https://orcid.org/0000-0003-3254-286X
Abstract
Purpose
The surgical approach for colloid cysts of the third ventricle mainly consists of endoscopic or microscopic approach but few studies compare the neurologic outcomes and complications related to the different approaches. We retrospectively reviewed our results after resection of colloid cysts of the third ventricle using endoscopic surgery (ES) compared to open microsurgery (OS).
Methods
Fifty-one patients were included in the study of which 17 patients underwent ES. Colloid cyst size and Evans’ index were evaluated on CT or MRI scans. Presenting symptoms, neurologic outcomes and complications were compared between the two groups and analysed using Fisher’s exact test. Operative time and days of hospital stay were compared between the two groups, using independent sample t-test. The median follow-up time was 96 days and did not differ significantly between the groups.
Results
Shorter mean operative time (p = 0.04) and fewer days of hospital stay (p < 0.01) were found in the endoscopic group compared to the open microsurgical group. Presenting symptoms, neurological outcomes and postoperative complications were similar in the two groups.
Conclusions
ES showed similar neurologic outcomes and complications compared to OS for colloid cysts of the third ventricle. ES showed significantly shorter operative times and hospital stays compared to OS.
Introduction
Colloid cysts of the third ventricle are rare benign lesions located close to the foramina of Monro. The prevalence of these cysts has been approximated to be 1 in 8500 personsCitation1 with an estimated incidence of 0.9–3.2 per million peopleCitation2,Citation3. Although benign, they can cause acute obstructive hydrocephalus and sudden death by obstructing the foramina of MonroCitation4,Citation5. The mortality rate from cerebral herniation due to ventricular obstruction has been reported to be 5%Citation1. However, more commonly, the patients develop symptoms of hydrocephalus such as headache, nausea, and vomitingCitation4,Citation6. Headache, often of paroxysmal nature, has been reported to be the most common symptom. This headache is caused by the colloid cyst acting as a ball valve that temporarily obstructs the CSF flow and raises the intracranial pressure (ICP). Some patients report that the headache is relieved in the lying down position, opposite to what is seen in ‘high pressure’ headache. Diagnosis is confirmed using radiologic imaging through computed tomography (CT) or magnetic resonance imaging (MRI)Citation7. Lumbar puncture is not advised in the diagnosisCitation7 and has even been suspected as a cause of sudden death in colloid cyst patientsCitation2.
Colloid cysts have traditionally been operated through open microsurgery (OS), but advances with the endoscopic equipment and introduction of technical nuances to the endoscopic approach have made this approach the first-hand choice in several neurosurgical centersCitation8–11. There is currently no consensus on the approach of choice that yields the most favourable results, in the treatment of patients with colloid cysts.
The microsurgical approaches have been associated with lower risk of recurrence, fewer re-operations, and a greater likelihood of total resection. Endoscopic surgery (ES) on the other hand, has been reported to have fewer complications, shorter operative time, and reduced length of hospital stayCitation12–14. In addition, ES has seen development during the recent decades, and a fairly equal rate of total resection in comparison to the microsurgical methodsCitation15. Some of the complications of these surgical procedures are memory deficits, seizures, infections, and intracerebral hemorrhagesCitation2,Citation3,Citation13,Citation14,Citation16,Citation17.
The aim of this study was to retrospectively review the perioperative outcomes and complications in patients who underwent surgery for colloid cysts of the third ventricle by endoscopic or open microsurgical approach at our institution between 1997 and 2016.
Patients and methods
All patients (n = 51) who underwent surgery for colloid cyst of the third ventricle between 1997 and 2016 at the Department of Neurosurgery, Sahlgrenska University Hospital, Gothenburg, Sweden, were included. During this period, the choice of operative method depended on the senior surgeon who was on call when the patient was admitted, who later performed the procedure. In total, six neurosurgeons performed the surgeries, of whom three performed the endoscopic procedures. The digital medical records of all patients who underwent surgery for intracranial cysts, hydrocephalus, and brain tumour at Sahlgrenska University Hospital were identified. Patients undergoing surgery were then selected, first by using IBM Cognos version 10.2.1 for the presence of the word ‘colloid cyst’ (including possible misspellings) and then by manually reviewing the medical records. Information on pre- and postoperative symptoms, and complications were collected from the patient charts and analysed.
The diagnosis of colloid cyst was confirmed by pathology in 44 (86%) patients. In the cases where the histopathological report was missing (5 in the OS group and 2 in the ES group), the diagnosis was based on the combination of radiographic and intraoperative findings.
Maximal cyst diameter and Evans’ index were measured on MRI or CT scans by a neuroradiologist (author DZ). All patients underwent first time operations for colloid cysts, except for one patient in the OS group who underwent a re-operation (previously operated with OS five years earlier, before for the inclusion period). The median follow-up time was 96 days (n = 45, P25=69, P75=149) and did not differ significantly between the groups. Three patients in the ES group and four in the OS group were lost to follow-up. Patient cohort characteristics are presented in .
Table 1. Characteristics of patients undergoing endoscopic or open microsurgical treatment of colloid cysts of the third ventricle.
In the MS group, the approach was performed through a transcallosal route in 29 patients and through a transcortical route in 5 patients. ES was performed by placement of a burr hole approximately 3 cm lateral to Kocher’s point on the right side. After opening the meninges a rigid endoscope was inserted transcortically to the frontal horn of the right ventricle where the colloid cyst was incised with scissors. Cyst content was aspirated through a thin catheter inserted through the endoscope. The remaining cyst capsule was then dissected from its attachment at the roof of the third ventricle and while grabbed with endoscopic forceps, the cyst was taken out with the endoscope.
Ethics
The study was approved by the local ethical committee in Gothenburg, D-number 328-14. All patient data were de-identified at the time of data analysis and presentation.
Statistical analysis
All analysis were done using IBM® SPSS® Statistics, version 24.0 (Chicago, IL, USA). Information on symptoms and complications were stored using dichotomous variables and analysed with Fisher’s exact test (two-sided). Operative time and hospital stay were presented as means ± SD and analysed with independent sample t-test. Variables that were not normally distributed were presented as medians and quartiles (P25 and P75) and analysed with Mann–Whitney U-test. All tests were two-tailed and alpha was set to < 0.05.
Results
Fifty-one patients underwent surgery for colloid cysts of the third ventricle; 17 (33%) were from the ES group and the remaining were from the OS group. Mean postoperative hospital stay was significantly (p < 0.01) shorter for the ES group (5.6 days (±SD 6.1)) when compared to the OS group (11.3 days (±SD 10.4)). Mean operative time was significantly (p = 0.04) shorter in the ES group (148 (±SD 50) minutes) when compared to the OS group (198 (±SD 50) minutes).
Acute surgery (within 24 hours) was performed on five patients in the ES group and nine patients in the OS group. Presenting symptoms, postoperative improvement and complications are presented in . Nine patients in the ES group (53%) and 20 patients in the OS group (59%) presented with hydrocephalus symptoms. Eight patients in the OS group and one patient in the ES group presented with reduced level of consciousness (Glasgow comma scale (GCS) <9).
Table 2. Presenting symptoms, postoperative outcomes and complications for patients with colloid cysts of the third ventricle treated with endoscopic surgery or open microsurgery.
In two patients in the OS group and in two patients in the ES group, an external ventricular drainage (EVD) was initially placed overnight before the resection of the colloid cyst. In seven patients in the OS group and in five patients in the ES group, an EVD was placed when resection of the colloid cyst was completed, to monitor the intra-cranial pressure postoperatively for a maximum of two days. No patient received a permanent cerebrospinal fluid shunt at the follow-up visit.
In two patients in the OS group, ES was attempted but total cyst removal failed; and hence, the procedure was immediately converted to OS. These two converted cases were included in the OS group. Postoperative complications were not significantly higher (p = 0.32) in the OS group (24%) when compared to the ES group (12%).
Discussion
Although few published studies compare ES and OS for colloid cysts of the third ventricle, our findings of shorter mean operative time and mean hospital stay for ES compared to OS are in agreement with previous studies.Citation12,Citation14,Citation18,Citation19. Shorter operative time can be associated with smaller incisions and a more favourable approach angle to the attachment site of the colloid cyst in the roof of the third ventricle in the ES method.
The study showed that the total complication rate was in line with previous studiesCitation13,Citation14,Citation20,Citation21. Although postoperative complications occurred in two patients (12%) in the ES group and eight patients (24%) in the OS group, the difference was not significant. Lack of statistical power may be one reason for this finding. Nevertheless, the results of this study indicate that ES seems to be a safe procedure comparable to OS in regards to the complication rate.
As colloid cysts of the third ventricle are located in close proximity to the fornices, iatrogenic fornix injury has been shown to be associated with short-term memory disturbanceCitation17. Due to the retrospective design of this study, postoperative short-term memory disturbance could not be systematically assessed. We believe that formal neurocognitive testing preoperatively at baseline and postoperatively could be feasible and valuable to evaluate the short-term memory disturbance in patients with colloid cysts of the third ventricle. Formal neuro-cognitive testing could then be used to compare short-term memory disturbance with the two surgical approaches. A prospective study design using a standardized protocol for short-term memory disturbance, pre- and postoperatively, could be valuable in future studies to determine short-term memory disturbance related to surgery.
In two patients of the OS group, ES was attempted initially which failed, and the procedures were converted to OS during the same procedure. These were in fact the first two patients at our institution to be operated on with the endoscopic approach, and therefore, we believe that a learning effect was present. Similarly, previous studies have shown that a learning curve is present when introducing the endoscopic approach. We believe that several variables such as different surgical instrumentation, angle of anatomic view, and new technical tools may contribute to the learning curve.
It has been shown that sub-total resection of colloid cysts increases the risk of recurrenceCitation12,Citation15,Citation16. Therefore, complete resection of the colloid cyst should be attempted. In this study, the only re-operation due to recurrence was found in a patient in the OS group who had a recurrence as detected on MRI investigation five years postoperatively. Accordingly, future studies should include long-time monitoring to determine the recurrence rate and provide sufficient data for comparison.
OS has traditionally been considered as the “gold standard” for surgical treatment of colloid cysts of the third ventricleCitation20,Citation22,Citation23. In OS, access to colloid cysts of the third ventricle is gained either through a transcallosal or a transcortical route through the lateral ventricle and foramen of Monro. Both the transcallosal and transcortical routes have been associated with a high degree of total resection and low recurrence ratesCitation13,Citation20,Citation22. However, the incidence of complications such as memory deficit, venous infarction, and meningitisCitation13,Citation22 urges the need for safer and improved approaches.
Due to technical advancements such as the introduction of neuronavigation and small diameter endoscopesCitation8, ES has emerged as a compelling, minimally-invasive alternative to OS. In this approach, a burr hole is used in favour of a craniotomy, potentially reducing the risk of bone flap infections. Previous studies and the results of the present study with reduced operative time and shorter hospital stay, support the usefulness of ESCitation12,Citation14. More importantly, lower complication rates have been reported with this approach in previous studiesCitation13,Citation14. Furthermore, the types of complications resemble those of the OS approach, including memory deficit, hemiparesis, and meningitisCitation12,Citation13,Citation21.
Despite the retrospective design of this study, a consecutive patient series with a relatively large number of patients from a defined geographical location was evaluated. The surgical approach, either endoscopic or microscopic, was largely based on the preference of the senior neurosurgeon on call and therefore, no systematic bias was present in this regard. We believe that future prospective studies with long-term follow-up data may be highly valuable in evaluating the postoperative results of the surgical treatment of colloid cysts of the third ventricle.
Conclusions
Endoscopic surgery showed similar rates of clinical outcomes and complications compared to open microsurgery. Significantly shorter mean operative time and mean hospital stay were observed in the group who underwent ES.
Disclosure statement
The authors have no conflicts of interest to declare.
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