adaptation (accommodation) of specific circuits can strengthen the brain`s ability to distinguish between and respond to such stimuli over time. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

Recurrent neuromyelitis optica in Brazilian patients: clinical, immunological, and neuroimaging characteristics

Neuromyelitis optica has not been thoroughly studied in Brazilian patients following the discovery of NMO-IgG and its specific antigen aquaporin-4. In this study we aimed to describe the clinical NMO-IgG immunological status and neuroimaging characteristics of recurrent neuromyelitis optica in a series Brazilian patients. We undertook a retrospective study of 28 patients with recurrent neuromyelitis optica, according to 1999 Wingerchuk`s diagnostic criteria. Data on NMO-IgG status, clinical features, and MRI findings were analyzed. Three men and 25 women were evaluated. Median age at onset of disease was 26 years (range 7-55); median time of follow-up was 7 years (range 2-14). The mean time elapsed between the first and the second attack was 17 months (median 8.5; range 2-88). NMO-IgG was detected in 18 patients (64.3%). Four patients died due to respiratory failure. Most patients presented with cervical (36%) and cervical-thoracic myelitis (46.4%). Holocord lesion was the most common pattern of involvement (50%) on the axial plane. We did not find a statistical association between myelitis extension and NMO-IgG result. Our series of Brazilian patients showed a younger age of onset than previously reported. In our series, in contrast to previous reports, there was no correlation between the extension of myelitis and NMO-IgG positivity.

Diffuse analgesic effects of unilateral repetitive transcranial magnetic stimulation (rTMS) in healthy volunteers

We investigated the analgesic effects of unilateral repetitive transcranial magnetic stimulation (rTMS) of the motor cortex (M1) or dorsolateral prefrontal cortex (DLPFC) in two models of experimental pain in healthy volunteers. Two studies were carried out in parallel in two groups of 26 paid healthy volunteers. The effects of active or sham rTMS (frequency, 10 Hz; intensity, 80% resting motor threshold) applied to the right M1 or DLPFC were compared in a double-blind randomized cross-over design. In the first series of experiments, we analyzed the effects of rTMS on thermal (heat and cold) detection and pain thresholds measured on both hands and the left foot, by standardized quantitative sensory testing methods. In the second series of experiments, we measured the effects of M1 or DLPFC rTMS on the threshold and recruitment curves of the RIII nociceptive reflex evoked by ipsilateral electrical stimulation of the sural nerve and recorded on the biceps femoris of both lower limbs. In both studies, measurements were taken before and up to 60 min after the end of rTMS. Active rTMS of both M1 and DLPFC significantly increased the thermal pain thresholds, measured for both hands and the left foot, this effect being most marked for cold pain. These effects, which lasted at least 1 h after rTMS, were selective because they were not associated with changes in non-painful thermal sensations. By contrast, the second study showed that rTMS of M1 or DLPFC had no significant effect on the threshold or recruitment curve of the nociceptive flexion RIII reflex. Our findings demonstrate that unilateral rTMS of M1 or DLPFC induces diffuse and selective analgesic effects in healthy volunteers. The lack of effect on the RIII reflex suggests that such analgesic effects may not depend on the activation of descending inhibitory systems. (C) 2009 International Association for the Study of Pain. Published by Elsevier B. V. All rights reserved.

The Elevated Interferon Gamma Production is an Important Immunological Marker in HAM/TSP Pathogenesis

Human T-lymphotropic virus type 1 (HTLV-1) is the agent of the HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), which may Occur in > 5% of patients during their lifetime. HTLV-1-infection causes disturbances in the immune system, and the viral load may also play an important role in the pathogenesis of HAM/TSP. Some cytokines are involved in the pathogenesis of this disorder. We have determined IL-2, IL-4, IL-10, IL-12 p70, IFN-gamma and TNF-alpha production among HTLV-1-infected subjects from our HTLV-out Clinic in Institute of Infectious `Emilio Ribas` in Sao Paulo city, Brazil. PBMC obtained from healthy controls (n = 32), asymptomatic HTLV-1 carriers (n = 68) and HAM/TSP patients (n = 44) were grown in the absence and in the presence of phytohaemagglutinin (PHA), and the supernatants` fluids were measured for cytokines production. IL-2 levels were increased in the a-symptomatic HTLV-1 carriers, and IFN-gamma was increased in both groups of patients (asymptomatic HTLV-1 carriers and more significantly among HAM/TSP patients). IL-4, IL-10, TNF-alpha and IL-12 p70 levels were not significantly increased on both groups of patients, as compared with controls. The major finding Of this Study is that IFN-gamma was an important cytokine for the HAM/TSP pathogenesis. Therefore, immune modulation of IFN-gamma may be critical to treat of HAM/TSP patients.

Physiological Responses to Brain Stimulation During Limbic Surgery: Further Evidence of Anterior Cingulate Modulation of Autonomic Arousal

Background: In view of conflicting neuroimaging results regarding autonomic-specific activity within the anterior cingulate cortex (ACC), we investigated autonomic responses to direct brain stimulation during sterecitactic limbic surgery. Methods: Skin conductance activity and accelerative heart rate responses to multi-voltage stimulation of the ACC (n = 7) and paralimbic subcauclate (n = 5) regions were recorded during bilateral anterior cingulotomy and bilateral subcauclate tractotomy (in patients that had previously received an adequate lesion in the ACC), respectively. Results: Stimulations in both groups were accompanied by increased autonomic arousal. Skin conductance activity was significantly increased during ACC stimulations compared with paralimbic targets at 2 V (2.34 +/- .68 [score in microSiemens +/- SE] vs. .34 +/- .09, p = .013) and 3 V (3.52 +/- .86 vs. 1.12 +/- .37, p = .036), exhibiting a strong ""voltage-response"" relationship between stimulus magnitude and response amplitude (difference from 1 to 3 V = 1.15 +/- .90 vs. 3.52 +/- .86, p = .041). Heart rate response was less indicative of between-group differences. Conclusions: This is the first study of its kind aiming at seeking novel insights into the mechanisms responsible for central autonomic modulation. It supports a concept that interregional interactions account for the coordination of autonomic arousal.

Human choriogonadotropin prior to controlled ovarian stimulation and in vitro fertilization improves implantation, and pregnancy rates

Our purpose was to retrospectively compare controlled ovarian stimulation(COH) in IVF cycles with administration of hCG on the day of menses (D1-hCG) with women not receiving hCG at day 1 of menses (Control). Data on maternal age, endocrine profile, amount of rFSH required, embryo characteristics, implantation and pregnancy rates were recorded for comparison between D1-hCG (n = 36) and Control (n = 64). Dose of rFSH required to accomplish COH was significantly lower in D1-hCG. Following ICSI, more top-quality embryos were available for transfer per patient in the D1-hCG and biochemical pregnancy rates per transfer were significantly higher in the D1-hCG. Significantly higher implantation and on-going pregnancy rates per embryo transfer were observed in D1-hCG (64%) compared to Control (41%). Administration of D1-hCG prior to COH reduces rFSH use and enhances oocyte developmental competence to obtain top quality embryos, and improves implantation and on-going pregnancy rates. At present it is not clear if the benefit is related to producing an embryo that more likely to implant or a more receptive uterus, or merely fortuitous and related to the relatively small power of the study.

A randomized, double-blind clinical trial on the efficacy of cortical direct current stimulation for the treatment of major depression

Preliminary findings suggest that transcranial direct current stimulation (tDCS) can have antidepressant effects. We sought to test this further in a parallel-group, double-blind clinical trial with 40 patients with major depression, medication-free randomized into three groups of treatment: anodal tDCS of the left dorsolateral prefrontal cortex (active group-`DLPFC`); anodal tDCS of the occipital cortex (active control group-`occipital`) and sham tDCS (placebo control group-`sham`). tDCS was applied for 10 sessions during a 2-wk period. Mood was evaluated by a blinded rater using the Hamilton Depression Rating Scale (HDRS) and Beck Depression Inventory (BDI). The treatment was well tolerated with minimal side-effects that were distributed equally across all treatment groups. We found significantly larger reductions in depression scores after DLPFC tDCS [HDRS reduction of 40.4 % (+/-25.8%)] compared to occipital [HDRS reduction of 21.3 % ( +/-12.9%)] and sham tDCS [HDRS reduction of 10.4 % (+/-36.6%)]. The beneficial effects of tDCS in the DLPFC group persisted for 1 month after the end of treatment. Our findings support further investigation on the effects of this novel potential therapeutic approach - tDCS - for the treatment of major depression.

High voltage electrical stimulation as an alternative treatment for chronic ulcers of the lower limbs

High voltage electrical stimulation has been recommended as a means of accelerating the wound healing process. The effects of high voltage electrical stimulation were evaluated in the treatment of three volunteers with chronic ulcers of the lower limbs. After fifteen weeks of treatment, a reduction was found in the area of all the ulcers, suggesting that high voltage electric stimulation is an effective therapeutic option for chronic ulcers.

Electrical Stimulation During Gait Promotes Increase of Muscle Cross-sectional Area in Quadriplegics: A Preliminary Study

Increases in muscular cross-sectional area (CSA) occur in quadriplegics after training, but the effects of neuromuscular electrical stimulation (NMES) along with training are unknown. Thus, we addressed two questions: (1) Does NMES during treadmill gait training increase the quadriceps CSA in complete quadriplegics?; and (2) Is treadmill gait training alone enough to observe an increase in CSA? Fifteen quadriplegics were divided into gait (n = 8) and control (n = 7) groups. The gait group performed training with NMES for 6 months twice a week for 20 minutes each time. After 6 months of traditional therapy, the control group received the same gait training protocol but without NMES for an additional 6 months. Axial images of the thigh were acquired at the beginning of the study, at 6 months (for both groups), and at 12 months for the control group to determine the average quadriceps CSA. After 6 months, there was an increase of CSA in the gait group (from 49.8 +/- A 9.4 cm(2) to 57.3 +/- A 10.3 cm(2)), but not in the control group (from 43.6 +/- A 7.6 cm(2) to 41.8 +/- A 8.4 cm(2)). After another 6 months of gait without NMES in the control group, the CSA did not change (from 41.8 +/- A 8.4 cm(2) to 41.7 +/- A 7.9 cm(2)). The increase in quadriceps CSA after gait training in patients with chronic complete quadriplegia appears associated with NMES.

Effects of Cold Stress, Corticosterone and Catecholamines on Phagocytosis in Mice: Differences between Resting and Activated Macrophages

Objective: We subjected mice to acute cold stress and studied the effect on phagocytosis by peritoneal macrophages mediated by 3 types of phagocytic receptors: Fc gamma, complement receptors 3 (CR3) and mannose and beta-glucan receptors. Methods: Mice were subjected to a cold stress condition (4 C for 4 h), and then peritoneal macrophages were harvested and phagocytosis assays performed in vitro. Results: We found a striking difference between resting and lipopolysaccharide (LPS)-activated macrophages (by intraperitoneal injection of LPS 4 days before the stress experiment): for resting macrophages cold stress caused a decrease in phagocytosis mediated by Fc gamma or mannose receptors, while for activated macrophages we observed an increase in phagocytosis by the 3 types of receptors. These effects were associated with an increase in plasma concentrations of corticosterone and catecholamines following the cold stress. In order to verify whether these hormone changes could account for the observed effects on phagocytosis, we performed in vitro assays by incubating macrophages harvested from nonstressed animals with these hormones for 4 h at 37 degrees C and measuring their phagocytic capacity. The following experiments were done: (a) with resting (nonactivated) macrophages; (b) with macrophages previously activated in vitro by incubation with LPS; (c) with macrophages previously activated in vivo by intraperitoneal injection of mice with LPS, 4 days before harvesting the cells. We found that for resting macrophages, corticosterone decreased phagocytosis mediated by Fc gamma and mannose and beta-glucan receptors, but catecholamines had no effect. For macrophages activated either in vivo or in vitro, catecholamines caused an increase in phagocytosis (excluding mannose receptors) while corticosterone had no effect. Conclusion: The above findings suggest that stress can regulate phagocytosis in different ways, depending on the kind of phagocytic receptor involved, the level of stress hormones and the physiological state of the macrophages. Copyright (C) 2010 S. Karger AG, Basel

The medial forebrain bundle mediates cardiovascular responses to electrical stimulation of the medial prefrontal cortex

The medial prefrontal cortex (MPFC) is involved in cardiovascular control. MPFC electrical stimulation has been reported to cause depressor and bradycardic responses in anesthetized rats. Although the pathway involved is yet unknown, there is evidence indicating the existence of a relay in the lateral hypothalamus (LH). The medial forebrain bundle (MFB) that courses in the lateral portion of the LH carries the vast majority of telencephalic afferent as well efferent projections, including those from the MPFC. To evaluate if the hypotensive pathway originating in the MPFC courses the MFB, we studied the effect of coronal or sagittal knife cuts through the LH and other brain areas on the cardiovascular responses to MPFC electrical stimulation. Knife cuts were performed using blades I to 6 mm wide. Results indicate that the neural pathway descending from the MFB decussates early in the vicinity of MPFC, crossing the midline within the corpus callosurn and yielding two descending pathways that travel rostro-caudally in the lateral portion of the LH, within the MFB. The decussation was confirmed by histological analysis of brain sections processed after the injection of biotinilated dextran amine in the site of the stimulation in the MPFC. Because knife cuts through the LH ipsilateral had minimal effects on the cardiovascular responses and knife cuts performed contralateral to the stimulated MPFC had no effect on the response to MPFC stimulation, data indicate that the contralateral limb of the pathway may be only activated as an alternative pathway when the ipsilateral pathway is blocked. (c) 2009 Elsevier B.V. All rights reserved.