In certain neurosurgical procedures, the use of a stereotaxic frame is required. It is then possible to set a precise target (depending of the type of the surgery) to be reached by the surgeon. The fixation of the stereotactic frame on the awake patient's head is done under local anesthesia by screwing the frame directly into the skull. This procedure is reported as "painful" to "extremely painful" by patients. The objective of this study is to determine whether the hypnosis is effective in decreasing the pain perceived by the patient during the disposal of the stereotactic frame.

The role of hypnosis (no sedative drug administered) and hypnosedative procedures (hypnosis with the adjunct of a sedative drug) during surgical procedures has been largely discussed during the past 10 years, and those techniques are now widely practiced in the surgical field, for example during thyroidectomies. In neurosurgery specifically, the successful use of hypnosedation during awake neurosurgical procedures has been recently reported, with a positive feedback from the patients, together with good results regarding extent of resection, in the case of brain lesions located in eloquent areas.

Since 1990, many research groups identified the existence of hypnosis-related phenomena and their influence on the pain signal perception. These authors show that there is a modulation of the anterior cingulate area activity together with modified interconnectivity with other critical regions involved in nociception. In this context, the potential of hypnosis in pain modulation and, more extensively, patient management in surgical anesthetics was established.

In various neurosurgical procedures, the use of a stereotactic frame is required; by using coordinates (x, y and z), which are computed and reported on the frame before the intervention, it is possible to set a precise target (dependent on the type of surgery) to be reached by the surgeon. For instance, during a Deep Brain Stimulation (DBS) performed in a patient suffering from Parkinson's disease (PD), the electrodes are introduced into the brain, deep down to the sub-thalamic nuclei (STN), which are situated in a very little area located in the upper brainstem. The mounting of the stereotactic frame on the patient's head is performed under local anesthesia (LA), as the patient is awake during the mounting procedure and later on during the surgical intervention. This mounting is done by screwing the device directly into the patient's skull, through the skin. This moment is reported as "painful" to "extremely painful" by patients, and most of them confess to keep a very unpleasant memory of the event, even several years after the procedure and despite the fact that the surgery had a positive effect on their functional outcome.

As exposed above, there is still room for improvement in the management of pain and comfort of patients undergoing functional procedures in neurosurgery, especially during the placement of the stereotactic frame. To our opinion, hypnosis could represent a serious therapy against pain and anxiety generated by the frame fixation, especially those whom facial expressions and feelings might be altered by their pathology (i.e. Parkinson's disease). In fact, this technique has already been abundantly reported as an important adjuvant to the management of pain and comfort during surgeries such as thyroidectomies) and resection of brain tumors.

The main objective of this study is to determine whether hypnosis is effective in decreasing the pain perceived by the patient during the placement of the stereotactic frame on the patient's head.

The secondary aims of this study are: 1) to measure the stress perceived during the procedure by submitting the patient to validated scores and 2) to evaluate the incidence of Post-traumatic Stress Disorder (PTSD), according to the Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV) criteria.

Inclusion Criteria:

• Patients undergoing a stereotactic procedure as listed previously
• Patients ≥ 18 y.o.

Exclusion Criteria:

• Patients < 18 y.o.
• Patients unable to take decisions by their own
• Patients undergoing deep brain stimulation for obsessive-compulsive disease treatment
• Patients refusing to participate to the study
• Pregnancy
• Invasive monitoring of epilepsy
• Psychiatric comorbidity

No masking