Alfonso Marrelli

Reliability of transcranial magnetic stimulation-related measurements of tibialis anterior muscle in healthy subjects.

OBJECTIVE The main purpose of this study was to determine the reliability of transcranial magnetic stimulation (TMS)-related measurements linked to the corticospinal control of the tibialis anterior (TA) muscle in healthy subjects. METHODS Inter-investigator and intra-investigator (within-session with a 1.5-h interval; between-session with a 4-week interval) reliability of the motor threshold, recruitment curve with its slope and MEP area at the plateau, MEP latency, maximum MEP (MEPmax) area, and duration of the maximum and minimum silent period (SPmax and SPmin) were assessed in 50 (29 men and 21 women) healthy subjects (mean age 44.8 years, range 22-74 years) using intraclass correlation coefficients (ICC), standard error of measurement (SEM) and smallest real difference (SRD). RESULTS The high ICC values and lower SEM and SRD values indicate a good intra- and inter-investigator reliability for motor threshold (ICC range 0.94-0.98), MEP latency (ICC range 0.79-0.93), SPmax (ICC range 0.89-0.95) and SPmin (ICC range 0.79-0.81) in healthy subjects. CONCLUSIONS These results suggest that the TMS-related measurements investigated are reliable in healthy subjects. SIGNIFICANCE These data could be useful in further studies on cortical excitability changes, such as those induced by therapeutic interventions (e.g. rehabilitative treatment).

Reliability of TMS-related measures of tibialis anterior muscle in patients with chronic stroke and healthy subjects.

A lack of normative data for transcranial magnetic stimulation (TMS)-related measures of the lower limb muscles in patients with stroke prevents us from understanding whether changes in TMS-related measures are induced by treatment or are due to their variability and/or the natural evolution of the disease. The purpose of this study was to determine the reliability of three TMS-related measures: motor threshold (MT), motor evoked potential latency (MEP Lat) and MEP amplitude (MEP Amp), linked to the corticospinal control of the tibialis anterior (TA) muscle in sixteen patients with chronic stroke and in sixteen aged-matched healthy subjects. Test-retest reliability was estimated using the intraclass correlation coefficient (ICC) with its 95% confidence interval (95% CI) and standard error of measurement (SEM). In healthy subjects the reliability of all the TMS-related measures yielded an ICC≥0.75. Similar reproducibility levels were found in patients with chronic stroke, with the exception of MEP Amp on the paretic side (ICC=0.38). These results suggest that the TMS-related measures investigated are reliable both in healthy subjects and, with the exception of MEP Amp on the paretic side, in patients with chronic stroke.

Visual evoked potentials and serum magnesium levels in juvenile migraine patients

Changes in visual evoked potentials and decreased intracellular magnesium levels have been separately described in patients affected by migraine both during the attacks and in the interictal periods. An inverse correlation between increased P100 amplitude and lowered serum magnesium levels was found in children suffering from migraine with and without aura in a headache‐free period. A 20‐day treatment with oral magnesium pidolate seemed to normalize the magnesium balance in 90% of patients. After treatment, the reduced P100 amplitude confirmed the inverse correlation with the serum magnesium level. These data seem to suggest the hypothesis that higher visual evoked potential amplitude and low brain magnesium level can both be an expression of neuronal hyperexcitability of the visual pathways related to a lowered threshold for migraine attacks.

Geomagnetic activity, humidity, temperature and headache: Is there any correlation?

SYNOPSIS

Spectral Analysis of Visual Potentials Evoked by Pattern-Reversal Checkerboard in Juvenile Patients With Headache

Changes in visual evoked potentials, mainly affecting the amplitude of the major positive wave, are referred to by many authors and are related to the pathophysiological basis of primary headache.

Visual Evoked Potentials in Alzheimer's Disease:Electrophysiological Study of the Visual Pathways and Neuropsychological Correlates

Visual Evoked Potentials [VEP] abnormalities are reported in Alzheimer’s Disease [AD] patients. It is necessary to understand the pathophysiology, clinical relevance and the relationship with the different visual pathways. We performed a study on AD patients compared to Multi-Infarct Dementia [MID] patients by means of different visual stimuli considered selective in stimulating Magnocellular [M], Parvocellular [P] and Koniocellular [K] system. All the patients underwent a neuropsychological assessment and evaluation of disability. Our results seem to confirm major involvement of both the M system and the K system in AD patients, in accordance with the pathophysiological hypotheses regarding visual disturbances in AD. Moreover, the neurophysiological data seem to be related both to the neuropsychological features of dysexecutive syndrome and apraxia and also to disability.

Seasonal and meteorological factors in primary headaches.

SYNOPSIS

Facial emotion recognition in schizophrenia: an event-related potentials study.

Previous studies extensively reported an impaired ability to recognize emotional stimuli in patients with schizophrenia. We used pictures from Ekman and Friesen in an event-related potentials study to investigate the neurophysiological correlates of the fear emotional processing compared with happiness in patients with schizophrenia versus healthy subjects. A significant lower P300 amplitude for fear processing but not for P100, N170 and N250 amplitude was found in schizophrenics compared to controls. These data suggest that the ability of basic visual processing is preserved in schizophrenia, whereas facial affect processing is impaired.

Emotional reactivity in mesial temporal lobe epilepsy: A pilot study

PURPOSE Emotional reactivity (ER) is the early rapidly evoked response to a salient emotional stimulus which influences an individuals coping mechanisms, eliciting adaptive responses. We investigated ER in patients with mesial temporal lobe epilepsy (MTLE) in order to obtain an emotion-processing measure that can be related to behavioral regulation. METHODS We measured ER in twelve patients with (MTLE) using the International Affective Picture System (IAPS), the most widely employed instrument to measure ER, and compared their results with those of a matched sample of healthy subjects. Ninety color pictures depicting events with different kinds of affective valence (pleasant, unpleasant, and neutral) were shown to the patients. Unpleasant and pleasant pictures were also distinguished depending on whether or not they involved social human conditions. The ER was rated on the basis of valence and arousal. RESULTS Patients with MTLE showed higher mean arousal and valence ratings than controls for neutral and socially pleasant pictures. A higher valence for unpleasant pictures and a trend toward significantly higher arousal and valence for pleasant pictures were also recorded. CONCLUSIONS Patients with MTLE seem to feel the environment in a more sensitive and positive way compared with controls, likely in relationship with social functioning alterations.