Interhemispheric hygroma after decompressive craniectomy: does it predict posttraumatic hydrocephalus?

The aim of this study was to determine the incidence of posttraumatic hydrocephalus in severely head-injured patients who required decompressive craniectomy (DC). Additional objectives were to determine the relationship between hydrocephalus and several clinical and radiological features, with special attention to subdural hygromas as a sign of distortion of the CSF circulation.

Methods The authors conducted a retrospective study of 73 patients with severe head injury who required DC. The patients were admitted to the authors’ department between January 2000 and January 2006. Posttraumatic hydrocephalus was defined as: 1) modified frontal horn index greater than 33%, and 2) the presence of Gudeman CT criteria. Hygromas were diagnosed based on subdural fluid collection and classified according to location of the craniectomy.

Results Hydrocephalus was diagnosed in 20 patients (27.4%). After uni- and multivariate analysis, the presence of interhemispheric hygromas (IHHs) was the only independent prognostic factor for development of posttraumatic hydrocephalus (p < 0.0001). More than 80% of patients with IHHs developed hydrocephalus within the first 50 days of undergoing DC. In all cases the presence of hygromas preceded the diagnosis of hydrocephalus. The IHH predicts the development of hydrocephalus after DC with 94% sensitivity and 96% specificity. The presence of an IHH showed an area under the receiver-operator characteristic of 0.951 (95% CI 0.87–1.00; p < 0.0001).

Conclusions Hydrocephalus was observed in 27.4% of the patients with severe traumatic brain injury who required DC. The presence of IHHs was a predictive radiological sign of hydrocephalus development within the first 6 months of DC in patients with severe head injury.