Intraventricular and periventricular lesions often result in obstructive hydrocephalus and can be effectively managed by ventriculoscopy. This avoids the significant risk of injury to vascular and neural structures that are encountered during open craniotomy and exposure of these deep lesions. It is important to consider endoscopic third ventriculostomy (ETV) in any adult patient with obstructive hydrocephalus given the significantly higher long-term success rate of primary ETV compared with VP shunts. Supervised training and mentorship are important in obtaining the skills and experience to safely perform ventriculoscopic procedures.
Key points
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Many intraventricular and periventricular lesions can be safely and effectively diagnosed and treated by ventriculoscopy through a single burr hole.
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Always consider endoscopic third ventriculostomy (ETV) for any adult patient with obstructive hydrocephalus given the significantly higher long-term success rate of primary ETV versus ventriculoperitoneal (VP) shunt.
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Consider ETV for any patient with obstructive hydrocephalus that presents with shunt dysfunction or delayed failure of a primary ETV.
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Evaluation of ventriculoscopic procedures must focus on patient-related outcomes not postoperative imaging.
Video content accompanies this article at http://www.neurosurgery.theclinics.com .
Introduction
Rationale for Ventriculsocopy
Open treatment of lesions of the brain can result in significant morbidity and mortality. Approximately 10% of all central nervous system (CNS) tumors/cysts are at least partly intraventricular.
This article will focus exclusively on ventriculoscopic management of conditions that present with hydrocephalus in adults. It will not discuss the use of endoscopy to improve visualization in open procedures (ie, endoscopic-assisted craniotomy) or the endoscopic management of skull base lesions (ie, transphenoidal).
Potential problems of ventriculoscopic procedures include: (1) restriction in access or instrumentation may result in only partial treatment of a lesion and (2) increased technical complexity and a significant learning curve may result in more serious or frequent complications. Evaluation of ventriculoscopic procedures, including their indications, restrictions, results, and complications, must focus on patient-related outcomes, not on postoperative imaging.
Important Developments for Modern Ventriculoscopy
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Lespinasse (1910) used a cystoscope in the first recorded case of endoscopy of the ventricles and coagulation of the choroid plexus (CP).
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Walter Dandy (1918) used a nasal speculum to access the ventricles and a cystoscope to remove the CP.
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Mixter (1919) performed the first successful third ventriculostomy.
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Hopkins (1959) developed the Rod-Lens system used in rigid endoscopes.
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Storz (1960) developed fiber optic bundles used in flexible light cables.
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Triple-chip camera provides excellent resolution in rigid and flexible endoscopes.
Principles of ventriculoscopy
Surgeon Training and Experience
Ventriculoscopic training is ideally acquired during a neurosurgical residency and/or fellowship under the supervision of a consultant neurosurgeon, who has specific training and experience in ventriculoscopy. Hands-on, didactic training courses can provide supervised teaching and training on cadaver heads. Mentorship by a neurosurgeon with experience in ventriculoscopy is helpful.
Preoperative Considerations
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Selection of appropriate patients for the management of obstructive hydrocephalus and/or resection or biopsy of intraventricular lesions.
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Anesthesia issues and intraoperative monitoring: Arterial line is recommended for accurate control of blood pressure (BP) both intraoperatively and postoperatively.
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Adjuncts to prevent and control intraventricular hemorrhage (IVH): Tranexamic acid (TXA) infusion, close BP control, endoscopic bipolar coagulator.
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Intraoperative neuronavigation to facilitate both ventricular access and identification of intraventricular anatomy, especially in patients with intraventricular scarring, cyst formation, and/or septations due to previous surgery, infection, or IVH.
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Preoperative plan for an entry point to provide a safe trajectory to reach the target(s).
Intraoperative Strategies
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Strategies to prevent/manage intraoperative bleeding. Most intraventricular bleeding will stop with time, irrigation with body temperature isotonic solution, endoscopic bipolar, TXA, BP control ± short periods of mild hypotension.
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Conversion to an open craniotomy is rarely needed with the above strategies.
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Use of an external ventricular drain (EVD) for postoperative management of IVH, potential persistent hydrocephalus and/or intracranial pressure (ICP) monitoring.
Ventriculoscopic System, Instruments, and Adjuncts
Endoscopy cart
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Computer with camera input for rigid and flexible ventriculoscopes
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Endoscopic camera, preferably triple chip and 4K compatible.
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Ability to save/store pictures and video.
Irrigation system
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Continuous irrigation with body temperature isotonic fluid.
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Only use gravity to control intraventricular fluid flow to prevent intraoperative raised ICP.
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Prevent air entry into the intravenous (IV) tubing as intraventricular air markedly distorts visualization.
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Ensure endoscope working port for fluid egress from the ventricles, is open during the procedure to prevent raised ICP.
Rigid ventriculoscope
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Both 0° and 30° endoscopes are available but the 0° scope is most commonly used for ventriculoscopy ( Fig. 1 A). Ensure scope is “white-balanced,” and image is clear.
Fig. 1
( A ) Rigid ventriculoscope. ( B ) Endoscopic scissors, graspers, spreaders, and biopsy forceps. ( C ) Flexible ventriculoscope. ( D ) Tip of the endoscopic side-cutting tissue resection device.
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Self-retaining adjustable scope holder ( Fig. 2 A) frees-up both hands for manipulation of endoscopic instruments and prevents inadvertent scope movement ( Fig. 2 B).
Fig. 2
( A ) Self-retaining adjustable holder for the rigid ventriculoscope. ( B ) Holder frees-up both hands to manipulate endoscopic instruments.
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Endoscopic instruments: scissors, spreaders, balloon, graspers, biopsy forceps, and bipolar coagulation probe ( Fig. 1 B).
Flexible ventriculoscope
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360° mobility of the tip improves navigation within the ventricular system ( Fig. 1 C).
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Image quality lower than the rigid endoscope.
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Flexible ventriculoscope can be introduced through the cannula that holds the rigid scope or through a “Peel-Away” catheter.
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Flexible endoscopic instruments are longer and more difficult to manipulate.
Endoscopic side-cutting variable-aspirating tissue resection device
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Hand-held device mounts directly onto the central working port of a 6 mm rigid ventriculoscope ( Fig. 1 D; [CR] and [CR] ).
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Mechanical, nonthermal device that cuts tissue and aspirates the fragments ( Fig. 1 D; [CR] , [CR] ).
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Useful to empty contents of a cyst or cystic tumor, remove and/or debulk an intraventricular tumor or cyst ( [CR] , [CR] ).
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Tissue fragments collected are suitable for pathology.
Ventriculoscopic procedures
Diagnostic Ventriculoscopy
Ventriculoscopic biopsy of a ventricular lesion may be done alone but is often done simultaneously with endoscopic treatment of the hydrocephalus. This could include: (1) endoscopic third ventriculostomy (ETV); (2) fenestration of the septum pellucidum; (3) fenestration of an arachnoid cyst; (4) ventriculoscopic removal or debulking of an obstructing intraventricular lesion; (5) opening of a narrowed or occluded foramen of Monro (FOM); (6) Ventriculoperitoneal (VP) shunt insertion/revision or; (7) EVD insertion.
Endoscopic Third Ventriculostomy (ETV)
Primary ETV
First procedure for untreated congenital or acquired obstructive hydrocephalus in a patient that has no shunt in place and no previous ETV.
Indications for primary ETV.
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Congenital aqueductal web ( Fig. 3 B; Fig. 6 G).
Fig. 3
( A ) Axial T2 MRI brain showing hydrocephalus and periventricular edema ( asterisk ). ( B ) Sagittal T2 MRI brain with aqueductal web ( arrow ) resulting in stenosis of cerebral aqueduct. Basilar artery (#) and floor (F) of third ventricle at the planned ETV site.
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Third ventricle/pineal region/midbrain-tectal masses resulting in aqueduct compression/narrowing ( Figs. 4 A–D and 5 A ). Either ETV alone ± endoscopic biopsy/debulking of solid lesions or fenestration of tumor, pineal, or arachnoid cysts ( Figs. 4 E and 5 B).
Fig. 4
( A – D ) MRIs (A: T2; B–D: T1 + GAD) of a pineal germinoma (T) resulting in obstructive hydrocephalus due to aqueduct stenosis. Hydrocephalus results in bowing down of the floor of the third ventricle ( F ) at the planned ETV site. ( E ) Intraoperative view of the floor of the third ventricle through the rigid ventriculoscope. Both the ETV ( asterisk ) and biopsy of the germinoma (T) were done with the rigid ventriculoscope passed through a single burr hole. Mammillary body (M).
Fig. 5
( A ) Preoperative sagittal T1 MRI. Large pineal cyst (P) results in obstructive hydrocephalus due to aqueduct stenosis. Hydrocephalus results in bowing down of the floor of the third ventricle (F) at the planned ETV site. ( B ) Post-ETV sagittal 3-dimensional T2 Space MRI. Large CSF flow void ( asterisk ) through the ETV. Small residual pineal cyst (P) after endoscopic fenestration of the cyst into the third ventricle. Both the ETV and fenestration of the cyst were done with the rigid ventriculoscope passed through a single burr hole.Related posts:
Hydrocephalus Pathophysiology and Epidemiology
Adult Hydrocephalus Clinical Subtypes
Guidelines for Diagnosis and Management of Idiopathic Normal Pressure Hydrocephalus
Diagnostic and Prognostic Biomarkers of Idiopathic Normal Pressure Hydrocephalus in Cerebrospinal Fluid and Blood
Temporary Drainage of Cerebrospinal Fluid for Diagnosis and Treatment of Hydrocephalus
Spinal Cerebrospinal Fluid Leaks/Intracranial Hypotension
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