Neurosurg Rev (2005) 28: 35–36DOI 10.1007/s10143-004-0369-y
REVIEW
Philippe Decq
Endoscopic third ventriculostomy for obstructive hydrocephalus
Published online: 27 November 2004# Springer-Verlag 2004
The authors of this article make an exhaustive review ofthe indications, the techniques and the results of endo-scopic third ventriculostomy (ETV) for the treatment ofobstructive hydrocephalus. They are experienced endo-scopic neurosurgeons whose international reputation hasalready been made in this field of neurosurgery. They tookpart, with others, and by the means of endoscopy, in thebirth of the concept of minimally-invasive surgery and itsapplication to neurosurgery. As they underline it, thistechnique has made considerable great strides over the lastten years. More and more often from now on, neurosur-geons prefer to carry out an ETV rather than to insert acerebrospinal fluid (CSF) shunt for the treatment ofobstructive hydrocephalus. What are the reasons of thissuccess? After the enthusiasm of the first procedures withtheir harvests of attractive endoscopic pictures broughtback from the center of the brain, it is appropriate to riseabove this and to analyze the reasons for this success in thelight of this work.
Technological progress Unquestionably, technology hasprogressed, in particular in the miniaturization of thetelescopes and in particular of the instruments. Beyondthis technical progress, neurosurgery, like other disci-plines, has benefited from the enthusiasm for endoscopyand the concept of minimally-invasive surgery to which itgave birth. It is from now on possible to reach, see and acton the level of the floor of the third ventricle, a difficultarea to reach by conventional neurosurgical techniques, atthe cost of a simple burr hole.
The absence of foreign bodies Shunts have radicallytransformed the prognosis of hydrocephalus, but have ledto infectious or mechanical complications which remaintoo frequent. The patients themselves never consider withpleasure the insertion of a foreign body with which theywill live and of which they doubt the long-term reliability.The prospect of obtaining an identical result without theinsertion of a foreign body is surely one of the reasons forthe success of ETV, both from the surgeon’s and thepatient’s point of view.
A simple technique After being familiarized with thematerial (handling of the endoscope, work on the videomonitor, control of the video connections), this procedureis summarized initially with a puncture of the frontal hornof the lateral ventricle, which is current practice inneurosurgery. The delicate phase lies in the opening ofthe floor of the third ventricle. A consensus based onpractice and experience was established regarding thelocalization of the opening to be made, in the center of avirtual triangle joining together the infundibulum and thetwo mamillary bodies. The opening is carried out in thesimplest possible way using “conventional” instrumentsfor endoscopy (monopolar coagulating probes, Fogartycatheter) or specific instruments developed for thispurpose (ventriculocisternostomy forceps, double ballooncatheter, aspiration-section device). The principle is toinflict the least possible trauma on the level of the floor ofthe third ventricle and to avoid any risk to the subjacentstructures (basilar artery, cranial nerves). No additionalmaneuver is necessary and the neurosurgeon must knowhow to resist the attraction of the pictures which areoffered to him, and which might inbue him with thecuriosity to go and observe various anatomical structuresat the cost of inappropriate movements of the endoscope.The aphorism usually retained for this type of surgery is tocompare it with the tactics of the bank-robber: go in, takethe money and go out immediately.
An effective technique The pioneer teams all report thesame results, being maintained in the long term, with a
This commentary refers to the article http://dx.doi.org/10.1007/s10143-004-0365-2
P. Decq (*)Service de Neurochirurgie, Hôpital Henri Mondor,94010 Creteil Cedex, Francee-mail: [email protected].: +33-1-49812201Fax: +33-1-49812202
clinical improvement in the neighborhood of 70% to 80%,which is comparable with the results of shunts, but with amuch lower rate of complication, even if it is perhapsunderestimated still today. ETV has also made it possibleto discuss again the validity of the concept of shunt-dependency, since it is possible to propose this techniquein the case of shunt dysfunction, even if the shunt wereimplanted many years before. This conjunction ofidentical and favorable observations also explains therise of ETV, which becomes little by little a routinetechnique in the neurosurgical departments.
But the ETV remains one treatment for hydrocephalus anddoes not bring a final cure Experience has taught us thatthe opening created could close again, sometimes withdramatic consequences as for acute shunt dysfunctions.After the enthusiasm of the first years of thinking that theabsence of shunt was equivalent to the cure, it is importantto note that ETV is only one of the possible treatments ofobstructive hydrocephalus, even if it is surely that whichmust be proposed as the first intention. Long-term controlmust thus be continued.
A different approach to physiopathology The physiopa-thology of hydrocephalus remains poorly understood. The
concept of circulation which supposes a secretion in adefinite place (the choroid plexus), ways of flow(ventricles then peri-cerebral subarachnoid spaces) and aresorption (Pacchioni’s granulations) is probably partlyinaccurate, even if it remains operational still today. Onespeaks more and more about ascending diastolic anddescending systolic flow of CSF, pulled by the pulsationsof the vascular tree. In this context, ETV must beconsidered to act on restoring the pressure balancebetween the ventricular and the cisternal spaces, againallowing a synchronous pulsation of the intraventricularCSF. Its mode of action is thus very different from that of ashunt, with physiopathological consequences which re-main to be studied.
An essential partner: the MRI with its flow analysissequences ETV has also benefited greatly from theprogress of MRI. Thanks to this technique, it is nowpossible to analyze the presence, the direction and theintensity of CSF flows and their synchronous character invarious CSF spaces (ventricles, cisterns, subarachnoidspaces). And it is on this new information that onedetermines and will determine the new indications forETV.
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