Accuracy of tunnelated vs. bolt-connected external ventricular drains

Ventriculostomy is one of the most common neurosurgical procedures and an important tool in the treatment and monitoring of elevated intracranial pressure. Low accuracy has frequently been reported in the literature with risk of drain misplacement over 20% and with a need for reinsertion in up to 40%. As an alternative to the tunnelated EVD technique we often use a bolt-connected EVD. The aim of the present study was to investigate whether the use of bolt-connected EVDs would lead to higher accuracy, fewer passes and reoperations due to poor placement compared to tunnelated EVDs.

We retrospectively identified all patients who received an EVD from January 1st 2008 to December 31st 2010. Postoperative images were evaluated for anatomical placement of the EVD-tip, distance from tip to optimal placement and were categorized as optimal, suboptimal and undesired. Patient files were evaluated for EVD technique, number of passes and postoperative complications and handling.

147 patients with 154 separate EVDs met the inclusion criteria. We found a statistical significant higher accuracy in the bolt-group compared to the tunnelated-group (p=0.023). Eleven patients were reoperated following ventriculostomy and we found a statistical significant 11.9% reduction in reoperations due to poor placement in the bolt-group (p=0.006).

We have showed in this study that by using a bolt-connected EVD and maintaining the freehanded technique we can significantly increase precision and decrease the number of reoperations due to poor placement.