Publications (13)39.66 Total impact
-
Article: Defective visual inhibition in photosensitive idiopathic generalized epilepsy.
[show abstract] [hide abstract]
ABSTRACT: To assess the visual system excitability of photosensitive patients with idiopathic generalized epilepsy (IGE) with the paired-pulse flash-evoked potential (paired F-VEP) technique. We studied 19 photosensitive patients with IGE (16 women) showing a photoparoxysmal electroencephalographic (EEG) response (PPR). Twenty-two normal subjects of similar age and sex acted as controls (17 women). We recorded F-VEPs from occipital and central electrodes. Stimuli were single flashes, intermingled to flash pairs at the interstimulus interval (ISI) of 333, 125, 62.5, 50, 33, and 16.5 msec (i.e., at the internal frequency of 3, 8, 16, 20, 30, and 60 Hz). Recordings were done both with closed and open eyes. The single F-VEP was split into a "main complex" and a "late response," which were measured separately. As to paired stimuli, the "test" F-VEP emerged from electronic subtraction of the single F-VEP to the paired F-VEP. Grouped data were analyzed by means of nonparametric analyses of variance (ANOVAs). In patients, the single F-VEP showed some enhanced components in its early "main complex." Then, the "test" F-VEP behaved differently than controls, particularly if recorded with closed eyes, when the normal inhibition was abolished at given ISIs, corresponding to an internal frequency of 16-30 Hz. In patients with a posterior PPR, impaired inhibition was evident over the occipital region only, but in those with a widespread PPR, it also involved the central areas. The paired F-VEP technique documents a defective inhibition in the visual system of photosensitive patients with IGE, whose features and timing likely underlie the PPR origin.Epilepsia 02/2012; 53(4):695-704. · 3.96 Impact Factor -
Article: Cortical excitability changes associated with fixation-off sensitivity: a case report.
[show abstract] [hide abstract]
ABSTRACT: "Fixation-off sensitivity" (FOS) is an ideal human model for studying the features of epileptic discharges. Physiologically, FOS is expected to correspond to enhanced excitability of widespread cortical structures. To test this hypothesis, we measured by transcranial magnetic stimulation (TMS), the excitability level of the primary motor area in a 22-year-old woman with eyelid myoclonias and absences, who presented with generalized FOS. We also explored her visual system by pattern-reversal and flash-visual evoked potentials (VEPs). Both outside and within FOS, the cortical silent period was dramatically short, indicating defective γ-aminobutyric acid (GABA)(B) inhibition as a persistent background factor. The same was true for the short-interval intracortical inhibition, a TMS marker of cortical GABA(A) inhibition. The FOS state corresponded then to a pathologic enhancement of intracortical facilitation, a TMS marker of Glu/Asp transmission. During FOS, the flash VEP exhibited a hugely enhanced afterdischarge, expressing a pathologic overactivity of secondary visual areas. Within the limits of a single-case study, we thus provide electrophysiologic evidence supporting a grossly imbalanced cortical excitability, in both the frontal and posterior areas, as an important correlate of the present FOS subtype.Epilepsia 06/2011; 52(8):e89-92. · 3.96 Impact Factor -
Article: Complex pattern of convulsive syncope in glossopharyngeal neuralgia: video/EEG report and short review.
[show abstract] [hide abstract]
ABSTRACT: A 65-year-old woman presented with three "convulsive" events that were preceded by stabbing pain extending from the left submandible zone to the neck and ipsilateral ear. Video-electroencephalography captured a typical attack, where electrocardiography showed bradycardia for 17 seconds and asystole for at least 9 seconds. The patient lost consciousness while her head/gaze turned right. She then manifested tonic extension of her left limbs followed by adduction of her left limb and flexion of her right upper limb. Her gaze deviated upward and her left upper limb manifested swimming-like automatisms. The full episode lasted about 70 seconds, and the EEG showed progressive diffuse high-amplitude slowing. A diagnosis of convulsive syncope resulting from classic glossopharyngeal neuralgia was made. Carbamazepine led to steady remission. Glossopharyngeal neuralgia is a rare condition (incidence of 0.7/100.000/year), whereas the occurrence of syncope is about 20%, and that of convulsive syncope is about 5%.Epilepsy & Behavior 02/2011; 20(2):407-9. · 2.34 Impact Factor -
Article: Paired-pulse flash-visual evoked potentials: new methods revive an old test.
[show abstract] [hide abstract]
ABSTRACT: We aimed at reviving with modern technology the paired flash-visual evoked potential (F-VEP) testing of the visual system excitability. In the 1960s, methodological problems hindered this test, which was expected to provide important physiologic information. We studied 22 consenting healthy subjects (10 men). We recorded F-VEPs from electrodes over occipital and central brain regions. We delivered single flashes, mixed at random to flash pairs at the interstimulus interval (ISI) of 333, 125, 62.5, 50, 33, and 16.5 ms, (i.e. an internal frequency (IF) of 3, 8, 16, 20, 30, and 60 Hz). Recordings were performed with the subject's eyes closed and opened. The F-VEP was split into a "main complex" and an "afterdischarge", which we analyzed statistically in relation to the eye state (closed or open) and to the changes due to paired stimulation. The eye state affected the single F-VEP size, latency and shape significantly (p<0.05). On paired stimulation, the test (second) F-VEP exhibited significant (p<0.05), ISI-dependent size changes, such as a progressive decrease for ISIs from 62.5 to 16.5 ms (IFs of 16-60 Hz), whose timing/amount varied significantly (p<0.05) according to the eye state and to the F-VEP epoch considered. Suppression of the test F-VEP was never complete, even for the shortest ISI (ISI=16.5 ms, IF=60 Hz). The eye state (closed or open) must be considered meticulously when studying F-VEPs. F-VEP changes on paired stimulation express neural inhibition within the visual system, which can be depicted as ISI-dependent curves. Modern equipment and simplified measures render this an easy test, with statistical validity, providing specific information on the excitability properties of the visual system.Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 02/2011; 122(8):1622-8. · 3.12 Impact Factor -
Article: Re: Modulation of human motor cortex excitability by valproate.
Psychopharmacology 02/2011; 216(1):145-6. · 4.08 Impact Factor -
Article: The routine circular coil is reliable in paired-TMS studies.
[show abstract] [hide abstract]
ABSTRACT: Motor cortex excitability can be measured by transcranial magnetic stimulation (TMS) using different coil types, but paired-TMS was originally devised with a figure-of-eight coil. We asked whether the most popular, circular coil was suited to the every-day assessment of cortical excitability, particularly paired-TMS indexes, and if it reduced the measurement error. We studied 12 right-handed, healthy subjects (34±7.6 years). Resting motor threshold (MT), cortical silent period (CSP), short-interval intracortical inhibition (SICI) at the 2, 3, 4 and 5 ms interstimulus intervals (ISIs) and intracortical facilitation (ICF) at the 14 and 16 ms ISIs were measured. Intrinsic variability of these indexes was evaluated in terms of Coefficients of Variation, to estimate the measurement error. This sequence was carried out both using a figure-of-eight coil over the hand motor area and a circular coil centred at the vertex. Testing was repeated 8-13 months later. On average, MT, SICI and ICF did not show any statistically significant difference (p>0.05) when studied with the figure-of-eight as compared with the circular coil. CSP was significantly shorter (p=0.007) with the figure-of-eight coil. Using either coil did not affect measurement variability. There was no significant session-to-session group difference at any of the variables using either coil type. Except for the CSP duration, the TMS testing and retesting of cortical excitability, particularly the paired-pulse indexes, did not vary significantly as a function of the coil used. Routine circular coils can be used reliably in paired-TMS studies designed to measure longitudinal changes in cortical excitability though they do not reduce the measurement error.Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 11/2010; 122(4):784-8. · 3.12 Impact Factor -
Article: Defective Fas-mediated T-cell apoptosis predicts acute onset CIDP.
[show abstract] [hide abstract]
ABSTRACT: Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyneuropathy (CIDP) are immune-mediated neuropathies. GBS is characterized by acute onset and subsequent remission of symptoms, whereas CIDP displays slow progression over at least 2 months. However, a small proportion of CIDP patients display acute onset CIDP (a-CIDP) resembling that of GBS. The Fas receptor is involved in shutting off the immune response and its defective function predisposes to auto-immune diseases. In CIDP patients, Fas function is lower than in GBS patients and healthy controls. This study is aimed at assessing whether evaluation of T-cell Fas function helps in early discrimination between GBS and a-CIDP. Fas function was evaluated in patients with acute onset polyneuropathy: 55 retrospective patients analyzed after development of GBS or a-CIDP before year 2005; 50 prospective patients analyzed at onset after year 2005 and followed up for development of GBS or a-CIDP. In both groups, a-CIDP patients displayed defective Fas function, whereas GBS patients displayed normal function. These findings suggest that the evaluation of Fas function in acute onset polyneuropathy helps in early prediction of long-term outcome.Journal of the Peripheral Nervous System 07/2009; 14(2):101-6. · 2.80 Impact Factor -
Article: SLE-related longitudinal myelitis with favorable outcome.
The Canadian journal of neurological sciences. Le journal canadien des sciences neurologiques 06/2009; 36(3):393-7. · 0.97 Impact Factor -
Article: Complex movement disorders in primary antiphospholipid syndrome: a case report.
[show abstract] [hide abstract]
ABSTRACT: Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by recurrent thrombotic events and/or pregnancy morbidity that may be isolated (Primary APS) or associated with other diseases, mainly of autoimmune origin (Secondary APS). A variety of neurological symptoms may occur in association with the disease, including movement disorders. We report on a 79 year old woman with an unremarkable past medical history who progressively developed psychomotor agitation and insomnia through a period of four months, followed by an acute onset complex hyperkinetic syndrome with chorea, focal left foot dystonia, oral dyskinesias and severe speech impairment. Brain MRI showed multiple subcortical lesions without basal ganglia involvement, and a large cortical lesion in the left posterior temporal lobe that appeared to be ischemic. These findings along with a strongly elevated titer of anticardiolipin (aCL) and anti-beta(2) glycoprotein-I antibodies and positive Lupus Anticoagulant (LAC) suggested a diagnosis of Antiphospholipid Syndrome, confirmed 14 weeks later as a Primary syndrome. The autoimmune mechanisms possibly responsible for the patient's clinical picture are discussed. This case underlines the importance of taking into account APS as a cause of unusual movement disorders even in elderly patients without evidence of previous thrombotic events.Journal of the neurological sciences 05/2009; 281(1-2):101-3. · 2.32 Impact Factor -
Article: Generalized peripheral nerve hyperexcitability associated with lithium.
The Journal of neuropsychiatry and clinical neurosciences 01/2009; 21(3):346-7. · 2.34 Impact Factor -
Article: Ketogenic diet: electrophysiological effects on the normal human cortex.
[show abstract] [hide abstract]
ABSTRACT: To explore the cortical electrophysiology of the ketogenic diet (KD) in the normal human. KD is effective against refractory epilepsy, but its precise mechanism is obscure. At the transmitter level, an enhancement of GABA inhibition has often been proposed. We studied eight healthy volunteers undergoing a "classic" KD for 2 weeks. We measured several biochemical variables at baseline (T0), after 1 week (T1) and 2 weeks (T2) of KD, then 3 months after the KD conclusion (T3). Ketosis was quantified as 24-h ketonuria. At the same time, we studied the motor cortical excitability by means of transcranial magnetic stimulation (TMS). We also quantitatively evaluated the EEG signal in search of frequency shifts over the rolandic areas. Significant (p < 0.05) neurophysiological changes appeared at T2. These consisted of a strengthening of short-latency cortical inhibition (SICI), a TMS index which is thought to reflect GABA-A inhibition in the cortex. Then, there was an enhancement of the beta EEG band over the perirolandic region, similar to that following administration of GABA-A agonists. All changes disappeared at T3. A standard, short-term KD affected the cortical physiology of the normal human. The main changes were an augmented SICI and an increased perirolandic beta EEG activity, which are compatible with a lower level of neural excitation within the cortex.Epilepsia 09/2007; 48(9):1756-63. · 3.96 Impact Factor -
Article: Slow repetitive TMS for drug-resistant epilepsy: clinical and EEG findings of a placebo-controlled trial.
[show abstract] [hide abstract]
ABSTRACT: To assess the effectiveness of slow repetitive transcranial magnetic stimulation (rTMS) as an adjunctive treatment for drug-resistant epilepsy. Forty-three patients with drug-resistant epilepsy from eight Italian Centers underwent a randomized, double-blind, sham-controlled, crossover study on the clinical and EEG effects of slow rTMS. The stimulus frequency was 0.3 Hz. One thousand stimuli per day were given at the resting motor threshold intensity for 5 consecutive days, with a round coil at the vertex. "Active" rTMS was no better than placebo for seizure reduction. However, it decreased interictal EEG epileptiform abnormalities significantly (p < 0.05) in one-third of the patients, which supports a detectable biologic effect. No correlation linked the rTMS effects on seizure frequency to syndrome or anatomic classification, seizure type, EEG changes, or resting motor threshold (an index of motor cortex excitability). Although the antiepileptic action was not significant (p > 0.05), the individual EEG reactivity to "active" rTMS may be encouraging for the development of more-powerful, noninvasive neuromodulatory strategies.Epilepsia 03/2007; 48(2):366-74. · 3.96 Impact Factor -
Article: Excitability of the human epileptic cortex after chronic valproate: a reappraisal.
[show abstract] [hide abstract]
ABSTRACT: We explored the action of chronic valproic acid (VPA) on the human epileptic cortex by means of transcranial magnetic stimulation (TMS). TMS is an emerging biomarker for neurotropic drugs. We had 15 drug-naive patients with different epileptic syndromes. Interictally, we measured several TMS indexes of cortical excitability before commencing VPA and 3 months later. At that time, all patients were clinical responders to the drug, whose plasma levels were in the "therapeutic range". We then compared the two conditions, while 18 healthy subjects, of whom 12 were retested at a similar delay, acted as controls. In the pooled patients, the baseline resting motor threshold to TMS was similar to that of controls, but it increased significantly (P < 0.05) after VPA. Intracortical facilitation, another index of cortical excitability, was abnormally enhanced at baseline but decreased significantly after VPA (P < 0.05). On splitting patients according to their diagnosis, the threshold increase was significant (P < 0.05) among partial, but not generalized epilepsies. The reverse was true for changes in intracortical facilitation. TMS phenomena had no linear relation to VPA serum levels. Based on the known pharmacology of TMS effects, VPA reduced the intrinsic membrane excitability of motor cortical neurons, possibly through changes in Na+ channel activity. Then, VPA corrected a transmitter-mediated interneuronal hyper-excitability of the primary motor cortex. The former effect was best seen in partial, and the latter in generalized epilepsy patients.Brain Research 07/2006; 1099(1):160-6. · 2.73 Impact Factor
Top co-authors
Top Journals
Institutions
-
2006–2012
-
Università degli Studi del Piemonte Orientale "Amedeo Avogadro"
- Interdisciplinary Research Center of Autoimmune Diseases IRCAD
Alessandria, Piedmont, Italy
-
