Since 1995, any patients over 6 months of age with triventricular hydrocephalus have been considered for endoscopic third ventriculostomy (ETV) in a number of hospitals. The third ventricle has to be greater than 4 mm in width and a contraindication is the communicating hydrocephalus. The most used preoperative study is MRI. The endoscope is introduced into the lateral ventricle through a burr hole placed just over or near the coronal suture; the endoscope is then passed into the third ventricle via the foramen of Monro, and the shunt is performed by perforating the floor of third ventricle between the infundibular recess of the pituitary stalk and the anterior border of the mamillary bodies.
The basilar artery is just behind the perforated membrane, so great care must be taken during surgical procedure. The instruments causing the fenestration are various: we used a forceps, bipolar cautery or unipolar cautery. The fenestration in the membrane is then enlarged by a balloon catheter of about 5 mm in width. Since a second unnoticed membrane may be present an early failure of the operation is possible.
Complications: hypothalamic injury; transient third and sixth nerve palsies; subarachnoid hemorrhage; subdural hemorrhage at the entry site; infection (factor risk especially for pre-shunted patients); cardiac arrest; obstruction by gliotic tissue (delayed failure); increased concentration of protein and fibrinogen causing early obstruction of the stoma. Mortality rates of 1 to 5% have been observed in medical literature.
The basilar artery is just behind the perforated membrane, so great care must be taken during surgical procedure. The instruments causing the fenestration are various: we used a forceps, bipolar cautery or unipolar cautery. The fenestration in the membrane is then enlarged by a balloon catheter of about 5 mm in width. Since a second unnoticed membrane may be present an early failure of the operation is possible.
Complications: hypothalamic injury; transient third and sixth nerve palsies; subarachnoid hemorrhage; subdural hemorrhage at the entry site; infection (factor risk especially for pre-shunted patients); cardiac arrest; obstruction by gliotic tissue (delayed failure); increased concentration of protein and fibrinogen causing early obstruction of the stoma. Mortality rates of 1 to 5% have been observed in medical literature.
References
- Handbook of Neurosurgery - fifth edition - Mark S. Greenberg - ed. Thieme.
- Kandrian D, van Gelder J, Florida D, Jones R, Vonau M, Teo C, Stening W, Kwok B. Long-term reliability of endoscopic third ventriculostomy. Neurosurgery 56:1271-1278, 2005.
- Mobbs JR, Vonau M, Davies MA, .Death after late failure of endoscopic third ventriculostomy: a potential solution. Neurosurgery 53:384-386, 2003.
