Neurosurgery Blog

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.

Neurosurgery:June 2010 – Volume 66 (6):1064–1073. DOI:10.1227/01.NEU.0000369605.79765.3E

Damage to the facial nerve during surgery in the cerebellopontine angle is indicated by A-trains, a specific electromyogram pattern. These A-trains can be quantified by the parameter “traintime,” which is reliably correlated with postoperative functional outcome. The system presented was designed to monitor traintime in real-time.

METHODS: A dedicated hardware and software platform for automated continuous analysis of the intraoperative facial nerve electromyogram was specifically designed. The automatic detection of A-trains is performed by a software algorithm for real-time analysis of nonstationary biosignals. The system was evaluated in a series of 30 patients operated on for vestibular schwannoma.

RESULTS: A-trains can be detected and measured automatically by the described method for real-time analysis. Traintime is monitored continuously via a graphic display and is shown as an absolute numeric value during the operation. It is an expression of overall, cumulated length of A-trains in a given channel; a high correlation between traintime as measured by real-time analysis and functional outcome immediately after the operation (Spearman correlation coefficient [ρ] = 0.664, P < .001) and in long-term outcome (ρ = 0.631, P < .001) was observed.

CONCLUSION: Automated real-time analysis of the intraoperative facial nerve electromyogram is the first technique capable of reliable continuous real-time monitoring. It can critically contribute to the estimation of functional outcome during the course of the operative procedure.