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Tremor is frequently described in patients with multiple sclerosis (MS) but remains poorly characterized using neurophysiological techniques. Accelerometric (ACC) and electromyographic (EMG) recordings were performed in 26 MS patients complaining of clumsiness, associated (n = 16) or not associated (n = 10) with visible tremor. Seventeen healthy subjects with physiological tremor (PT) and eight patients with essential tremor (ET) served as controls. Signals were analyzed using non-linear Empirical Mode Decomposition (EMD) and related Hilbert-Huang Transform (HHT), compared to the standard linear spectral analysis using Fast Fourier Transform (FFT). The presence of cerebellar signs and motor deficit was assessed on clinical examination. Using FFT, tremor was found in all patients with ET and 12% of subjects with PT, but in none of the MS patients, even in the presence of visible tremor. In contrast, EMD-HHT analysis of ACC-EMG coupling showed common frequency peaks characterizing tremor related to a central generator in 62.5% of MS patients with visible tremor, 40% of MS patients without visible tremor, 29% of subjects with PT, and all patients with ET. In EMD-HHT analysis, tremor characteristics were similar in subjects with PT and MS patients, regardless of the presence of a visible tremor, but these characteristics clearly differed in patients with ET. A visible tremor in MS patients was associated with more frequent cerebellar signs and less motor deficit at the upper limb. The low-frequency tremor observed in MS patients could therefore originate in lesions of the brainstem (midbrain) or cerebellothalamic circuits, or may correspond to an enhanced PT, partly favored by cerebellar dysfunction and being more visible during movement execution in the absence of concomitant motor deficit.

Background: Somatosensory evoked potentials (SSEPs) are increasingly performed for the assessment of peripheral neuropathies, but no practical guidelines have yet been established in this specific application., Study Aim: To determine the relevant indication criteria and optimal technical parameters for SSEP recording in peripheral neuropathy investigation., Methods: A survey was conducted among the French-speaking practitioners with experience of SSEP recording in the context of peripheral neuropathies. The results of the survey were analyzed and discussed to provide recommendations for practice., Results: SSEPs appear to be a second-line test when electroneuromyographic investigation is not sufficiently conclusive, providing complementary and valuable information on central and proximal peripheral conduction in the somatosensory pathways., Conclusions: Guidelines for a standardized recording protocol, including the various parameters to be measured, are proposed., Clinical Relevance: We hope that these proposals will help to recognize the value of this technique in peripheral neuropathy assessment in clinical practice., (Copyright © 2015 Elsevier Masson SAS. All rights reserved.)

Neurophysiological investigation, based on accelerometric (ACC) and electromyographic (EMG) recordings, is an essential step in the diagnosis of tremor. Among various signal analysis methods, fast Fourier transform (FFT) is the most frequently used in this domain. However, FFT has several limitations: first, it assumes that tremor is a periodic and linear signal, which is not true; second, it cannot distinguish between different types of tremor, when their frequency overlap in similar range, such as essential tremor (ET) and physiological tremor (PT). Therefore, we decided to apply a non-linear method of signal analysis based on empirical mode decomposition (EMD) and Hilbert Huang transform (HHT), according to various procedures and compared to a more classical FFT approach. A first group of 8 healthy subjects with PT and a second group of 8 patients with ET were included in this study. At individual level, FFT was effective to highlight ET in the 8 patients, but PT in only 2 subjects. The EMD-HHT procedures performed better than FFT, revealing a common peak of PT in all subjects. Moreover, at group level, our EMD-HHT method allowed to clearly differentiate the two groups, especially by giving evidence for the existence of low frequency oscillations (around 4Hz) in subjects with PT. Although their physiological origin remains largely unknown, such slow oscillations seem to be of great importance to highlight PT and they have been much underestimated in the literature. Our original EMD-HHT approach is able to provide substantial improvement in the neurophysiological characterisation of the different types of tremor, especially for diagnostic application., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)

Objective: To compare the pain-related evoked potentials (PREPs) obtained by superficial electrical stimulation using a concentric planar electrode to those obtained by CO2 laser stimulation., Methods: In 12 healthy subjects, PREPs, sympathetic skin reflexes (SSRs), motor reaction times (mRTs), and the conduction velocity (CV) of the recruited nerve fibres were assessed in response to electrical and laser stimulation., Results: In response to superficial electrical stimulation, PREP latencies and mRTs were shorter, while PREP amplitude tended to be increased. By contrast, SSR amplitudes and latencies and estimated CVs of the stimulated nerve fibres did not differ between electrical and laser stimulation. Fifteen minutes after PREP recordings, the residual pain intensity and the degree of unpleasantness were higher for laser stimulation than for electrical stimulation. In addition, CO2 laser stimuli induced dyschromic spots on the skin. For these reasons, all subjects declared that they would prefer superficial electrical stimulation rather than CO2 laser stimulation if they had to perform PREPs again., Conclusions: The estimated CVs of the recruited nerve fibres and the localized pinprick sensation felt by the subjects suggest that small-diameter fibres in the A-delta range, conveying "first-pain" information, were stimulated in response to superficial electrical stimulation as for laser stimulation. Superficial electrical stimulation using a concentric planar electrode could be a valuable alternative to laser stimulation for assessing PREPs in the practice of clinical neurophysiology., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)

During the past decade, a large amount of work on transcranial magnetic stimulation (TMS) has been performed, including the development of new paradigms of stimulation, the integration of imaging data, and the coupling of TMS techniques with electroencephalography or neuroimaging. These accumulating data being difficult to synthesize, several French scientific societies commissioned a group of experts to conduct a comprehensive review of the literature on TMS. This text contains all the consensual findings of the expert group on the mechanisms of action, safety rules and indications of TMS, including repetitive TMS (rTMS). TMS sessions have been conducted in thousands of healthy subjects or patients with various neurological or psychiatric diseases, allowing a better assessment of risks associated with this technique. The number of reported side effects is extremely low, the most serious complication being the occurrence of seizures. In most reported seizures, the stimulation parameters did not follow the previously published recommendations (Wassermann, 1998) [430] and rTMS was associated to medication that could lower the seizure threshold. Recommendations on the safe use of TMS / rTMS were recently updated (Rossi et al., 2009) [348], establishing new limits for stimulation parameters and fixing the contraindications. The recommendations we propose regarding safety are largely based on this previous report with some modifications. By contrast, the issue of therapeutic indications of rTMS has never been addressed before, the present work being the first attempt of a synthesis and expert consensus on this topic. The use of TMS/rTMS is discussed in the context of chronic pain, movement disorders, stroke, epilepsy, tinnitus and psychiatric disorders. There is already a sufficient level of evidence of published data to retain a therapeutic indication of rTMS in clinical practice (grade A) in chronic neuropathic pain, major depressive episodes, and auditory hallucinations. The number of therapeutic indications of rTMS is expected to increase in coming years, in parallel with the optimisation of stimulation parameters., (Copyright © 2011 Elsevier Masson SAS. All rights reserved.)

Since about 15 years, transcranial magnetic stimulation (TMS) is used as a technique to investigate the function of specific cortical regions. Single pulse TMS studies have targeted the dorsolateral premotor cortex (dlPMC) to characterize premotor-motor interactions in movement disorders. Repetitive TMS (rTMS) trials have targeted the dorsolateral prefrontal cortex (dlPFC) to treat depression. In almost all previous studies, these targets have been defined according to a "standard" scalp distance to the site of stimulation evoking motor responses of maximal amplitude in the contralateral hand ("hand motor hotspot" corresponding to the primary motor cortex, M1). The "standard" procedure of coil positioning locates the dlPMC and dlPFC as 2-3 and 5cm, respectively, anterior to the "hand motor hotspot". The aim of our study was to compare the locations of M1, dlPMC and dlPFC targets provided by the "standard" procedure of coil positioning and those provided by using a neuronavigation system integrating individual brain magnetic resonance imaging (MRI). Twenty-two patients were enrolled, all being treated for depressive symptoms in the context of chronic pain syndrome. The centers of the dlPMC and dlPFC regions were accurately targeted by the "standard" procedure in 14 and eight patients (64 and 36% of the series), respectively. In the other patients, the "standard" procedure located the dlPMC target on the M1/dlPMC border and the dlPFC target on the dlPMC/dlPFC border. On average, the MRI-guided location of M1, dlPMC, and dlPFC was, respectively, 6.1mm posterior, 31.7mm anterior and 69.0mm anterior to the "hand motor hotspot". The "standard" procedure failed to accurately locate the dlPMC and dlPFC targets by about 1 and 2cm, respectively. A statistical analysis of the MRI coordinates (x, y, z) of the targets revealed that the M1 target was more posterior, the dlPMC target more superficial and the dlPFC target more anterior, lateral, and deeper, using neuronavigation compared to the "standard" procedure. This study confirms that the "standard" procedure of coil positioning is not accurate to target a desired cortical region. Target location can be improved by the use of a navigation system taking individual brain anatomy into account. The present results incline to be cautious on the pathophysiological interpretations of previous results reported in TMS studies based on "standard" targeting, e.g. regarding premotor-motor interactions. Similarly, the inaccuracy of the "standard" procedure of coil positioning could partly explain the between-study variability of the therapeutic effects produced by rTMS in patients with depression. Our results strongly support a more anterior and lateral placement of the TMS coil for dlPFC stimulation in the treatment of depression.

Nasal obstruction is a frequent symptom of consultation in paediatric otorhinolaryngology. Usually, adenoid hypertrophy is the cause. Sometimes the examination reveals the presence of polyps in the nose. The antrochoanal polyp of Killian is particularly frequent in childhood. The obstruction is usually unilateral, but the posterior extension of a bulky polyp to the oropharynx can cause a major discomfort, sometimes a respiratory distress. We report the observation of a 10-year-old patient presenting a bulky polyp of Killian, visible in the oropharynx and then discuss the features of this polyp in the literature.