Reference : Reduced excitability of the motor cortex in untreated patients with de novo idiopathi...
Scientific journals : Article
Human health sciences : Neurology
Reduced excitability of the motor cortex in untreated patients with de novo idiopathic “grand mal” seizures
Delvaux, Valérie mailto [Centre Hospitalier Universitaire de Liège - CHU > > Neurologie Sart Tilman >]
Alagona, Giovanna [> > > >]
GERARD, Pascale [Centre Hospitalier Universitaire de Liège - CHU > > Neurologie CHR >]
De Pasqua, Victor [Centre Hospitalier Universitaire de Liège - CHU > > Neurologie CHR >]
Delwaide, Paul mailto [Université de Liège - ULiège > Services généraux (Faculté de médecine) > Relations académiques et scientifiques (Médecine) >]
Maertens De Noordhout, Alain mailto [Centre Hospitalier Universitaire de Liège - CHU > > Neurologie CHR >]
Journal of Neurology, Neurosurgery & Psychiatry
BMJ Group
Yes (verified by ORBi)
United Kingdom
[en] Adolescent ; Adult ; Aged ; Case-Control Studies ; Electroencephalography ; Epilepsy, Tonic-Clonic/diagnosis/etiology/physiopathology ; Evoked Potentials, Motor ; Female ; Humans ; Magnetics/diagnostic use ; Male ; Middle Aged ; Motor Cortex/physiopathology ; Multivariate Analysis ; Recurrence ; Time Factors ; gamma-Aminobutyric Acid/physiology
[en] 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.
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