Hydrocephalus: An Owner’s Manual Part 6 of 6
A Mother’s Companion
Generally, a CT is a better study to look at shunt function than is an MRI.
When evaluating shunt function in the ER, the size and shape of the ventricles on CT are of most significance. Being able to compare a CT obtained in the ER under symptomatic conditions to a past CT obtained for simple surveillance (during a period when the hydrocephalus was asymptomatic and the patient was well) can make all the difference in the world (and possibly prevent unnecessary surgery). Such a comparison will often make the diagnosis of a shunt malfunction much easier.
It is reasonable to obtain a surveillance head CT (without contrast; your doctor will know the meaning of this) every three years during childhood through the growth spurt at puberty. In adults, surveillance CT is obtained following a shunt revision but is rarely necessary otherwise. In reality, shunted patients are occasionally seen for headache in the ER and often a CT scan will be obtained at that time. These studies are often normal and reassuring to the physician and the family.
Most patients with a shunt and a headache will not have a malfunction and do not need a CT scan. This is a clinical decision.
It is worth remembering that a CT is a static image of one moment in time. It does not replace a careful history and physical examination.
A shunt series is often helpful. This is a plain set of regular xrays, including at least two views of the skull, chest, and abdomen. The purpose is to follow the shunt tubing throughout its course, looking for kinks, disconnections, or tubing out of place (such as when the abdominal catheter has pulled up out of the belly and is coiled under the skin—where it won’t work properly).
Once a child starts kindergarten, a medic alert tag is recommended, ex. Obstructive hydrocephalus with VP shunt.
Carrying a digital copy of the latest surveillance CT when traveling will help in the evaluation of a person with a shunt issue. Check with your local hospital or physician as to how to obtain a copy of the CT scan on CD or flash drive.
The Special Case of Infancy
Throughout this monograph, we have assumed the skull is a closed box with a fixed volume. However, this is not the case in infancy, up to about eighteen months of age. During this time, the head is rapidly expanding with normal growth and the skull is composed of several plates of bone, which interact with each other along what are called suture lines. These sutures are very pliable and capable of separating, allowing for expansion of the skull and the underlying brain.
Therefore, the volume of the space inside the skull is not fixed in infants. The box is open.
What this means in practical terms is that hydrocephalus in infants is manifested by an enlarging head circumference, which is why your pediatrician measures the head circumference at the well baby checks.
One can also feel along the sutures, which separate and leave gaps in hydrocephalus.
The anterior fontanelle, the soft spot on the top of a baby’s head, becomes very tense or taut from the underlying pressure.
An important finding at the time the diagnosis is made, as well as in the presence of a shunt malfunction, is that of sunsetting. This occurs when pressure inside the head affects that part of the brain which controls eye movements. The eyes are forced to look down, sometimes very forcibly. This is an ominous finding and requires emergent evaluation and intervention to prevent permanent brain injury or death.
One more thing. Although infants can get pretty sick from hydrocephalus, only in the most extreme cases do they suffer acutely life-threatening problems with a shunt malfunction (because the head just expands a little more; in untreated infantile hydrocephalus, the head is capable of truly monstrous expansion). Adults, on the other hand, with a fixed amount of space, very often have acutely life-threatening issues with shunt malfunction and hydrocephalus. There is little room for compensation in adults, in whom the box is always closed.
In the presence of obstructive hydrocephalus (but not communicating or non-obstructive hydrocephalus, and not normal pressure hydrocephalus) there is sometimes an alternative to shunting: IIIrd ventriculostomy.
In this case the surgeon creates an artificial opening between the obstructed ventricle and the CSF space at the base of the brain. This effectively bypasses the obstruction to the flow of CSF and allows it to be reabsorbed through regular pathways.
IIIrd ventriculostomy is performed through an endoscope by a qualified neurosurgeon and is only available when the anatomy is favorable. There are potentially significant complications, but the benefit if it works is that lifelong shunting can be avoided.
It would be beneficial to keep the following information in one place.
My Hydrocephalus Log
My neurosurgeon is:
Recommend that every adult family member keep the neurosurgeon’s card in their wallet or purse, or on their iphone. Give the card to college roommates, landlords, and place in employee health records as well.
Type of hydrocephalus:
Normal pressure hydrocephalus (NPH)
The original cause of my hydrocephalus:
Congenital (born with it)
Date of most recent shunt:
Date of first shunt:
Number of revisions:
Have I ever had a shunt removed because of infection:
End of the Hydrocephalus Owner’s Manual Series.
Disclaimer: The information contained in this blog is simply that, information. I am not doling out specific medical advice. Nothing contained herein is meant to replace a complete evaluation by a qualified member of the medical establishment. This page is nonfiction.