The shunt placement surgery this morning was successful. Our pediatric neurosurgeon placed a roughly two inch long shunt in Whitney's head above and slightly in front of her right ear. Now we pray that the shunt functions properly and does not become infected. Please praise God for a successful placement and petition Him that the shunt both works and is long-lived.
For more than you ever really wanted to know about shunts, and how we got to this point, please keep reading.
What is a shunt?
A shunt is a straw like device that is placed beneath the scalp and inserted into the brain to relieve pressure in the brain. Whitney, like many kids with the myelomeningocele form of spina bifida has hydrocephalus (sometime referred to as "water on the brain," although this term is not accurate). Hydrocephalus develops as cerebro-spinal fluid is unable to properly circulate from the ventricles inside the brain up and down the spinal cord and around the outside of the brain. As a result, the cerebro-spinal fluid builds up in the ventricles, placing pressure on the brain. Shunts are designed to relieve the pressure.
To my understanding, the shunt has three parts: the portion that is inserted into the ventricles, a valve, and a catheter. The three pieces fit together like a flexible child's straw with loops (the ones my parents only let us use on very rare occasions). The piece that extends into the brain in infants is inserted between sections of the skull. The valve is attached to the former piece and is outside the skull. The catheter attaches to the other side of the valve and runs under the skin to the abdomen. The catheter empties into the abdomen through a small incision. The upper portion of the shunt is visible as a raised area on the head. The cathether is about the thickness of a spaghetti noodle and is not visible.
The valve in the shunt opens when the pressure in the ventricles increases to a certain point and bleeds off cerebro-spinal fluid into the catheter (and consequently into the abdomen) until the pressure is reduced to a point where the valve closes. The cerebro-spinal fluid is reabsorbed by the body from the abdomen.
Shunts have a limited lifespan. According to the Spina Bifida Association of America, "[a]bout 40% of shunts will malfunction and need to be changed (or revised) within 1 year of insertion, 60% will require a revision within 5 years, and 80-85% within 10 years. About 20% will require multiple revisions in their lifetime." Typically, only the top portions of the shunt need to be replaced.
Why Did Whitney Need A Shunt?
Approximately 80% of children with a myelomeningocele require a shunt. When we were at CHOP, the chief neurosurgeon told us that he was positive that Whitney would require a shunt based on the swelling of her ventricles at 24 weeks. Since that time, ultrasounds have shown that Whitney's ventricles continued to grow.
Our pediatric neurosurgeon in Grand Rapids is very conservative. Although we encouraged him to implant a shunt and close the lesion on Whitney's back at the same time, he wanted to wait to see if the hydrocephalus subsided after the closure before deciding to install a shunt. During the last week, Whitney's head size increase by two centimeters, suggesting that her ventricles were continuing to expand. The soft spots on Whitney's head were tense from the internal pressure, and her eyes rolled slightly downward (called "sunset eyes"). Finally, Whitney had CT scans last Wednesday (1/9) and on Monday (1/14). The CT scan definitively showed that the ventricles had grown.
We had been told to plan for a shunt surgery on Monday, then Wednesday (today), then Friday. Early yesterday evening, the pediatric neurosurgeon told us that he would perform the surgery this morning at 8:30. Again, we didn't have much time to prepare.
After the surgery, the surgeon reported that Whitney's cerebrospinal fluid was under significant pressure. This was reassuring because it demonstrated the necessity of the surgery. Whitney is currently recovering in the NICU.