Hydrocephalus Surgery

Ventriculoperitoneal shunt operation

The position of the child is important to correctly implant the shunt. The head is turned sharply to the left to accommodate a right occipital placement. The burr hole is placed approximately 4 cm up from the inion and 3-4 cm off the mid-line. This occipital placement allows a relatively straight shot into the body of the ventricle, so that the shunt catheter is mostly within it. This trajectory avoids the risk of going too low through the internal capsule, which can happen with shunt placement sites that are more lateral and inferior.

A ventricular catheter of adequate length needs to be selected so as to place the tip anterior to the foramen of Munroe, where there is less choroid plexus. This is done so as to lessen the risk of occlusion. Generally, a 6 cm catheter is used in a small newborn; an 8 cm catheter in an older infant and young child; and a 10 cm catheter is used in a children 18 months or older. Perioperative antibiotics can be used, though there is no definitive data showing that this is mandatory.

The shoulder blades should be raised to elevate the chest and neck and allow for a straight passage of the shunt passer, with no secondary incisions between the head and the abdomen. The abdominal incision is a horizontal incision, either just below the rib cage or just lateral to the umbilicus. Once the shunt is placed in position, the dura is opened with a pinpoint cautery so as to create an opening just big enough to allow the passage of the catheter (a large dural opening can allow CSF to flow around the shunt and cause a subcutaneous fluid collection). The ventricle is tapped using a rigid brain cannula and, once a good flow of CSF has been obtained, the ventricular catheter is fed into the ventricle through this tract. This is done without a stylette.

Fluid should then be aspirated from the lower end of the shunt to insure that the valve system is opened, and then it should then be placed in the peritoneal cavity. A large amount of tubing can be placed in the peritoneal cavity, even enough to allow for full growth of the child. 15-20" of peritoneal catheter is usually inserted at the same time as the initial shunt placements.

Ventriculoatrial and ventriculopleural shunting

For hydrocephalus surgery involving ventriculoatrial shunts, an incision is made across the anterior border of the sternomastoid muscle to expose the jugular vein. Alternately, the shunt can be placed in the common facial vein just as it enters the jugular vein. Once the jugular vein is isolated with ligatures, the vein is tied off distally. A small opening is then made into the jugular vein to pass the shunt into the right atrium of the heart.

The right atrium can be targeted easily using electrocardiographic (EKG) control. This is done by attaching an alligator clip to the stylette of the distal tubing, and connecting it to "lead 2" of the anaesthesia EKG machine. The atrium is indicated by the P wave configuration becoming more and more upright, and when it becomes a biphasic P-wave the tip has just entered the atrium (the optimal placement). A chest x-ray done in the recovery room should confirm that the catheter is at the correct location (the T6 level). If a ventriculoatrial shunt is used, lengthening should be considered when the shunt tip rises above the T4 level, since distal malfunction is significantly more common above that.

Endoscopic surgery

Endoscopic hydrocephalus surgery is advantageous when compared to conventional craniotomy, as it causes much less trauma to the patient, resulting in reduced post surgery recovery time. In some cases, endoscopic surgery can be carried out only with local anaesthesia. Operating endoscopically means that the entire procedure is carried out through a small hole in the patient's head.

The endoscopic system is made up of a number of parts. First there is a guide tube; this can be a flexible or a rigid tube which is used to guide the tool to the correct position. A flexible tube has controls at the end so that it can be twisted to the correct position. This guide tool will have a camera and a light so that the surgeon can see the operation site on a monitor. Through the endoscope's tube, a number of different tools can be inserted, including: forceps, scissors, probes, catherers, and lasers.

Risks of hydrocephalus surgery

Certain risks must be considered with any surgery. Although your surgeon will take every precaution to avoid complications, among the most common risks possible with shunt surgery are: infection, malfunction, disconnection, or obstruction. The sudden release of CSF during or after surgery can cause a subdural hematoma (blood clot) to form. Other possible risks include hemorrhage (excessive bleeding) within the brain. The most common problem encountered in patients with shunts is that the shunts can malfunction. Usually the problem is that the shunt catheter (either in the brain or the abdomen) becomes blocked, and the shunt can't properly drain. Rarely, the shunt valve becomes blocked or stops functioning. Shunt malfunctions occur in approximately 30-40% of children in the year after the shunt is inserted. By five years, approximately 60% of children will have had their shunts changed, and by 10 years nearly 85% will have had at least one shunt revision.

Recovery

Some symptoms such as headaches may disappear immediately because of the release of excess pressure. Generally, the patient may be allowed to be up and about, and a gradual return to normal activity will be encouraged. The length of the patient's hospital stay will be determined by his or her rate of recovery and availability of support at home.

By the time of your post-operative visit to the surgeon, you may have noticed further improvement, and the incisions may be less sore. Your surgeon will remove skin sutures (stitches) that are not absorbable, and he will examine the incision and evaluate neurological functions.

If a neurological problem remains, rehabilitation may be necessary to maximize the patient's improvement. However, recovery may be limited by the extent of damage already caused by the hydrocephalus or associated condition and by the brain's limited ability to heal. If further surgery is needed to remove a brain tumour or correct a birth defect, this may be scheduled in a subsequent operation.

Follow-up tests may be required including: ultrasound, CT scanning, magnetic resonance imaging (MRI), or plain x-rays to ensure the shunt is working correctly. You and your family will be instructed to notify the neurosurgeon if problems occur. Don't hesitate to contact your physician if any of the following symptoms occur:

If you are the patient, your surgeon will help determine when you can return to work and with what limitations. If a work release is necessary, it will be provided during a post-operative visit. Driving a motor vehicle will be possible once your surgeon determines that you have recovered fully. Do not drive after taking narcotic pain medication.





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