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Endoscopic Third Ventriculostomy

In ETV the endoscope is navigated from the lateral ventricle through the foramen of Munro into the third ventricle. The ventriculostomy is the production of a small hole in the bottom of the brain allowing CSF to bypass any obstruction to CSF outflow.

ETV involves introducing an endoscope through the skull and brain into the ventricles. A ventricular endoscope is a thin tube which contains a light source to illuminate inside the cerebral ventricles as well as an optic system for taking the light back to the video camera which is connected to the outer end of the ventricular endoscope. It is introduced through the brain into the ventricular system.

In ETV the endoscope is navigated from the lateral ventricle through the foramen of Munro into the third ventricle. The ventriculostomy is the production of a small hole in the bottom of the brain allowing CSF to bypass any obstruction to CSF outflow.

After the endoscope, has been removed a Rickham reservoir might be inserted. This will allow drainage of CSF if the ventriculostomy were to close and would also allow for testing of the CSF circulation. Some neurosurgeons leave a Rickham reservoir in the site of the burr hole in all patients.

Indications

The most common procedure for which it is used is the ETV. Apart from the anatomy of the CSF circulation problem and the underlying condition, age is an important factor. There is a decrease in the long-term success of ETV in children under 6 months of age. However, a trail of ETV may still be indicated to avoid a CSF shunt.

Other procedures for which it is used are:

  • Aqueductoplasty
  • Fenestration of ventricular cysts
  • Biopsy of ventricular tumours and lesions
  • Colloid cyst removal
  • Shunt catheter placement

Aqueductoplasty involves directly opening the aqueduct when it is blocked. This is not always indicated or possible. The area around the aqueduct is particularly sensitive and needs to be treated with great care. However, if there is a thin membrane within the aqueduct or aqueduct web this may be a suitable indication for aqueductoplasty.

Fenestration basically means making an opening in the wall of a cyst. A cyst if a fluid filled cavity. Within the ventricular system this may have quite a thin wall. Opening that wall of the cyst or fenestrating the cyst may restore normal CSF circulation.

The endoscope may also be used when performing open procedures such as tumour removal of aneurysm clipping. The use of the endoscope in combination with open procedures is termed endoscopic assisted surgery. It allows the surgeon to see behind structures which may be out of the surgeon's direct vision using the microscope.

Risks & potential complications

The risks of endoscopic third ventriculostomy are outlined as follows:

Risks Specific to ETV

Introduction of the endoscope

When introducing an endoscope into the brain there is a small risk of introducing an infection despite the use of sterile conditions and prophylactic antibiotics. An infection within the CSF is termed meningitis. An infection of the brain is termed encephalitis. In the vast majority of cases, should this occur, it can be treated with antibiotics. This risk of this occurring is less than 2%.

By passing the endoscope through the brain there is a small risk of causing a haemorrhage, i.e., bleeding within the brain or within the ventricular system. This may be of no consequence or it may be very serious or even cause death. This risk of a life-threatening haemorrhage or a haemorrhage that causes a stroke which results in paralysis or other neurological deficits is less than 2%.

Risks of the ventriculostomy

The floor of the third ventricle is usually quite thin. Various techniques are used to make the hole in the ventricle and the technique is dependent on the neurosurgeon. The floor of the third ventricle contains structures important for memory and that have a role in hormone regulation. Although they are normally no clinical consequence of making the hole in the floor of the third ventricle there is a small risk. There is some evidence that mild endocrine (hormone) dysfunction may be more common that we currently appreciate.

Under the floor of the third ventricle is a large and important artery called the basilar artery. It must be stressed that this may also happen with CSF shunts and overall is extremely rare. It is one of the structures about which neuro surgeons are most concerned when performed the ventriculostomy as puncturing it or one of its branches can result in death or other serious complications. This is of course very rare but is still a risk of the procedure.

Long term risks

Like CSF shunts, ETVs are not without failure. The ventriculostomy can close which may cause a recurrence of symptoms or symptoms of raised intracranial pressure such as headache, vomiting, blurred or double vision, and lethargy leading to drowsiness and coma. Several late deaths after ETV have been reported in the literature. These are presumably due to closure of the ventriculostomy and acute hydrocephalus. It must be stressed that this may also happens with CSF shunts and overall is extremely rare.

Failure of the procedure

Although the ETV may be technically successful, the ventriculostomy may still not resolve the CSF circulation problem in all cases. An assessment of the chances of the success of the ventriculostomy depends upon the patient's age and the underlying condition. A proper assessment needs to take these factors into account and can normally be provided to you by your neurosurgeon.

General Surgical Risks

The operation involves making an incision and therefore the normal risks of any surgery apply. These include but are not limited to the risks of infection of the wound, bleeding, CSF leakage and wound dehiscence. A scar will inevitably form but this is behind the hairline.

Risks of General Anaesthetic

The procedure normally takes in the order of 20-40 minutes including all surgical parts of the procedure. It requires a general anaesthetic which has its own set of risks. These are included on the general anaesthetic web page.

Please note that these notes are to supplement the process of informed consent that takes place between the patient and/or family and your neurosurgeon and does not replace that process. The information here does not consider individual circumstances and does not include all risks. If there are any questions you should discuss these with your neurosurgeon.

  • Australian Medical Association
  • Neurosurgical Society of Australasia
  • The Sydney Children Hospitals Network
  • Sydney Adventist Hospital
  • Norwest Private Hospital
  • Royal Australasian College of Surgeons