Changes of motor evoked potential amplitudes following magnetic stimulation after hyperventilation.

The influence of hyperventilation on amplitudes of motor evoked potentials (MEP) following cortical and root magnetic stimulations was tested in ten healthy volunteers. Hyperventilation significantly increased MEP amplitude following cortical stimulation (p < 0.01) but failed to change MEP amplitude following root stimulation. This finding is compatible with the concept of hyperventilation as a promoter of greater excitability at the level of cortical structures. The provoking method applied during magnetic cortical stimulation might be a useful procedure in studying some functional affections associated with hyperventilation, such as hyperventilation tetany or panic disorder.