CT measurement of the ventricular catheter length in shunt surgery.

When inserting a ventricular shunt, the length of the ventricular catheter is a deciding factor in the avoidance of complications. The author has devised a standardized method of determining this length which has been shown to achieve consistently successful results. It is determined from the CT scan scout film of the individual patient with hydrocephalus. The length is half the distance between the external auditory meatus and the mid-point of the coronal suture of the skull. The catheter is inserted by the frontal approach and is directed perpendicular to the skull, aiming at the inner canthus of the ipsilateral eye. The burrhole is located in the same parasagittal plane as the pupil either in front of or behind the coronal suture. The catheter tip has been demonstrated by repeated follow-up CT scans to lie just anterior to the foramen of Monro. This method was used in 175 patients and it proved to be highly successful.