Although shunting is relatively simple as a surgical procedure, it has complications, the main ones being a postoperative subdural hematoma (the bridging dural veins stretch and rupture but the procedure has been performed safely in patients who must take anticoagulants after shunting); infection of the valve and catheter, sometimes with ventriculitis and occasionally bacteremia; occlusion of the tip of the catheter in the ventricle; and, particularly in infants and children, the “slit ventricle syndrome” (see below). Orthostatic headaches can be overcome by raising the opening pressure of the shunt valve. Misplacement of the catheter may rarely transect tracts in the deep hemispheral white matter and cause serious neurologic deficits, mainly hemiplegia. It is our impression that this occurs more often when the catheter is inserted from the posterior rather than through the frontal or parietal regions. The incidence of catheter blockage is reduced by placing it in the anterior horn of the ventricle (usually the right side is used), where there is no choroid plexus. Meticulous aseptic technique and the preoperative and postoperative administration of antibiotics have apparently reduced the incidence of shunt infections but the latter has been difficult to establish. Most shunts in adults are brought to termination in the peritoneum (ventriculoperitoneal shunt). Perforation of the stomach or bowel is possible. Rare complications of ventriculoatrial shunting are pulmonary hypertension and pulmonary embolism and nephritis, which are caused by low-level infection of the shunt tube with Staphylococcus.
Puncture of the floor of the third ventricle by endoscopic techniques (“third ventriculostomy”) has been explored as an alternative to shunting, especially in children with congenital aqueductal stenosis. Cinalli and colleagues have suggested, and we concur based on experience with a limited number of our own adult patients, that third ventriculostomy is sometimes an effective treatment of shunt failure but Sankey et al had disappointing long-term results when the procedure was used as a primary approach.
Once the CSF is shunted, the ventricles may diminish in size within a week or two, even when the hydrocephalus has been present for a year or more. This indicates that hydrocephalic compression of the cerebrum is at least partly reversible. Indeed, in Black’s series, the ventricles failed to return to normal in only 1 of his 11 shunted patients, and in that patient, there was no clinical improvement. Clinical improvement occurs within a few weeks, the gait disturbance being slower to reverse than the mental disorder. Symptoms of cerebral atrophy because of Alzheimer disease and related conditions are not altered by shunting, but this approach to the treatment of degenerative dementia has been periodically, and unadvisedly, resurrected, as discussed by Silverberg and associates.
The use of acetazolamide to reduce CSF volume and pressure has gone through periods of popularity for treating NPH in adults (comments about its use in children are found below) and Alperin et al have shown imaging changes of reduced periventricular white matter changes, presumed to be a reflection of transependymal transgression of water, but clinical effects in our patients have been minimal. A few case series. For example, by Aimard and colleagues have reported benefit.
Treatment of Infantile and Childhood Hydrocephalus