ACCURATE PLACEMENT OF CORONAL VENTRICULAR CATHETER USING STEREOTAXIC COORDINATE-GUIDED FREE-HAND PASSAGE - TECHNICAL NOTE

Long-term patency of the ventricular catheter of a cerebrospinal fluid shunt depends on the positioning of the hole-bearing segment of the c atheter. Placement of this segment near the choroid plexus or injured ependyma increases the probability of obstruction. Proper positioning for a coronal shunt in turn depends on the ventricular catheter length and target coordinates. The authors describe a method of calculating the catheter length based on bone landmarks on skull radiographs, and a technique for accurate ventricular catheter placement using free-han d passage guided by simple stereotactic coordinates based on visible a nd palpable surface anatomy. The insertion trajectory is aligned with the coronal obliquity of the lateral ventricle so that, even with slit ventricles, the entire hole-bearing segment of the catheter can be re liably situated within the anterior hem. The predetermined catheter le ngth also fixes the tip at the foramen of Monro, away from the choroid plexus and injured ependyma. Of 160 children undergoing ventriculoper itoneal shunt insertion using this technique, only three required cath eter revision during a mean follow-up period of 39 months. Radiographi c grading of the ventricular catheter position in 112 children showed a satisfactory placement rate of 93.2%; all three children with occlus ion showed poor catheter positioning. Thus, this method results in acc urate ventricular catheter placement with a 1.9% obstruction rate, whi ch compares favorably to the 16% to 18% incidence of proximal obstruct ion reported in the literature. This technique is applicable to patien ts of all ages but is particularly suitable for children because of th e greater variability in head size.