Transcortical-transventricular approach in colloid cysts of the third ventricle: surgical experience with 26 cases

Endoscopic trans-septal interforniceal approach for excision of colloid cysts of the third ventricle using the rotational technique

Colloid cysts of the third ventricle are benign intracranial lesions that account for 0.5 to 2% of all brain tumors and are even rarer in pediatric population. Dandy was the first to successfully excise a colloid cyst of the third ventricle via a transcortical transventricular approach in 1921. For several decades to follow, the transcortical transventricular and transcallosal microsurgical approaches remained the cornerstone of surgical management of these lesions. With time and refinements in endoscopic equipment and techniques, endoscopic resection of colloid cysts evolved into a currently well-established and appealing minimally invasive alternative to microsurgery. Endoscopic endochannel techniques for colloid cysts of the third ventricle may either be transforaminal or trans-septal interforniceal, depending on the pathoanatomical features of the colloid cyst and its relation to the juxtaposed anatomical structures. The endoscopic trans-septal interforniceal approach is required to access the rare subset of colloid cysts that extend superior to the roof of the third ventricle between the two fornices insinuating themselves between the leaflets of the septum pellucidum. In this article, the surgical technique of the endochannel endoscopic trans-septal interforniceal approach is elaborated upon. A representative case is presented along with an operative video.

Use of the 3D exoscope for the supracerebellar infratentorial approach in the concorde position: an effective and ergonomic alternative. Illustrative cases

BACKGROUND

The supracerebellar infratentorial approach provides wide flexibility as a far-reaching corridor to the pineal region, posterior third ventricle, posterior medial temporal lobe, posterolateral mesencephalon, quadrigeminal cistern, and thalamus. Traditionally, the patient is placed in the sitting position, allowing gravity retraction on the cerebellum to widen the supracerebellar operative corridor beneath the tentorium. What this approach gains in anatomical orientation it lacks in surgeon ergonomics, as the sitting position presents technical challenges, forces the surgeon to adopt to an uncomfortable posture while performing the microsurgical dissection/tumor resection under the microscope, and is also associated with an increased risk of venous air embolism.

OBSERVATIONS

In this article, the authors present the use of the three-dimensional (3D) exoscope with a standard prone Concorde position as an alternative for the treatment of lesions requiring a supracerebellar infratentorial approach for lesions in the pineal region, posterior third ventricle, and the superior surface of the cerebellar vermis. The authors present four illustrative cases (one pineal cyst, one ependymoma, and two cerebellar metastases) in which this approach provided excellent intraoperative visualization and resulted in good postoperative results. A step-by-step description of our surgical technique is reviewed in detail.

LESSONS

The use of the 3D exoscope with the patient in the prone Concorde position is an effective and ergonomically favorable alternative to the traditional sitting position for the treatment of lesions requiring a supracerebellar infratentorial approach. This technique allows improved visualization of deep structures, with a possible decreased risk of potential complications.

Retrospective evaluation of endoscopic treatment in colloid cyst of the third ventricle

Introduction

Endoscopic methods have gained a well-established position in surgical treatment of colloid cysts of third ventricle. However, the possibility of total tumor removal with this method and the long-term effectiveness of treatment are being questioned.

Aim

Personal twenty years’ experience in treatment of third ventricle colloid cysts is presented on the basis of retrospective analysis.

Material and methods

The study group included 58 patients diagnosed by neuroimaging (head CT/MRI) with third ventricle colloid cyst. Post-hospital follow-up ranged from 18 to 42 months. Long-term follow-up head CT/MRI was performed in 39 patients.

Results

The colloid cyst was removed totally in 47 (81%) patients. In 11 cases, the colloid cyst’s wall was tightly adherent to the roof of the third ventricle, which limited the radicality of the procedure. Sixteen patients demonstrated memory impairments, 4 patients epilepsy and another 2 akinetic mutism in the direct postoperative course. One patient died as a result of complications unrelated to the procedure. The average hospitalization was 5 days. In the late period after surgery, remission of the most, previously, reported ailments and symptoms has been reported. Surgical treatment for hydrocephalus was needed in 7 patients. In 3 cases cyst recurrence was diagnosed which required reoperation.

Conclusions

The endoscopic methods allow the total removal of a third ventricle colloid cyst in most patients. Leaving a small coagulated fragment of the cyst rarely results in its recurrence. This method results in effective treatment with a low complications rate, shortens hospitalization time and brings the patient a high level of satisfaction with a quick recovery.

Perspectives on Endoscopic Transseptal Interforniceal Approach for Retroforaminal Colloid Cysts

BACKGROUND

Although the interforniceal approach with the preservation of the fornix is useful during the endoscopic approach for retroforaminal colloid cysts, it carries a significant risk of memory and cognitive difficulties. Because most reports have reported the endoscopic approach to colloid cysts through the foramen with little emphasis on retroforaminal cysts, the aim of this study was to investigate colloid cysts as a special entity with regard to their different characteristics and surgical approaches and outcomes.

METHODS

In this retrospective study, 12 patients with third ventricular colloid cysts with retroforaminal extensions were included. All patients underwent endoscopic transseptal interforniceal approach with tumor resection. The surgical technique was briefly described, and preoperative and postoperative data were evaluated.

RESULTS

Among the 12 patients included in this study, most of our patients were males. Average diameter of the colloid cyst was relatively large (average 22 mm). Gross total resection was achieved in 10 cases (83.3%). The stable images showed no local recurrence in the long-term follow-up period except in 1 case at the 28-month follow-up period.

CONCLUSIONS

Retroforaminal colloid cyst represents a unique entity that requires special attention to its mode of growth. The endoscopic approach for retroforaminal colloid cysts is nearly the same as that for foraminal cysts. It has a lower incidence rate of postoperative memory changes, lower chances of total resection, and lower incidence rate of hard contents. Moreover, sufficient knowledge on morbid anatomy is important to avoid fornix injury.

Real-Time Intraoperative Pressure Monitoring to Avoid Surgically Induced Localized Brain Injury Using a Miniaturized Piezoresistive Pressure Sensor

Neurosurgical procedures often cause damage to the brain tissue at the periphery from surgical manipulations. Especially during retraction, a large amount of pressure could be applied on the brain surface, which can damage it, leading to brain herniation, which can be fatal for patients. To resolve this issue, we have developed a pressure sensor that can be used to monitor the applied pressure during surgery for intraoperative care. This device was tested on a rodent model to create a superficial surgically induced damage profile for three different applied pressures (30, 50, and 70 mmHg) and compared to a standard intracranial pressure monitoring system. Magnetic resonance imaging has been performed after surgical procedures to detect the herniation caused by applied pressure. To evaluate the damage to brain cells and tissue rupture, histological analysis was performed using hematoxylin and eosin staining. A scoring system was developed to understand the severity of the surgically induced brain injury, which will help neurosurgeons to limit the pressure to an optimum point without causing damage.

The Activation of Phosphatidylserine/CD36/TGF-β1 Pathway prior to Surgical Brain Injury Attenuates Neuroinflammation in Rats

Neuroinflammation plays an important pathological role in experimental surgical brain injury (SBI). Apoptotic associated with phosphatidylserine (PS) externalization promotes anti-inflammatory mediator TGF-β1 release. In the present study, we investigated the anti-neuroinflammation effect of PS liposome or isoflurane pretreatment via PS/CD36/TGF-β1 signaling in a rat model of SBI. A total of 120 male Sprague-Dawley rats (weighing 280-330 gms) were used. SBI was induced by partial right frontal lobe corticotomy. Intranasal PS liposome or isoflurane inhalation was administered prior to SBI induction. CD36 small interfering RNA (siRNA) was administered intracerebroventricularly. Recombinant Annexin V protein (rAnnexin V) was delivered intranasally. Post-SBI assessments included neurological tests, brain water content, Western blot, and immunohistochemistry. Endogenous CD36 protein levels but not TGF-β1 was significantly increased within peri-resection brain tissues over 72 h after SBI. SBI rats were associated with increased brain water content surrounding corticotomy and neurological deficits. PS liposome pretreatment significantly reduced brain water content and improved some neurological deficits at 24 hours and 72 hours after SBI. PS liposome increased CD36 and TGF-β1 protein levels, but decreased IL-1β and TNFα protein levels in peri-resection brain tissues at 24 hours after SBI. CD36 siRNA or rAnnexin V partially countered the protective effect of PS liposome. Isoflurane pretreatment produced similar antineuroinflammation and neurological benefits in SBI rats partially by upregulating CD36/Lyn/TGF-β1 signaling. Collectively, our findings suggest that the activation of PS/CD36/TGF-β1 pathway by PS liposome or isoflurane prior to SBI could attenuate neuroinflammation and improve neurological outcomes in rats. PS liposome or isoflurane pretreatment may serve as an effective preventive strategy to minimize the brain injury caused by neurosurgical procedures in patients.

White Matter-Governed Superior Frontal Sulcus Surgical Paradigm: A Radioanatomic Microsurgical Study—Part I

BACKGROUND

Frontal subcortical and intraventricular pathologies are traditionally accessed via transcortical or interhemispheric-transcallosal corridors.

OBJECTIVE

To describe the microsurgical subcortical anatomy of the superior frontal sulcus (SFS) corridor.

METHODS

Cadaveric dissections were undertaken and correlated with magnetic resonance imaging/diffusion-tensor imaging-Tractography. Surgical cases demonstrated clinical applicability.

RESULTS

SFS was divided into the following divisions: proximal, precentral sulcus to coronal suture; middle, 3-cm anterior to coronal suture; and distal, middle division to the orbital crest. Anatomy was organized as layered circumferential rings projecting radially towards the ventricles: (1) outer ring: at the level of the SFS, the following lengths were measured: (A) precentral sulcus to coronal suture = 2.29 cm, (B) frontal bone projection of superior sagittal sinus (SSS) to SFS = 2.37 cm, (C) superior temporal line to SFS = 3.0 cm, and (D) orbital crest to distal part of SFS = 2.32 cm; and (2) inner ring: (a) medial to SFS, U-fibers, frontal aslant tract (FAT), superior longitudinal fasciculus I (SLF-I), and cingulum bundle, (b) lateral to SFS, U-fibers, (SLF-II), claustrocortical fibers (CCF), and inferior fronto-occipital fasciculus, and (c) intervening fibers, FAT, corona radiata, and CCF. The preferred SFS parafascicular entry point (SFSP-EP) also referred to as the Kassam-Monroy entry point (KM-EP) bisects the distance between the midpupillary line and the SSS and has the following coordinates: x = 2.3 cm (lateral to SSS), y ≥ 3.5 cm (anterior to CS), and z = parallel corona radiata and anterior limb of the internal capsule.

CONCLUSION

SFS corridor can be divided into lateral, medial, and intervening white matter tract segments. Based on morphometric assessment, the optimal SFSP-EP is y ≥ 3.5 cm, x = 2.3 cm, and z = parallel to corona radiata and anterior limb of the internal capsule.

Surgically-induced brain injury: where are we now?

Neurosurgical procedures cause inevitable brain damage from the multitude of surgical manipulations utilized. Incisions, retraction, thermal damage from electrocautery, and intraoperative hemorrhage cause immediate and long-term brain injuries that are directly linked to neurosurgical operations, and these types of injuries, collectively, have been termed surgical brain injury (SBI). For the past decade, a model developed to study the underlying brain pathologies resulting from SBI has provided insight on cellular mechanisms and potential therapeutic targets. This model, as seen in a rat, mouse, and rabbit, mimics a neurosurgical operation and causes commonly encountered post-operative complications such as brain edema, neuroinflammation, and hemorrhage. In this review, we elaborate on SBI and its clinical impact, the SBI animal models and their clinical relevance, the importance of applying therapeutics before neurosurgical procedures (i.e., preconditioning), and the new direction of applying venom-derived proteins to attenuate SBI.

Modification of kynurenine pathway via inhibition of kynurenine hydroxylase attenuates surgical brain injury complications in a male rat model

Neurosurgical procedures result in surgically induced brain injury (SBI) that causes postoperative complications including brain edema and neuronal apoptosis in the surrounding brain tissue. SBI leads to the release of cytokines that indirectly cause the stimulation of kynurenine 3-monooxygenase (KMO) and the release of neurotoxic quinolinic acid (QUIN). This study tested a KMO inhibitor, RO 61-8048, to prevent postoperative brain edema and consequent neuronal apoptosis in an in vivo model of SBI. A rodent model of SBI was utilized which involves partial resection of the right frontal lobe. A total of 127 Sprague-Dawley male rats (weight 275-325 g) were randomly divided into the following groups: Sham surgical group, SBI, SBI + DMSO, SBI + RO 61-8048 (10 mg/kg), SBI + RO 61-8048 (40 mg/kg), and SBI + RO 61-8048 (40 mg/kg) + KAT II inhibitor PF-04859989 (5 mg/kg). RO 61-8048 was administered by intraperitoneal injection after SBI. Postoperative assessment at different time points included brain water content (brain edema), neurological scoring, and western blot. SBI increased brain water content (ipsilateral frontal lobe), decreased neurological function, and increased apoptotic markers compared with sham animals. Treatment with RO 61-8048 (40 mg/kg) reduced brain water content and improved long-term neurological function after SBI. RO 61-8048 increased the expression of kynurenic acid while reducing QUIN and apoptotic markers in the surrounding brain tissue after SBI. These neuroprotective effects were reversed by PF-04859989. This study suggests KMO inhibition via RO 61-8048 as a potential postoperative therapy following neurosurgical procedures.

Awake Surgical Management of Third Ventricular Tumors: A Preliminary Safety, Feasibility, and Clinical Applications Study

BACKGROUND

Endoscopic and microneurosurgical approaches to third ventricular lesions are commonly performed under general anesthesia.

OBJECTIVE

To report our initial experience with awake transsulcal parafascicular corridor surgery (TPCS) of the third ventricle and its safety, feasibility, and limitations.

METHODS

A total of 12 cases are reviewed: 6 colloid cysts, 2 central neurocytomas, 1 papillary craniopharyngioma, 1 basal ganglia glioblastoma, 1 thalamic glioblastoma, and 1 ependymal cyst. Lesions were approached using TPCS through the superior frontal sulcus. Pre-, intra-, and postoperative neurocognitive (NC) testing were performed on all patients.

RESULTS

No cases required conversion to general anesthesia. Awake anesthesia changed intraoperative management in 4/12 cases with intraoperative cognitive changes that required port re-positioning; 3/4 recovered. Average length of stay (LOS) was 6.1 d ± 6.6. Excluding 3 outliers who had preoperative NC impairment, the average LOS was 2.5 d ± 1.2. Average operative time was 3.00 h ± 0.44. Average awake anesthesia time was 5.05 h ± 0.54. There were no mortalities.

CONCLUSION

This report demonstrated the feasibility and safety of awake third ventricular surgery, and was not limited by pathology, size, or vascularity. The most significant factor impacting LOS was preoperative NC deficit. The most significant risk factor predicting a permanent NC deficit was preoperative 2/3 domain impairment combined with radiologic evidence of invasion of limbic structures – defined as a “NC resilience/reserve” in our surgical algorithm. Larger efficacy studies will be required to demonstrate the validity of the algorithm and impact on long-term cognitive outcomes, as well as generalizability of awake TPCS for third ventricular surgery.

Postoperative Seizure Rate After Transcortical Resection of Subcortical Brain Tumors and Colloid Cysts: A Single Surgeon's Experience

When deciding on a surgical route to reach subcortical brain tumors and colloid cysts, many surgeons advocate the use of transcallosal, transsulcal, or skull base approaches over transcortical approaches due to a high reported incidence of postoperative seizures. We have retrospectively analyzed all patients operated upon by a senior neurosurgeon (Ricardo J. Komotar) who undertook transcortical approaches for the resection of subcortical brain tumors and colloid cysts. We have also performed a comprehensive review of the literature to estimate postoperative seizure risk after transcortical approaches for the resection of deep tumors and colloid cysts. Of 27 patients who underwent transcortical approaches for the resection of subcortical brain tumors and colloid cysts, zero had postoperative seizures. A comprehensive review of the literature shows an 8.3% postoperative risk of seizures after the transcortical approach. Our institution has never experienced a postoperative seizure following the transcortical approach for the resection of deep tumors and colloid cysts. For this reason, we advocate selecting a surgical approach that obtains adequate lesion exposure and minimizes the violation and retraction of eloquent cortex, venous structures, and white matter tracts, rather than on presumed postoperative seizure risk.

Valproic Acid Pretreatment Reduces Brain Edema in a Rat Model of Surgical Brain Injury

Surgically induced brain injury (SBI) results in brain edema and neurological decline. Valproic acid (VA) has been shown to be neuroprotective in several experimental brain diseases. In this study, we investigated the pretreatment effect of VA in a rat model of SBI. A total of 57 male Sprague-Dawley rats were use in four groups: sham, SBI + vehicle, SBI + low dose (100 mg/kg) VA, and SBI + high dose (300 mg/kg) VA. SBI was induced by partially resecting right frontal lobes. Shams underwent identical surgical procedures without brain resection. VA or vehicle was administered subcutaneously 30 min prior to SBI. At 24 and 72 h post SBI, neurobehavior and brain water content were assessed as well as matrix metalloproteinases (MMPs) activities. There was significantly higher brain water content within the right frontal lobe in SBI rats than in shams. Without neurobehavioral improvements, the low-dose but not high-dose VA significantly reduced brain edema at 24 h post SBI. The protection tends to persist to 72 h post SBI. At 24 h post SBI, low-dose VA did not significantly reduce the elevated MMP-9 activity associated with SBI. In conclusion, VA pretreatment attenuated brain edema at 24 h after SBI but lacked MMP inhibition. The single dose VA was not associated with neurobehavioral benefits.

Phosphoinositide 3-Kinase Gamma Contributes to Neuroinflammation in a Rat Model of Surgical Brain Injury

Neuroinflammation plays an important role in the pathophysiology of surgical brain injury (SBI). Phosphoinositide 3-kinase gamma (PI3Kγ), predominately expressed in immune and endothelial cells, activates multiple inflammatory responses. In the present study, we investigated the role of PI3Kγ and PI3Kγ-activated phosphodiesterase 3B (PDE3B) in neuroinflammation in a rat model of SBI. One hundred and fifty-two male Sprague Dawley rats (weight 280-350 g) were subjected to a partial right frontal lobe corticotomy model of SBI. A PI3Kγ pharmacological inhibitor (AS252424 or AS605240) was administered intraperitoneally. PI3Kγ siRNA, human recombinant active-PI3Kγ protein, or human recombinant active-PDE3B protein were administered intracerebroventricularly. Post-SBI assessments included neurobehavioral tests, brain water content, Western blot, and immunohistochemistry. Endogenous PI3Kγ levels were increased within peri-resection brain tissues after SBI, accompanied by increased brain water content and neurological functional deficits. There was a trend toward increased endogenous PDE3B phosphorylation after SBI. The selective PI3Kγ inhibitors AS252424 and AS605240 reduced brain water content surrounding corticotomy and improved neurological function after SBI. SBI increased and PI3Kγ inhibitor decreased levels of myeloperoxidase, cluster of differentiation 3, mast cell degranulation, E-selectin, and IL-1 in peri-resection brain tissues. Direct administration of human recombinant active-PI3Kγ protein and active-PDE3B protein countered the protective effect of AS252424. PI3Kγ siRNA reduced PI3Kγ levels, decreased brain water content within peri-resection brain tissues, and improved neurological function after SBI. Collectively, our findings suggest that PI3Kγ contributed to neuroinflammation after SBI. The use of selective PI3Kγ inhibitors may be a novel approach to ameliorating SBI via their anti-inflammation effects. Significance statement: Life-saving or elective neurosurgeries often involve unavoidable damages to neighboring, nondiseased brain tissues. Such surgical brain injury (SBI) is attributable exclusively to the neurosurgical procedure itself and may cause postoperative complications that exacerbate neurological function. Although the importance of this medical problem is fully acknowledged, intraoperative administration of adjunctive treatment such as steroids and mannitol to patients undergoing neurosurgery appear not to be efficient remedies for SBI. To date, the issue of perioperative neuroprotection specifically against SBI has not been well studied. Using a clinically relevant rat model of SBI, we are exploring a new neuroprotective strategy targeting phosphoinositide 3-kinase gamma (PI3Kγ). PI3Kγ activates multiple inflammatory responses. By attenuating neuroinflammation, selective PI3Kγ inhibition would limit postoperative complications and benefit neurological outcomes.

Combination of Neuroendoscopic and Stereotactic Procedures for Total Resection of Colloid Cysts with Favorable Neurological and Cognitive Outcomes

BACKGROUND

Despite a wide range of surgical procedures, an unresolved debate remains regarding which attempt is optimal for the treatment of colloid cysts in the third ventricle. In this article, we present a new combination of stereotactic and endoscopic techniques.

METHODS

This prospective study includes 27 consecutive patients with symptomatic primary and recurrent colloid cysts. All cysts were removed via a neuroendoscope through a rostral transfrontal, transforaminal approach. The endoscope was supported by an additional cannula fixed in the stereotactic frame. Both tools were inserted into one lateral ventricle through two separate burr holes using stereotactic guidance.

RESULTS

The median operating time was 135 minutes. All cysts were removed completely, and no mortality or permanent complications related to surgery occurred. The mean time of observation was 43.5 months (range, 3-78 months), and no clinical or radiologic recurrences were observed. One patient with a history of an infected ventriculoperitoneal shunt did not improve after cyst removal, but improved after subsequent reimplantation of the shunt. In all other cases, symptoms resolved (67%) or decreased (30%). Cognitive functions improved or remained unchanged in all 10 elective cases examined neuropsychologically before and after surgery.

CONCLUSIONS

The techniques we describe for removal of colloid cysts are safe and effective, even for recurrent cases, and they provide 100% total resection, favorable cognitive outcomes, low risk of recurrence, and low risk of morbidity. The disadvantages of this method are a longer time for surgery and the need for more complex instrumentation compared with conventional endoscopic resection.

Minimizing Collateral Brain Injury Using a Protective Layer of Fibrin Glue: Technical Note

BACKGROUND

Neurosurgical procedures expose the brain surface to a constant risk of collateral injury. We describe a technique where the brain surface is covered with a protective layer of fibrin glue and discuss its advantages.

METHODS

A thin layer of fibrin glue was applied on the brain surface after its exposure in 34 patients who underwent different craniotomies for tumoral and vascular lesions. Data of 35 more patients who underwent standard microsurgical technique were collected as a control group. Cortical and pial injuries were evaluated using an intraoperative visual scale. Eventual abnormal signals at the early postoperative T2-weighted fluid-attenuated inversion recovery (T2FLAIR) magnetic resonance imaging (MRI) sequences were evaluated in oncological patients.

RESULTS

Total pial injury was noted in 63% of cases where fibrin glue was not used. In cases where fibrin glue was applied, a significantly lower percentage of 26% (P < 0.01) had pial injuries. Only 9% had injuries in areas covered with fibrin glue (P < 0.0001). Early postoperative T2FLAIR MRI confirmed the differences of altered signal around the surgical field in the two populations.

CONCLUSION

We propose beside an appropriate and careful microsurgical technique the possible use of fibrin glue as alternative, safe, and helpful protection during complex microsurgical dissections. Its intrinsic features allow the neurosurgeon to minimize the cortical manipulation preventing minor collateral brain injury.

Symptomatic colloid cysts in the third ventricle of monozygotic twins

In this case report we describe colloid cysts in the third ventricles of monozygotic twin sisters. They were 26 years old when their condition was discovered. One woman was admitted to us on an emergency basis, with signs of high intracranial pressure such as unconsciousness and extension posturing. Her sister was also brought to the hospital since she had a history of attacks of headache. They were both operated with removal of the colloid cysts, and the clinical courses are described in the case report. In reviewing the literature another 30 familial cases were found. Of these were two pairs of monozygotic and one pair of dizygotic twins.

Intraoperative Conversion from Endoscopic to Open Transcortical-Transventricular Removal of Colloid Cysts as a Salvage Procedure

OBJECTIVE

 To describe the transcortical-transventricular as an intraoperative salvage procedure and its effect of operative time and outcome.

METHODS

 Thirty-three patients were included in the study. Twenty patients had an endoscopic operation, five had a transcortical-transventricular approach, and eight underwent an interhemispheric approach for resection. Based on common cyst location in the roof of the third ventricle, we propose a simple classification of surgical operative zones based on relationships defined by the anterior column of the fornix, the septal vein, and the medial atrial vein.

RESULTS

 Complete capsule removal was achieved in 35% of endoscopic operations, 100% of transcortical-transventricular operations, and 63% of the interhemispheric operations. Operative time was 176 minutes for endoscopic operations, whereas the operative time for cases that converted to the transcortical-transventricular approach was 190 minutes (p=0.39).

CONCLUSION

 A surgical-based classification of zones within the roof of the third ventricle that can be accessed with microsurgical techniques is proposed. Both endoscopic and microsurgical cyst aspiration and excision remain options. We believe that younger patients, patients with large cysts that fill the third ventricle, or those with recurrence after prior treatment would benefit from open transcortical excision as a safe and effective operative approach using modern image-guided systems. Consent was formally obtained or waived for all subjects present within this study.

Endoscopic Versus Microsurgical Resection of Third Ventricle Colloid Cysts

Objective:

Endoscopic resection of colloid cysts has been performed as an alternative to microsurgical resection and stereotactic aspiration since 1982. To date, there are limited published studies comparing these procedures. In this study, we present the largest series of endoscopic resections published to date and compare outcomes to a cohort of microsurgical resections performed at the same institution.

Methods:

A retrospective chart review was conducted for all patients in the Calgary Health Region undergoing resection of a colloid cyst between 1991 and 2004. Comparison was made between patients treated with endoscopic resection versus microsurgical resection.

Results:

Twenty-five endoscopic and nine microsurgical procedures were performed. Complete resection was achieved in 24 of 25 procedures in the Endoscopic group, compared with all 9 procedures in the Microsurgical group. Patients in the Endoscopic group had a reduced operative time (mean 104 minutes versus 217 minutes) and reduced length of stay (3.8 days versus 8.4 days) compared to the Microsurgical group. One patient in the Endoscopic group had a complication (hemiparesis/pulmonary embolus). By contrast, 3 patients in the Microsurgical group had complications (seizure, ventriculitis/bone flap infection, and transient memory deficit). There was one recurrence in each group which both occurred at 5 years follow-up. The mean length of follow-up is 38 months in the Endoscopic group and 33 months in the Microsurgical group.

Conclusion:

Endoscopic resection of colloid cysts can be performed with significantly lower risk of complication than microsurgical resection and with equivalent surgical success. Operative time and length of hospital stay are both significantly reduced with endoscopic resection.

Long-term results of the neuroendoscopic management of colloid cysts of the third ventricle: a series of 90 cases

BACKGROUND

The endoscopic removal of third ventricular colloid cysts has been developed as an alternative to microsurgical transcortical-transventricular and transcallosal approaches.

OBJECTIVE

To examine the value of endoscopic technique by reviewing the large number of endoscopically treated patients with long-term follow-up in 2 neurosurgical centers.

METHODS

A retrospective chart review was conducted for all patients admitted for resection of a third ventricular colloid cyst to the Radboud University Nijmegen Medical Centre (Nijmegen, The Netherlands) and the Hôpital Henri Mondor (Paris, France) between 1994 and 2007. Both clinical and radiological symptoms and operative results were evaluated.

RESULTS

Postdischarge clinical follow-up was available for 85 patients over a mean period of 4 years 3 months. Permanent morbidity occurred in 1 patient (persisting preoperative memory deficit). Follow-up imaging of 80 evaluable patients showed that total or nearly total cyst removal was possible in 46 individuals (57.5%). Residual cyst was present in 34 patients (42.5%), and 6 required repeated endoscopic surgery for symptomatic regrowth. Recurrent cysts were mainly seen within the first 2 years after surgery.

CONCLUSION

It is debatable whether the higher numbers of recurrent or residual cysts can be justified by the slightly lower complication rates achieved with endoscopic removal. However, results have been improving over the years. Moreover, the modifications observed on control magnetic resonance images justify the need for regular control imaging for at least the first 2 years postoperatively.

Pediatric colloid cysts of the third ventricle: management considerations

PURPOSE

Pediatric colloid cysts (CC) have a congenital origin, and yet, there are very few studies focussing exclusively on their occurrence in the pediatric population. Pediatric CC has been associated with more aggressive clinical and radiological patterns than their adult counterparts. In this study, undertaken on children with anterior third ventricular CC, excised using the interhemispheric transcallosal approach, the characteristic clinicoradiological features and management options are studied.

METHODS

Five pediatric patients (aged 16 years or less; mean age 13.8 years; mean duration of symptoms:7.6 months) out of 38 patients with CC operated between 1995 to 2009 were included. The clinical manifestations included those of raised intracranial pressure (n = 4); exacerbation of occipital headache on reading (n = 1); secondary optic atrophy (n = 3); and, drop attacks (n = 1). On computed tomography scan, the cyst was hyperdense, enhancing in two patients and not enhancing in three patients. All had bilateral lateral ventricular dilatation with periventricular lucency. On magnetic resonance imaging (n = 3), the cyst was T1 hypointense and T2 isointense in one, hyperintense on both T1 and T2 with a hypointense capsule and nonenhancing on contrast in one (with a giant colloid cyst), and T1 hyperintense and T2 hypointense in one patient. An interhemispheric, transcallosal trajectory combined with transforminal approach (n = 3); combined transforminal and subchoroidal approaches (n = 1); and, interforniceal approach (n = 1) were used.

RESULTS

Total excision was performed in four patients. In one patient, a small part of capsule was left attached to thalamostriate vein. Symptoms of raised intracranial pressure showed improvement in all the patients with resolution of hydrocephalus. There was no tumor recurrence at follow-up.

CONCLUSIONS

Pediatric colloid cysts are rarer than their adult counterparts due to their late detection only after manifestations of raised intracranial pressure, visual or cognitive dysfunction or drop attacks occur. Their radiological appearance varies depending upon the amount of mucoid content, cholesterol, proteins, and water content. The fast development of clinical manifestations in children may be related to rapid enlargement of cyst due to higher water content within them. The transcallosal approach is the "gold standard" of surgery and usually ensures gratifying and lasting results.

Rosiglitazone, a PPAR gamma agonist, attenuates inflammation after surgical brain injury in rodents

INTRODUCTION

Surgical brain injury (SBI) is unavoidable during many neurosurgical procedures. This inevitable brain injury can result in post-operative complications including brain edema, blood-brain barrier disruption (BBB) and cell death in susceptible areas. Rosiglitazone (RSG), a PPAR-gamma agonist, has been shown to reduce inflammation and provide neuroprotection in experimental models of ischemia and intracerebral hemorrhage. This study was designed to evaluate the neuroprotective effects of RSG in a rodent model of SBI.

METHODS

65 adult male Sprague-Dawley rats were randomly divided into sham, vehicle and treatment groups. RSG was administered intraperitoneally in two dosages (1 mg/kg/dose, 6 mg/kg/dose) 30 min before surgery, and 30 min and 4 h after surgery. Animals were euthanized 24 h following neurological evaluation to assess brain edema and BBB permeability by IgG staining. Inflammation was examined using myeloperoxidase (MPO) assay and double-labeling fluorescent immunohistochemical analysis of IL-1beta and TNF-alpha.

RESULTS

Localized brain edema was observed in tissue surrounding the surgical injury. This brain edema was significantly higher in rats subjected to SBI than sham animals. Increased IgG staining was present in affected brain tissue; however, RSG reduced neither IgG staining nor brain edema. RSG also did not improve neurological status observed after SBI. RSG, however, significantly attenuated MPO activity and qualitatively decreased IL-1beta and TNF-alpha expression compared to vehicle-treated group.

CONCLUSION

SBI causes increased brain edema, BBB disruption and inflammation localized along the periphery of the site of surgical resection. RSG attenuated inflammatory changes, however, did not improve brain edema, BBB disruption and neurological outcomes after SBI.

Matrix metalloproteinase inhibition attenuates brain edema in an in vivo model of surgically-induced brain injury

OBJECTIVE

Neurosurgical procedures can result in brain injury by various means, including direct trauma, hemorrhage, retractor stretch, and electrocautery. This surgically-induced brain injury (SBI) can cause postoperative complications such as brain edema after blood-brain barrier (BBB) disruption. The present study seeks to test a matrix metalloproteinase (MMP) inhibitor for preventing postoperative brain edema and BBB disruption in an in vivo model of surgically-induced brain injury.

METHODS

A rodent model of SBI was used which involves resection of a part of the right frontal lobe. A total of 89 Sprague-Dawley male rats (weight, 300-350 g) were randomly divided into four groups: 1) SBI with vehicle treatment (0.1% dimethyl sulfoxide), 2) SBI with single treatment of MMP inhibitor-1 (an inhibitor of MMP-9 and MMP-2), 3) SBI treated daily (total 3 times) with MMP inhibitor-1, and 4) sham surgical group. Postoperative assessment at different time periods included evaluation of BBB permeability, brain water content (brain edema), neurological scoring, histology, immunohistochemistry, and zymography for MMP enzymatic activity. Temporal magnetic resonance imaging studies were also performed to assess postoperative edema.

RESULTS

The results indicate that SBI caused increased brain water content (ipsilateral frontal lobe) and BBB permeability compared with sham animals. Treatment with MMP inhibitor-1 attenuated MMP-9 and MMP-2 activity and decreased brain water content with preservation of the BBB.

CONCLUSION

Inhibition of MMP-9 and MMP-2 attenuates brain edema and BBB disruption after SBI. The study suggests a potential role for MMP inhibition as preoperative therapy before neurosurgical procedures.

Matrix metalloproteinase inhibition attenuates brain edema after surgical brain injury

BACKGROUND

Neurosurgical operations can result in inevitable brain injury due to the procedure itself. This surgical brain injury (SBI) can cause post-operative complications such as brain edema following blood-brain barrier (BBB) disruption leading to neurological deficits.

METHODS

We tested whether inhibition of matrix metalloproteinases (MMPs) 9 and 2 provided neuroprotection against SBI. A rodent SBI model, which involves a partial frontal lobe resection, was used to evaluate two treatment regimens of MMP inhibitor-1 (inhibitor of MMP-9 and MMP-2); a single dose (5 mg/kg, pretreatment) and daily dose treatment (5 mg/kg x 3, pre- and post-treatment). Postoperative assessment at different time periods included brain water content (brain edema), immunohistochemical analysis, zymography for MMP enzymatic activity, and neurological assessment.

FINDINGS

The results indicate that SBI caused localized edema around the site of surgical resection with concomitant increase in MMP-9 and MMP-2 activity. Both treatment regimens with MMP inhibitor-1 decreased brain edema and attenuated the rise in MMP-9 and MMP-2 activity. An increased expression of MMP-9 was also seen in the neurons and neutrophils in the affected brain tissue at the periphery of surgical resection.

CONCLUSIONS

The study suggests a potential role for MMP inhibition as preoperative therapy before neurosurgical procedures.

Inhibition of Src tyrosine kinase and effect on outcomes in a new in vivo model of surgically induced brain injury

OBJECT

Brain tissue at the periphery of a neurosurgical resection site is vulnerable to injury by a variety of mechanisms including direct trauma, edema, hemorrhage, retractor stretch, and electrocautery. The goal in the present study was to develop an in vivo model of surgically induced brain injury and to test an Src tyrosine kinase inhibitor for neuroprotective properties in this model.

METHODS

The authors developed a new surgically induced brain injury model in rats. This model involves resection of part of the frontal lobe. Sprague-Dawley male rats weighing between 300 and 350 g were divided randomly into four groups: Group 1, surgical injury with vehicle treatment; Group 2, surgical injury after treatment with PP1 (an Src tyrosine kinase inhibitor with known neuroprotective properties); Group 3, sham surgery; and Group 4, control. Postoperative assessment included blood-brain barrier (BBB) permeability studies, and histological, immunohistochemical, and Western blot analyses. The authors found that surgical injury caused localized edema and disruption of the BBB compared with findings in the sham surgery group. Treatment with PP1 was associated with decreased edema, decreased breakdown of the BBB, decreased expression of both vascular endothelial growth factor and phosphorylated extracellular signal-regulated kinase 1 and 2, and preservation of ZO-1 expression.

CONCLUSIONS

In this study the authors describe a simple and reproducible in vivo animal model of surgically induced brain injury. Pretreatment with PP1 results in improved outcomes in this model, which suggests a possible role for Src tyrosine kinase inhibitors as preoperative therapy for planned neurosurgical procedures.

TREATMENT OPTIONS FOR THIRD VENTRICULAR COLLOID CYSTS

OBJECTIVE

We retrospectively reviewed our experience treating third ventricular colloid cysts to compare the efficacy of endoscopic and transcallosal approaches.

METHODS

Between September 1994 and March 2004, 55 patients underwent third ventricular colloid cyst resection. The transcallosal approach was used in 27 patients; the endoscopic approach was used in 28 patients. Age, sex, cyst diameter, and presence of hydrocephalus were similar between the two groups.

RESULTS

The operating time and hospital stay were significantly longer in the transcallosal craniotomy group compared with the endoscopic group. Both approaches led to reoperations in three patients. The endoscopic group had two subsequent craniotomies for residual cysts and one repeat endoscopic procedure because of equipment malfunction. The transcallosal craniotomy group had two reoperations for fractured drainage catheters and one operation for epidural hematoma evacuation. The transcallosal craniotomy group had a higher rate of patients requiring a ventriculoperitoneal shunt (five versus two) and a higher infection rate (five versus none). Intermediate follow-up demonstrated more small residual cysts in the endoscopic group than in the transcallosal craniotomy group (seven versus one). Overall neurological outcomes, however, were similar in the two groups.

CONCLUSION

Compared with transcallosal craniotomy, neuroendoscopy is a safe and effective approach for removal of colloid cysts in the third ventricle. The endoscope can be considered a first-line treatment for these lesions, with the understanding that a small number of these patients may need an open craniotomy to remove residual cysts.

Neuroprotection against surgically induced brain injury

BACKGROUND

Neurosurgical procedures are carried out routinely in health institutions across the world. A key issue to be considered during neurosurgical interventions is that there is always an element of inevitable brain injury that results from the procedure itself because of the unique nature of the nervous system. Brain tissue at the periphery of the operative site is at risk of injury by various means, including incisions and direct trauma, electrocautery, hemorrhage, and retractor stretch.

METHODS/RESULTS

In the present review, we will elaborate upon this surgically induced brain injury and also present a novel animal model to study it. In addition, we will summarize preliminary results obtained by pretreatment with PP1, an Src tyrosine kinase inhibitor reported to have neuroprotective properties in in vivo experimental studies. Any form of pretreatment to limit the damage to the susceptible functional brain tissue during neurosurgical procedures may have a significant impact on patient recovery.

CONCLUSION

This brief review is intended to raise the question of 'neuroprotection against surgically induced brain injury' in the neurosurgical scientific community and stimulate discussions.

Complete Microsurgical Resection of Colloid Cysts with a Dual-port Endoscopic Technique

Objective:

A dual-port endoscopic approach, used for the surgical management of colloid cysts, was developed with the following goals: 1) a direct, unobstructed, high-illumination endoscopic view of the attachment point of the colloid cyst to the tela choroidea, and 2) a gross total resection of the colloid cyst capsule using microsurgical techniques.

Methods:

Eleven symptomatic, hydrocephalic, colloid cyst patients who underwent operation with a unilateral, precoronal-frontopolar dual-port endoscopic technique were retrospectively assessed. Preoperative magnetic resonance imaging scans were analyzed, comparing the lateral precoronal to the frontopolar approach, to determine the degree of angulation that would be required to directly view the roof of the third ventricle. Clinical outcome and radiographical follow-up were assessed.

Results:

The frontopolar approach achieved an approach angle to the roof of the third ventricle of only 15 ± 4 degrees compared with 56 ± 6 degrees (P&lt; 0.0001) for the precoronal approach. The view obtained from the frontopolar endoscope allowed excellent visualization of the cyst attachment point. Microsurgical dissection techniques, using many standard microsurgical instruments introduced through the second port, were satisfactorily accomplished. Complete resections were obtained in 10 out of 11 dual-port patients. Worsening of memory deficits occurred in one patient. There was no cyst recurrence with a mean follow-up period of 26 ± 27 months.

Conclusion:

The dual-port endoscopic technique described is an alternative to classic microsurgical craniotomy approaches. The technique allows excellent visualization of the colloid cyst attachment and permits microdissection techniques.

NADPH oxidase inhibition improves neurological outcomes in surgically-induced brain injury

Neurosurgical procedures can result in brain injury by various means including direct trauma, hemorrhage, retractor stretch, and electrocautery. This surgically-induced brain injury (SBI) can cause post-operative complications such as brain edema. By creating a mouse model of SBI, we tested whether NADPH oxidase, an important reactive oxygen species producing enzyme, is involved in SBI using transgenic mice lacking gp91phox subunit of NADPH oxidase (gp91phox KO) and apocynin, a specific inhibitor of NADPH oxidase. Neurological function and brain edema were evaluated at 24 h post-SBI in gp91phox KO and wild-type littermates grouped into SBI and sham-surgery groups. Alternatively, mice were grouped into vehicle- and apocynin-treated (5 mg/kg, i.p. 30 min before SBI) groups. Oxidative stress indicated by lipid peroxidation (LPO) was measured at 3 and 24 h post-SBI. The gp91phox KO mice, but not the apocynin-treated mice showed significantly improved neurological scores. Brain edema was observed in both gp91phox KO and wild-type groups after SBI; however, there was no significant difference between these two groups. Brain edema was also not affected by apocynin-pretreatment. LPO levels were significantly higher in SBI group in both gp91phox KO and wild-type groups as compared to sham group. A trend, although without statistical significance, was noted towards attenuation of LPO in the gp91phox KO animals as compared to wild-type group. LPO levels were significantly attenuated at 3 h post-SBI by apocynin-pretreatment but not at 24 h post-SBI. These results suggest that chronic and acute inhibition of NADPH oxidase activity does not reduce brain edema after SBI. Long-term inhibition of NADPH oxidase, however improves neurological functions after SBI.

Posterior interhemispheric approach: surgical technique, application to vascular lesions, and benefits of gravity retraction

OBJECTIVE

To review an experience with the posterior interhemispheric approach applied to vascular lesions in the posterior midline, to examine the effects of patient position and gravity retraction of the occipital lobe, and to identify circumstances requiring increased exposure by sectioning the falx and tentorium.

METHODS

During a 6.5-year period, 46 posterior interhemispheric approaches were performed to treat 28 arteriovenous malformations, 10 dural arteriovenous fistulae, seven cavernous malformations, and one posterior cerebral artery aneurysm. Twenty-three patients were positioned prone and 23 patient were positioned laterally.

RESULTS

A standard posterior interhemispheric approach was used in 38 patients, and the occipital bitranstentorial/falcine approach was used in seven patients. A contralateral occipital transfalcine approach was used with one thalamic cavernous malformation. All lesions were resected completely and/or obliterated angiographically, with good neurological outcomes in 83% of patients and no operative mortality. Blood loss was lower, operative durations were shorter, postoperative cerebral edema was decreased, and visual outcomes were improved in patients positioned laterally.

CONCLUSION

The posterior interhemispheric approach, without additional dural cuts, is appropriate for most vascular lesions in the posterior midline. Gravity retracts the occipital lobes when patients are positioned laterally, enhancing operative exposure and reducing morbidity. Extension of the posterior interhemispheric approach to a transtentorial or transfalcine approach is required for falcotentorial dural arteriovenous fistulae and vein of Galen arteriovenous malformations, but is not usually necessary with cavernous malformations or other arteriovenous malformations.

Surgically induced brain injury in rats: the effect of erythropoietin

Brain tissue at the edge of a surgical resection site is at risk for damage from direct trauma, retractor stretch, hemorrhage, edema, and electrocautery. In this study we used a new rodent model of surgically induced brain injury (SBI) to study this tissue at the edge of a resection site. The SBI model entails stereotaxic resection of part of the right frontal lobe. We tested pretreatment with erythropoietin, a known neuroprotectant, for protective effects in this model. Three groups of male Sprague-Dawley rats (280-330g) were used: SBI without treatment (n=63), SBI with EPO treatment (n=76), and Sham surgery (n=12). Rats were sacrificed 24h, 72h, and 7 days after SBI or Sham surgery. Postoperative assessment included mortality, histology, immunohistochemistry, Evans blue exudation, brain water content, and magnetic resonance imaging. No difference was found between untreated and EPO-treated groups in mortality, histology, TUNEL, magnetic resonance imaging, or blood-brain-barrier breakdown. The EPO-treated group had statistically more brain water content at 24h than the untreated group. Immunohistochemistry demonstrated a qualitative increase in VEGF in the EPO-treatment group. We conclude that EPO does not ameliorate damage in SBI, and may increase brain edema early after surgery.

Intracranial metastasis of lung adenocarcinoma mimicking colloid cyst of the third ventricle

A patient with intracranial lung adenocarcinoma metastasis mimicking a colloid cyst of the third ventricle is reported. These tumours may be associated with excessive bleeding and may infiltrate into surrounding structures. Open microsurgery rather than endoscopic surgery should be considered for these cases, particularly a transcortical-transventricular or transcallosal approach, in order to avoid serious complications.