Ketamine for empiric treatment of cortical spreading depolarization after subdural hematoma evacuation

Background: It is widely known that some patients surgically treated for subdural hematoma (SDH) experience neurologic deficits not clearly explained by the acute brain injury or known sequelae like seizures. There is increasing evidence that cortical spreading depolarization (CSD) may be the cause. A recent article demonstrated that CSD occurred at a rate of 15 % and was associated with neurological deterioration in a subset of patients following chronic subdural hematoma evacuation. Furthermore, CSD can lead to ischemia leading to worsening neurologic deficits. CSD is usually detected on electrocorticography (ECoG) and needs cortical strip electrode placement with equipment and expertise that may not be readily available. Case Description: We report three cases of patients with subdural hematoma (SDH) not undergoing ECoG in whom CSD was suspected to be the cause of their neurologic deficits post evacuation. Extensive workup including neuroimaging and electroencephalography (EEG) were inconclusive. Patients were subsequently treated with ketamine infusion and had resultant neurological recovery. Conclusions: Ketamine infusion can help reverse neurologic deficits in patients with SDH in whom the deficits are not explained by neuroimaging or electrographic seizure. CSD is a known phenomenon that can result in neurological injury and must remain in the differential diagnosis of such patients. Though only limited cases are discussed (n = 3), this small case series provides the basis for conducting clinical trials evaluating the efficacy of ketamine in improving functional outcome in brain-injured patients demonstrating evidence of CSD.