Cranioplasty as the treatment for contralateral subdural effusion secondary to decompressive craniectomy: a case report and review of the relevant literature.

Subdural effusion (SDE) is a common complication secondary to decompressive craniectomy (DC). This current case report describes a patient with contralateral SDE with a typical clinical course. Initially, he made a good recovery following a head trauma that caused a loss of consciousness and was treated with decompressive craniectomy. However, he only achieved temporary relief after each percutaneous fluid aspiration from an Ommaya reservoir implanted into the cavity of the SDE. He was eventually transferred to the authors' hospital where he underwent cranioplasty, which finally lead to the reduction and disappearance of his contralateral SDE. Unexpectedly, his clinical condition deteriorated again 2 weeks after the cranioplasty with symptoms of an uncontrolled bladder. A subsequent CT scan found the apparent expansion of the whole cerebral ventricular system, indicating symptomatic communicating hydrocephalus. He then underwent a ventriculoperitoneal shunt procedure, which resulted in a favourable outcome and he was discharged 2 weeks later. A review of the current literature identified only 14 cases of contralateral SDE that were cured by cranioplasty alone. The mechanism of contralateral SDE has been widely discussed. Although the exact mechanism of contralateral SDE and why cranioplasty is effective remain unclear, cranioplasty could be an alternative treatment option for contralateral SDE.