Hydrocephalus (a literal translation from the Greek yields the colloquial name for the condition, water on the brain) is a common complication of intraventricular bleeding in the fragile, underdeveloped brain tissue of premature infants. Even if the bleeding causes no immediate brain injury and the baby recovers, the blood that remains inside the ventricles—the fluid-filled spaces inside the brain—can sometimes block the circulation of cerebrospinal fluid, leading to a buildup of pressure. If it isn't relieved, the increasing pressure, which causes the baby's head to enlarge, can damage the brain.
From his medical records, I could see that the ultrasound scans taken while the boy was in the neonatal unit had shown no signs of bleeding in the brain. Something wasn't making sense. After telling the boy's parents about my concerns, I obtained an urgent ultrasound of his head that afternoon. The scan showed hugely enlarged ventricles, confirming the hydrocephalus diagnosis. But the ultrasound image did not tell me why the fluid was accumulating. We needed to get a CT scan in order to obtain a better picture of the brain and ventricles. The baby also needed the expertise of a neurosurgeon.
The CT also confirmed the hydrocephalus. Although the cause was not clear, the neurosurgeon felt that the boy probably had a very small intraventricular bleed while he was in the neonatal unit. The problem had not been significant enough to show up on an ultrasound, but it had been enough to block the ventricles.
To treat the hydrocephalus, a pediatric neurosurgeon inserted a thin plastic tube, called a shunt, into the ventricles. Then he connected the tube to a tiny one-way valve on the outside of the skull and threaded the tube under the baby's skin along the neck and chest. The open end of the shunt was placed in the abdomen, where the fluid could be safely reabsorbed into the bloodstream.
I was still puzzled. If the bleeding had been there all along, why had the baby's head begun to enlarge relatively recently? The neurosurgeon didn't know.
We soon found out. After the surgery for the shunt, the baby didn't seem to be recovering as quickly or fully as expected. The neurosurgeon suspected something else was going on, so he ordered another scan. The answer this time was definitive. Deep inside the baby's brain was an abnormal mass that had not been obvious on the first study. By blocking the flow of cerebrospinal fluid through the ventricles, it was causing the hydrocephalus. The next step, an MRI scan, showed that the mass was a tumor. That explained, at last, why the boy's head had started to grow so abruptly and rapidly.
In my more than 25 years as a pediatrician, I have never ceased to be awed by the dedication and skills of pediatric neurosurgeons. They were able to remove the malignant tumor completely. But the treatment did not end there. The baby had multiple additional operations, several courses of chemotherapy, and he will require more treatment in the future, possibly including a bone marrow transplant. Once his condition stabilizes, I will be doing another developmental assessment and will continue to do so at regular intervals. So far, he's responding well to the treatment, and we're all keeping our hopes up for the future.
Medical students and pediatric residents sometimes get annoyed because I am constantly reminding them to measure the head circumference at each well-baby visit and to plot it on the growth chart. Measuring the head is one way of following the growth of a baby's brain. For this little boy, that routine procedure may have saved his life.
Mark Cohen is a pediatrician with Kaiser Permanente in Santa Clara, California. The cases in Vital Signs are real, but the authors have changed the patients' names and other details to protect their privacy.