Hypnosis and virtual reality are potential tools for treating acute. Nevertheless, the neurophysiological correlates of such tools used together, i.e. 'virtual reality hypnosis' (VRH) (Patterson et al., 2004) remain mostly understudied. This study aims to improve our knowledge and understanding of the dissociation (i.e., a mental separation of components of behaviours that normally would be processed together) occurring during VRH. This is a clinical trial aiming at understanding if the VRH reduces pain during a port-a-cath intervention in oncological patients and if dissociation may explain the pain alteration.

The study will be focused on oncological patients undergoing a port-a-cath placement procedure. Day-1 and Day-2 with a one-day follow-up Day-3:

I. Day-1: Oncological Population (Feasibility)

1. Recruitment and questionnaires on the day of the port-a-cath preparation consultation (DAY-1): i. A medical screening will be performed to assess eligibility, ii. Elkins Hypnotizability Scale. iii. State Trait Anxiety Inventory-trait (anxiety trait) iv. Dissociative Experience Scale. v. Tellegen Absorption Scale. vi. Questionnaire of Immersion Propensity.

II. Day-2:

1. Intervention day:

   i. Visual Analogy Scale:

   • Anxiety.
   • Pain. ii. 4-Electrodes EEG device from Oncomfort during port-a-cath (Port) placement procedure under Virtual Reality Hypnosis (VRH), combined standard monitoring (spO2, heart rate, etc.) iii. Adverse events will be recorded throughout the experiment iv. Visual Analogy Scale:
   • Dissociation.
   • Pain.
   • Anxiety
   • Absorption.
   • Arousal/wakefulness.
   • Automaticity v. Time Perception (open-ended question) vi. Presence questionnaire. vii. Satisfaction questionnaire.

2. Follow-up (DAY-3):

   i. A follow-up questionnaire using the Brief Pain Inventory (BPI) French version will be sent to the patient one week after the intervention to measure outcomes.

Inclusion Criteria: Subject more than 18 years old

Exclusion Criteria:

1. Low auditory and/or visual acuity precludes the use of the device.
2. Head or face wounds precluding the use of the device.
3. Schizophrenia, dissociative disorder or any other psychiatric disorder.
4. Non-proficiency in French (Research language).
5. Patient under 18 years old.
6. Phobia of deep water.
7. Allergy to cutaneous electrodes.
8. Chronic pain and/or chronic analgesics consumption.
9. Medication affecting the autonomic nervous system.
10. Dizziness.

Methodology of virtual reality hypnosis prevents masking participants and experimenter.