26.1 Introduction

While well-established indications for neuroendoscopy and neuroendoscopic procedures have been defined, new techniques are constantly being developed. Endoscopic third ventriculostomy (ETV) and aqueductoplasty have moved from novel to goldstandard treatment for selected forms of obstructive hydrocephalus.1,2,3,4,5,6,7 Some forms of obstructive hydrocephalus require advanced endoscopic options. Fenestration of the septum pellucidum and intraventricular septae, and Monro foraminoplasty are good options for selected cases of monoventricular hydrocephalus.6,7 Recently, lamina terminalis (LT) fenestration has been used as a rescue procedure when ETV or aqueductoplasty is not feasible. It has been observed by some authors that fenestration of the LT during open microsurgery reduces the incidence of shunt-dependent hydrocephalus after aneurysmal subarachnoid hemorrhage.1,2,3 An endoscopic transventricular transforaminal route has been proposed as a feasible procedure and could represent an alternative to an ETV for a selected subgroup of patients (Fig. 26.1). In this chapter we will review in detail the indications, operative technique, clinical outcome, and potential complications of endoscopic transventricular lamina terminalis fenestration (LTF).

26.2 Indications/Contraindications

Endoscopic transventricular LTF is indicated for patients with obstructive hydrocephalus in whom an ETV or aqueductoplasty is not technically possible or who have a high risk of failure based on known risk factors.1,2,3 Some neuroendoscopists make the decision to perform this procedure intraoperatively after observing that local conditions preclude successful ETV.2 Preoperative factors correlating with ETV failure include neonatal intraventricular hemorrhage and/or meningitis, shunt infection and malfunction, age younger than 2 years, previous ETV failure, and an intraventricular inflammatory process. Intraoperative factors suggesting ETV failure include abnormal anatomy of the third ventricle, thickened or scarred membranes in the basal subarachnoid space, no pulsation of the free ETV edges, and a nonpatent basal subarachnoid space.1,3 Intraoperative findings precluding successful completion of an ETV include an abnormally thick floor of the third ventricle, poor landmarks in the floor, or vascular structures obstructing the floor from below.3

In cases of inflammatory pathologies involving the basal subarachnoid space such as fungal or tuberculous meningitis with hydrocephalus, endoscopic LT fenestration may be more successful than ETV because the LT suprachiasmatic cisterns are less involved in these processes. These conditions create extensive scarring of the basal cisterns, limiting the CSF flow from the ETV. Lamina terminalis fenestration allows CSF drainage from the third ventricle into the patent suprachiasmatic and LT cisterns and into the convexity arachnoid granulations.3

Relative contraindications include abnormal anatomy of the anterior third ventricle, thickened LT that precludes the surgeon from differentiating the optic chiasm from the LT, and an anterior communicating artery aneurysm.3

26.3 Operative Technique

Related posts:

23 Septum Pellucidum Fenestration 21 Endoscopic Third Ventriculostomy 22 Aqueductoplasty and Stenting 25 Endoscopic Shunt Placement 27 Endoscopic Approach to the Fourth Ventricle 29 Neuroendoscopic Considerations in the Pediatric Patient

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