Hydrocephalus has traditionally been thought to be caused by an imbalance of production and absorption of cerebrospinal fluid in the brain. Shunts can drain the excess fluid, but are no panacea: they must be managed and replaced throughout life, and often lead to complications. Now, research by Children's Hospital Boston neurosurgeon Joseph Madsen, MD, and his collaborators is beginning to overturn the old view—and may result in better treatments for hydrocephalus, which affects some 1 in 500 newborns.
Studies at Children's Neurodynamics Lab and at Stony Brook University suggest that the key to understanding hydrocephalus isn't about the amount of fluid in the brain, but the fluid's pulsing motion. These pulsations, linked to the heartbeat, may help ensure adequate blood flow in the brain. However, the brain's capillary beds need to be buffered from the pulses to prevent undue mechanical stress. Dr. Madsen and colleagues have discovered such a buffering system in the brain and speculate that its malfunction contributes to hydrocephalus. "One reason people with hydrocephalus get headaches may be that shunts don't buffer fluid pulsations," Dr. Madsen speculates.
He and his collaborators are also exploring other possible mechanisms for treating hydrocephalus, and even the possibility of using drugs. One theory holds that leaky blood
vessels have a role; another, inspired by recent glaucoma research at Children's, proposes that mechanical stress on capillaries triggers an inflammatory pathway that causes brain damage. Serendipitously, research teams at Children's have created animal models of hydrocephalus—in mice and zebrafish—so Dr. Madsen hopes to put these and other new ideas to the test.