The natural history of postoperative hydrocephalus after pediatric hemispherectomy for medically refractory epilepsy: an institutional experience.

OBJECTIVE: Hemispherectomy is a complex surgical intervention for medically refractory epilepsy, and its surgical sequelae continue to be defined. The incidence, timing, and predictors of postoperative hydrocephalus are not well understood. Correspondingly, the aim of this study was to define the natural history of the development of hydrocephalus after hemispherectomy based on the authors' institutional experience.

METHODS: The authors performed a retrospective review of their departmental database for all relevant cases between 1988 and 2018. Demographic and clinical results were abstracted and analyzed using regression analyses to identify predictors of postoperative hydrocephalus.

RESULTS: Of the 114 patients who satisfied selection criteria, there were 53 females (46%) and 61 males (53%) with mean ages of 2.2 and 6.5 years at first seizure and at hemispherectomy, respectively. There were 16 patients (14%) with a history of previous seizure surgery. In terms of surgery, the mean estimated blood loss was 441 ml, with a mean operative time of 7 hours, and 81 patients (71%) required intraoperative transfusions. A planned postoperative external ventricular drain (EVD) was placed in 38 patients (33%). The most common procedural complications were infection and hematoma, occurring in 7 patients (6%) each. Overall, there were 13 patients (11%) with postoperative hydrocephalus requiring permanent CSF diversion, occurring at a median of 1 year (range 0.1-5 years) after surgery. On multivariable analysis, a postoperative EVD (OR 0.12, p < 0.01) was significantly associated with a decreased likelihood of postoperative hydrocephalus, whereas previous surgery history (OR 4.32, p = 0.03) and postoperative infection complication (OR 5.14, p = 0.04) were significantly associated with increased likelihood of postoperative hydrocephalus.

CONCLUSIONS: Postoperative hydrocephalus mandating permanent CSF diversion following hemispherectomy can be expected in approximately 1 in 10 cases, presenting months after surgery on average. A postoperative EVD appears to reduce this likelihood, whereas postoperative infection and previous history of seizure surgery were shown to statistically increase this likelihood. These parameters should be carefully considered in the management of pediatric hemispherectomy for medically refractory epilepsy.