Improvement in clinical outcomes following optimal targeting of brain ventricular catheters with intraoperative imaging

Abstract

Object The accurate placement of cerebral ventricular shunt catheters in hydrocephalus is an important clinical problem. Malfunction of shunts remains their most common complication and greatest liability, and the influence of catheter position on shunt function remains poorly defined. The objectives of this study were as follows: 1) determine the accuracy of intraventricular catheter placement with respect to a historically favored target, defined as a 1-cm radius sphere at the anterior lip of the ipsilateral foramen of Monro; 2) confirm that this target represents a satisfactory site for frontal and occipital catheter placement by examining whether inaccuracy is associated with more shunt failures; and 3) determine whether catheter trajectory, use of image confirmation, or other factors are associated with either the accuracy or the longevity of shunts. Methods A retrospective cohort analysis was conducted on 236 patients with 426 ventricular shunts placed or revised at the University of Minnesota over a 10-year period. Results Accuracy of shunt placement was optimal in 43.9% of patients and suboptimal or poor in 56.1% of patients. Time to failure was significantly affected by the accuracy of catheter placement with respect to the ipsilateral foramen of Monro, with a 57% higher risk of failure with suboptimal placement (hazard ratio [HR] 1.57, 95% CI 1.26–1.96; p < 0.001) and a 66% higher risk with poor placement (HR 1.66, 95% CI 1.45–1.89; p < 0.001) relative to optimal placement. The odds of highly suboptimal or unacceptable placement were significantly increased by lack of any intraoperative imaging (OR 5.89, 95% CI 2.36–14.65; p < 0.001). Use of a nonfrontal posterior trajectory also showed a trend toward poor placement (OR 1.64, p = 0.138). Conclusions The historical target for catheter tip placement within 1 cm of the foramen of Monro in the ipsilateral lateral ventricle was associated with significantly longer revision-free survival compared with other locations. This effect remained significant after adjusting for age and whether there was a prior history of shunting. The accuracy of catheter placement in both pediatric and adult patients was strongly associated with use of intraoperative fluoroscopic confirmation. In analyses comparing intraoperative fluoroscopy and no imaging, there was a non–statistically significant difference in the 3-year time to failure, but the worst-case scenario of catastrophic short-term failure was almost completely avoided with fluoroscopy. The authors conclude that accuracy of placement is critical for shunt survival, and that use of intraoperative imaging confirmation may optimize outcomes by avoiding the majority of unacceptable placements.

Shunt Surgery in Idiopathic Intracranial Hypertension Aided by Electromagnetic Navigation

“…A US-based survey on ventriculostomy practice showed that in slit ventricles 51.7% of participants nowadays use image guidance, while 41.6% use freehand techniques and 6.7% use the Ghajar guide [38]. Clearly, the rate of shunt malfunction increases with suboptimally placed ventricular catheters [39]. …”

Ommaya reservoir with ventricular catheter placement for chemotherapy with frameless and pinless electromagnetic surgical neuronavigation

“…While the accuracy rates of 75% and 63% in the EMN and ONN groups in our series, respectively, may appear small in comparison with reported accuracy rates in the literature for optical navigation guided ventricular catheter placement of over 90%, they must be viewed against the backdrop of our stricter definition for accuracy; we defined "accurate" placement as within 5 mm of the target site along each of the three coordinate axes, a narrower margin for error than other authors have described (such as a 4 mm cylinder, or a 1 cm radius around the target site) [14,26]. Within our series the computation of accuracy and precision was internally valid and consistent, and yielded a significant difference in favor of electromagnetic navigation over optical neuronavigation.…”

“…When Ommaya reservoirs are used for the delivery of intraventricular chemotherapy, precise positioning of the distal end of the ventricular catheter at the foramen of Monro is essential to provide adequate CSF penetration and to avoid toxic drug release into the brain parenchyma [2,25,26]. Frameless stereotaxy has emerged as an accepted practice for the placement of these catheters.…”

The role of imaging in the development of neurosurgery

“…Intraoperative MRI, again where available, may be useful in several settings including tumour resection; a systematic review of 12 non-randomised cohort studies found intraoperative MRI to be more effective than conventional neuronavigation-based surgery in increasing the extent of tumour resection, enhancing quality of life, or prolonging survival after glioblastoma multiforme, but acknowledged at best level 2 evidence, and the limitations and sources of bias in the studies [65]. A recent retrospective study from one US center suggests that use of intraoperative imaging for placement of ventricular shunt catheters may optimise outcomes through avoidance of most unacceptable placements [66].…”