Despite the advances in the management of headache disorders, many patients suffering from chronic migraine are refractory to current treatments. New treatments backed by good evidence are therefore in great need. Electrical stimulation of peripheral nerves is used to treat various painful conditions including headache disorders. More recently it has been reported good outcome in these painful conditions with subcutaneous placement of leads at the level of C1 and stimulation of the greater occipital nerve: This procedure is named Occipital Nerve Stimulation (ONS). The clinical conditions treated with ONS include occipital neuralgia, Trigeminal Autonomic Cephalalgias (TACs), migraine and transformed migraine. The surgical procedure is divided in two steps. In the first step, with the patient in prone position under local anaesthesia, a vertical incision of 2 cm is made in posterior cervical region in the midline on the external occipital protuberance. Under fluoroscopy control, a Tuohy needle is passed transversely in the subcutaneous space across the base of the greater occipital nerve at the level of C1 starting from the midline incision towards the mastoid process and following the trajectory of the nuchal line. A quadripolar wire lead is introduced into the Touhy needle by medial to lateral direction; under fluoroscopy control the needle is withdrawn and the lead is connected to an external cable for intraoperative testing with an external stimulator.

The stimulation parameters are chosen to obtain paraesthesias in the innervation territory of the greater occipital nerve. The lead is then sutured to the underlying fascia with a silicone fastener and a silk sutures. In some cases, according to Franzini lead fixation techniques. Pisces Quad lead may be fixed to the lateral portion of the superficial fascia transfixing the plastic tip of the lead with a suture needle through a vertical incision of 4 cm lateral to the external occipital protuberance. After a 7-15 days trial period of external stimulation, if the patient reported at least 50% decrease in headache intensity and/or frequency associated with a decrease headache medication use, a permanent implant of a single channel IPG or a dual-channel IPG is then performed under general anesthesia. The parameters used for chronic stimulation are usually: Frequency 30-60 Hz, Pulse Width 90-400 microsec, Amplitude 1.5-9.0 Volts, bipolar stimulation configuration, cyclic mode.

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