Some patients with chronic subdural hematomas and transient neurological symptoms do not respond to standard antiepileptic drugs. The investigators think that some of them could have cortical depression rather than epileptic discharges. After an intensive literature review, the investigators found out that some antiepileptic dugs (Lamotrigine, Topiramate) were found to be efficient to treat cortical depression in other conditions (migraine, subarachnoid hemorrhage). In contrast, some other drugs (Levetiracetam) were not proved to be efficient. Knowing that, the investigators want to compare the efficacy of Topiramate against Levetiracetam in two different groups, the NESIS group (based on a NESIS score of 4 or more - increased risk of cortical depression) versus a non-NESIS group (score of 3 or less - increased risk of epileptic discharges).