Alpha and beta EEG power reflects L-dopa acute administration in parkinsonian patients.

AIM: To evaluate the effect of an acute L-dopa administration on eye-closed resting state electroencephalographic (EEG) activity of cognitively preserved Parkinsonian patients. METHODS: We examined 24 right-handed patients diagnosed as uncomplicated probable Parkinson's disease (PD). Each patient underwent Unified Parkinson's Disease Rating Scale (UPDRS)-part-III evaluation before and 60 min after an oral load of L-dopa-methyl-ester/carbidopa 250/25 mg. Resting condition eyes-closed EEG data were recorded both pre- and post L-dopa load. Absolute EEG power values were calculated at each scalp derivation for Delta, Theta, Alpha and Beta frequency bands. UPDRS scores (both global and subscale scores) and EEG data (power values of different frequency bands for each scalp derivation) were submitted to a statistical analysis to compare Pre and Post L-Dopa conditions. Finally, a correlation analysis was carried out between EEG spectral content and UPDRS scores. RESULTS: Considering EEG power spectral analysis, no statistically significant differences arose on Delta and Theta bands after L-dopa intake. Conversely, Alpha and Beta rhythms significantly increased on centro-parietal scalp derivations, as a function of L-dopa administration. Correlation analysis indicated a significant negative correlation between Beta power increase on centro-parietal areas and UPDRS subscores (Rigidity of arms and Bradykinesia). A minor significant negative correlation was also found between Alpha band increase and resting tremor. CONCLUSIONS: Assuming that a significant change in EEG power spectrum after L-dopa intake may be related to dopaminergic mechanisms, our findings are consistent with the hypothesis that dopaminergic defective networks are implicated in cortical oscillatory abnormalities at rest in non-demented PD patients.

1-Hz repetitive transcranial magnetic stimulation increases cerebral vasomotor reactivity: a possible autonomic nervous system modulation.

BACKGROUND: Neuromodulation techniques, i.e. repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), can modify cerebral hemodynamics. High frequency rTMS appeared to decrease cerebral vasomotor reactivity (VMR), while there is still poor evidence about the effect of low frequency (LF) rTMS on cerebral blood flow (CBF) and VMR. HYPOTHESIS: The present study aimed to test if LF rTMS decreases CBF and increases cerebral VMR. Monolateral or bilateral hemispheric involvement and duration of the effect were considered. A possible role of autonomic nervous system in CBF and VMR modulation was also investigated. METHODS: Twenty-four right-handed healthy subjects underwent randomly real (12) or sham (12) 20-min 1-Hz rTMS on left primary motor cortex. Mean flow velocity and VMR of middle cerebral arteries were evaluated by means of transcranial Doppler before (T0), after 10 min (T1) and after 2 (T2), 5 (T3) and 24 h (T4) from rTMS. Heart rate variability (HRV) was studied within the same timing interval, assessing low frequency/high frequency (LF/HF) ratio as index of autonomic balance. RESULTS: After real rTMS compared with sham stimulation, MFV decreased bilaterally at T1 (F = 3.240, P = .030) while VMR increased bilaterally (F = 5.116, P = .002) for at least 5 h (T3). LF/HF ratio decreased early after real rTMS (F = 2.881, P = .040). CONCLUSION: 1-Hz rTMS may induce a bilateral long-lasting increase of VMR, while its effect on MFV is short-lasting. Moreover, HRV changes induced by rTMS suggest a possible autonomic nervous system modulation.

Mobile phone emissions modulate brain excitability in patients with focal epilepsy.

BACKGROUND: Electromagnetic fields (EMFs) emitted by mobile phones had been shown to increase cortical excitability in healthy subjects following 45 min of continuous exposure on the ipsilateral hemisphere. OBJECTIVE: Using Transcranial Magnetic Stimulation (TMS), the current study assessed the effects of acute exposure to mobile phone EMFs on the cortical excitability in patients with focal epilepsy. METHODS: Ten patients with cryptogenic focal epilepsy originating outside the primary motor area (M1) were studied. Paired-pulse TMS were applied to the M1 of both the hemisphere ipsilateral (IH) and contralateral (CH) to the epileptic focus before and immediately after real/sham exposure to the GSM-EMFs (45 min). The TMS study was carried out in all subjects in three different experimental sessions (IH and CH exposure, sham), 1 week apart, according to a crossover, double-blind and counter-balanced paradigm. RESULTS: The present study clearly demonstrated that an acute and relatively prolonged exposure to GSM-EMFs modulates cortical excitability in patients affected by focal epilepsy; however, in contrast to healthy subjects, these effects were evident only after EMFs exposure over the hemisphere contralateral to the epileptic focus (CH). They were characterized by a significant cortical excitability increase in the exposed hemisphere paired with slight excitability decrease in the other one (IH). Both sham and real EMFs exposure of the IH did not affect brain excitability. CONCLUSION: Present results suggest a significant interaction between the brain excitability changes induced by EMFs and the epileptic focus, which eliminated the excitability enhancing effects of EMFs evident only in the CH.