The precise incidence of the Trephined Syndrome is poorly known but is described to be 7% up to 26%. It is much likely underestimated since it concerns patients with preexisting neurological symptoms and often multiple comorbidities. Furthermore its presentation varies in a way, that in certain patients the Trephined Syndrome manifests itself by neurological aggravation, while in other patients it is only the absence of evolution in rehabilitation, followed then by improvement after cranioplasty, which makes it possible to retain this diagnosis a posteriori.