Papers by Josep Bargalló Valls
Muscle & Nerve, 2015
Low intensity electrical stimuli of digital nerves may generate a double peak potential (DPp), co... more Low intensity electrical stimuli of digital nerves may generate a double peak potential (DPp), composed of a cathodal (caAP) and an anodal (anAP) potential in orthodromic recordings. We studied the effects on caAP and anAP of stimuli of variable intensity, duration, and frequency. We also applied a conditioning stimulus to study potential differences in recovery time. The anAP was obtained in 33 of 40 healthy subjects (82.5%) and 4 of 20 patients with various types of sensory neuropathies (20%). Changes in stimulus duration and intensity had reciprocal effects on the amplitude of the anAP and the caAP. There were significant differences between caAP and anAP in recovery time after a conditioning stimulus. The caAP and anAP are 2 interdependent waveforms generated by different effects of the same stimulus over axons at the verge of depolarization. This article is protected by copyright. All rights reserved.
Supplements to Clinical neurophysiology
Experimental Brain Research, 2015
Journal of Neurology, Neurosurgery & Psychiatry, 2014
. Demonstrative recordings showing the decrease in CHEPs amplitude of HD patients (right side gra... more . Demonstrative recordings showing the decrease in CHEPs amplitude of HD patients (right side graphs) with respect to healthy subjects (left side graphs) in the condition Rest (Upper) and React (Lower) traces.
Experimental Brain Research, 2015
We analyzed the effects of an anesthetic sciatic nerve block on the cutaneomuscular reflex (cMR) ... more We analyzed the effects of an anesthetic sciatic nerve block on the cutaneomuscular reflex (cMR) and the cutaneous silent period (cSP) of foot muscles, in order to investigate further the type of fibers involved in their generation. In 14 neurologically normal patients with indication for surgical treatment of hallux valgus, we recorded from the extensor digitorum brevis muscle the reflex responses elicited by high-intensity electrical stimulation of the big toe at various time periods, ranging from 0 to 20 min, after ultrasound-guided sciatic nerve popliteal anesthetic block. The first effect was a delay in cSP onset latency, with no changes in end latency. The cMR remained unaltered up to when subjects were no longer able to maintain the contraction. The effects of local anesthetics on peripheral nerves allow for recognition of the different types of fibers contributing to the cMR and the cSP in muscles of the lower limb.
Brain Stimulation, 2015
Background: The Default Mode Network (DMN) is severely compromised in several psychiatric and neu... more Background: The Default Mode Network (DMN) is severely compromised in several psychiatric and neurodegenerative disorders where plasticity alterations are observed. Glutamate and GABA are the major excitatory and inhibitory brain neurotransmitters respectively and are strongly related to plasticity responses and large-scale network expression. Objective: To investigate whether regional Glx (Glutamate þ Glutamine) and GABA could be modulated within the DMN after experimentally-controlled induction of plasticity and to study the effect of intrinsic connectivity over brain responses to stimulation. Methods: We applied individually-guided neuronavigated Theta Burst Stimulation (TBS) to the left inferior parietal lobe (IPL) in-between two magnetic resonance spectroscopy (MRS) acquisitions to 36 young subjects. A resting-state fMRI sequence was also acquired before stimulation. Results: After intermittent TBS, distal GABA increases in posteromedial DMN areas were observed. Instead, no significant changes were detected locally, in left IPL areas. Neurotransmitter modulation in posteromedial areas was related to baseline fMRI connectivity between this region and the TBS-targeted area. Conclusions: The prediction of neurotransmitter modulation by connectivity highlights the relevance of connectivity patterns to understand brain responses to plasticity-inducing protocols. The ability to modulate GABA in a key core of the DMN by means of TBS may open new avenues to evaluate plasticity mechanisms in a key area for major neurodegenerative and psychiatric conditions.
Medicina clínica, Jan 20, 2002
Patients with type 1 diabetes mellitus (DM1) and end-stage renal disease (ESRD) usually exhibit a... more Patients with type 1 diabetes mellitus (DM1) and end-stage renal disease (ESRD) usually exhibit a severe polyneuropathy (PNP) whose progression can be halted after kidney and pancreas transplantation (KPT). We studied the evolution of both PNP and autonomous cardioregulatory function (ACF) in patients with DM1 and ESRD within the first year after KPT. PATIENTS AND MEHTOD: The study was carried out in 26 patients who underwent KPT and whose organs were functioning normally at least during one year after KPT. They were examined neurophysiologically in three different periods: a) before KPT; b) 1-3 months after KPT, and c) 12 months after KPT. We evaluated PNP by measuring the conduction velocity (CV) and the amplitude of the compound action potentials (ACAP) of common peroneal, posterior tibial and sural nerves. ACF was evaluated by measuring the change in the interval separating two consecutive QRS complexes in the electrocardiogram during quiet breathing and Valsalva manoeuvre. All ...
Medicina Clínica, 2002
Recibido el 30-8-2001; aceptado para su publicación el 5-2-2002.
Electroencephalography and Clinical Neurophysiology/Evoked Potentials Section, 1992
We studied the changes in motor pathway excitability induced by transcranial magnetic stimulation... more We studied the changes in motor pathway excitability induced by transcranial magnetic stimulation of the motor cortex, using paired stimuli (conditioning and test stimulus) and varying interstimulus interval (ISI). The effects induced depended on the stimulus intensity. At a low intensity, there was inhibition of the response to the test stimulus at ISIs of 5-40 msec, followed by facilitation at ISIs of 50-90 msec. At a high intensity, there was facilitation at ISIs of 25-50 msec, followed by inhibition at ISIs of 60-150 msec and, occasionally, by another phase of facilitation at ISIs of more than 200 msec. Only tentative explanations are currently possible for these effects: the inhibition observed at low intensities and short ISIs may be due to activation of cortical inhibitory mechanisms. The facilitation that follows may arise from the coincidence of various factors that transiently increase the excitability in alpha motoneurons. The early facilitation observed at high intensities seems to be a consequence of a rise in cortical excitability induced by the conditioning stimulus, causing an increase in the number or size, or both, of descending volleys from the test stimulus. The profound inhibition that follows probably results from a combination of both segmental and suprasegmental inhibitory mechanisms.
Muscle & Nerve, 2011
The brainstem pathways that mediate the somatosensory blink reflex (SBR) are not completely under... more The brainstem pathways that mediate the somatosensory blink reflex (SBR) are not completely understood. We hypothesized that the circuits of the SBR might be affected separately from those of the trigeminal blink reflex (TBR). We examined 7 patients with mesencephalic lesions and 8 patients with medullary lesions. The SBR was elicited by median nerve stimulation. The TBR was elicited by supraorbital nerve stimulation. In patients with upper brainstem lesions, the TBR was normal, whereas the SBR was generally abnormal. The SBR was either absent or small and was significantly delayed with respect to control subjects. The opposite was the rule in patients with lower brainstem lesions who had delayed or absent TBR and no abnormal findings in the SBR. The SBR is mediated through circuits in the upper brainstem. Study of the SBR can be helpful in the neurophysiological assessment of patients with mesencephalic lesions.
Electroencephalography and Clinical Neurophysiology/Electromyography and Motor Control, 1995
Poster session 42. Transcranial magnetic stimulation (3) magnetic responses were found in the pat... more Poster session 42. Transcranial magnetic stimulation (3) magnetic responses were found in the patients with the more severe pareses.
Electroencephalography and Clinical Neurophysiology/Evoked Potentials Section, 1994
Soleus muscle responses are difficult to elicit by cortical stimulation in normal humans at rest.... more Soleus muscle responses are difficult to elicit by cortical stimulation in normal humans at rest. We have studied in normal volunteers the behavior of the soleus and tibialis anterior muscle responses to maximal intensity transcranial magnetic stimulation (TMS) in the following experimental conditions: lying in supine position, active ankle dorsal flexion, active plantar flexion, standing on the soles, standing on the toes, and standing on the heels. At rest, consistent responses were recorded in the soleus to 61% of the stimuli, only. Maximal facilitation of the response in the soleus occurred when standing on the toes. In this condition, responses were recorded to 100% of the stimuli, at a latency that was, on average, 5.2 msec shorter than the latency of the responses at rest, and similar to the latency of the responses recorded in the tibialis anterior muscle when standing on the heels. Central motor conduction time, calculated in conditions of maximal facilitation, was not different for soleus or tibialis anterior muscles. We conclude that the soleus muscle receives short latency excitatory inputs from cortico-spinal axons activated by TMS, with a conduction time similar to that for the tibialis anterior. Such short latency cortico-spinal connections to the soleus muscle may become functionally effective only during maximum enhancement of motoneuronal excitability by muscle contraction.
Handbook of Clinical Neurophysiology, 2003
Supplements to Clinical Neurophysiology, 2006
Pain, 2008
Patients with meralgia paresthetica (MP) usually experience not only paraesthesias and decreased ... more Patients with meralgia paresthetica (MP) usually experience not only paraesthesias and decreased tactile sensation, but also painful dysesthesias in the distribution of the lateral femoral cutaneous nerve (LFCN). We aimed at assessing whether there is any functional impairment of small fibres of the LFCN in patients with MP. We carried out a clinical, psychophysical and neurophysiological study in 14 patients with MP and 14 healthy control subjects. We assessed pain in the last 2months, thermal thresholds and small fibres conduction by using a visual analogue scale (VAS-pain), quantitative sensory testing (QST) and contact heat-evoked potentials (CHEPs), respectively. Data were grouped for control subjects, non-affected side and affected side of patients with MP. Patients marked a VAS-pain of 4.3+/-1.5. In the affected side, thresholds for warm and heat pain sensations were elevated and the amplitude of CHEPs was reduced in comparison to the non-affected side and controls (Bonferroni's test; p<0.001 for all comparisons). The amplitude of CHEPs correlated inversely with duration of the symptoms (r=-0.57, p=0.002), as well as with heat pain thresholds (r=-0.18, p=0.01). No significant correlations were found between CHEPs and VAS-pain (p>0.05 for all correlations). Besides the involvement of large myelinated fibres, partial loss of function in small fibres may also account for the painful symptoms of patients with MP, especially in those with longer disease duration.
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Papers by Josep Bargalló Valls