External ventricular drainage or ventriculostomy is a common neurosurgical technique and accurate placement of the ventricular catheter is one of the most important variables in the longevity of shunt survival 1) 2).
Cerebrospinal fluid (CSF) external drainage devices are used to drain CSF and to monitor the flow of CSF from the ventricular system in order (1) to control intracranial pressure (ICP), (2) to evaluate CSF chemistry and cytology, and (3) to provide temporary egress for CSF in patients with infected or malfunctioning cerebrospinal fluid shunts.
The optimal setting for EVD placement in regards to safety and accuracy of placement is poorly defined.
After days of use, a decision is made to remove the EVD or replace it with a shunt, involving EVD weaning and CT imaging to observe ventricular size and clinical status. This practice may lead to prolonged hospital stay, extra radiation exposure, and neurological insult due to ICP elevation.
Ventriculostomy entry sites are commonly selected by freehand estimation of Kocher's point or approximations from skull landmarks and a trajectory toward the ipsilateral frontal horn of the lateral ventricles.
There is insufficient evidence to recommend the occipital approach versus frontal point of entry for the ventricular catheter; therefore, both entry points are options for the treatment of pediatric hydrocephalus 3).
Real-time transcranial ultrasound monitoring through an enlarged bur hole is a feasible, safe, and effective technique for the placement of ventricular catheters in pediatric patients without a patent fontanelle 4).
3D ultrasound with the described setup is a promising technique for accurate, fast, and user-friendly navigated placement of catheters for cerebrospinal fluid diversion 5).
The standard method of ventriculostomy catheter placement is a freehand pass technique using surface anatomical landmarks.
Retrospective evaluation was performed on the head computed tomography (CT) scans of 97 patients who underwent 98 freehand pass ventriculostomy catheter placements in an ICU setting. Using the postprocedure CT scans of the patients, 3D measurements were made to calculate the accuracy of ventriculostomy catheter placement.
The mean distance (+/- standard deviation [SD]) from the catheter tip to the Monro foramen was 16 +/- 9.6 mm. The mean distance (+/- SD) from the catheter tip to the center of the bur hole was 87.4 +/- 14.0 mm. Regarding accurate catheter tip placement, 56.1% of the catheter tips were in the ipsilateral lateral ventricle, 7.1% were in the contralateral lateral ventricle, 8.2% were in the third ventricle, 6.1% were within the interhemispheric fissure, and 22.4% were within extraventricular spaces.
The accuracy of freehand ventriculostomy catheterization typically required 2 passes per successful placement, and, when successful, was 1.6 cm from the Monro foramen. More importantly, 22.4% of these catheter tips were in nonventricular spaces. Although many neurosurgeons believe that the current practice of ventriculostomy is good enough, the results of this study show that there is certainly much room for improvement 6).
The use of image guidance technology added approximately 36 minutes to the time from when the need was identified to when successful drainage was achieved (p = 0.002), but added only 4 minutes of operative time (p = 0.12). Accuracy of placement demonstrated a statistically significant improvement in the accuracy of ventriculostomy over historical data. There were two registration failures which were converted to the traditional technique; there were no other complications arising from the use of image-guided technology. Electromagnetic image guidance is feasible and accurate. Image guidance technology eliminated unacceptably placed catheters and may reduce the risk of catheter-associated intracerebral hemorrhages 7).
52 interventions with PCV was prospectively analyzed with regard to technical success, procedural time, time from the initial cranial computed tomography (CCT) until procedure and transfer to the intensive care unit (ICU). Additionally, the data was compared with a retrospective control group of 12 patients with 13 procedures of conventional burr-hole ventriculostomy (OP-ICP). The PCV was successful in all cases (52 of 52; 95% CI 94-100%). In 1 case a minor hemorrhage into the ipsilateral lateral ventricle was observed on CT scans due to an initially unsuccessful puncture (95% CI 0-6%). No infections occurred (95% CI 0-6%). In the control group with OP-ICP one catheter infection and one unsuccessful catheter placement occurred (each 8%, 95% CI 0-20%). The PCV led to a significant decrease of procedure time from 45 +/- 11 min (OP-ICP) to 20 +/- 12 min (PCV). The interval from the initial CCT until procedure (PCV 28 +/- 11 min, OP-ICP 78 +/- 33 min) and transfer to the ICU (PCV 69 +/- 34 min, OP-ICP 138 +/- 34 min) could also be significantly reduced (each with p<0.05, Mann-Whitney U-test). Percutaneous CT-controlled ventriculostomy is a safe and efficient method for ICP catheter placement during initial trauma room management. It significantly reduces the time of initial trauma room treatment 8).
Patients who underwent ventriculostomy placement in the ICU differed in important ways (i.e. indication for placement and the administration of pre-procedure prophylactic antibiotics) from patients treated in the OR. However, the available data suggests that complications of hemorrhage, infection, and non-functional drains may be mitigated by ventriculostomy placement in the OR 9).
A study design of a single center, prospective, randomized controlled trial to investigate whether guided ventriculostomy is superior to the standard freehand technique. One strength of this study is the prospective, randomized, interventional type of study testing a new easy-to-handle guided versus freehand ventricular catheter placement. A second strength of this study is that the power calculation is based on catheter accuracy using an available grading system for catheter tip location, and is calculated with the use of recent study results of our own population, supported by data from prominent studies 11).