Activating effect of nasal and oral hyperventilation on epileptic electrographic phenomena: reflex mechanisms of nasal origin.

In experiments on animals, airflow through the nasal cavity elicits rhythmic synchronized activity that can trigger and/or elicit epileptic electrographic activities in the limbic structures of the brain. This could be demonstrated in studies of lower vertebrates (frogs and turtles). In the turtle the elicited paroxysmal activity often had the shape of regular high-voltage activity in the theta-frequency range (average frequency, 4.1 Hz). It was further proven in clinical experiments that nasal deep breathing with a closed mouth effectively activates epileptic electrographic phenomena of a temporal (limbic) origin. The activating effect was more pronounced on the side ipsilateral to the ventilated nasal meatus. It could also be evoked by air insufflation into the nasal cavity. This effect was suppressed by anesthesia of the mucous membrane in the upper nasal meatus. Possible mechanisms of this, probably reflex, phenomenon are discussed.