Accepted Manuscript Aqueduct Stent Placement: Indications, Technique and Clinical Experience Jiefeng Geng, MD, Dongdong Wu, MD, Xiaolei Chen, MD PhD, Meng Zhang, MD, Bainan Xu, MD, PhD, Xinguang Yu, MD, PhD PII:

S1878-8750(15)00779-2

DOI:

10.1016/j.wneu.2015.06.031

Reference:

WNEU 2983

To appear in:

World Neurosurgery

Received Date: 10 February 2015 Revised Date:

14 June 2015

Accepted Date: 15 June 2015

Please cite this article as: Geng J, Wu D, Chen X, Zhang M, Xu B, Yu X, Aqueduct Stent Placement: Indications, Technique and Clinical Experience, World Neurosurgery (2015), doi: 10.1016/ j.wneu.2015.06.031. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT AQUEDUCT STENT PLACEMENT: INDICATIONS, TECHNIQUE AND CLINICAL EXPERIENCE

Jiefeng Geng MDa, Dongdong Wu MDa, Xiaolei Chen MD PhDa, Meng Zhang MDa,

a

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Bainan Xu MD, PhDa, Xinguang Yu MD, PhDa

Department of Neurosurgery, PLA General Hospital, 28 Fuxing Road, Haidian

District, Beijing 100853, China

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 Jiefeng Geng and Dongdong Wu contributed equally to this study.

Corresponding author: Xiaolei Chen, MD, PhD Department of Neurosurgery Chinese PLA General Hospital

China Tel:+86-10-66938318

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Beijing 100853

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E-mail address for the first author: [email protected]

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FAX: +86-10-68150287

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E-mail address: [email protected]

ACCEPTED MANUSCRIPT ABSTRACT OBJECTIVE: Complicated hydrocephalus, such as trapped fourth ventricle, is challenging. Aqueduct stent placement is a possible alternative to the conventional

clinical experiences of aqueduct stent placement.

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multiple shunts approach. This paper discusses the indications, techniques, and

METHODS: We retrospectively analyzed a series of 10 consecutive patients with

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hydrocephalus and had aqueduct stent placement between February 2009 and May 2014. The clinical and imaging data were collected and the indications, technique and

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clinical experience of aqueduct stent placement were analyzed and discussed.

RESULTS: Among the 10 patients (mean age 38 years, range from 5 months to 69 years), eight patients harbored an obstructive hydrocephalus caused by aqueductal obstruction. The underlying pathology consisted of intra-ventricular tumor in 3 cases,

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intra-ventricular cysticercosis in 2 cases, and membranous or inflammatory obstruction in 3 cases. Two patients presented trapped fourth ventricle (TFV) resulted from Dandy-Walker malformation and shunt placement respectively. Aqueduct stents were placed endoscopically in 8 cases while the other 2 were placed microscopically.

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There were no deaths due to aqueduct stent placement. Post-operatively, all of the patients showed improvement or resolution of their symptoms. After an average

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follow-up period of 27 months (range from 1 to 51months), recurrence of aqueductal obstruction has not been observed. In one patient, there was a complication of transient oculomotor paralysis after aqueduct stent placement. A stent migration was observed in one patient after maintaining stable for about 4 years.

CONCLUSIONS: Aqueduct stent placement is technically feasible and can be useful in selected patients either through endoscopic or open surgery.

KEYWORDS

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Aqueduct stent placement, aqueductal stenosis, third ventriculostomy, trapped fourth

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ventricle, cerebrospinal fluid

ACCEPTED MANUSCRIPT INTRODUCTION

With

the

development

of

neuro-endoscopic

technology,

endoscopic

third

ventriculostomy (ETV) has become the standard procedure for the management of obstructive hydrocephalus caused by aqueductal stenosis. This procedure, as well as

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shunt, is regarded an effective weapon to treat hydrocephalus by surgeons. However, these two procedures are not omnipotent for all kind of hydrocephalus (3 ,8 ,14). Firstly, for patients who suffer an obstructive hydrocephalus, certain anatomical

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variations of the floor of the third ventricle will make it not feasible to perform an ETV. Even after ETV is successfully performed, the stoma of ETV can be blocked by

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tumors or inflammatory hyperplasia of membranous, and cause the failure of ETV. Secondly, for patients who suffer a trapped fourth ventricle (TFV), ETV or supratentorial shunt can only treat the supratentorial hydrocephalus, leaving the trapped fourth ventricle unsolved. In these two kinds of situations, the aqueduct stent placement (ASP) seems to be helpful, as aqueductoplasty alone is regarded unable to

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solve the problem for its high risk of failure (4 ,7 ,11 ,14). Over the past decades of years, some variations of this procedure for the treatment of aqueductal stenosis (AS), TFV and related disturbances of cerebrospinal fluid (CSF) circulation have been reported (2 ,4 ,5 ,12 ,14 ,15 ,17 ,18). Nevertheless, to our knowledge, detailed reports

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aimed at ASP are still lacking in the literature, and the indications for ASP are still controversial. So we present our experience with ASP, focusing on indications,

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technique and clinical experience.

METHODS

Patients More than 700 patients suffered from hydrocephalus were treated at our department between February 2009 and May 2014. Among them, 10 cases had ASP. We retrospectively analyzed the clinical features, intra-operative findings and clinical outcome of all these 10 patients to determine the indications for the ASP. MRI

ACCEPTED MANUSCRIPT scanning was approved by Medical Science Ethics Committee of the Chinese PLA General Hospital. Our institute ethical committee approved the procedure, and all patients gave signed informed consent to such procedure and to offer clinical data for

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our analysis.

Surgical Technique

The aqueduct stents were placed through two different approaches. In 2 cases, craniotomies and open surgery for tumor resection were performed, while the

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aqueduct stents were placed during open surgery under the microscope. In all the other 8 cases, an endoscopic approach was used. And the aqueduct stents were placed All procedures were performed under general anesthesia.

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through the endoscope.

Endoscopic Approach

In general, the patients were placed supine and the head was placed in a horseshoe-shaped headrest. The best trajectory was planned according to the

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pre-operative MRI or with neuro-navigation guidance (VectorVision Compact, BrainLab, Feldkirchen, Germany). A 3-cm linear skin incision was then made, and a frontal burr hole was placed accordingly just behind the hairline for cosmetic reasons.

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A cruciate dural incision was then made. The lateral ventricle was cannulated with a peer-away sheath. A 6-mm diameter rigid lens (LOTTA, Karl Storz, Tuttlingen, Germany) was then inserted. The endoscope is advanced through the foramen of

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Monro into the third ventricle, the floor of the third ventricle was identified and the obstructed aqueduct inlet was inspected with the aid of 30° diagnostic optics. The membrane occluding the inlet of aqueduct can be easily perforated with the aid of the small tip of a 3 French Fogarty balloon catheter, which was softly inserted into the aqueduct. If the membranous obstruction was located distally that could not be visualized with the rigid scopes, a 2.5-mm steerable fiberscope (FlexScope, Karl Storz, Tuttlingen, Germany) was then introduced. Besides, the flexible scope was also used to check aqueductal patency and inspect the cavity of the fourth ventricle. After that, the rigid endoscope was inserted again into the lateral ventricle and a multi-perforated

ACCEPTED MANUSCRIPT ventricular catheter tip was inserted either with grasping forceps through the working channel of the rigid endoscope (LOTTA, Karl Storz, Tuttlingen, Germany) without rigid stylet. Because the catheter is very soft, it can be easily pushed sliding down through the aqueduct. Hence, there will be no problem with the insertion angle of the

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stent. We usually measure on the MRI console the distance from the inferior medullary velum to certain intra-ventricular landmarks (e.g. the foramen of Monro on the same side or interthalamic adhesion). The ventricle part of a shunt catheter was then cut according to the distance measured, followed by making several small side

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holes on the proximal part (Figure 1). The catheter was then advanced to the desired distance into the fourth ventricle, with the proximal end of the catheter left at the

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specific intra-ventricular landmarks which were decided on MR imaging. The catheter was left in place and the endoscope was then withdrawn while looking for active bleeding and checking the surface of the catheter to ensure the presence of side holes into the third or lateral ventricle. The burr hole was packed with gelatin sponge. To prevent sub-galeal CSF accumulation and fistula, the galea should be tightly sutured.

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The operation procedures were performed under continuous irrigation with 36 °C Ringer's solution to maintain a clear view and achieve hemostasis.

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Open Surgery

In 2 cases with big tumors (1 glioma, 1 yolk sac tumor) located in the third ventricle, craniotomy and open surgery had to be performed. After the maximal tumor resection,

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a multi-perforated ventricular catheter was then inserted with grasping forceps into the aqueduct microscopically after the exposure of the aqueduct. The catheter was advanced into the fourth ventricle to the adequate distance measured pre-operatively on MRI images. Side holes of the catheter at the third and lateral ventricle were confirmed with the microscope. An intra-operative MR imaging study was routinely performed to verify the position of the stent.

Outcome Assessment All patients underwent routine MR scans before and after surgeries to verify the

ACCEPTED MANUSCRIPT position of the catheter and the ventricular morphology. The cases enrolled in this study were routinely followed-up at 1-month, 3month, and 6-month interval, followed by a routine 1-year interval afterwards. Both clinical and imaging findings were

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evaluated and recorded.

RESULTS

A summary of the 10 patients who underwent ASP are listed in Table 1.The mean age

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of the patients was 38 years (range from 5 months to 69 years). The mean follow-up period was 27 months (range from 1 to 51 months). There were 4 female patients and

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6 male patients. Eight patients harbored an obstructive hydrocephalus caused by aqueductal obstruction. The underlying pathology consisted of intraventricular tumors in 3 cases (pilocytic astrocytoma, craniopharyngioma and germinoma, respectively), intra-ventricular cysticercosis in 2 cases and membranous or inflammatory obstruction in 3 cases. Two patients presented a trapped fourth ventricle (TFV)

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resulted from Dandy-Walker malformation (DWM) and post-infectious hydrocephalus respectively. Difficult anatomical variation of the floor of the third ventricle was identified in 2 patients, including a thickened floor of the third ventricle and extreme

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narrow space between the basilar artery and the dorsum sellae, making it unfeasible for a successful ETV. Two patients had shunt before. Two patients had a history of failure of ETV. The main presenting symptoms were headache (40%; 4/10 cases),

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nausea and vomiting (40%; 4/10 cases), and dizziness (30%; 3/10 cases). A impairment of consciousness was observed in 20%(2/10 cases), with one patient being comatose at admission. An increasing head circumference was observed in one patient while a grand mal seizure was observed in another. The pre-operative MRI study revealed supratentorial hydrocephalus in all of the 10 patients. Eight patients underwent ASP endoscopically while the other two patients underwent ASP microscopically. The operation procedure was uneventful in all cases. Postoperatively, signs and symptoms of intracranial hypertension resolved in all cases. After an average follow-up period of 27 months (range from 1 to 51months), recurrence

ACCEPTED MANUSCRIPT of aqueductal stenosis has not been observed. Post-operatively, one patient suffered from transient mild oculomotor paralysis, which completely resolved 3 weeks after surgery. A stent migration was observed in a patient after maintaining stable for 4 years and was solved by subsequent surgery including stent removal, ETV and

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aqueductoplasty.

Illustrative cases

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Patient 1 (FIGURE 1)

A 9-year-old boy presented with headache for 1 week and a history of VP shunt for

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hydrocephalus. CT images showed evidence of a posterior cranial fossa cystic lesion with hydrocephalus. The MRI scan revealed significant supratentorial hydrocephalus, aqueductal obstruction, cerebellar vermis hypoplasia, and a TFV consistent with DWM with hydrocephalus. The patient was considered for an ETV, shunt removal

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and ASP.

A right frontal pre-coronal burr hole was placed. The routine procedure described above was performed before a rigid neuro-endoscope was introduced into the

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ventricular system. The site between the infundibular recess and the mamillary bodies in the midline was considered for the ventriculostomy. The perforation was made with a biopsy forceps, which was subsequently expanded with 3-French Fogarty catheter.

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The endoscope was carefully advanced to the inter-peduncular cistern to visualize the clivus and the basilar artery. Subsequently, a flexible scope was introduced and confirmed a totally obstructed aqueduct. The aqueduct stent was placed after the aquedutoplasty was performed.

The post-operative course was uneventful. The symptom of headache disappeared. There was no evidence of any gaze restriction or other complications except a subdural collection which improved within one week after surgery. A post-operative MRI study confirmed the stent position and patency. MRI scans obtained one month

ACCEPTED MANUSCRIPT after surgery revealed evidence of reduction in the ventricular dilation, mild reduction in the fourth ventricle size, and a flow void through the third ventriculostomy site. The child continues to do well at 2-year follow-up.

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Patient 2 (Figure 2) A 19-year-old female presented with epileptic seizure. MRI images revealed a lesion occupying the third ventricle. The foramen of Monro on both sides were occluded, with aqueductal stenosis and grossly dilated ventricles. Pilocytic astrocytoma was

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confirmed after endoscopic biopsy. As the tumor invaded the floor of third ventricle, it is impossible to perform an ETV during the same endoscopic procedure. The patient

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was planned for craniotomy, tumor resection, and ASP with open surgery. A trans-callosal interforniceal approach was used. After the maximal safe resection of the tumor was achieved, the inlet of aqueduct was verified and the aqueduct stent was placed microscopically. Then intra-operative MRI scan was performed to confirm the position of the aqueduct stent.

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After the surgery, the patient made an uneventful recovery. There was no epileptic seizure and no new neurologic deficit post-operatively. MRI scans obtained 6 months after surgery confirmed good position and patency of the aqueduct stent, and also

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confirmed the total relief of the hydrocephalus. The patient continues to do well at 4-year follow-up.

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DISCUSSION

Indications

In 1920, Dandy (6) inserted a rubber catheter through the aqueduct from the fourth ventricle and became the first one to perform ASP. After that, some variations of this procedure had been reported for the treatment of all kinds of disturbances of CSF circulation. Nevertheless, indications for ASP are still controversial. So we discuss the indications for ASP on the basis of our experience.

ACCEPTED MANUSCRIPT Trapped fourth ventricle (TFV) occurs as the result of occlusions of CSF at the level of the fourth ventricle outlets and the aqueduct, mostly in patients with shunted post-infectious or post-hemorrhagic hydrocephalus (1 ,16). Occasionally, TFV can also occur as the result of Dandy-Walker malformation associated with aqueductal

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stenosis (15). The occlusion of the aqueduct is often related to over drainage of the supratentorial shunt and inflammatory change, most of which are thought to be irreversible (4 ,13 ,16). Several treatment options for TFV have been reported, including the following: placement of a shunt in the fourth ventricle, microsurgical

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aqueduct canalization, microsurgical fenestration of the outlets of the fourth ventricle and endoscopic procedures. Placement of a shunt in the fourth ventricle, the most

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commonly used procedure, is associated with a high rate of dysfunction and complication (4 ,12). On the contrary, endoscopic aquedutoplasty may reestablishes CSF physiological circulation, equilibrates the transtentorial pressure gradients and eliminates the need for another placement of artificial material (12). However, aquedutoplasty alone are associated with high risk of restenosis of the aqueduct and it

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can only be performed for the translucent membranous stenosis or aqueduct obstruction (10 ,14). Fritsch, et al (9) treated 13 patients with aqueductoplasty. Among the eight patients in whom aqueductoplasty was performed alone, six developed

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restenosis after surgery. However, there were no treatment failures in patients in whom a stent was placed. Fritsch MJ, et al (10) think that in patients with TFV and a history of intraventricular hemorrhage or meningitis, it is almost impossible that

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aqueductoplasty alone will stay open. A literature review from Gallo, et al (12) suggests that no re-stenosis occurred in patients who underwent aqueductal stent placement while 53% of re-stenosis were observed in patients who underwent aquedutoplasty alone. In our study, two patients (patient 3 and patient 9) were afflicted by TFV as a result of DWM and shunted post-infectious hydrocephalus respectively. These two patients all underwent aqueduct stent placement. In patient 3, an ETV was also performed simultaneously to ensure shunt independence. In patient 9, hydrocephalus was controlled by a single supratentorial shunt, while the stent communicating with the fourth ventricle. Similar results were reported by other

ACCEPTED MANUSCRIPT authors (4 ,12 ,15), indicating stent placement may be the optimal strategy for this kind of patients.

Endoscopic third ventriculostomy (ETV) has been a common neuro-endoscopic

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operation for treatment of obstructive hydrocephalus caused by aquedutcal stenosis. However disastrous complications can happen in rare cases. The floor of third ventricle is the area where ETV is performed. Long-termed pathological conditions of hydrocephalus, intra-ventricular hemorrhage and infections can induce various

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anatomical variations of the floor of the third ventricle, such as the thickened, inclined and depressed floor of third ventricle, which will increase the risk of injury to

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hypothalamus, brainstem, and arteries (19). Some of these variations are even considered to be the contraindications for ETV, even with the help of navigation and experienced operation skills. For examples, in some cases, it is impossible to distinguish the mammillary body, infundibular recess and some other landmarks. It is also not recommended to perform ETV when the floor of third ventricle is depressed

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downward and attached by the basilar artery, leaving no space for ETV (FIGURE 3). In our study, two patients (patient number 2 and patient number 6 in Table 1) suffered an obstructive hydrocephalus which can be treated with ETV. However, because of

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their special anatomical features, the space between the basilar artery and the dorsum sellae is extremely narrow. Hence a ETV was found not feasible. These two patients underwent ASP alternatively. Both patients presented a disappearance of symptoms

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postoperatively. And their post-operative MRI images confirmed the total relief of their hydrocephalus.

According to our experience, in cases with third ventricle tumors, especially with gliomas and other malignant tumors, we always have concern that the ETV stoma will possibly been obstructed by the recurrent tumor, which may potentially happen even after the successful removal of the primary tumor. So, in this kind of cases, we would like to perform ASP in the same surgical procedure to secure the long-term patency of aqueduct. For cases with inflammatory hyperplasia, especially in post-hemorrhage

ACCEPTED MANUSCRIPT and post-meningitis patients, and cause recurrent hydrocephalus. The high revision rate in this group has led to a change in our treatment strategy toward initial stent placement (10). In our study group, five patients (patients 1, 5, and 7) with obstructive hydrocephalus had ASP for possible failure of ETV. Two of them had a history of

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failure of ETV for the re-obstruction of the stoma by intra-ventricular aseptic inflammatory changes, while the other one was affected by intraventricular cysticercosis which was considered to be a potential failure factor of ETV.

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In summary, the indications for ASP can be concluded as: 1. trapped fourth ventricle(TFV). 2. patients harboring a obstructive hydrocephalus caused by

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aqueductal stenosis in which ETV is not feasible for anatomical reasons. 3. patients harboring a obstructive hydrocephalus caused by aqueductal stenosis in which there is a potential risk of failure of ETV (e.g. recurrent tumor in third ventricle).

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Complications

Transient or permanent oculomotor paralysis, subdural collection, transient dysconjugate gaze paresis, infection, facial paresis, tectal injury, and stent migration

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were reported as complications of ASP (4 ,7 ,10 ,12 ,15 ,18). Though the catheter used to stent the aqueduct is soft, it can injure the aqueduct when it is inserted with forceps, as the aqueduct is delicate and generally not a straight tube but has a curved

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shape (18). It means we should inserted the catheter gently and conform to the physiological curvature of the aqueduct to avoid injury to surrounding eloquent structures. Nevertheless, there is still a risk of injury to the peri-aqueductal structures in case of distorted anatomy. In our study, one patient had post-operative transient oculomotor paralysis after ASP. A stent migration was observed in another patient after maintaining stable for about 4 years. Ersahin (7) reported 2 stent migrations of 23 patients treated with ASP. To solve this problem, Fritsch (11) utilized a long stent measuring 12 to 14 cm which was connected to a burr hole reservoir to prevent it migration. Ersahin (7) and Mohanty (15) used the stent with a proximal shoulder to

ACCEPTED MANUSCRIPT prevent it from migrating into the fourth ventricle. If a working shunt is present, Cinalli et, al (4) suggested to connect the stent to a subcutaneous reservoir or a preexisting shunt system to allow easy removal in case of infection, which can also prevent stent migration. To prevent stent migration, we recommend anchoring the

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distal end of the stent to subgalea, which is now being tested in our institution.

CONCLUSION

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On the basis of our results, mid-term cerebrospinal fluid circulation restoration can be achieved with ASP. ASP is technically feasible and can be useful in selected patients

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either through endoscopic or open surgery. To further establish ASP as a therapeutic strategy, accumulation of further cases and long-term follow-up data are necessary, although our results, in the limited and highly selective series, are encouraging.

Disclosures

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The authors declare that they have no personal financial or institutional interest in any of the drugs,materials or devices described in this article.

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Acknowledgement This study is sponsored by National Natural Science Foundation of China (81271515)

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and Young Physician Scholarship of PLA General Hospital.

ACCEPTED MANUSCRIPT REFERENCES

1.

Ang BT, Steinbok P, Cochrane DD: Etiological differences between the isolated

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lateral ventricle and the isolated fourth ventricle. Childs Nerv Syst 22:1080-1085, 2006. 2.

Backlund EO, Grepe A, Lunsford D: Stereotaxic reconstruction of the aqueduct

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of Sylvius. J Neurosurg 55:800-810, 1981.

Buxton N, Ho KJ, Macarthur D, Vloeberghs M, Punt J, Robertson I:

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Neuroendoscopic third ventriculostomy for hydrocephalus in adults: report of a single unit's experience with 63 cases. Surg Neurol 55:74-78, 2001. 4.

Cinalli G, Spennato P, Savarese L, Ruggiero C, Aliberti F, Cuomo L, Cianciulli E,

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Maggi G: Endoscopic aqueductoplasty and placement of a stent in the cerebral aqueduct in the management of isolated fourth ventricle in children. J Neurosurg 104:21-27, 2006.

Crosby RM, Henderson CM, Paul RL: Catheterization of the cerebral aqueduct

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5.

6.

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for obstructive hydrocephalus in infants. J Neurosurg 38:596-601, 1973. Dandy W: The diagnosis and treatment of hydrocephalus resulting from strictures

of the aqueduct of Sylvius. Surg Gynecol Obstet 31:340-318, 1920. 7. 8.

Ersahin Y: Endoscopic aqueductoplasty. Childs Nerv Syst 23:143-150, 2007. Feng H, Huang G, Liao X, Fu K, Tan H, Pu H, Cheng Y, Liu W, Zhao D:

Endoscopic third ventriculostomy in the management of obstructive hydrocephalus: an outcome analysis. J Neurosurg 100:626-633, 2004.

ACCEPTED MANUSCRIPT 9.

Fritsch

MJ,

Kienke

S,

Manwaring

KH,

Mehdorn

HM:

Endoscopic

aqueductoplasty and interventriculostomy for the treatment of isolated fourth ventricle in children. Neurosurgery 55:372-377; discussion 377-379, 2004.

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10. Fritsch MJ, Kienke S, Mehdorn HM: Endoscopic aqueductoplasty: stent or not to stent. Childs Nerv Syst 20:137-142, 2004.

11. Fritsch MJ, Schroeder HW: Endoscopic aqueductoplasty and stenting. World

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Neurosurg 79:S20.e15-18, 2013.

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12. Gallo P, Szathmari A, Simon E, Ricci-Franchi AC, Rousselle C, Hermier M, Mottolese C: The endoscopic trans-fourth ventricle aqueductoplasty and stent placement for the treatment of trapped fourth ventricle: long-term results in a series of 18 consecutive patients. Neurol India 60:271-277, 2012.

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13. James HE: Spectrum of the syndrome of the isolated fourth ventricle in posthemorrhagic hydrocephalus of the premature infant. Pediatr Neurosurg 16:305-308, 1990.

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14. Miki T, Nakajima N, Wada J, Haraoka J: Indications for neuroendoscopic

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aqueductoplasty without stenting for obstructive hydrocephalus due to aqueductal stenosis. Minim Invasive Neurosurg 48:136-141, 2005. 15. Mohanty A: Endoscopic third ventriculostomy with cystoventricular stent placement in the management of dandy-walker malformation: technical case report of three patients. Neurosurgery 53:1223-1228; discussion 1228-1229, 2003. 16. Oi S, Matsumoto S: Pathophysiology of aqueductal obstruction in isolated IV ventricle after shunting. Childs Nerv Syst 2:282-286, 1986.

ACCEPTED MANUSCRIPT 17. Sagan LM, Kojder I, Poncyljusz W: Endoscopic aqueductal stent placement for the treatment of a trapped fourth ventricle. J Neurosurg 105:275-280, 2006. 18. Schroeder HW, Oertel J, Gaab MR: Endoscopic aqueductoplasty in the treatment

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of aqueductal stenosis. Childs Nerv Syst 20:821-827, 2004. 19. van Aalst J, Beuls EA, van Nie FA, Vles JS, Cornips EM: Acute distortion of the anatomy of the third ventricle during third ventriculostomy. Report of four cases. J

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Neurosurg 96:597-599, 2002.

ACCEPTED MANUSCRIPT FIGURE CAPTIONS

FIGURE 1. Patient 3. Preoperative sagittal (A) MRI images demonstrate the aqueduct obstruction associated the large trapped fourth ventricle. Postoperative MRI

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scans confirmed the stent in good position (B) and flow void signal (White arrow) through the anterior floor of the third ventricle (C). The tailored aqueduct stent is shown (D). Intra-operative findings with the flexible scope revealed membranous aqueductal stenosis (E), and patency after aqueductoplasty (F). After aqueduct stent

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placement, the rigid scope was used to check the surface of the catheter to ensure the presence of side hole into the third ventricle (G). Final inspection confirmed that the

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stent coming from the aqueduct through the foramen of Monro into the lateral ventricle (H).

FIGURE 2. Patient 4. Pre-operative axial T1-weighted (A), T2-weighted (B), T1 enhanced (C) and sagittal T2-weighted (D) MRI images demonstrate the

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intra-ventricular tumor which obstructs the aqueduct and causes the dilation of the bilateral ventricles. Postoperative MRI scans show the stent in position (E) and the tumor was totally removed (F). Histology diagnosis of tumor is pilocytic astrocytoma

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(WHO Grade I).

FIGURE 3. Patient Number 2 in Table 1. Preoperative sagittal MRI image (A)

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demonstrates the aqueduct obstruction and hydrocephalus, while the basilar artery was attached to the third ventricular floor and dorsum sellae (Black arrow), making it dangerous and difficult to perform an ETV. Postoperative sagittal MRI image (B) reveals the stent in good position.

ACCEPTED MANUSCRIPT

Table1 Summary of patient data Etiology

Main preoperative symptoms

History proccedure

Simultaneous shunting

Simultaneous procedure

Approach

Unsatisfactory Endoscopy ETV

62y/F

Aqueductal intraventricular stenosis, cysticercosis

Dizziness, headache, vomitting, ataxia

None

No

2

51y/M

Aqueductal stenosis

None

No

Failed ETV

3

9y/M

TFV, Dandy-Walker malformation

Weakness in the limbs, urinary incontinence Headache

VPS

Yes

ETV shunt removal

4

19y/F

Grand mal seizures

Endoscopic biopsy

No

5

5m/M

Aqueductal stenosis, intraventricular tumor(pilocytic astrocytoma) Aqueductal stenosis

Nausae, vomitting, increasing HC

ETV, choroids plexus coagulation

No

6

56y/M

Aqueductal stenosis, intraventricular cysticercosis

Headache, weakness in the limbs

None

7

48y/M

Aqueductal stenosis, intraventricular hyperplasia of membrane structures

Dizziness, headache, vomitting, ataxia

ETV, foraminoplasty

8

53y/M

Aqueductal stenosis, intraventricular tumor(craniopharyngioma)

Dizziness, headache, vomitting, nausae

9

69y/F

TFV, PIH, slit ventricle

Disturbance of consciousness

10

17y/F

Aqueductal stenosis, pineal region tumor(germinoma)

Coma

Endoscopy

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1

Complications

Initial clinical improvement

Subsequent surgery

Follow up

No

Yes

No

Symptom-free(51 mo)

Stent migration

Yes

Stent removal, ETV, aqueductoplasty

Good life quality (35 mo)

No

Yes

No

Symptom-free(20 mo)

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No. Age/sex

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Endoscopy

Open surgery

Transient mutism

Yes

No

Good life quality (41 mo)

ETV, choroids plexus coagulation

Endoscopy

Transient oculomotor paralysis

Yes

No

Symptom-free(36 mo)

No

Failed ETV

Endoscopy

No

Yes

No

Symptom-free(36 mo)

No

ETV

Endoscopy

No

Yes

No

Good life quality (4 mo)

None

No

Biopsy

Endoscopy

No

Yes

Tumor resection

Symptom-free(16 mo)

VPS, diverter valve replacement and upgrade ETV, biopsy, bilateral EVD

Yes

No

Endoscopy

No

Yes

No

Symptom-free(39 mo)

No

Tumor resection

Open surgery

Transient mutism

Yes

No

Good life quality (1 mo)

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Tumor resection

TFV trapped fourth ventricle; DWM, Dandy-Walker malformation; ETV, endoscopic third ventriculostomy; VPS, ventrculo-peritoneal shunt; PIH, post infectious hydrocephalus; EVD, external ventricular drainage.

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ACCEPTED MANUSCRIPT

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ACCEPTED MANUSCRIPT

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ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT Highlights 1. Aqueduct stent placement (ASP) is technically feasible and can be useful in selected cases. 2. Indications and technique of ASP are discussed in detail.

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3. ASP can be performed either through endoscopic or open surgery.

ACCEPTED MANUSCRIPT Abbreviations and Acronyms AS:Aqueductal stenosis ASP: Aqueduct stent placement

CT:Computed tomography DWM:Dandy-Walker malformation ETV: Endoscopic third ventriculostomy

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EVD: External ventricular drainage.

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MRI:Magnetic resonance imaging PIH: Post infectious hydrocephalus

PTFV:Potentially trapped fourth ventricle TFV:Trapped fourth ventricle

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VPS: Ventriculo-peritoneal shunt

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CSF:Cerebrospinal fluid

Aqueduct Stent Placement: Indications, Technique, and Clinical Experience.

Complicated hydrocephalus, such as trapped fourth ventricle, is challenging. Aqueduct stent placement is a possible alternative to the conventional mu...
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