Shunt timing is a critical factor in preventing damage and promoting recovery of the hydrocephalic brain. On the other hand, the decision to place a shunt is never taken lightly, because of all the long term problems associated with these systems, namely tissue blockage and infection. This concern is compounded in cases of mild and/or slowly progressing hydrocephalus, or when time is required to treat an accompanying brain infection.

We often stress that shunting decisions would benefit greatly from a better knowledge of the underlying pathology of the hydrocephalic brain. In fact, Dr. Canady likes to remind us that our goal is to treat the brain and not the shunt.

In general, our studies, along with those from several other laboratories, have shown in animal models that very late shunting promotes little or no improvement in cell death, connectivity, gliosis, and neurological function. Early shunting, however, can restore many features of brain morphology and function. Nevertheless, some features, especially those related to synaptic activity and neurotransmitter levels, do not return to normal after early shunting. One possibility for this incomplete response is that the recovery time needs to be longer than we allowed. On the other hand, since so many other features recovered fully during our post-shunt duration, we believe that some parameters may be irreversibly altered. These are the pathological changes that should be targeted by supplemental therapies.