Surgical Approaches to Tumours of the Ventricle

Introduction

Tumours that arise within the ventricles present a unique neurosurgical challenge. "…these are among the most formidable areas to access surgically because of their deep location, their intimate association with numerous perforating arteries, supplying critical areas of the deep regions of the brain, and their intimate and circumferential associations with multidimensional white matter tracts" (Yasargil).

Thorough knowledge of the anatomy is extremely important for the correct planning of the optimal approach to the tumours which often have large size and are associated with hydrocephalus.

The session will give an introduction into the tumour pathology of the ventricles, review of the relevant anatomy of the ventricles, main approaches to lateral, third and fourth ventricles, important technical steps, tips and tricks, possible complications and tips to avoid them.

Anatomy of the Ventricular System

Lateral Ventricles

Frontal horn – anterior to foramen Monroe

• Floor – rostrum of the corpus callosum
• Roof – junction between genu with the body of the corpum callosum
• Medial wall – septum pellucidum
• Posterior wall – thalamus

Body – behind foramen Monroe

• Floor – thalamus
• Roof – body of the corpus callosum
• Medial wall – septum pellucidum and fornix
• Lateral wall – caudate nucleus

Temporal horn

• Floor – hipocampus (medially) and collateral eminence (laterally)
• Roof – tapetum, Caudate nucleus, part of internal capsule, amygldala
• Lateral wall – tapetum and optic radiation
• Medial wall – hippocampus
• Anterior wall – amygdala

Occipital horn – atrium

• Floor – collateral trigone
• Roof – cospus callosum
• Medial wall – forceps major (connecting occipital lobes) and the bulb of the callosum
• Lateral wall – caudate nucleus and tapetum

Anatomy of the Ventricular System

3rd Ventricle

The Third Ventricle is located between the pituitary fossa and corpus callosum.

The floor extends from the optic chiasm anteriorly to the aqueduct of Sylvius posteriorly:

• Optic chiasm
• Infundbulum of hypothalamus
• Tuber cinereum
• Mamillary bodies
• Posterior perforated substance
• Part of the tectum

The roof extends from foramen of Monro to the supra-pineal recess. It has four layers:

• Body of the fornix
• Two layers of tela choroidea procudced by pia mater membranes
• Velum interpositum

Lateral wall thalamus and hypothalamus. Anterior wall extends from foramen of Monro to the optic chiasm.

Posterior wall extends from the suprapineal recess (superiorly) to the aqueduct of Sylvius (inferiorly).

Anatomy of the Ventricular System

4th Ventricle

Upper roof - superior cerebellar peduncle, superior medullary vellum and lingula.

Lower roof - inferior medullary vellum and the nosils (horizontaly). Tela choroidea and choroid plexus arranged vertically. Communicates with cerebellopontine cistern and the lateral recess.

Floor – rhombdoidal, divided horizontally into two unequal triangles by the medullary stria. The superior pontine triangle has its apex towards the aqueduct. The inferior medullary triangle points towards the obex.

Figure 1 .9 - K and L - see opposite. Posterior views. K, enlarged view of the floor of the fourth ventricle. The median sulcus divides the floor longitudinally in the midline. Each half of the floor is divided longitudinally by an irregular sulcus, the sulcus limitans, which deepens lateral to the facial colliculus and hypoglossal triangles to form the superior and inferior foveae. A darkened area of cells, the locus ceruleus, is located at the rostral end of the sulcus limitans. The stria medullaris crosses the floor at the level of the lateral recess. The hypoglossal and vagal nuclei and the area postrema are stacked one above the other in the lower part of the floor to give the configuration of a pen nib and, thus, the area is referred to as the calamus scriptorius. L, another fourth ventricular floor. The paired veins of the superior cerebellar peduncle course on the outer surface of the superior peduncles and join superiorly to form the vein of the cerebellomesencephalic fissure. The median posterior medullary vein ascends on the medulla and splits into the paired veins of the inferior cerebellar peduncle at the caudal margin of the floor. That left vein is hypoplastic. The left vein of the cerebellomedullary fissure passes along the lateral recess and ascends to join the petrosal group of veins in the cerebellopontine angle. Cer.Med., cerebellomedullaryCer., cerebellarCN, cranial nerveColl., colliculusEmin., eminenceFiss., fissureHypogl., hypoglossalInf., inferiorMed., median, medullaryMid., middlePed., pedunclePost., posteriorStriae Med., Stria medullarisSup., superiorV., vein.

Saggital Section of Brain In Situ

Mouse over the image to see the name of the structures.

  

Patterns of Structural Presentation of Intraventricular Tumors

The structural presentation of masses affecting the anterior and mid-third ventricular region may be divided in three major groups important for selection of the optimal surgical corridor:

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• Extraaxial intraventricular
• Intraaxial with ventricular component
• Basal with ventricular extension

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Relationship Between Type of Tumour and Common Site of Predilection

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Colloid cyst

• Foramen Monro
• Antero-superior 1/3 of the ventricle

Neurocytoma

• Around foramen Monro

Subependymoma

• Around foramen Monro
• 4th ventricle

Tuberous sclerosis

• Foramen of Monroe
• Frontal horn

Choroid plexus papilloma

• Trigone
• 4th ventricle

Meningioma

• Velum interpositum
• 3rd ventricle
• trigone

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Histology of Tumour by Location and Age Group

General Technical Principles of Transcranial Approaches to the Ventricles

For any ventricular tumour the essence of surgery is represented by the ability to access and resect these lesions avoiding critical brain and vascular areas. Often more complex trajectories along "safe corridors" will be preferred to more direct transcerebral trajectories to the ventricle.

The approach should be individually planned according to particular tumour and its anatomical location and relationships. However classical approaches for each intraventricular region are well described in the literature.

Goals of Surgery

• Definition of histology
• Maximal excision of the lesion
• Relief of symptoms and signs resulting from local mass effect
• Relief of the alteration in CSF dynamics

Objectives of Surgery

• Obtaining a maximal exposure and flexibility for lesion access and manipulation
• Minimal manipulation, injury or sacrifice of normal neural and vascular structures

General Technical Principles of Transcranial Approaches to the Lateral and Third Ventricles

General Technical Principles of Transcranial Approaches to the Ventricles

Main Approaches to the Tumours of Third Ventricle

Potential operative methods in the management of lesions affecting the anterior and mid-third ventricle (Apuzzo).

Microsurgical (Craniotomy)

Basal

1. Transsphenoidal

2. Transcranial

Subfrontal (midline, oblique)

• Subchiasmatic
• Transsphenoidal

Pterional

• Opticocarotid
• Lateral carotid

Subtemporal

Superior

1.Transcortical 

• Transforaminal
• Subchoroidal

2.Transcallosal

• Transbiforaminal
• Interforniceal

Combined

1.Transcallosal-subfrontal

2.Transcallosal-pterional

3.Transcallosal-frontotemporal

Basal - Transsphenoidal Approach

Advantages

• Excellent and rapid access to sella turcica
• Visual system and 3rd ventricullar region rapidly decompressed (in soft and cystic lesions)
• Indicated in cases when chiasm is prefixed, sinus is aerated, opticocarotid access is limited and lamina terminalis is not distended by tumour (when subfrontal approach will be preferred)

Limitations, Disadvantages

• Solid texture of tumours
• Adherences to vascular and neural structures limits total tumour removal

Potential Complications

• Lesion to olfactory, optic nerves, damage to perforating branches from ACoA, A1

Basal Craniotomy – Subfrontal Approach

Advantages

• Uni-/bilateral pproach to midline suprasellar tumours
• Good visualisation of the optic nerves and carotid arteries
• Opening of anterior chiasmatic cistern
• Minimal retraction and manipulation of the optic nerves
• Possibility to extend the flap to pterion for antero-lateral corridor
• Lamina terminalis may be incised to offer tumour access or visualisation in the area above sella turcica but below the foramen of Monro, particularly with prefixed chiasm

Limitations, Disadvantages

• Careful preservation of perforating branches from the anterior cerebral artery and ACoA
• Limited superior access or visualisation

Potential Complications

• Hypothalamic injury
• Lesion to olfactory, optic, oculomotor, trochlear, trigeminal, abducent nerves, carotid artery, circle of Willis, cavernous synus
• CSF leak

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Basal craniotomy - Pterional Approach

Advantages

• Good access to removal of tumours from temporal horn as well as from the third ventricle.
• Shortest access from scalp to sella turcica
• Good anterolateral visualisation of the ipsilateral carotid and optic chiasm
• Visualisation of the retrosellar space is possible
• Indicated in suprasellar tumours with prefixed chiasm

Limitations, Disadvantages

• Care must be taken to preserve peforating vessels to the visual system
• Tumour removal sometimes difficult because of obstruction by various nerves and vessels
• Limited superior access or visualisation

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Basal Craniotomy – Subtemporal Approach

Advantages

• Good exposure for tumours in parasellar, posterior, dorsum sella and posterior perforated space regions
• Can be combined with pterional approach

Limitations, Disadvantages

• Posterior communicating artery with its perforating branches to the region
• Medial angulation of the tentorium may limit exposure
• Extensive temporal retraction often necessary
• Poor visualisation of prepontine area
• Ipsilateral III-rd and IV-th nerces are in the line of the approach
• Limited superior access or visualisation

Potential Complications

• Hypothalamic injury
• Lesion to olfactory, optic, oculomotor, trochlear, trigeminal, abducent nerves, carotid artery, circle of Willis, cavernous synus
• CSF leak

Superior Craniotomy – Transcortical Approach

• Classically performed through the right middle frontal gyrus
• Optimally used in the presence of ventriculomegaly
• Intraoperative ultrasound/neuronavigation might be very helpful for intraoperative orientation

Advantages

• Good visualisation of ipsilateral foramen of Monro
• Satisfactory visual alignment for lesions of the middle and midanterior part of III-rd ventricle
• Optimal angulation for subchoroidal exposure

Limitations, Disadvantages, Potential Complications

• Poor visual alignment for the interforniceal maneuver or visualisation of the contralateral foramen
• Sacrifice of neural tissue
• Higher incidence of postoperative seizures

Superior Craniotomy – Transcallosal Approach to Lateral and Third Ventricle

Interhemispheric exposure of the body of the corpus callosum in the pericoronal region followed by a 2-3 cm incision.

Advantages

• Constant anatomy
• Shorter transit to the diencephalic roof
• Flexibility of exploration of the III-rd ventricular cavity
• Visualisation of both foramen of Monroe
• Ventricular size is irrelevant
• No major disruption of neural tissue

Limitations, Disadvantages, Potential Complications

• Risk of contralateral hemiparesis
• Bilateral cingulate retraction may cause postoperative mutism

Transcallosal Approach to Lateral and Third Ventricles

Surgical Steps

• Supine position
• Parasagittal craniotomy extended few mm across midline
• Neuronavigation, preoperative location of the bridging veins will help with planning of the position and size of craniotomy
• Dura is opened in "C" shaped manner with base oriented to the saggital sinus and special attention to large cortical veins
• Gentle temporary retraction of the medial surface of the frontal lobe until enough CSF is released. The ventricle may be punctured
• Entrance in interhemispheric fissure in stepwise fashion using cotton balls of increasing sizes placed at the anterior and posterior end of dissection between falx and brain
• Knowledge of the anatomy of the region (and anatomical variants) is crucial
• Corpus callosum is incised 10-15 mm in the midline between two pericallosal arteries and CSF is drained. Foramen Monro is localised (landmarks: thalamostriate vein, septal, frontal subependymal, caudate, choroid plexus

Large tumours in the ventricle may prevent visualisation of the anatomy. Safest strategy – central debulking followed by hemosthazis and dissection of the periphery of the tumour.

Mouse over to view approaches to the tumours of third ventricle.

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Combined Approaches

Different options are available:

• Yasargil – two simultaneous small craniotomies for transcallosal and pterional approaches
• Ehni and Ehni – large frontotemporoparietal bone flap for multiple corridors exposure
• Apuzzo – bone flap allowing exposure of the cerebral midline in the pericoronal region for transcallosal approach and entire frontal floor medial to pterion for subfrontal and lateral optic access, ideal for basal masses with large mid and anterior sellar attachements. Not suitable for tumours extending in temporal area

Combined approaches will be used when a single corridor provides inadequate exposure.

Mouse over to view indications.

The frontal interhemispheric transcallosal approach will be used to dissect the the superior, superoposterior and superolateral portions of the tumour.

The subchiasmatic portions of the tumour are better explored via the pterional transsylvian approach.

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Approaches to Posterior Part of Third Ventricle/Pineal Area and Trigonum

Posterior parieto-occipital interhemispheric approach.

Indications

• Intraventricular tumours from the posterior portion of the third ventricle
• Tumors from posterior 1/3 of the lateral ventricle (trigone)
• Tumours of pineal and parapineal areas extended into 3rd ventricle

Technique

• Sitting position / prone position
• Parasplenial approach entering the posterior part of precuneus anterio to the parieto-occipital sulcus
• Posterior callosal cistern and parietooccipital sulcus are identified and vein of Rosenthal the dorsal mesencephalic cistern can be opened to drain the CSF. (Do not confuse vein orf Rosenthal with dorsal mesencephalic cisterns, also dark). If brain is tensed, the posterior horn can be punctured and CSF released
• Central debulking of tumour followed by its dissection
• The feeding vessels to the tumor normally would be on the lateral or inferior aspects

Approaches to Fourth Ventricle

4th ventricle is a conduit for the passage of CSF from lateral and 3rd ventricles to the craniospinal subarachnoid space.

Anatomy:

• Roof – cerebellum and its peduncles
• Floor – pons and medulla.
• Lateral recesses – foramen Luschka – cerebellopontine angle cisterns
• Caudally – foramen Magendie – cisterna magna.
• Cranially – aqueduct of Sylvius

Knowledge of detailed anatomy is important and is well described in the literature by Mahsushima and Rhoton (Matshushima T, Rhoton AL Jr, Lenkey C. Microsurgery of the fourth ventricle: Part 1. Microsurgical anatomy. Neurosurgery 1982; 11: 631-667)

Common lesions of 4th ventricle:

• Medullobrasoma, astrocytoma, ependymoma, choroid plexus papilloma, dermoid/epidermoid tumours

Surgical Considerations

CSF diversion may need to be considered for patients with hydrocephalus. Intraoperative monitoring - brainstem auditory evoked responses, monitoring of blood pressure and pulse, dorsal motor neucleus of the vagus, nucleus of the tractus solitarius are near the floor of the fourth ventricle.

• Positioning – prone (concord) or sitting
• Surgical approach
• Midline linear vertical incision
• Y-shaped incision through the fascia-muscle leaving a cuff attached to the bone will help with water-tight closure at the end of procedure
• Careful dissection of the soft tissues from the arch of C1 vertebra
• Craniotomy/craniectomy with opening of the foramen magnum +/- removal of the arch of C1 vertebra
• Dura opened in Y-shaped fashion (fig)
• Lateral retraction of the cerebellar tonsils will provide access to the fourth ventricle. A third retractor might be needed for elevation of the inverior vermis.
• Dissection of the inferior tela in the cerebellomedullary fissure often can gain adequate exposure without splitting the cerebellar vermis. Splitting the vermis is also acceptable
• Tumour debulking with cusa followed by further microsurgical dissection
• Goal of dissection – to find and protect the floor of the fourth ventricle
• Closure in watertight fashion

Complications of Approaches to 3rd Ventricle

Hemiparezis

Memory loss – most common postoperative problem (30% - transitory memory loss) – amnesia for recent events – produced by damage to fornix, hyppocampus, mamillary bodies

• Alterations of consciousness
• Gastrointestinal hemorrhage
• Increased endocrynopathy
• Visual loss
• Aseptic or infectious meningitis
• Seizures
• Hydrocephalus
• Mutism (corpus callosum damage)

Complications of Approaches to 4th Ventricle

Complications of surgical resection of 4th ventricular tumours:

• Cranial nerve palsied (eye movement disorders, facial palsies, hypoglossal, vagal nerve dysfunction)
• Gait ataxia (injury to inferior vermis and flocculonodular lobe)
• Limb dysmetria (dentate nucleus or red nucleus injury)
• Aseptic meningitis
• CSF leak, pseudomeningoceles (reduced by watertight closure and replacement of the bone flap
• Cerebellar mutism
• Confusion, hallucinations, paranoia
• Air embolism
• Pneumocephalus
• Vascular injury
• Infection
• Tension pneumocephalus

Self Assessment

Question 1

Match the structure with the damage in the question below. Use the image as a guide.

 Question 1

Self Assessment

Question 2

Match preferred approach to tumour location

 Question

Self Assessment

Question 3

Select all the correct answers.

 Question

Self Assessment

Question 4

Select all the correct answers.

 Question

Session Key Points

Key Points Ventricles represent a region which might be affected by numerous pathological processes They are surrounded by densely packed vital anatomical structures involved in functions ranging from basic preservation of consciousness and homeostasis to functions of memory, personality and emotion Surgery of these processes will have to consider individually selected approach aiming to minimize damage to neural and vascular structures and respectively potential risk of complications which often are devastating A thorough knowledge of anatomy of these regions and comfortable use of different microneurosurgical approaches along with knowledge of their advantages and limitations is of paramount importance A deep review of literature, sustained by constant exposure to cadaveric dissections and "absorption" of the experience of other masters of neurosurgery along with personal devotement to this subject represent key factors to success of mastering these particular and challenging tumours

Session Summary

Learning Objectives Having completed this session you will now be able to: State the relevant anatomy for the approaches to ventricular tumours Describe the patterns of structural presentation of intraventricular tumors Define the general technical principles of transcranial approaches to the ventricles Explain the main approaches to the tumours of third and fourth ventricles Illustrate potential complications of the different approaches to the ventricles References Yaşargil, M. Gazi M.D.; Abdulrauf, Saleem I. M.D. Surgery of Intraventricular Tumors, Neurosurgery: June 2008 - Volume 62 - Issue 6 - p SHC1029-SHC1041. G. Samandouras. The Neurosurgeon's Handbook. Oxford University Press. 2010. Apuzzo MLJ: Surgery of the Third Ventricle. 2nd ed. Baltimore, Md: Williams&Wilkins, 1998. Lozier AP, Bruce JN. Surgical approaches to posterior third ventricular tumors. Neurosurg Clin N Am 2003;14(4):527-45. Anderson RC, Ghatan S, Feldstein NA. Surgical approaches to tumors of the lateral ventricle. Neurosurg Clin N Am 2003;14(4):509-25. Vecil GG, Lang FF. Surgical resection of metastatic intraventricular tumors. Neurosurg Clin N Am 2003;14(4):593-606. Dumont AS, Farace E, Schiff D, Shaffrey ME. Intraventricular gliomas. Neurosurg Clin N Am 2003;14(4):571-91. McDermott MW. Intraventricular meningiomas. Neurosurg Clin N Am 2003;14(4):559-69. Kunwar S. Endoscopic adjuncts to intraventricular surgery. Neurosurg Clin N Am 2003;14(4):547-57. Kaye, Andrew and Black, Peter. Operative Neurosurgery. Churchill Livingston, Dec 7, 1999.