References of "Maertens De Noordhout, Alain"
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See detailEvoked potentials and transcranial magnetic stimulation in migraine: published data and viewpoint on their pathophysiologic significance.
Schoenen, Jean ULg; Ambrosini, Anna; Sandor, Peter S et al

in Clinical Neurophysiology (2003), 114(6), 955-72

Migraine is a disorder in which central nervous sytem dysfunction might play a pivotal role. Electroneurophysiology seems thus particularly suited to study its pathophysiology. We have extensively ... [more ▼]

Migraine is a disorder in which central nervous sytem dysfunction might play a pivotal role. Electroneurophysiology seems thus particularly suited to study its pathophysiology. We have extensively reviewed evoked potential and transcranial magnetic stimulation studies performed in migraineurs in order to identify their pathophysiologic significance. Publications available to us were completed by a Medline search. Retrieved and personal data were compared with respect to methodology and interpreted according to present knowledge on cortical information processing. Results are in part contradictory which appears to be method-, patient- and disease- related. Nonetheless, both evoked potential and transcranial magnetic stimulation studies demonstrate that the cerebral cortex, and possibly subcortical structures, are dysfunctioning interictally in both migraine with and without aura. These electrophysiologic abnormalities tend to normalise just before and during an attack and some of them seem to have a clear familial and predisposing character. Besides the studies of magnetophosphenes which have yielded contrasting results, chiefly because the method is not sufficiently reliable, most recent electrophysiologic investigations of cortical activities in migraine favour deficient habituation and decreased preactivation cortical excitability as the predominant interictal dysfunctions. We propose that the former is a consequence of the latter and that it could favour both interictal cognitive disturbances as well as a cerebral metabolic disequilibrium that may play a role in migraine pathogenesis. To summarize, electrophysiologic studies demonstrate in migraine between attacks a cortical, and possibly subcortical, dysfunction of which the hallmark is deficient habituation. [less ▲]

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See detailEffects of repetitive transcranial magnetic stimulation on visual evoked potentials: new insights in healthy subjects
Fumal, Arnaud ULg; Bohotin, V.; Vandenheede, Michel et al

in Experimental Brain Research (2003), 150(3), 332-340

In a previous comparative study with migraineurs, we found in 24 normal subjects that the amplitude of the pattern-reversal visual evoked potential (PR-VEP) in the first block of 100 responses and its ... [more ▼]

In a previous comparative study with migraineurs, we found in 24 normal subjects that the amplitude of the pattern-reversal visual evoked potential (PR-VEP) in the first block of 100 responses and its habituation over 6 sequential blocks were significantly decreased after 1 Hz repetitive transcranial magnetic stimulation (rTMS), while 10 Hz rTMS had no significant effect. We report here our results on the reproducibility of the rTMS effect studied in ten of these subjects by repeating the recordings for each frequency three times on different days. We have also reanalysed the data obtained in 24 normal subjects, looking separately at the results in those stimulated at an intensity equal to phosphene threshold (group 1; n=14) and those stimulated at 110% of motor threshold because of unelicitable phosphenes (group 2; n=10). We finally determined the precise duration of the rTMS effect. Despite some interindividual variability, the effects of both rTMS frequencies on first block amplitude, habituation between first and sixth block and habituation slope over the six blocks were highly reproducible. The only difference between the two groups of subjects was the effect of 1 Hz rTMS on the second measured PR-VEP component. Whereas first block amplitude of the first P1-N1 component and habituation were decreased in both groups, such a decrease was found for the second P1-N2 component only in group 1 stimulated at phosphene threshold. The dishabituation of the N1-P1 component after 1 Hz rTMS was maximal at 15 min, but lasted up to 33 min, while that of P1-N2 disappeared after 3 min. There was a non-significant trend ( p=0.06) for a reduction of first block amplitude after 10 Hz rTMS in the total group of subjects, but no effect on habituation. The inhibitory effect of 1 Hz rTMS, which reduces in healthy controls both first block PR-VEP amplitude and habituation, probably by decreasing the preactivation excitability level of the underlying visual cortex, is thus reproducible and long lasting. Long trains of 10 Hz rTMS tend to attenuate reproducibly the cortical preactivation level in normal subjects, but they do not affect habituation at all, which contrasts with their effect in migraineurs, in whom, as previously reported, they significantly correct the habituation deficit. The absence of an effect of 1 Hz rTMS on PR-VEP P1-N2 in subjects stimulated at 110% of motor threshold may be explained by the deeper anatomical location of the cortical generators of this component and the lower stimulation intensity used. Taken together our results confirm that the effect of rTMS on the underlying cortex depends on several variables such as frequency, intensity and level of cortical preactivation. [less ▲]

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See detailAdapted multiple point stimulation MUNE technique
WANG, François-Charles ULg; BOUQUIAUX, Olivier ULg; DE PASQUA, Victor ULg et al

in Bromberg, Mark (Ed.) Motor Unit Number Estimation (MUNE) (2003)

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See detailElectrophysiological studies in migraine: a comprehensive review of their interest and limitations
Ambrosini, Anna; Maertens De Noordhout, Alain ULg; Sandor, P. et al

in Cephalalgia : An International Journal of Headache (2003), 23(Suppl. 1), 13-31

Electrophysiological methods may help to unravel some of the pathophysiological mechanisms of migraine. Lack of habituation is the principal and most reproducible interictal abnormality in sensory ... [more ▼]

Electrophysiological methods may help to unravel some of the pathophysiological mechanisms of migraine. Lack of habituation is the principal and most reproducible interictal abnormality in sensory processing in migraineurs. It is found in evoked potential (EP) studies for every stimulation modality including nociceptive stimuli, and it is likely to be responsible for the increased intensity dependence of EP. We have hypothesized that deficient EP habituation in migraine could be due to a reduced preactivation level of sensory cortices because of hypofunctioning subcortico-cortical aminergic pathways. This is not in keeping with simple hyperexcitability of the cortex, which has been suggested by some, but not all, studies of transcranial magnetic stimulation (TMS). A recent study of the effects of repetitive TMS on visual EP strongly supports the hypothesis that migraine is characterized by interictal cortical hypoexcitability. With regard to pain mechanisms in migraine, electrophysiological studies of trigeminal pathways using nociceptive blink and corneal reflexes have confirmed that sensitization of central trigeminal nociceptors occurs during migraine attacks. [less ▲]

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See detailMotor and phosphene thresholds to transcranial magnetic stimuli: a reproducibility study
Fumal, Arnaud ULg; Bohotin, V.; Vandenheede, Michel et al

in Acta Neurologica Belgica (2002), 102(4), 171-175

OBJECTIVES: As repetitive transcranial magnetic stimulation (rTMS) is often applied on different days, it is of interest to know whether motor (MT) and phosphene (PT) thresholds are reproducible across ... [more ▼]

OBJECTIVES: As repetitive transcranial magnetic stimulation (rTMS) is often applied on different days, it is of interest to know whether motor (MT) and phosphene (PT) thresholds are reproducible across time and whether the intensity determined on the first day can be used in subsequent sessions. METHODS: We studied MT and PT over 5 separate recordings in 10 healthy volunteers using a focal coil and a Magstim(Rapid stimulator. After the initial recording (session 1), the others (2 to 5) were performed respectively after 1 day, 7 days, 1 month and 4 months. RESULTS: Mean MT at rest were 65.30 +/- 5.54%, 65.7 +/- 7.18%, 60.4 +/- 4.27%, 61.8 +/- 4.34%, and 63 +/- 9.1% at sessions 1 to 5. Mean PT were 71.43 +/- 6.68%, 66.29 +/- 10.67%, 60.71 +/- 8.64%, 60.57 +/- 8.08%, and 68.71 +/- 15.48% at sessions 1 to 5. MT and PT were reproducible (ANOVA analysis), however, as shown by coefficients of variation, variability between the first 3 sessions exceeded 10% for MT in 3 subjects and in 4 subjects for PT. CONCLUSIONS: It seems preferable to determine thresholds and adapt output intensity of the stimulator at each rTMS session. [less ▲]

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See detailSingle motor axon conduction velocities of human upper and lower limb motor units. A study with transcranial electrical stimulation
Dalpozzo, Francesca; GERARD, Pascale ULg; De Pasqua, Victor ULg et al

in Clinical Neurophysiology (2002), 113(2), 284-291

OBJECTIVES: To calculate conduction velocities (CV) of single motor axons innervating hand, forearm and leg muscles, weak anodal electrical transcranial stimuli were used and single motor unit potentials ... [more ▼]

OBJECTIVES: To calculate conduction velocities (CV) of single motor axons innervating hand, forearm and leg muscles, weak anodal electrical transcranial stimuli were used and single motor unit potentials were recorded in 17 normal subjects. METHODS: The central motor conduction time and neuromuscular transmission delay were subtracted from the latency of unit response to cortical stimulation and single motor axon CV were calculated. RESULTS: In extensor indicis proprius (EIP) units, CV ranged from 30.3 to 76.1m/s (mean: 51.3 +/- 7.1m/s, 139 units). In first dorsal interosseous (FDI), they ranged from 45.1 to 66.2m/s (mean: 54.6 +/- 2.6m/s, 88 units). In tibialis anterior (TA), velocities ranged from 27.8 to 55.9m/s (mean: 41.3 +/- 7.5m/s, 123 units). In FDI units, velocities were compared with those obtained with the F-wave method (range: 50.3-64.5m/s, mean: 58.1 +/- 2.0m/s). CONCLUSIONS: Compared with previously published values, the present method gives better access to slow-conducting units, first recruited by transcranial stimulation and voluntary effort. The spectrum of individual CV was much broader for EIP and TA than for FDI. A linear decline of maximal CV with age was observed, while minimal CV were not affected, suggesting that aging causes a selective loss of the fastest-conducting units. [less ▲]

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See detailEffects of repetitive transcranial magnetic stimulation on visual evoked potentials in migraine.
Bohotin, V.; Fumal, Arnaud ULg; Vandenheede, M. et al

in Brain : A Journal of Neurology (2002), 125(Pt 4), 912-22

Between attacks, migraine patients are characterized by potentiation instead of habituation of stimulation-evoked cortical responses. It is debated whether this is due to increased or decreased cortical ... [more ▼]

Between attacks, migraine patients are characterized by potentiation instead of habituation of stimulation-evoked cortical responses. It is debated whether this is due to increased or decreased cortical excitability. We have studied the changes in visual cortex excitability by recording pattern-reversal visual evoked potentials (PR-VEP) after low- and high-frequency repetitive transcranial magnetic stimulation (rTMS), known respectively for their inhibitory and excitatory effect on the cortex. In 30 patients (20 migraine without, 10 with aura) and 24 healthy volunteers, rTMS of the occipital cortex was performed with a focal figure-of-eight magnetic coil (Magstim). Nine hundred pulses were delivered randomly at 1 or 10 Hz in two separate sessions. Stimulus intensity was set to the phosphene threshold or to 110% of the motor threshold if no phosphenes were elicited. Before and after rTMS, PR-VEP were averaged sequentially in six blocks of 100zztieresponses during uninterrupted 3.1 Hz stimulation. In healthy volunteers, PR-VEP amplitude was significantly decreased in the first block after 1 Hz rTMS and the habituation normally found in successive blocks after sustained stimulation was significantly attenuated. In migraine patients, 10 Hz rTMS was followed by a significant increase of first block PR-VEP amplitude and by a reversal to normal habituation of the potentiation (or dishabituation) characteristic of the disorder. This effect was similar in both forms of migraine and lasted for at least 9 min. There were no significant changes of PR-VEP amplitudes after 1 Hz rTMS in migraineurs and after 10 Hz rTMS in healthy volunteers, nor after sham stimulation. The recovery of a normal PR-VEP habituation pattern after high-frequency rTMS is probably due to activation of the visual cortex and the dishabituation in healthy volunteers to cortical inhibition. We conclude, therefore, that the deficient interictal PR-VEP habituation in migraine is due to a reduced, and not to an increased, pre-activation excitability level of the visual cortex. [less ▲]

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See detailMagnetic stimulation in multiple sclerosis ans peripheral neuropathies
MAERTENS DE NOORDHOUT, Alain ULg

in Pascual-Leone, Alvara; Davey, N. J.; Rothwell, John (Eds.) et al Handbook of transcranial Magnetic Stimulation (2002)

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See detailIntravascular malignant lymphomatosis: report of 2 neurological cases
Vandenheede, Michel; Dioh, Alioune ULg; Maertens De Noordhout, Alain ULg et al

in Acta Neurologica Belgica (2002), 102(2), 76-81

We report two cases of intravascular malignant lymphomatosis (IML) with a clinical expression limited to the central nervous system. The first patient presented with signs of cerebral, cerebellar and ... [more ▼]

We report two cases of intravascular malignant lymphomatosis (IML) with a clinical expression limited to the central nervous system. The first patient presented with signs of cerebral, cerebellar and spinal cord involvement. The second had an isolated involvement of the spinal cord. In both cases the diagnosis was made at post-mortem examination; pre-mortem examination of biopsy tissue from peripheral nerve and muscle in the first case, spleen and liver in the second were unhelpful for the diagnosis of lymphoma. We review the published literature on IML, its ante-mortem diagnosis and treatment. [less ▲]

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See detailActualités thérapeutiques des céphalées trigéminales autonomes.
Vandenheede, Michel; MAERTENS DE NOORDHOUT, Alain ULg

in Médecine et Hygiène (2002)

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See detailIpsilateral motor responses to focal transcranial magnetic stimulation in healthy subjects and acute-stroke patients
Alagona, Giovanna; DELVAUX, Valérie ULg; GERARD, Pascale ULg et al

in Stroke (2001), 32(6), 1304-1309

BACKGROUND AND PURPOSE: Prevalence and characteristics of ipsilateral upper limb motor-evoked potentials (MEPs) elicited by focal transcranial magnetic stimulation (TMS) were compared in healthy subjects ... [more ▼]

BACKGROUND AND PURPOSE: Prevalence and characteristics of ipsilateral upper limb motor-evoked potentials (MEPs) elicited by focal transcranial magnetic stimulation (TMS) were compared in healthy subjects and patients with acute stroke. METHODS: Sixteen healthy subjects and 25 patients with acute stroke underwent focal TMS at maximum stimulator output over motor and premotor cortices. If present, MEPs evoked in muscles ipsilateral to TMS were analyzed for latency, amplitude, shape, and center of gravity (ie, preferential coil location to elicit them). In stroke patients, possible relationships between early ipsilateral responses and functional outcome at 6 months were sought. RESULTS: With relaxed or slightly contracting target muscle, maximal TMS over the motor cortex failed to elicit ipsilateral MEPs in the first dorsal interosseous (FDI) or biceps of any of 16 normal subjects. In 5 of 8 healthy subjects tested, ipsilateral MEPs with latencies longer than contralateral MEPs were evoked in FDI muscle (in biceps, 6 of 8 subjects) during strong (>50% maximum) contraction of the target muscle. In 15 of 25 stroke patients, ipsilateral MEPs in the unaffected relaxed FDI (in biceps, 6 of 25 stroke patients) were evoked by stimulation of premotor areas of the affected hemisphere. Their latencies were shorter than those that MEPs evoked in the same muscle by stimulation of the motor cortex of the contralateral unaffected hemisphere. Such responses were never obtained in normal subjects and were mostly observed in patients with subcortical infarcts. Patients harboring these responses had slightly better bimanual dexterity after 6 months. CONCLUSIONS: Ipsilateral MEPs obtained in healthy individuals and stroke patients have different characteristics and probably different origins. In the former, they are probably conveyed via corticoreticulospinal or corticopropriospinal pathways, whereas in the latter, early ipsilateral MEPs could originate in hyperexcitable premotor areas. [less ▲]

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See detailTremblement essentiel: diagnostic différentiel et traitement
DELVAUX, Valérie ULg; MAERTENS DE NOORDHOUT, Alain ULg

in Médecine et Hygiène (2001), 59

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See detailReduced excitability of the motor cortex in untreated patients with de novo idiopathic “grand mal” seizures
Delvaux, Valérie ULg; Alagona, Giovanna; GERARD, Pascale ULg et al

in Journal of Neurology, Neurosurgery & Psychiatry (2001), 71(6), 772-776

OBJECTIVES: Transcranial magnetic stimulation (TMS) was used to investigate motor cortex excitability, intracortical excitatory, and inhibitory pathways in 18 patients having experienced a first "grand ... [more ▼]

OBJECTIVES: Transcranial magnetic stimulation (TMS) was used to investigate motor cortex excitability, intracortical excitatory, and inhibitory pathways in 18 patients having experienced a first "grand mal" seizure within 48 hours of the electrophysiological test. All had normal brain MRI, and were free of any treatment, drug, or alcohol misuse. Results were compared with those of 35 age matched normal volunteers. METHODS: The following parameters of responses to TMS were measured: motor thresholds at rest and with voluntary contraction, amplitudes of responses, cortical silent periods, and responses to paired pulse stimulation with interstimulus intervals of 1 to 20 ms. RESULTS: In patients, there were significantly increased motor thresholds with normal amplitudes of motor evoked potentials (MEPs), suggesting decreased cortical excitability. Cortical silent periods were not significantly different from those of normal subjects. Paired TMS with short interstimulus intervals (1-5 ms) induced normal inhibition of test MEPs, suggesting preserved function of GABAergic intracortical inhibitory interneurons. On the contrary, the subsequent period of MEP facilitation found in normal subjects (ISIs of 6-20 ms) was markedly reduced in patients. This suggests the existence of abnormally prolonged intracortical inhibition or deficient intracortical excitation. In nine patients retested 2 to 4 weeks after the initial seizure, these abnormalities persisted, although to a lesser extent. CONCLUSION: The present findings together with abnormally high motor thresholds could represent protective mechanisms against the spread or recurrence of seizures. [less ▲]

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See detailNeuromuscular transmission in migraine: a single-fiber EMG study in clinical subgroups.
Ambrosini, Anna; Maertens De Noordhout, Alain ULg; Schoenen, Jean ULg

in Neurology (2001), 56(8), 1038-43

OBJECTIVE: To search for impairment of neuromuscular transmission by single-fiber electromyography (SFEMG) in patients with common forms of migraine. BACKGROUND: P/Q Ca(2+) channels are genetically ... [more ▼]

OBJECTIVE: To search for impairment of neuromuscular transmission by single-fiber electromyography (SFEMG) in patients with common forms of migraine. BACKGROUND: P/Q Ca(2+) channels are genetically abnormal in most cases of familial hemiplegic migraine (International Headache Society [IHS] code 1.2.3) and may be involved in other types of migraine. Besides in the brain, these channels are found in motor nerve endings, where they control stimulation-induced acetylcholine release. If they are functionally abnormal, the neuromuscular transmission might be impaired. METHODS: Sixty-two migraineurs (18 without aura, IHS code 1.1; 19 with typical aura, IHS code 1.2.1; 10 with prolonged aura, IHS code 1.2.2; 15 with and without aura) and 16 healthy control subjects underwent stimulation SFEMG. Results were expressed as the mean value of consecutive differences (MCD) and percentage of single-fiber abnormalities (abnormal jitter or impulse blocking). RESULTS: Average MCD was comparable in control subjects and migraineurs (17.1 +/- 2.6 versus 17.5 +/- 4.7 microsec). By contrast, single-fiber abnormalities were found in 17 patients but in none of the control subjects (p = 0.036). Most of these patients had unilateral sensorimotor symptoms and/or aphasia and/or loss of balance during the aura. SFEMG abnormalities were significantly correlated with the occurrence of these clinical features and with a diagnosis of migraine with prolonged aura. CONCLUSIONS: Stimulation SFEMG shows mild abnormalities of neuromuscular transmission in a subgroup of migraineurs with aura, characterized by clinical features frequently found in human P/Q Ca(2+) channelopathies. These abnormalities might thus be due to genetically modified P/Q Ca(2+) channels. [less ▲]

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See detailNeuromuscular transmission in migraine patients with prolonged aura
Ambrosini, Anna; MAERTENS DE NOORDHOUT, Alain ULg; SCHOENEN, Jean ULg

in Acta Neurologica Belgica (2001), 101(3), 166-70

P/Q Ca2+ channels are genetically abnormal in most cases of familial hemiplegic migraine (FHM) and may be involved in other types of migraine. They are also found at the neuromuscular junctions, where ... [more ▼]

P/Q Ca2+ channels are genetically abnormal in most cases of familial hemiplegic migraine (FHM) and may be involved in other types of migraine. They are also found at the neuromuscular junctions, where they control stimulation-induced acetylcholine release. Prolonged aura is a very frequent clinical feature in FHM patients. The objective of this study was thus to explore neuromuscular transmission in migraine with typical and prolonged aura patients. We performed single fiber electromyography (SFEMG) in such patients and compared them to a group of healthy volunteers. Results were expressed as mean jitter (MCD) and percentage of single endplate abnormalities. Mean MCD was on average comparable in controls and migraineurs. By contrast, single endplate abnormalities were only found in patients (p < 0.01), especially in those with prolonged aura (p < 0.001). These results suggest subtle impairment of neuromuscular transmission in a subgroup of migraineurs characterized by prolonged aura, which might be due to dysfunctioning P/Q Ca(2+)-channels. [less ▲]

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See detailTarget-Controlled Infusion of Propofol and Remifentanil Combined with Bispectral Index Monitoring for Awake Craniotomy
Hans, Pol ULg; Bonhomme, Vincent ULg; Born, J. D. et al

in Anaesthesia (2000), 55(3), 255-9

We describe the target-controlled administration of propofol and remifentanil, combined with monitoring of the bispectral index, during an awake craniotomy for removal of a left temporo-parietal tumour ... [more ▼]

We describe the target-controlled administration of propofol and remifentanil, combined with monitoring of the bispectral index, during an awake craniotomy for removal of a left temporo-parietal tumour near the motor speech centre. Target concentrations of the two drugs were adjusted according to the patient's responses to painful stimuli and surgical events, and the need for speech testing. Allowing the effect-site concentrations of propofol and remifentanil to decrease during surgery allowed the performance of cortical speech mapping and the testing of the patient's ability to speak. Although the bispectral index was not used as a guide for the administration of the drugs, its value correlated better with the patient's responsiveness than did the predicted effect-site concentrations of propofol. Side-effects, comprising hypotension, respiratory depression and airway obstruction, were related to rapid increases in drug infusion rates and were easily managed. [less ▲]

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See detailIpsilateral motor responses to focal TMS in normal man and stroke patients.
ALAGONA G.; DELVAUX, Valérie ULg; Delwaide, Paul ULg et al

in Clinical Neurophysiology (2000), 111(Suppl. 1), 11512-05

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See detailIpsilateral motor responses to focal transcranial magnetic stimulation in normal and stroke patients.
ALAGONA G.; DELVAUX, Valérie ULg; GERARD, Pascale ULg et al

in Journal of Neurology, Neurosurgery & Psychiatry (2000), Neurosurgery and Psychiatry

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