Background & aims: Pulsed radiofrequency (PRF) of the occipital nerves (greater & lesser GON & LON), is a minimally invasive technique for chronic headache management, due to its neuromodulative and analgesic properties. Due to a clinical observation of sedation during the procedure, the aim of this study was to investigate whether PRF of the occipital nerves can also cause sedation, using an objective measurement device.
Methods: Patients sufferring from chronic headache, not responding to systemic pharmacotherapy, were scheduled for PRF following a standardized protocol (needle 22G, 54 mm, with a 4 mm active tip, PRF of 40-60 V, 2Hz, impedance 150-400 Ω, plateau temperature 42°C, time: 6 min each). The Bispectral Index anaesthesia device was used to measure sedation (0=deep sedation-100=no sedation) and recorded every minute  throughout the procedure. 
Results: 22 patients were studied. BIS values were lowered in all but 3 patients during GON stimulation, and in all patients during LON stimulation. Values of decline compared to baseline ranged between 0-23 (median 8.5) for  GON, and 1-27 (median 14) for LON, with LON decline being significantly lower (p<0.05). 
Conclusions: Pulsed radiofrequency of the occipital nerves and especially of the LON led to mild sedation in all patients. Further studies are required in order to investigate this effect and clarify the exact mode of action of pulsed radiofrequency.

CAN PULSED RADIOFREQUENCY OF THE OCCIPITAL NERVES CAUSE SEDATION? A NEW PERSPECTIVE OF A CLASSIC TECHINQUE