Ventricular catheter trajectories from traditional shunt approaches: a morphometric study in adults with hydrocephalus.

OBJECT

The purpose of this study was to compare the margins of error of different shunt catheter approaches to the lateral ventricle and assess surface anatomical aiming landmarks for free-hand ventricular catheter insertion in adult patients with hydrocephalus.

METHODS

Four adults who had undergone stereotactic brain magnetic resonance (MR) imaging and had normal ventricles, and 7 prospectively recruited adult patients with acute hydrocephalus were selected for inclusion in this study. Reconstructed MR images obtained prior to surgical intervention were geometrically analyzed with regard to frontal, parietal, and parietooccipital (occipital) approaches in both hemispheres.

RESULTS

The ventricular target zones were as follows: the frontal horn for frontal and occipital approaches, and the atrium/posterior horn for parietal approaches. The range of possible angles for successful catheter insertion was smallest for the occipital approach (8 degrees in the sagittal plane and 11 degrees in the coronal plane), greater for parietal catheters (23 and 36 degrees ), and greatest for the frontal approach in models of hydrocephalic brains (42 and 30 degrees; p < 0.001 for all comparisons except frontal vs parietal, which did not reach statistical significance). There was no single landmark for aiming occipital or parietal catheters that achieved ventricular target cannulation in every case. Success was achieved in only 86% of procedures using occipital trajectories and in 66% of those using parietal trajectories.

CONCLUSIONS

The occipital approach to ventricular catheter insertion provides the narrowest margin of error with regard to trajectory but has less aiming point variability than the parietal approach. The use of patient-specific stereotaxy rather than generic guides is required for totally reliable, first-pass ventricular catheterization via a posterior approach to shunt placement surgery in adults.