Correspondence

Endoscopic Laser Third Ventriculostomy

N Engl J Med 1993; 329:207-208July 15, 1993

Article

To the Editor:

Dr. Cohen (Feb. 25 issue)1 briefly describes endoscopic laser third ventriculostomy for the relief of hydrocephalus due to stenosis of the aqueduct of Sylvius. I wonder whether this is the safest way to treat the condition. Ventriculocisternostomy, which was devised in 1938 by Torkildsen,2 bypasses the aqueduct by shunting fluid from the lateral ventricle to the cisterna magna. Although the implantation of a permanent catheter is required, no valve is needed, and both ends of the shunt are within the nervous system. Thus, the shunt is not subject to the complications of shunts to the right cardiac atrium or to the peritoneal or pleural spaces. In my experience -- a dozen or so procedures -- this approach worked, continued working, and was remarkably free of complications. Although perhaps not as elegant as Dr. Cohen's third ventriculostomy, it is just as physiologic: both procedures deliver ventricular fluid to the same ultimate destination as the aqueduct -- the subarachnoid space surrounding the brain, where most of the fluid is absorbed. The third ventriculostomy, however, requires manipulation in the immediate vicinity of the hypothalamus and basilar artery, both rather unforgiving structures. Torkildsen's shunt requires a short incision in the dura and arachnoid covering the spacious cisterna magna. In my opinion that is a such safer place for the neurosurgeon to be.

Francis A. Wood, M.D.
108 Llewellyn Rd., Montclair, NJ 07042

2 References

1. 1

   Cohen AR. Endoscopic laser third ventriculostomy. N Engl J Med 1993;328:552-552
   Full Text | Web of Science | Medline

2. 2

   Torkildsen A. A new palliative operation in cases of inoperable occlusion of the Sylvian Aqueduct. Acta Chir Scand 1939;82:117-124
   

Author/Editor Response

Dr. Cohen replies:

To the Editor: Torkildsen1 developed his procedure for palliation of intracranial hypertension when he encountered an unresectable lesion during exploratory infratentorial surgery. He used a rubber catheter to bypass the ventricular obstruction, placing the proximal end transcortically into a lateral ventricle through the burr hole used for diagnostic ventriculography. The distal end was placed in the cisterna magna at the site of posterior-fossa exploration. Torkildsen thought that his method of drainage was superior to standard third ventriculostomy, since in that era such a procedure would customarily have required a separate supratentorial craniotomy2,3.

Torkildsen's operation has been virtually abandoned in favor of the simpler extracranial cerebrospinal fluid shunts. The ventriculoperitoneal shunt is effective for a wider variety of conditions than Torkildsen's shunt. It has become the mainstay of the surgical management of hydrocephalus.

Dr. Wood reminds us that Torkildsen's valveless intracranial shunt is not subject to some of the complications associated with extracranial shunts, a point well taken. The overdrainage problems seen with extracranial shunts are not encountered with Torkildsen's shunt, since siphoning of cerebrospinal fluid does not occur when the distal end of this shunt remains in the subarachnoid space.

I believe that endoscopic third ventriculostomy is superior to Torkildsen's procedure, although the two operations have several similarities. Each is effective only in the setting of noncommunicating hydrocephalus -- that is, an obstruction to the circulation of cerebrospinal fluid between the ventricles and subarachnoid space. Each will succeed only if cerebrospinal fluid pathways over the convexities are patent -- that is, there is no concomitant communicating hydrocephalus. Each procedure functionally sidesteps the ventricular obstruction.

The main advantage of endoscopic third ventriculostomy is the elimination of the need for an implanted shunt of any type. All ventricular shunts are foreign bodies whose long-term implantation is associated with risks of infection and obstruction.

Endoscopic third ventriculostomy, first performed successfully by Mixter in 1923,4 did not achieve popularity because of the primitive nature of the instruments and the high surgical morbidity. The procedure I illustrated is a resurrection of Mixter's operation with better instrumentation. Injury to the basilar artery is uncommon because the operation is carried out under the surgeon's direct vision. Injury to the hypothalamus is also rare because hydrocephalus has already attenuated the third ventricular floor before fenestration occurs, perhaps displacing hypothalamic nuclei laterally. Pulsations of the brain keep the fenestration open, thus eliminating the need for a ventricular shunt.

Alan R. Cohen, M.D.
New England Medical Center, Boston, MA 02111

4 References

1. 1

   Torkildsen A. A new palliative operation in cases of inoperable occlusion of the Sylvian Aqueduct. Acta Chir Scand 1939;82:117-124
   

2. 2

   Stookey B, Scarff J. Occlusion of the aqueduct of Sylvius by neoplastic and non-neoplastic processes with a rational surgical treatment for relief of the resultant obstructive hydrocephalus. Bull Neurol Inst N Y 1936;5:348-377
   

3. 3

   Dandy WE. An operative procedure for hydrocephalus. Bull Johns Hopkins Hosp 1922;33:189-190
   

4. 4

   Mixter WJ. Ventriculoscopy and puncture of the floor of the third ventricle: preliminary report of a case. Boston Med Surg J 1923;188:277-278
   Full Text

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   Giuseppe Cinalli, Paolo Cappabianca, Raffaele de Falco, Pietro Spennato, Emilio Cianciulli, Luigi Maria Cavallo, Felice Esposito, Claudio Ruggiero, Giuseppe Maggi, Enrico de Divitiis. (2005) Current state and future development of intracranial neuroendoscopic surgery. Expert Review of Medical Devices 2:3, 351-373
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   Dieter Hellwig, Joachim Andreas Grotenhuis, Wuttipong Tirakotai, Thomas Riegel, Dirk Michael Schulte, Bernhard Ludwig Bauer, Helmut Bertalanffy. (2004) Endoscopic third ventriculostomy for obstructive hydrocephalus. Neurosurgical Review
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   V SIOMIN, S CONSTANTINI. (2004) Basic principles and equipment in neuroendoscopy. Neurosurgery Clinics of North America 15:1, 19-31
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   D BROCKMEYER. (2004) Techniques of endoscopic third ventriculostomy. Neurosurgery Clinics of North America 15:1, 51-59
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