Lack of habituation causes high intensity dependence of auditory evoked cortical potentials in migraine
; ; De Pasqua, Victor et al
in Brain (2003), 126(Part 9), 2009-2015
Migraineurs are characterized interictally by lack of habituation, or even potentiation, of cortical evoked potentials during repetitive stimulation and by a strong intensity dependence of auditory evoked ... [more ▼]
Migraineurs are characterized interictally by lack of habituation, or even potentiation, of cortical evoked potentials during repetitive stimulation and by a strong intensity dependence of auditory evoked potentials (IDAP). To determine whether these two features of sensory processing are interrelated, we have studied them simultaneously on the same recordings of auditory evoked potentials (AEPs). AEPs were obtained at four different stimulation intensities in 14 patients suffering from migraine without aura (MO) and 14 healthy volunteers (HV). For each intensity, 120 trials were averaged off-line globally and over four sequential blocks of 30 trials. IDAP was expressed by the amplitude/stimulus intensity function (ASF slope) for global and block averages. Habituation was calculated as the percentage amplitude variation between the first and fourth blocks for each stimulus intensity. The IDAP slope for global averages was higher in MO (1.05 +/- 0.27 muV/10 dB) than in HV (0.64 +/- 0.45 muV/10 dB) (P = 0.008), but IDAP slopes for block averages were greater in MO only at the fourth block (P = 0.048). First block amplitudes tended to be lower in MO, except at 80 dB. There was a potentiation of AEP amplitudes at every stimulus intensity in MO, contrasting with habituation in HV. IDAP slopes were negatively correlated with mean habituation percentages in pooled data from patients and controls (r = -0.610; P = 0.0006). This study confirms that IDAP is higher in migraineurs than in healthy controls. It also shows that the AEP habituation is replaced by potentiation at all stimulus intensities. The negative correlation found between IDAP and habituation suggests that the latter is able to have a strong influence on the former and perhaps even lead to it. In migraine, the habituation deficit amplifies the IDAP and may thus be the causal functional abnormality. We propose that it is due to a decreased pre-activation level of sensory cortices, a hypothesis also supported in this study by the lower amplitude of first AEP blocks in patients. [less ▲]Detailed reference viewed: 15 (0 ULg)
Post-stroke reorganization of hand motor area : a 1-year prospective follow-up with focal transcranial magnetic stimulation
DELVAUX, Valérie ; ; GERARD, Pascale et al
in Clinical Neurophysiology (2003), 114(Issue 4), 1217-1225Detailed reference viewed: 16 (5 ULg)
Effects of repetitive transcranial magnetic stimulation on visual evoked potentials: new insights in healthy subjects
Fumal, Arnaud ; ; 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 ▲]Detailed reference viewed: 5 (0 ULg)
Récupération motrice des AVC : etude longitudinale d'un an par SMT
DELVAUX, Valérie ; MAERTENS DE NOORDHOUT, Alain ; DE PASQUA, Victor
Poster (2002, April)Detailed reference viewed: 13 (4 ULg)
Single motor axon conduction velocities of human upper and lower limb motor units. A study with transcranial electrical stimulation
; GERARD, Pascale ; De Pasqua, Victor 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 ▲]Detailed reference viewed: 21 (5 ULg)
Changes in motor unit numbers in patients with ALS: a longitudinal study using the adapted multiple point stimulation method.
Wang, François-Charles ; Bouquiaux, Olivier ; De Pasqua, Victor et al
in Amyotrophic Lateral Sclerosis & Other Motor Neuron Disorders (2002), 3(1), 31-8
METHOD: The adapted multiple point stimulation (AMPS) method for calculating motor unit numbers (MUNE) was applied in 12 patients with amyotrophic lateral sclerosis (ALS) before riluzole therapy (T(0 ... [more ▼]
METHOD: The adapted multiple point stimulation (AMPS) method for calculating motor unit numbers (MUNE) was applied in 12 patients with amyotrophic lateral sclerosis (ALS) before riluzole therapy (T(0)) and again after 4, 8 and 12 months of treatment. RESULTS: Paired Student's t-test indicated a significant decrease of thenar MUNE and compound muscle action potential (CMAP) size at each 4-monthly interval, while average surface motor unit potential (SMUP) size did not change significantly over time. The rate of motor unit (MU) loss at month 4 was more than 20% in six patients (group 1) and less than 20% in six other patients (group 2). Comparison of groups 1 and 2 by Mann-Whitney U-testing indicated that percent changes in thenar MUNE and CMAP size compared to baseline were significantly different at months 4, 8 and 12, while no difference between the two groups was found for average SMUP size variations. In the group with a slow rate of MU loss, CMAP size remained stable, while in the group with a rapid rate of MU loss, there was a dramatic reduction in size of the CMAP. A positive correlation was found between percent change in thenar MUNE at T(4) and at T(12) (P < 0.001). CONCLUSION: AMPS is a useful technique to document MUNE, SMUP size and CMAP size changes over time in patients with ALS. [less ▲]Detailed reference viewed: 47 (12 ULg)
Ipsilateral motor responses to focal transcranial magnetic stimulation in healthy subjects and acute-stroke patients
; DELVAUX, Valérie ; GERARD, Pascale 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 ▲]Detailed reference viewed: 3 (3 ULg)
Prognostic value of decremental responses to repetitive nerve stimulation in ALS patients.
Wang, François-Charles ; De Pasqua, Victor ; Gerard, Pascale et al
in Neurology (2001), 57(5), 897-9
Decrement of the thenar compound muscle action potentials (CMAP), after repetitive nerve stimulation (RNS) of the median nerve at 3 Hz, was evaluated in patients with ALS before riluzole therapy. CMAP ... [more ▼]
Decrement of the thenar compound muscle action potentials (CMAP), after repetitive nerve stimulation (RNS) of the median nerve at 3 Hz, was evaluated in patients with ALS before riluzole therapy. CMAP size as well as motor unit number and size estimates were evaluated twice before and after 1 year of riluzole therapy. The correlation between decrement and CMAP size reduction per year was highly significant (r = 0.77), but no relationship could be demonstrated between decrement and other variables. The authors thus propose that decrement after RNS may be used as a predictor of further drop in CMAP size. [less ▲]Detailed reference viewed: 9 (0 ULg)
Reduced excitability of the motor cortex in untreated patients with de novo idiopathic “grand mal” seizures
Delvaux, Valérie ; ; GERARD, Pascale 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 ▲]Detailed reference viewed: 14 (7 ULg)
Subclinical cerebellar impairment in the common types of migraine: a three-dimensional analysis of reaching movements.
; ; et al
in Annals of Neurology (2001), 49(5), 668-72
Mutations in the CACNA1A gene can cause familial hemiplegic migraine (FHM) and/or cerebellar ataxia CACNA1A codes for the alpha1 subunit of P/Q-Ca2+ channels and is highly expressed in the cerebellum ... [more ▼]
Mutations in the CACNA1A gene can cause familial hemiplegic migraine (FHM) and/or cerebellar ataxia CACNA1A codes for the alpha1 subunit of P/Q-Ca2+ channels and is highly expressed in the cerebellum. Using a pointing paradigm and infrared optoelectronic tracking system, we found subclinical hypermetria and other subtle cerebellar signs in the common forms of migraine. These were more pronounced in migraine with than without aura. Whether this reflects involvement of Ca2+ channel genes in the common types of migraine needs to be investigated by genetic analyses. [less ▲]Detailed reference viewed: 16 (2 ULg)
Reduced gating of middle-latency auditory evoked potentials (P50) in migraine patients: another indication of abnormal sensory processing?
; De Pasqua, Victor ; et al
in Neuroscience Letters (2001), 306(1-2), 132-4
Habituation of cortical evoked responses to repetitive stimuli is reduced in migraine between attacks. To explore another aspect of information processing, we measured auditory sensory gating. The ... [more ▼]
Habituation of cortical evoked responses to repetitive stimuli is reduced in migraine between attacks. To explore another aspect of information processing, we measured auditory sensory gating. The amplitude of the P50 response to the second of two homologous stimuli was significantly less reduced in migraineurs than in healthy volunteers. This lack of auditory sensory gating may be due to a hypofunction of monoaminergic subcortico-cortical pathways, which is also supposed to cause the interictal deficit of cortical habituation to repetitive stimuli. [less ▲]Detailed reference viewed: 11 (0 ULg)
Electrophysiological study of central mechanisms of fatigue in multiple sclerosis.
DELVAUX, Valérie ; ; et al
in Clinical Neurophysiology (2000, August), 111(Suppl. 1), 12316-05Detailed reference viewed: 11 (1 ULg)
Post-stroke reorganization of hand motor area: a 1 year longitudinal study with focal transcranial magnetic stimulation.
DELVAUX, Valérie ; ; DE PASQUA, Victor et al
in Clinical Neurophysiology (2000), 111(Suppl. 1), 12517-06Detailed reference viewed: 30 (4 ULg)
Ipsilateral motor responses to focal transcranial magnetic stimulation in normal and stroke patients.
; DELVAUX, Valérie ; GERARD, Pascale et al
in Journal of Neurology, Neurosurgery & Psychiatry (2000), Neurosurgery and PsychiatryDetailed reference viewed: 27 (2 ULg)
Décréments lors de la stimulation nerveuse répétitive chez des patients souffrant de SLA
WANG, François-Charles ; DE PASQUA, Victor ; CRIELAARD, Jean-Michel
Conference (2000)Detailed reference viewed: 8 (0 ULg)
Is the decremental motor response a useful parameter for the follow-up of amyotrophic lateral sclerosis patients ?
WANG, François-Charles ; DE PASQUA, Victor ; Delwaide, Paul
in Journal of Neurology (2000)Detailed reference viewed: 4 (1 ULg)
Nombre et taille des unités motrices dans la sclérose latérale amyotrophique
WANG, François-Charles ; DE PASQUA, Victor ; GERARD, Pascale et al
in Magistris, Michel (Ed.) L’électroneuromyographie en l’an 2000 : mises au point (2000)Detailed reference viewed: 9 (0 ULg)
Projections from basal ganglia to tegmentum: a subcortical route for explaining to pathophysiology of Parkinson's disease signs ?
Delwaide, Paul ; PEPIN, Jean-Louis ; DE PASQUA, Victor et al
in Journal of Neurology (2000)Detailed reference viewed: 3 (0 ULg)