Vital Signs: High Head Pressure

An infant's rapidly growing skull provides a clue to a life-threatening condition.

By Mark Cohen|Wednesday, January 31, 2007
RELATED TAGS: FAMILY HEALTH

"Your next patient is ready, Dr. Cohen," the medical assistant said, placing a three-inch-thick chart on my desk. Like all the other infants I saw that morning, the boy was considered at high risk, and it is my job to oversee follow-up care for such patients after they leave the neonatal intensive care unit.

Now nine months old, the boy had been born very prematurely, weighing 1,400 grams—just over three pounds—at 31 weeks. According to the discharge summary, he had had mild respiratory distress syndrome, which results from immaturity of the lungs; it is one of the common complications of prematurity. But he had escaped the other major problems of premature infants, like sepsis (bloodstream infection), necrotizing enterocolitis (a serious and potentially fatal intestinal disorder), and intraventricular hemorrhage (bleeding inside the brain). When he was discharged, he was in very good shape.

Over the past eight months at home, however, he had not had an easy time. The chart notes told me that he was being treated for persistent gastroenterological reflux. Although this condition in infants is usually benign, it can sometimes cause recurrent vomiting, irritability, and failure to gain weight.

"I'm glad we also have an appointment with the gastroenterologist today," his mother said, with a worried look, "because the reflux is getting worse. He's been fussier for the past couple of weeks, and he's been vomiting much more often. He just doesn't seem like himself."

When I examined the baby, he appeared uncomfortable, and his head looked too big: The upper part of his skull appeared out of proportion to his face. That was a red flag. The rest of his examination was fairly unremarkable, although he wasn't as playful and interactive as I would have expected for an infant his age. The therapist then did a developmental assessment, which consists of playing with the baby and observing how he manipulates toys, solves simple puzzles, and so forth. Her findings confirmed that he was lagging in all areas, even after correcting for his preterm birth. The lag was particularly puzzling because the boy had done so well as a newborn.

While the therapist was doing the exam, I went back and looked at the baby's growth chart. His height and weight growth were fine, but when I plotted his head circumference, my jaw dropped. I repeated the head measurement after he was finished with the test, and I got the same number.

Up through his last visit to the pediatrician, at six months, the boy's head circumference had been following the curve between the 25th and 50th percentile. Today it was above the 95th percentile line. That was alarming. The baby's recent increase in vomiting and fussiness might have originated not in his stomach but in his head. I suspected that he had hydrocephalus, a condition in which increased cerebrospinal fluid squeezes the brain against the skull. His symptoms and his developmental delays might have been getting worse because of the increased pressure.

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.

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