Outlet fenestration for isolated fourth ventricle with and without an internal shunt

Trapped Fourth Ventricle: Pathophysiology, History and Treatment Strategies

Trapped fourth ventricle is a clinic-radiological entity characterised by progressive neurological symptoms due to enlargement and dilatation of fourth ventricle secondary to obstruction to its outflow. There are several causative mechanisms for the development of trapped fourth ventricle, including previous haemorrhage, infection or inflammatory processes. However, this condition is most commonly observed in ex preterm paediatric patients shunted for a post-haemorrhagic or post-infective hydrocephalus. Until the introduction of endoscopic aqueductoplasty and stent placement, treatment of trapped fourth ventricle was associated with high rates of reoperation and complications resulting in morbidity. With the advent of new endoscopic techniques, supratentorial and infratentorial approaches for aqueductoplasty and stent insertion have revolutionised the treatment of trapped fourth ventricle. Fourth ventricular fenestration and direct shunting remain viable options in cases where aqueduct anatomy and length of obstruction is not surgically favourable for endoscopic approaches. In this book chapter, we explore the background, historical developments,$ and surgical treatment strategies in the management of this challenging condition.

Case Report: A Rare Case of Fourth Ventricle to Spinal Subarachnoid Space Shunt Migration: Surgical Pearl and Literature Review

Background: In the event of syringomyelia communicating with the fourth ventricle, a fourth ventricle to cervical subarachnoid space shunting could be proposed.

Case Report: In this review article, we describe the case of a 40-year-old woman who had a previously implanted fourth ventricle to spinal subarachnoid space shunt for the treatment of syringomyelia in the context of Chiari syndrome. The catheter migrated intradurally to the lumbosacral space, but in the absence of neurological repercussions, we decided to leave it in place.

Conclusions: To the best of our knowledge, this is the first case described in the literature review of a catheter migration in the subarachnoid space from occipitocervical to lumbosacral level.

Trapped fourth ventricle: A case report and review of literature

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In this patient the diagnosis was missed. Initially we thought it was shunt infection or malfunction. A shunt series and septic work up were both normal.

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CT scan of the brain was delayed for 10 days due to financial constraints.

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The only option available for treatment was a fourth ventriculoperitoneal shunt.

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However, the patient did well and was fine by 12 month of follow up.

Introduction and importance

Trapped fourth ventricle (TFV) also known as isolated fourth ventricle (IFV) is a rare clinico-radiologic entity with only a few cases reported in the literatures.

The aim of this article is to present the first case of this condition in our center and highlight the challenges of arriving at clinical diagnosis and treatment in a resource limited setting.

Case presentation

An 18 months old girl who had ventriculoperitoneal shunt insertion for post meningitic hydrocephalus 4 months earlier presented with restlessness, ataxia, fever and inability to control her neck of one-week duration. On examination she was restless and had retro-colis with a Glasgow Coma Scale (GCS) score of 11/15 (E4V2M5).

She had an associated facial and abducent nerve palsies with global hypertonia, hyper-reflexia and muscle power of 3/5.

She was initially treated for shunt infection and malfunction. However, shunt series and CSF analysis were within normal limits and CSF culture yielded no growth of microorganisms. A CT scan of the brain which was ordered earlier was delayed for 10 days due to financial constraints. The CT scan revealed a trapped fourth ventricle and slit lateral and third ventricle.

She had emergency fourth ventriculoperitoneal shunt inserted on the left because of the pre-existing supratentorial shunt on the right.

She did well after the surgery and was discharged on the 10th postoperative day. She was doing well 12 months after the surgery.

Relevance and impact

TFV may occur after insertion of VPS for post-meningitic hydrocephalus. This may present a diagnostic dilemma. Insertion of a second VPS may be an option in a resource limited setting.

Trapped fourth ventricle-treatment options and the role of open posterior fenestration in the surgical management

BACKGROUND

Trapped fourth ventricle (TFV) is a rare and difficult to treat condition. Most patients have a past inciting event (infection, IVH, trauma) and history of prior CSF diversion. The symptoms are due to the mass effect on brainstem and cerebellum. Rarely, TFV can also be associated with syrinx formation due to a dissociated craniospinal CSF flow near the fourth ventricle outlets. We present our experience and outcomes of open posterior fenestration in 11 cases, along with an overview of the surgical management of TFV.

METHODS

Between 2011 and 2018, 11 patients of TFV were operated by the posterior approach fenestration of the fourth ventricle outlets and arachnoid dissection. The clinical and radiological findings of the patients were retrieved from the hospital database. The surgical technique is described in detail. The patients' neurological status and imaging findings in the follow-up were recorded and compared.

RESULTS

The average age of the patients was 23.55 years. The most common presenting symptoms were headache (9/11) and gait imbalance (7), with TB meningitis being the commonest etiology. Ten patients had a history of prior CSF diversion with two presenting with shunt malfunction. Mean follow-up duration was 33.33 months. The improvement in neurological status was observed in 9/11 patients, 2 remained status quo. On follow-up imaging, 8/11 (72.72%) patients had a decrease in the size of TFV while syrinx improved in 3/5 (60%).

CONCLUSION

Multiple surgical approaches have been described for TFV. Endoscopic fourth ventriculostomy with aqueductoplasty is gaining popularity in the past two decades. However, an open posterior fenestration of the midline fourth ventricle outlet (magendieplasty) along with sharp arachnoid dissection (adhesiolysis) along the cerebello-medullary cisterns and paracervical gutters is relatively simple and provides physiological fourth ventricular CSF outflow. This is especially useful in TFV with syrinx as the craniospinal CSF circulation is established.

Endoscopic Fourth Ventriculostomy: Suboccipital Transaqueductal Approach for Fenestration of Isolated Fourth Ventricle: Case Report and Technical Note

BACKGROUND

Trapped or isolated fourth ventricle is a known, late sequela after lateral ventricular shunt placement for hydrocephalus, particularly after infection or hemorrhage. It may cause brainstem compression and insidiously present with ataxia, dysarthria, and intracranial hypertension, further delaying diagnosis. There is no universally agreed on treatment algorithm, and options include open fenestration through a suboccipital craniotomy, fourth ventricle shunting, and minimally invasive options including endoscopic stenting and fenestration through a precoronal approach.

CASE DESCRIPTION

We describe a young child with epilepsy and symptomatic brainstem compression from a dilated fourth ventricle, with a history of streptococcal parietal abscess and posthemorrhagic hydrocephalus requiring shunt placement. Given his history of infection and nearly neurologically intact examination, we pursued minimally invasive endoscopy through a suboccipital, transaqueductal approach to fenestrate his fourth ventricle.

CONCLUSIONS

Magnetic resonance imaging (MRI) demonstrated complex, loculated hydrocephalus and a dilated fourth ventricle. Under electromagnetic navigation, we endoscopically fenestrated his fourth ventricle using a rarely described suboccipital, transaqueductal approach. He tolerated the procedure without complication and improved neurologically, although his follow-up MRI demonstrated no change in fourth ventricular dilation at 1 year. Although there was no decrease in size of the fourth ventricle on follow-up MRI, we describe an alternative, well-tolerated, suboccipital approach for the management of a trapped fourth ventricle. Fenestration of a web of tissue in the aqueduct of Sylvius provided long-term clinical improvement and may provide a rescue approach for patients who are not candidates for standard approaches.

Descending transtentorial herniation, a rare complication of the treatment of trapped fourth ventricle: case report

Descending transtentorial herniation (DTH) is a complication of raised pressure in the supratentorial compartment, usually resulting from mass lesion of several etiologies. The authors report an exceptional case of DTH complicating the implant of a CSF shunting device in the trapped fourth ventricle of a 17-year-old boy in whom a second CSF shunting device had been implanted for neonatal posthemorrhagic and postinfectious hydrocephalus. The insidious clinical and radiological presentation of DTH, mimicking a malfunction of the supratentorial shunt, is documented. Ultimately, the treatment consisted of removal of the infratentorial shunt and endoscopic acqueductoplasty with stenting. The absence of supratentorial mass lesion and other described etiologies of DTH prompted the authors to speculate on the hydrodynamic pathogenesis of DTH in the present case.

Suboccipital endoscopic management of the entrapped fourth ventricle: technical note

BACKGROUND

Entrapped fourth ventricle is the result of both inlet aqueduct and outlet fourth ventricular midline and lateral foraminae obstruction. It occurs as a sequalae of intracranial hemorrhagic or inflammatory disease condition. Usually it presents after previous shunting for communicating hydrocephalus with a period of improvement, after which manifestations of posterior fossa expanding process appear. The diagnosis of this rare condition is easy considering the patient past history and the recent clinical state, together with the midline CSF density of the dilated fourth ventricle in either the CT or MR images. The treatment options for this condition include open and endoscopic approaches together with the traditional ventricular to extracranial CSF diversionary procedures.

OBJECTIVE

The aim of the study was to adopt a procedure for treatment of entrapped fourth ventricle that carries the advantage of the minimally invasive technique thus avoiding the complications of the traditional opened and shunt surgeries as well as decreasing multiple procedures due to aqueduct restenosis or stent fall.

METHODS

Thirteen patients with symptomatic entrapped fourth ventricle underwent suboccipital endoscopic trans-fourth ventricular aqueductoplasty from May 2007 till November 2011. The Gabb endoscopic system was used and aqueductoplasty was performed using 3F Fogarty balloon followed by stent placement. Nine patients were females. The mean age was 3.6 years and the mean follow up period was 23 months. All cases had a previous one or two supratentorial VP shunt placement.

RESULTS

Short stent was used in eight patients. During the follow up, stent migration occurred in five of them. Three of these five patients developed posterior fossa compression manifestations due to aqueduct restenosis. Long stent from the aqueduct till the bur hole site for these three patients and the following five patients was used. All cases showed both clinical and radiologic improvement. Apart from the stent migration, no procedure-related complications were encountered.

CONCLUSION

Endoscopic suboccipital paramedian aqueductoplasty with the use of a stent is a safe and effective surgical option that-in our opinion-should stand as the first line treatment for the entrapped fourth ventricle. Long stent is better used after aqueductoplasty to avoid the restenosis if no stent is used or stent fall after short stents. However, good case selection, familiarity with this fairly common endoscopic approach and longer follow-up is needed for obtaining an optimal result.

Endoscopic transaqueductal or interventricular stent placement for the treatment of isolated fourth ventricle and pre-isolated fourth ventricle

OBJECT

The aim of our study is to evaluate the effectiveness of endoscopic transaqueductal or interventricular stent placement into the fourth ventricle for isolated fourth ventricle (IFV) and pre-isolated fourth ventricle (PIFV), in which occlusion of the fourth ventricle outlets and dilation of the fourth ventricle are seen while the aqueduct is still patent.

METHODS

We retrospectively analyzed pediatric patients who underwent endoscopic stent placement for IFV or PIFV.

RESULTS

Five patients with IFV and four patients with PIFV underwent endoscopic stent placement. The mean age was 11.5 months. Three patients with IFV underwent aqueductoplasty with stent connected to an extracranial shunt system. Two patients with IFV and supratentorially protruded fourth ventricle underwent interventriculostomy with stent. In these patients, the stent was not connected to the shunt system as functional shunt had been already placed using the contralateral ventricle. In four patients with PIFV, transaqueductal stent was placed and connected to the extracranial shunt system. In all patients, preoperative symptoms improved and magnetic resonance imaging demonstrated reduction of the size of the fourth ventricle. The mean follow-up period was 49.6 months (range 5 to 99 months). Three patients (33 %) underwent reoperation due to obstruction of the abdominal catheter, partial occlusion of the ventricular catheter, and retraction of the fourth ventricular catheter.

CONCLUSION

The endoscopic transaqueductal or interventricular stent placement into the fourth ventricle for the treatment of IFV is considered to be effective and safe. The transaqueductal stent placement for PIFV is also considered to be effective for resolution of symptoms and prevent progression into IFV.

Microsurgical outlet restoration in isolated fourth ventricular hydrocephalus: a single-institutional experience

PURPOSE

Isolated fourth ventricles as a consequence of shunted posthemorrhagic hydrocephalus can cause significant brainstem compression and subsequent clinical deficits in children. Several treatment options have been described. We report the clinical and radiological outcome after microsurgical fenestration of fourth ventricular outlet foramen via a suboccipital approach.

METHODS

In nine patients (age, 9 to 87 months; median age, 21 months), microsurgical reopening of formerly occluded outlet foramen of the fourth ventricle was performed under electrophysiological monitoring. Pre- and postoperative clinical outcome as well as radiological results are reported.

RESULTS

Mean follow-up for all children was 25 months. Three children older than 3 years were less significantly involved, the remaining six showed tremendous long tract signs and lower cranial nerve deficits. All children exhibited a remarkable improvement of their preexisting neurological deficits post-surgery. Despite successful fenestration, one child required additional internal drainage of fourth ventricle to the lateral ventricles due to malabsorption. Median diameters of the fourth ventricle changed markedly after surgery with anterior-posterior (a.p.) extension from 3.8 to 2.9 cm, lateral extension from 4.2 to 2.8 cm (p = 0.018), and craniocaudal extension from 5.8 to 4.7 cm, respectively. Also, the pontine a.p. diameter increased significantly from 0.8 to 1.5 cm (p = 0.022).

CONCLUSION

The clinical and radiological outcomes after microsurgical fenestration in children with an isolated fourth ventricle are very promising. This treatment modality is a safe and effective shunt-free option when electrophysiological monitoring and thorough preoperative neuroradiological work-up are applied.

Cranio-cervical decompression and expansile duroplasty for isolated fourth ventricle in a patient with Chiari II malformation

The management of isolated fourth ventricle in Chiari II malformation remains a complex challenge. Commonly accepted treatment options have been associated with high rates of complications and failure. Cranio-cervical decompression and autologous expansile duroplasty may be an effective primary intervention for this condition.

Contrast ventriculo-cisternography: an auxiliary test for suspected fourth ventricular outlet obstruction

PURPOSE

Fourth ventricular outlet obstruction (FVOO) causes obstructive hydrocephalus. Often, despite high-quality MRI sequences, differentiation between FVOO and communicating (absorptive) hydrocephalus is not easy. We describe our initial experience with five children with suspected FVOO that underwent CT ventriculography (CTV) or cisternography (CTC), to assist with this difficult diagnosis.

METHODS

Over 2.5 years, five children with suspected FVOO (5 months-7.5 years old) underwent CTV or CTC. Technical and clinical data were retrospectively collected.

RESULTS

Four children had progressive macrocephaly, and one child had progressive ventriculomegaly. On CTV/CTC, four of five children showed communication between the ventricular system and spinal subarachnoid space or prepontine cistern, as evidenced by passage of contrast material. One child had a FVOO and therefore underwent an endoscopic third ventriculostomy, and is since, symptom and shunt free for 2.5 years.

CONCLUSION

CT ventriculography in infants, and CT cisternography in elder children, may assist to differentiate between FVOO and communicating hydrocephalus. The importance of these tests is for children with MRI suggestive of FVOO related hydrocephalus, but with no clear demonstration of the obstruction site. The implication of this differentiation may be for deciding between treatment of hydrocephalus with a ventriculoperitoneal shunt or with an endoscopic third ventriculostomy.

Posterior fossa craniotomy for trapped fourth ventricle in shunt-treated hydrocephalic children: long-term outcome

OBJECT

Trapped fourth ventricle (TFV) is a rare late complication of postinfectious or posthemorrhagic hydrocephalus. This entity is distinct from a large fourth ventricle because TFV entails pressure in the fourth ventricle and posterior fossa due to abnormal inflow and outflow of CSF, causing significant symptoms and signs. As TFV is mostly found in children who were born prematurely and have cerebral palsy, diagnosis and treatment options are a true challenge.

METHODS

Between February 1998 and February 2007, 12 children were treated for TFV in Dana Children's Hospital by posterior fossa craniotomy/craniectomy and opening of the TFV into the spinal subarachnoid space. The authors performed a retrospective analysis of relevant data, including pre- and postoperative clinical characteristics, surgical management, and outcome.

RESULTS

Thirteen fenestrations of trapped fourth ventricles (FTFVs) were performed in 12 patients. In 6 patients with prominent arachnoid thickening, a stent was left from the opened fourth ventricle into the spinal subarachnoid space. One patient underwent a second FTFV 21 months after the initial procedure. No perioperative complications were encountered. All 12 patients (100%) showed clinical improvement after FTFV. Radiological improvement was seen in only 9 (75%) of the 12 cases. The follow-up period ranged from 2 to 9.5 years (mean 6.11 ± 2.3 years) after FTFV.

CONCLUSIONS

Fenestration of a TFV via craniotomy is a safe and effective option with a very good long-term outcome and low rate of morbidity.

Simplified aqueductal stenting for isolated fourth ventricle using a small-caliber flexible endoscope in a patient with neurococcidiomycosis: technical case report

OBJECTIVE

Endoscopic aqueductoplasty and stenting are a preferred treatment for isolated fourth ventricle syndrome related to membranous aqueductal obstruction. We describe a technique using a small-caliber flexible endoscope that may address some limitations of current strategies.

CLINICAL PRESENTATION

A 39-year-old woman with hydrocephalus caused by neurococcidiomycosis and a functional right frontal ventriculoperitoneal shunt presented with vomiting and an isolated fourth ventricle. Magnetic resonance imaging showed an enlarged fourth ventricle and exuberant basilar arachnoiditis obstructing the outlet foramina of the fourth ventricle. Ventriculography indicated aqueductal obstruction.

INTERVENTION

Aqueductoplasty was planned to allow spinal fluid to flow from the fourth ventricle to the ventriculoperitoneal shunt. A stent-endoscope construct was prepared by feeding a flexible endoscope through a ventricular catheter cut 4 cm from the tip. The flexible endoscope was contoured to fit the anatomy of the aqueduct. Uncomplicated aqueductoplasty was performed through a single left frontal burr hole using the stent-endoscope construct to perforate a membranous veil and inspect the fourth ventricle. The stent was deployed over the endoscope using the proximal end of the catheter to deliver and secure the stent as the endoscope was withdrawn.

CONCLUSION

Aqueductoplasty and stenting using a small-caliber flexible endoscope is feasible. The endoscope can be contoured to suit the anatomy of the aqueduct and improves visualization of the leading edge of the stent during deployment. Furthermore, when the endoscope is used to create the perforation, the target is not obscured by the shaft of the device used to make the perforation.

Unusual subacute diencephalic edema associated with a trapped fourth ventricle: resolution following foramen magnum decompression

INTRODUCTION

A 4-year-old girl with a ventriculoperitoneal shunt presented to us with complaints of ataxia and altered consciousness. These symptoms were subacute at onset and progressive in nature.

CASE REPORT

Radiological evaluation revealed a trapped fourth ventricle with brainstem compression, associated with abnormal diffuse diencephalic signal changes compatible with edema. The entrapment was managed by foramen magnum decompression, resulting in complete symptom resolution and improvement in the abnormal magnetic resonance findings.

DISCUSSION

While trapped fourth ventricle is a well-described entity, we could not find a similar reported case where such an acute clinical syndrome was associated with such a distinct radiological picture.

CONCLUSIONS

In this paper, we review the pre-morbid history, clinical syndrome, and imaging. We then discuss possible mechanisms, their implications on decision-making, and the preferred modes of treatment.

Surgical management of adult hydrocephalus

The management of adult hydrocephalus spans a broad range of disorders and ages. Modern management strategies include endoscopic and adjustable cerebrospinal fluid shunt diversionary techniques. The assessment and management of the following clinical conditions are discussed: 1) the adult patient with congenital or childhood-onset hydrocephalus, 2) adult slit ventricle syndrome, 3) multicompartmental hydrocephalus, 4) noncommunicating hydrocephalus, 5) communicating hydrocephalus, 6) normal pressure hydrocephalus, and 7) the shunted patient with headaches. The hydrodynamics of cerebrospinal fluid shunt diversion are discussed in relation to mechanisms of under- and overdrainage conditions. A rationale for the routine implementation of adjustable valves for adult patients with hydrocephalus is provided based on objective clinical and experimental data. For the condition of normal pressure hydrocephalus, recommendations are offered regarding the evaluation, surgical treatment, and postoperative management of this disorder.

Endoscope-assisted placement of a multiperforated shunt catheter into the fourth ventricle via a frontal transventricular approach

Object

Patients with symptomatic isolated fourth ventricle and multicompartmentalized hydrocephalus benefit from operative treatment, but the optimal surgical approach and technique have yet to be established. The authors report on their experience with the treatment of symptomatic adult patients by endoscope-assisted placement of a fourth ventricle shunt catheter via a frontal transventricular approach.

Methods

The authors describe a retrospective series of four patients treated for isolated fourth ventricle. The surgical technique is described in detail: use of a flexible endoscope with dual-port intraventricular access for direct visualization and for mechanical manipulation of a multiperforated panventricular catheter guided by frameless stereotaxy.

The transventricular approach allowed optimal catheter placement within the fourth ventricle. The use of the flexible endoscope permitted the neurosurgeon to use the endoscope as a tool to guide the ventricular catheter tip within the third ventricle and through the cerebral aqueduct. Clinical outcomes demonstrated neurological and radiographically verified improvement in all patients.

Conclusions

The endoscope-assisted dual-port technique provides a solution to the technical difficulties of fourth ventricle shunt placement. The multiple advantages of this technique include a single ventricular catheter shunt system that equalizes ventricular pressures, a frontal location for the ventricular catheter that facilitates valve placement and programming, and ventricular catheter placement within the fourth ventricle that does not allow the catheter to impinge on the fourth ventricle floor and makes the catheter less prone to obstruction.

The occurrence of obstructive vs absorptive hydrocephalus in newborns and infants: relevance to treatment choices

BACKGROUND AND OBJECTIVE

The classification of hydrocephalus in newborns and in infants is different from the classification in adulthood. This difference exists due to disparity in the source pathologies that produce the hydrocephalus, and the practical distinctions in prognosis and treatment choices. The objective of this paper is to present the spectrum of obstructive-communicating hydrocephalus, which is more complex in the pediatric group, and to propose the relevance of this particular classification to treatment options.

MATERIALS AND METHODS

The authors categorized infants with active hydrocephalus at time of presentation into the following four groups along the spectrum of communicating vs obstructive HCP. Group 1: patients with a purely absorptive (communicating) HCP. In these patients, tetraventricular dilatation is usually observed with occasional extraaxial fluid accumulation. An extracranial CSF diversion (shunt) is the treatment of choice. Group 2: patients with an obstructive component together with a persistent absorptive component. In these patients, a technically successful endoscopic procedure will not prevent progression of clinical symptoms of HCP. An extracranial CSF diversion (shunt) should be the treatment of choice even though some of these patients are currently treated by endoscopy. Group 3: patients with an obstructive component together with a temporary absorptive component. In these patients, a technically successful ETV should be followed by temporary CSF drainage [via LP, continuous spinal drainage (CLD), or ventriculostomy] with or without supplemental medical treatment (i.e., Diamox) for several days. Such temporary drainage may decrease failure rate in this subgroup. Group 4: patients with a purely obstructive HCP. In these patients, an endoscopic procedure (ETV) is the treatment of choice. According to this spectrum classification, the authors classify different entities with representative cases and discuss relevancy to treatment options and prognosis.

RESULTS

The data suggest that obstructive hydrocephalus in the very young population may be rather a combination of obstructive and absorptive problem. The outcome of the patient depends mainly not only on the basic pathology causing the hydrocephalus but also on the treatment that is chosen and its complications. While bleeding and infection represent the major causes for communicating hydrocephalus, patients with complex pathologies of congenital type and intra- or interventricular obstructions may reflect obstructive hydrocephalus. Treatment of these patients may be successful by shuntless procedures if the absorptive problem is not the major component. In transient absorptive hydrocephalus, temporary measures were effective in many cases leading to successful procedures of ETV and/or posterior-fossa decompression in selected cases.

CONCLUSIONS

Shuntless procedures are the dream of a pediatric neurosurgeon provided it solves the problem and does not imply unacceptable risk. However, the benefit has to be evaluated years after the procedure is performed, as only prospective multicenter studies will truly show which procedure may have the best overall results in the developing child. Until such studies are available, understanding the basic pathology or the combination of pathologies leading to hydrocephalus in a given child may open the window of opportunities for other than shunt surgery in many hydrocephalic children with major obstructive component.

Endoscopic aqueductal stenting via the fourth ventricle under navigating system guidance: technical note

OBJECTIVE

We report three patients with symptomatic isolated fourth ventricle after ventriculoperitoneal shunt placement for hydrocephalus associated with ventricular hemorrhage. All three patients were treated successfully with our new method of endoscopic aqueductal stenting under navigating system guidance.

METHODS

A therapeutic rigid endoscope was inserted through the thin cerebellar hemisphere, and endoscopic aqueductal stenting was performed via the enlarged fourth ventricle under navigating system guidance.

RESULTS

All three patients underwent successful procedures with good outcomes.

CONCLUSION

Our method of aqueductal stenting is a reasonable choice for initial treatment of patients with isolated fourth ventricle, and it entails less invasive neurosurgery.

Endoscopic aqueductoplasty and placement of a stent in the cerebral aqueduct in the management of isolated fourth ventricle in children

OBJECT

In this study the authors conducted a retrospective evaluation of the effectiveness of endoscopic aqueductoplasty, performed alone or accompanied by placement of a stent, in the treatment of an isolated fourth ventricle (IFV) in seven patients afflicted with loculated hydrocephalus after a hemorrhage or infection.

METHODS

Seven children with symptomatic IFV and membranous aqueductal stenosis underwent endoscopic aqueductoplasty alone or combined with placement of a stent in the cerebral aqueduct. The mean age of the patients at the time of surgery was 10 months. The mean duration of follow up was 26 months. In all patients a supratentorial shunt had already been implanted, and in five patients neuroendoscopy had already been performed because other isolated compartments had been present inside the ventricular system. Aqueductoplasty alone was performed in three patients and aqueductoplasty and aqueductal stent placement in four. A precoronal approach was performed in five patients and a suboccipital approach in two. Signs and symptoms of intracranial hypertension resolved in all cases. Stent placement was successful in all five cases, resulting in clinical and neuroimaging-confirmed improvements in the IFV. Restenosis of the aqueduct occurred in two patients in whom stents had not been placed. In one of these patients restenosis was managed by an endoscopic procedure, during which the aqueduct was reopened and a stent implanted; in the other patient a shunt was placed in the fourth ventricle. Hydrocephalus was controlled by a single shunt in six cases (86%) and by a double shunt in one case.

CONCLUSIONS

Endoscopic placement of a stent in the aqueduct is more effective in preventing the repeated occlusion of the aqueduct than aqueductoplasty alone and should be indicated as the initial treatment in each case of compatible anatomy.

Bilateral abducent and facial nerve palsies following fourth ventricle shunting: two case reports

CASE REPORTS

Treatment of isolated fourth ventricle syndrome is difficult and there is no widely agreed method. Fourth ventriculo-peritoneal shunting is the most commonly utilized procedure for the management of this syndrome. Complications from shunting are common and are usually related to malfunction, infection, dislocation and overdrainage. We present two unusual cases in which both patients developed bilateral abducens and facial nerve palsies following shunting of an isolated fourth ventricle. Magnetic resonance imaging (MRI) in both cases revealed collapse of the fourth ventricles with downward displacement of the brain stem. In the first case the trans-tentorial pressure difference was equilibrated with the aid of a "Y" connector between the supratentorial and infratentorial shunts, with full recovery of the neurological deficits; in the second case this approach failed and following a complicated neurosurgical course successful endoscopic aqueductal stenting was performed.

DISCUSSION

Pathogenesis of cranial nerve palsies following fourth ventricle shunting and the rationale of treatment are discussed and the literature is reviewed.

Management strategies for treatment of the trapped fourth ventricle

BACKGROUND

An isolated or trapped fourth ventricle (TFV) is an occasional, serious sequela of hemorrhagic, infectious, or inflammatory conditions of the central nervous system. The TFV usually occurs after successful shunting of the lateral ventricles. It may be heralded by delayed clinical deterioration after an initial period of symptomatic improvement. The typical clinical findings suggest an expanding posterior fossa mass lesion. Surgical treatments include CSF diversionary procedures as well as open and endoscopic approaches. Complications related to the treatment of the TFV are common and relate to catheter obstruction and cranial nerve or brainstem dysfunction.

METHODS

The author reviews the clinical features, pathophysiology, and available treatment options for the TFV, with special reference to complication avoidance and advances in ventriculoscopy and frameless stereotaxy.

CONCLUSIONS

Treatment of the TFV remains a formidable challenge. However, prompt recognition and intervention may aid in the preservation of life and neurological function.

Endoscopic aqueductoplasty and interventriculostomy for the treatment of isolated fourth ventricle in children

OBJECTIVE

There are different approaches for the treatment of isolated fourth ventricle in children, including a suboccipital ventriculoperitoneal shunt, suboccipital craniotomy with microsurgical fenestration, and endoscopic fenestration. We discuss the indications, surgical methods, and outcome of 18 patients who underwent endoscopic treatment for isolated fourth ventricle.

METHODS

We retrospectively reviewed the medical histories of 18 patients with an isolated fourth ventricle. Surgical procedures included endoscopic aqueductoplasty, endoscopic aqueductoplasty with a stent, endoscopic interventriculostomy (lateral ventricle or third ventricle to fourth ventricle), and endoscopic interventriculostomy with a stent. Operations were performed between July 1997 and June 2002. The mean age of the patients at the time of surgery was 3 years. The mean follow-up was 29 months. All patients had a supratentorial ventriculoperitoneal shunt.

RESULTS

Clinical symptoms (impairment of consciousness, tetraparesis, and ataxia) improved in all patients. Reduction of the size of the fourth ventricle was observed in all patients. Seven patients required reoperation because of restenosis (39% revision rate). Restenosis occurred between 2 weeks and 7 months after surgery (average, 3 mo). Four patients underwent reoperation with stent placement, and three patients underwent reaqueductoplasty. We had the following complications: one infection, one asymptomatic subdural hygroma, one transient oculomotor paresis, and one permanent oculomotor paresis (4 [22%] of 18 patients).

CONCLUSION

The significant failure rate of fourth ventricle shunts has led to the development of alternative treatment methods. Endoscopic aqueductoplasty or interventriculostomy presents an effective, minimally invasive, and safe procedure for the treatment of isolated fourth ventricle in pediatric patients. Compared with suboccipital craniotomy and microsurgical fenestration, endoscopic aqueductoplasty is less invasive, and compared with fourth ventricle shunts, it is more reliable and effective.