Decompressive craniectomy, interhemispheric hygroma and hydrocephalus: A timeline of events?

BACKGROUND: Decompressive craniectomy (DC) is a known risk factor for the development of post-traumatic hydrocephalus. The occurrence of subdural hygroma (SH) was also reported in 23-56% of patients after DC and it seemed to precede hydrocephalus in more than 80% of cases. We analyzed the relationship among DC, SH and hydrocephalus. METHODS: From 2007 to 2011, 64 patients underwent DC after head trauma. Variables we analyzed were: intaventricular hemorrhage, age, GCS, distance of craniectomy from the midline, evacuation of a hemorrhagic contusion (HC) and infection. Logistic regression was used to assess the independent contribution of the predictive factors to the development of hydrocephalus. RESULTS: Nineteen patients (29.7%) developed hydrocephalus. Interhemispheric SH was present in 8/19 patients with hydrocephalus and temporally preceded the occurrence of ventricular enlargement. Moreover, most patients who developed a interhemispheric SH had been undergone DC whose superior margin was close to the midline. Logistic regression analysis showed that craniectomy closer than 25mm to the midline was the only factor independently associated with the development of hydrocephalus. CONCLUSION: Craniectomy close to the midline can predispose patients to the development of hydrocephalus. SH could be generated with the same mechanism, and these three events could be correlated on a timeline.