Pneumatic evoked potential. Sensory or auditive potential?

Study Aim: In this study, evoked potentials (EPs) to a pneumatic, innocuous, and calibrated stimulation of the skin were recorded in 22 volunteers.

Methods: Air-puff stimuli were delivered through a home-made device (INSA de Lyon, Laboratoire Ampère, CHU de Saint-Étienne, France) synchronized with an EEG recording (Micromed(®)).

Results: A reproducible EP was recorded in 18 out of 22 subjects (82% of cases) with a mean latency of about 120-130ms, and maximal amplitude at Cz. This EP actually consisted of two components, an auditory and a somatosensory one. Indeed, it was significantly decreased in amplitude, but did not disappear, when the noise generated by the air-puff was masked. We also verified that a stimulation close to the skin but not perceived by the subject was not associated with any EP. Conduction velocity between hand and shoulder was calculated around 25m/s.

Conclusions: This preliminary study demonstrates that pneumatic EPs can be recorded in normal volunteers.