A new shunt for hydrocephalus that relies on CSF production rather than on ventricular pressure: initial clinical experiences.

Background: Ventricular shunting for hydrocephalus is one of the surgical procedures most frequently associated with complications. When the hydrocephalus is secondary to arachnoiditis the prognosis is usually poor.

Methods: Twenty-six patients with hydrocephalus secondary to chronic arachnoiditis due to meningeal cysticercosis were treated with a new ventriculoperitoneal shunt whose design is based on the rate of cerebrospinal fluid (CSF) production and shunt resistance rather than on ventricular pressure, which has been the principal parameter for most other shunting devices.

Results: The shunt has remained functional in 25 patients (96%). A peculiar response was documented in all cases by sequential CT scans; i.e.; the size of the ventricular cavities showed gradual reduction and about 1 month postsurgery the ventricles had returned to normal size. In all cases, fast clinical improvement was documented within the first 2 days after surgery with remission of all symptoms of intracranial hypertension. Improvement has continued for a mean follow-up of 9 +/- 2 months. In one case, the shunt was occluded a month after surgery, was withdrawn, and was replaced by a conventional shunt.

Conclusions: Our initial results contrast with the experience with other shunts, which in these patients have a rate of 50% occlusion within the first 4 months after surgery. Although a long-term follow-up is mandatory, it seems that the treatment of hydrocephalus by a shunt devoid of valve mechanisms, with drainage capacity limited to physiological parameters of CSF production, could avoid the unacceptable high frequency of overdrainage and occlusion that are the main complications of shunting devices that operate in relation to ventricular pressure.