Transient suppression of involuntary movements in cerebral palsy patients during dental treatment.

The efficacy of nitrous oxide (N2O) and oxygen (O2) inhalation in reducing involuntary movements in cerebral palsy (CP) dental patients was examined using electromyography (EMG) and H-reflex techniques. Quantification and analysis of the EMG data revealed a progressive elimination of these movements to a point resembling the state of a normal muscle at rest. There was a gradual decline in the number of bursts and an increase in the silent periods of the EMG while under N2O. The recovery period after cessation of N2O was characterized by a successive increase in the number of bursts and a simultaneous decrease in the silent periods of the EMG to a state similar to the baseline recorded prior to inhalation of N2O/O2. The H-reflex also was found to decrease gradually during inhalation of N2O/O2 to about one-half of the baseline. This parameter also returned to baseline after N2O wash-out. Our findings demonstrate quantitatively the effectiveness of N2O in reducing the central motor neuron pool excitability to an extent that suppresses involuntary movements and allows more controllable and comfortable dental management.