The chronic subdural hematoma is a common disease in the population over 60 years. For example, in patients over 70 years, it occurs every year 7 new cases per 100,000 people. A chronic subdural hematoma is an accumulation of blood in the intracranial space between brain membrane (dura mater) and the brain. The origin of blood in this area follows a minor brain injury, which causes the rupture of small vessels in the area. During its evolution, the volume of the hematoma increases. After a few weeks, the amount of fluid build-up can compress the brain. That's when clinical symptoms occur: persistent headaches, neurological deficits, seizures, impaired consciousness, cognitive functions (memory loss, impaired intellectual function, or hallucinations, etc.). The compression of the brain may cause impairment of consciousness resulting in more severe cases coma and death. At this stage, a neurosurgical intervention is necessary. Recurrences are numerous (15 to 25% recurrence over six months after neurosurgery). That is why in France, about 20% of medical teams administer a postoperative treatment with corticosteroids to reduce the risk of recurrence. Until now, the potential benefit of this treatment has not yet been confirmed by a clinical study. So the purpose of this research.