Infusion tests are now the gold standard for the diagnosis of chronic adult hydrocephalus (CAH), also known as normal pressure hydrocephalus. It is an invasive procedure using the same approach as a lumbar puncture. Once the intrathecal puncture is performed, the intracranial pressure is measured in lateral decubitus via a pressure head. Dynamic tests (injection of 0.9% NaCl at a constant flow rate) are performed after recording the basal pressure. This type of test lasts 30 to 45 minutes in lateral decubitus. Patients with CAH have cognitive-behavioral disorders that can alter the gesture and its interpretation in case of movements or contractures. Movement artefacts lead to a longer recording time. The longer the test, the more the patients' tolerance tends to decrease. Moreover, the patient's feeling towards this test is important because it may have to be repeated. Pain, anxiety and patient comfort are essential parameters to consider. Non-medicinal techniques (hypnosis, music therapy) have shown a tendency to reduce anxiety in pediatric and adult populations with an impact on instantaneous anxiety but also on personality-related anxiety. Most studies are focused on specific pathologies, primarily in palliative care, or on pediatric application. The use of these techniques in an elderly population with mild cognitive-behavioral disorders has not been explored.

The objective is to evaluate the impact of hypnosis on anxiety, pain and comfort during the lumbar infusion test.

Inclusion Criteria:

• Patient over 65 years old undergoing assessment for suspected CAH in day hospitalization for a lumbar infusion test
• No major cognitive impairment (MMSE>20)

Exclusion Criteria:

• Patient less than 65 years old
• Major cognitive impairment (MMSE<20)
• History of lumbar surgery
• Contraindication to lumbar puncture or infusion test
• Hearing impairment