Do the clinicoradiological outcomes of endoscopic fenestration for intracranial cysts count on age? An institutional experience
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/neuroindia.NI_934_15
Source of Support: None, Conflict of Interest: None
Background: The clinicoradiological outcome of endoscopic fenestration of intracranial cysts and predictors of an unfavorable outcome, including age, are under reported in the neurosurgical literature. In this cohort, our experience in the endoscopic fenestration of intracranial cysts is reviewed.
Keywords: Endoscopic fenestration, intracranial cysts, outcomes, ventricle
Modern neuroimaging techniques have revealed a higher incidence of congenital as well as acquired intracranial cysts., Treatment modalities for the intracranial cysts have been widely variable. As of now, management options for intracranial cysts include a conservative approach with serial imaging, shunt placement, or either open or endoscopic drainage of the cyst., However, the indication to perform surgery for intracranial cysts remains unclear due to poor understanding of the pathophysiology and natural history of the disease. The recent advancements in the field of endoscopic instrumentation and wide use of neuroendoscopic techniques have allowed us a minimally invasive surgical treatment modality for these lesions.,,,, Previous reports have shown that neuroendoscopic management of these lesions is a safe and effective therapeutic modality.,, Clinical outcome was better in the patients who underwent endoscopic treatment, and radiologically, the cyst size decreased approximately in 72–83% of the patients., Our institutional policy is to offer either open or endoscopic surgical intervention if the clinical symptoms are severe and conservative treatment has failed, or if the patient experiences neurological deficits, seizure, or hydrocephalus. This retrospective study reviews our institutional experiences with the endoscopic management of intracranial cysts with respect to the clinical and radiological outcomes.
This study was done after approval of the Institutional Review Board at Louisiana State University (LSU) Health-Shreveport. Information related to clinical history, endoscopic fenestration, neuroimaging, and outcomes of the patients with intracranial cysts between 1994 and 2013 was collected retrospectively by review of the patients' case reports and follow-up notes.
Patients and cyst characteristics
Patient demographics and cyst characteristics for those patients included in our study are listed in [Table 1]. In brief, the median age was 28 years (range: 0–82 years). Out of the 30 patients, 19 (63.3%) were males and 11 (36.7%) were females; 12 (40%) were Caucasians and 18 patients (60%) were African–Americans. Fifteen (50%) patients were children and 15 (50%) were adults. A third of the patients (n = 10) had arachnoid cysts while the remaining 20 patients (66.7%) had a host of other pathologies like septum pellucidum cyst (n = 3), Rathke's cleft cyst (n = 1), subependymal cyst (n = 3), neuroglial cyst (n = 5), posterior fossa cysts associated with Dandy–Walker Syndrome (n = 2), endodermal cyst (n = 2), pituitary cyst (n = 1), and choroid plexus cyst (n = 3). Arachnoid cysts were located in the suprasellar region (n = 2), Sylvian fissure (n = 1), cerebellopontine angle cistern (n = 2), and the supracerebellar (n = 2), parietal (n = 1), and pre-pontine (n = 2) regions. Radiologically, reduced cyst size was considered in the patients when reduction of size to <50% of the original size was obtained after endoscopic fenestration.
Endoscopic fenestration is an important treatment option for intracranial cysts due to significant morbidity associated with microsurgical fenestration and a higher incidence of shunt revision associated with a cystoperitoneal shunt. In this study, a rigid endoscope was used to fenestrate the intracranial cysts.
Procedure of endoscopic fenestration of the cyst
The procedure has been described for the right side paraventricular cyst ([Figure 1]a,[Figure 1]b,[Figure 1]c,[Figure 1]d,[Figure 1]e,[Figure 1]f). After taking informed consent and appropriate positioning, the patient was placed in the 3-point Mayfield fixation. The stealth neuronavigation system was then registered to a high degree of accuracy. The appropriate trajectory was confirmed and then a linear incision in the left parietal-occipital area was planned that would allow access to the cyst wall through the left occipital horn. After confirmation with neuronavigation, the operative part was painted and draped. The left parietal-occipital skin incision was made and soft tissue dissection was done down to the skull. A single burr hole was made and dura was opened in a cruciate manner. The underlying cortex was coagulated and incised using a number 11 blade knife. The appropriate trajectory was assessed and the stealth probe was advanced into the ventricle, which was accessed at only approximately 2 cm depth through the cortex. The 4 mm × 18 mm zero-degree endoscope was then introduced into the left occipital horn. Using stealth neuronavigation, the wall of the cyst was identified and found to be bulging [Figure 1]a. The wall had a very thin layer of neural tissue overlying it. The cyst wall was carefully opened using a blunt probe. A 3-French Fogarty catheter balloon was passed through the blunt probe opening [Figure 1]c. The Fogarty balloon was slowly inflated and drawn back through the opening that had already been made to achieve a larger fenestration [Figure 1]e. Once the initial fenestration was done, the endoscope was advanced into this area and it was confirmed that its distal end was indeed inside the cyst cavity. This area was also further explored, and once the wide fenestration of the cyst had been done, evaluation of the tract and interventricular space for hemostasis was performed. Any bleeding points were carefully controlled using constant warm saline irrigation. Once hemostasis was secured, the endoscope was withdrawn and a small piece of gel foam was placed at the cortical opening. The dural closure was supplemented using durafoam and fibrin glue. Skin and galea aponeurotica were closed and a sterile dressing placed over the wound.
In case the cyst had a different location, a separate safe and suitable entry point was considered with the help of the neuronavigation ensuring minimal damage to the neural tissue.
[Figure 1] depicts the different steps of endoscopic fenestration of intracranial cysts.
Preoperative and follow-up data were collected from the patients' case reports and follow-up notes. Neuroimaging studies were performed at 3-month intervals in the first year after the endoscopic treatment, at 6-month intervals for the following 2 years, and annually thereafter. The mean and median duration of follow-up were 67.1 and 43 months (range 6–197 months), respectively.
The analysis was conducted using Statistical Package for Social Sciences (SPSS) software, version 21.0 (IBM Corp., Armonk, NY). Univariate analysis was performed to identify the predictive factors for positive outcome of endoscopic intracranial cyst fenestration. A chi-square test was also used to demonstrate the significance of improvement of symptoms (pre- vs. post-endoscopic). A P value of <0.05 was considered to be significant.
Changes in cyst size after endoscopic intervention according to the age of the patient
Changes in cyst size in children after endoscopic fenestration
Changes in cyst size after endoscopic fenestration are listed in [Table 2]. The most recent follow-up showed decreased cyst size in 9 (60%) patients with no change in the remaining patients (n = 6,40%). The median time to reduction of the cyst size was 8 months (range: 3.5–15.5 months).
Changes in cyst size in adults after endoscopic fenestration
Changes in the cyst size after endoscopic intervention are listed in [Table 2]. The most recent follow-up showed a decreased cyst size in 10 (66.7%) patients with a change of cyst size in the remaining 5 (33.3%) patients. The median time to reduction of the cyst size was 9.0 months (range, 4.3-14.1months). Placement of shunts was required in 66.7% of the children and 33.3% of the adults, respectively. Patients with communicating hydrocephalus did not require shunt placement.
Changes in cyst size after endoscopic intervention according to cyst type
Changes in arachnoid cyst size after endoscopic intervention are listed in [Table 3]. Among 10 such patients, the most recent follow-up showed cyst size reduction in 7 (70%) of the patients with remaining 3 patients having no change in their cyst size (30%). The median time required for reduction in cyst size was 8.3 months (range: 5.8–10.4 months).
Other cyst types
Changes in the cyst sizes of other types of cysts after endoscopic intervention are listed in [Table 3]. For patients with a non-arachnoid cyst pathology, the most recent follow-up showed that only 60% (n = 12) of the patients had reduction of their cyst size at a median post-operative duration of 8.8 months (range: 3.5–15.5 months). The cyst size did not change in the remaining 8 (40%) patients.
Interestingly, adults with an arachnoid cyst and obstructive hydrocephalus showed better results in cyst reduction than children. On the contrary, other cyst types with communicative hydrocephalus in children showed better results compared to the adults [Table 4].
Changes in symptoms
There were significant differences in resolution of clinical symptoms after endoscopic fenestration of the intracranial cysts. The overall resolution of clinical symptoms was 83%, P= 0.0001. While headache (33.3% Vs. 6%, P= 0.0001) and neurological deficits (83% Vs. 10%, P= 0.0001) reduced significantly after endoscopic fenestration, the reduction in the seizures was not statistically significant (13.3% vs. 6.6%, P= 0.14).
We had two procedure related complications in our series. One patient developed intraventricular hemorrhage (IVH) after shunt replacement while another patient developed post-procedure ventriculitis and meningitis. Both patients recovered over a certain period of time after the procedure. There were no wound related complications or fornicial damage.
Predictors of positive outcome after endoscopic fenestration
Univariate analysis was performed to identify the predictors of a positive outcome after endoscopic fenestration, and the results are shown in [Table 5]. To investigate the effects of various factors on the improvement of symptoms of ICP, neurological deficits, cyst size, and mass effect, the following covariates were included in the model: children vs. adult, cyst type (arachnoid vs. other cysts), gender (male vs. female) and type of hydrocephalus (communicative vs. obstructive). All four factors including children, arachnoid cysts, female gender and communicative hydrocephalus positively affected the improvement of symptoms of ICP. Patients with communicative hydrocephalus showed significant difference in reduction of cyst size compared to those with obstructive hydrocephalus. Female patients showed a significant difference in the reduction of cyst size compared to the male patients. Similarly, patients with communicative hydrocephalus showed a significant difference in reduction of cyst size compared to the patients with obstructive hydrocephalus.
Predictors of positive outcome for ventriculoperitoneal and cystoperitoneal shunt revision after endoscopic fenestration
Out of 30 patients, 15 (50%) patients required either a ventriculoperitoneal (VP) or a cystoperitoneal shunt placement because the symptoms were not relieved by endoscopic fenestration. These shunts were placed during the follow-up period [Figure 2]a,[Figure 2]b,[Figure 2]c,[Figure 2]d,[Figure 2]e,[Figure 2]f. 13 (86.7%) of these patients eventually required shunt revisions. Univariate analysis was performed to identify the predictors of shunt revision after endoscopic fenestration, and the results are shown in [Table 6]. The following covariates were included in the model: children vs. adult, cyst type (arachnoid vs. other cysts), gender (male vs. female), and type of hydrocephalus (communicative vs. obstructive). In the univariate analysis, among the listed factors, adults, arachnoid cyst and communicative hydrocephalus showed a significant likelihood of requiring less shunt revisions after shunt placement.
Although some intracranial cysts remain static in their size, other cysts will grow and compress the adjacent brain tissues. Various mechanisms have been proposed for the growth of intracranial cysts although the exact underlying mechanism is unknown. While the microsurgical approach of craniotomy with cyst fenestration as well as the approach of placement of a cystoperitoneal shunt are still valuable techniques, these are associated with significant morbidity and a high incidence of failure (particularly the cystoperitoneal shunt). Endoscopic fenestration, a lesser invasive technique, is very promising and safe for the management of intracranial cysts. Our study failed to show a higher success rate of endoscopic fenestration compared to microsurgical fenestration (50% vs 83.3%) for intracranial cysts, a result very much comparable with the findings of previous studies., Nevertheless, this is the first study in the literature to compare the outcomes of endoscopic fenestration of intracranial cysts between children and adults, identifying the predictors of positive outcome in the endoscopically managed cysts.
During follow-up, most of our patients showed a good clinicoradiological outcome (complete remission or improvement of symptoms) after endoscopic fenestration. A majority of the cases also showed a decrease in the size of the cyst as well as reduced mass effect. These results were comparable with the findings of earlier studies.,, Reduction of cyst size is an important prognostic factor for a better outcome after treatment of intracranial cysts. In this study, 63.3% of patients showed reduced cyst size after endoscopic fenestration. In the published literature, cyst size reduction has been reported to be between 24.2–81.8%. In this study, the percentage of reduction of the cyst size in children and adults was 60% and 67%, respectively. There was no significant difference in cyst size reduction between children and adults.
Interestingly, there was a marked difference in the number of adults who had reduction in the size of the arachnoid cyst and obstructive hydrocephalus compared to children. However, other cysts with obstructive hydrocephalus did not show such a difference with respect to the age. Children with communicative hydrocephalus and other cyst types had lesser chances of cyst size reduction compared to the adults.
The intracranial cyst type may influence the outcome of the endoscopic intervention. Our data revealed reduction in size of the arachnoid cyst in 70% of the cases with complete or partial clinical remission in as high as 85% of the patients after endoscopic intervention. This finding is consistent with the findings in the existing literature, which reported 84.2% clinical remission with arachnoid cysts. There was a significant difference in clinicoradiological outcomes between arachnoid cysts and other cyst types. There was 100% reduction of mass effect in arachnoid cysts compared to 63% in other cysts. Although there was a marked difference in decreased mass effect in adults (71%) compared to children (60%), the difference was not statistically significant.
Another objective of this study was to identify the predictive factors for a positive outcome in endoscopic management of intracranial cysts. In the present study, the patients having an arachnoid cyst, female gender and communicative hydrocephalus showed statistically significant decrease in symptoms of intracranial pressure. Patients with communicative hydrocephalus showed a significant reduction in cyst size. Female gender and communicative hydrocephalus were identified as positive predictors for decreasing mass effect.
Another component of this study was to investigate the requirement of a cystoperitoneal shunt after the endoscopic management. In children, 67% of the cases required a VP shunt; whereas only 33% of the adults required a CSF diversion. In addition, the incidence of shunt revision in children were higher than in adults (60% vs 27%). The requirement of VP shunt placement (P = 0.0001) as well as subsequent revision (P = 0.001) were significantly different between children and adults. On univariate analyses, patients who had arachnoid cysts (P = 0.046) and communicative hydrocephalus (P = 0.0001) showed a significant likelihood of requiring less shunt revisions after shunt placement.
The present study is subject to a number of limitations. Limitations of this study include all the inherent limitations of a retrospective review. Although a uniform technique for neuroendoscopy was practiced, the overall management was performed by a number of neurosurgeons, and hence, there were certain individual differences in techniques. The influence of different cyst sizes and their location on the results could not be compared because the cysts were differing in pathology and were at varied locations, and the number of subjects in each of the subgroups was too small for any meaningful result to be obtained.
In summary, although endoscopic fenestration is an effective neurosurgical procedure for the management of intracranial cysts, the surgeon's experience and proper selection of patients are essential for an optimal patient outcome. Endoscopic fenestration is more beneficial in adults and in arachnoid cysts compared to children and other cyst types. In addition, predictive factors including adults, arachnoid cyst, female gender, and communicative hydrocephalus positively influenced the clinicoradiological outcome and requirement of shunt revision. Further randomized controlled studies of a large volume of patients with intracranial cysts and endoscopic intervention are required to accomplish a good comparison of the clinical outcome for endoscopic fenestration between children and adults or between different cyst types.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]