Subdural hygroma as a complication of endoscopic neurosurgery--two case reports

Retrocerebellar Ependymal Cyst Presenting with Obstructive Hydrocephalus in an Infant

Intracranial ependymal cysts (ECs) are rare benign lesions. They are frequently asymptomatic and arise in the supratentorial regions. Retrocerebellar ECs is a rare location. We present a case of 3-months-old infant who developed obstructive hydrocephalus, bulging fontanel, and macrocephaly secondary to a retrocerebellar EC. Magnetic resonance imaging (MRI) showed a large retrocerebellar cyst that compressed the cerebellum and the brainstem, producing fourth ventricle outlet obstruction and supratentorial hydrocephalus. Microsurgical fenestration of the cyst to the obex of the fourth ventricle and a cystic wall biopsy were performed. The procedure improved supratentorial hydrocephalus, as well as the patient's clinical condition. A histopathological study confirmed the diagnosis of an EC.

As far as we know, after a thorough review of the literature, this is the first reported case of retrocerebellar EC. It is a rare cause of hydrocephalus due to outlet obstruction of the fourth ventricle. Treatment of the cause itself was shown to be effective.

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

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

Subdural Hygroma Following Endoscopic Third Ventriculostomy: Understanding the Pathophysiology

BACKGROUND

Endoscopic third ventriculostomy (ETV) has overtaken the use of a ventriculoperitoneal shunt for the treatment of congenital hydrocephalus. Although ETV is relatively safe, several postoperative complications have been reported. One of the least described and understood complications is subdural hygroma following third ventriculostomy.

METHODS

In this series, we retrospectively analyzed patients who were managed for postventriculostomy subdural hygroma and analyzed the possible factors responsible for this condition.

RESULTS

A total of 248 patients who underwent ETV between 2014 and 2016 were included in this study. Twelve patients (4.8%) had developed subdural hygroma, including 6 patients with bilateral hygroma, 2 with contralateral hygroma, and 4 with ipsilateral subdural hygroma. Only 4 patients (1.6%) were symptomatic, with complains of pseudomeningocele, persistent vomiting, or headache. Significant mass effect was present in 2 patients with unilateral subdural hygroma, which improved after placement of a subduroperitoneal shunt. In 1 patient, the subdural hygroma decreased with persistent ventriculomegaly and improved after ventriculoperitoneal shunt implantation. One patient with posttraumatic hydrocephalus who had a bilateral subdural hygroma following ETV improved with conservative management. At a 12-month follow-up, all patients remained asymptomatic.

CONCLUSIONS

Post-ETV subdural hygroma may result from poor absorption of cerebrospinal fluid (CSF) in the subarachnoid space, dysfunction of the stoma with persistence of the ventriculosubdural fistula, or altered CSF cytology, such as hemorrhage. Most of these patients remain asymptomatic and improve with time. Symptomatic patients should be properly evaluated for the cause of the formation of subdural hygroma, which will guide the appropriate interventions.

Neuroendoscopic Approach to Intracranial Ependymal Cysts

BACKGROUND

Intraparenchymal cysts without communication to the ventricles or the subarachnoid space are named ependymal or epithelial cysts. The estimated ratio of their incidence compared with arachnoid cysts is 1:10. Neurologic deficit can occur when the cyst exerts mass effect on its surroundings. We evaluated the success rate of endoscopic fenestration of intracranial ependymal cysts.

METHODS

Our prospectively maintained endoscopy database was screened for all cases of ependymal cysts. The charts were retrospectively reviewed for symptoms, surgery, postoperative course, and complications. Magnetic resonance imaging scans performed before and after surgery were analyzed.

RESULTS

We identified 6 patients harboring an intracranial ependymal cyst. The cyst location was frontoparietal, parietal, occipital, or mesencephalic. Patients presented with several symptoms according to the location of the cyst (i.e., epilepsy, hemiparesis, diplopia, hemianopsia). All patients were treated by navigation-guided endoscopic fenestration of the cyst to the ventricular system. Two complications occurred: a cerebrospinal fluid leak, which was managed surgically by wound revision without the need for cerebrospinal fluid shunting, and a chronic subdural hematoma, which occurred 6 weeks after surgery and required burr hole evacuation. Follow-up period ranged from 6 months to 9 years. Magnetic resonance imaging revealed that all cysts decreased in size. Symptoms improved in all patients.

CONCLUSIONS

Endoscopic fenestration of ependymal cysts to an adjacent ventricular cavity is a treatment option with excellent long-term results and minimal morbidity. It should be considered as the therapy of choice to avoid craniotomy and shunt dependence.

Subdural hematoma after endoscopic third ventriculostomy: Struggling against the Laplace law

BACKGROUND

Endoscopic third ventriculostomy (ETV) is an ideal treatment for obstructive hydrocephalus. Although ETV is a safe procedure, several complications related to this procedure have been reported in the literature. We present a rare case of late onset symptomatic bilateral subdural hematoma after an uneventful ETV that proved particularly difficult to solve.

CASE DESCRIPTION

A 61-year-old male patient presented in our neurosurgery department three months after ETV (aqueductal stenosis) with progressive headaches and anomic aphasia. The MRI revealed bilateral chronic subdural hematomas (chSDH). They were treated via a burr hole evacuation, subduroperitoneal and external subdural drains proving to be refractory to the first two strategies. Postoperatively, his headaches improved. At the last follow-up the patient's status remains improved and there is no radiological evidence of significant residual collections.

CONCLUSION

This case confirms that chSDH formation is a rare possible complication following ETV even in the presence of a normal early postoperative image. Patients should be followed-up more closely for possible subdural collection formation. In the cases of very long-term hydrocephalus with a thin cerebral mantle, brain elastic properties are likely to be altered. As there is no possibility to close the internal shunt, the stoma, we advocate external subdural drainage to reinflate the brain, in the first intention or at least after an initial failed burr hole evacuation.

Endoscopic third ventriculostomy - effectiveness of the procedure for obstructive hydrocephalus with different etiology in adults

Introduction

After a time of domination of shunt placement, endoscopic third ventriculostomy (ETV) has been increasingly applied in treatment of obstructive hydrocephalus.

Aim

To assess the effectiveness of ETV in treatment of adults with three-ventricle hydrocephalus of different etiology.

Material and methods

Ninety-six patients with obstructive hydrocephalus were studied: 24 with primary aqueductal stenosis, 61 with brain tumor, and 2 with basilar tip aneurysm. In 9 patients the etiology of hydrocephalus remained undetermined. The assessment of treatment results was based on clinical and radiological criteria.

Results

Clinical improvement was observed in 74 (77.1%) patients, and radiological improvement in 52 (54.2%). One patient died. Follow-up of 24 patients with primary aqueductal stenosis has shown that in 20 (83.3%) of them clinical improvement has been stable, and in 14 (58.3%) radiological improvement has been observed. Two patients required shunt placement due to hydrocephalus recurrence 12–24 months after the ETV procedure. Among 9 patients with undefined hydrocephalus, 3 required shunt placement within 6 months after ETV (2 shunted previously). Endoscopic third ventriculostomy treatment in a patient with hydrocephalus caused by basilar tip aneurysm succeeded. The assessment of ETV effectiveness in oncological patients has been indirect in view of the underlying disease.

Conclusions

The best results of ETV treatment have been demonstrated for patients with primary aqueductal stenosis. Ventricle size cannot determine the effectiveness of treatment as an individual requirement. Endoscopic third ventriculostomy is effective in previously shunted patients although the prediction of outcome should be cautious. Endoscopic third ventriculostomy enables preparation for further therapy and is palliative treatment in oncological patients with secondary hydrocephalus.

Ventricular endoscopy in the pediatric population: review of indications

INTRODUCTION

Neuroendoscopy has greatly impacted pediatric neurosurgery over the past few decades. Improved optics and microsurgical tools have allowed neuroendoscopes to be used for a multitude of neurosurgical procedures.

DISCUSSION

In this review article, we present the breadth of intraventricular neuroendoscopic procedures for the treatment of conditions ranging from hydrocephalus and brain tumors to congenital cysts and other pathologies. We critically discuss treatment indications and reported success rates for neuroendoscopic procedures. We also present novel approaches, technical nuances, and variations from recently published literature and as practiced in the authors' institution.

Chronic subdural hematoma associated with the middle fossa arachnoid cyst: pathogenesis and review of its management

BACKGROUND

The pathogenesis of chronic subdural hematoma (CSDH) associated with an arachnoid cyst (AC) is still not clear. We propose an origin of initial bleeding of CSDH in patients with AC based on our experience and discuss the management of this disease.

MATERIALS AND METHODS

The total number of operations included in this study was 23. Eleven cases were indicated because of associated CSDH (group 1), and the other cases were due to different reasons (group 2). The relationship of the AC and dura was evaluated in patients who did not have CSDH (group 2) because patients with CSDH would have had structural changes of AC due to hematoma.

RESULTS

In group 1, the age distribution was from 8 to 61 years (mean 23.0). The development of CSDH was not related with Galassi types. The hematomas were located outside of the outer cyst membrane in six patients and both inside and outside in three patients. In two patients, the location could not be reviewed. After suspicion of the outer cyst membrane as the origin of the bleeding site, we found small bridging vessels between the dura and outer cyst membrane in three of five consecutive patients in group 2.

CONCLUSIONS

Based on our surgical experience of AC cyst, we found small bridging vessels between the dura and outer membrane of the AC. We suggested that these small vessels are the source of initial bleeding leading to CSDH in AC.

Hygromas after endoscopic third ventriculostomy in the first year of life: incidence, management and outcome in a series of 34 patients

BACKGROUND

Overdrainage in shunted patients is a known predisposing factor for the formation of hygromas, but little is known about risk factors in endoscopic third ventriculocisternostomy (ETV).

MATERIALS AND METHODS

We retrospectively analysed data of 34 patients younger than 1 year with obstructive hydrocephalus, undergoing ETV, with respect to incidence, management, outcome and possible risk factors for the formation of hygromas. Hygromas were arbitrarily defined as a collection of cerebrospinal fluid of more than 10 mm in diameter over the paramedian hemispheric convexities, diagnosed by ultrasonography.

RESULTS

They occurred in 9 of 34 (26%) patients 3 to 28 days after ETV. They were on the operated side in four and bi-lateral in five cases. There was no relevant age difference between patients with hygromas (median 127 days) and those without hygromas (median 166 days). Etiology of obstructive hydrocephalus had no impact on the frequency of hygromas. Hygromas occurred somewhat less frequently when a paediatric endoscope with an outer diameter of 3 mm was used for ETV instead of an endoscope with a diameter of 6 mm. Hygromas were asymptomatic and conservatively managed in five cases; 4 of 34 (12%) patients underwent surgery because of clinical symptoms of increasing intracranial pressure or increasing hygroma diameter. Two patients were treated with a temporary external drainage only and another two patients with an external drainage first and eventually a subduro-peritoneal shunt. There were no neurological long-term sequelae.

CONCLUSION

Clear predisposing factors for the formation of hygromas could not be identified, but the outer diameter of the endoscope may play a role.

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

OBJECT

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

METHODS

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

CONCLUSIONS

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

Risk reduction of subdural collections following endoscopic third ventriculostomy

OBJECT

To evaluate the efficacy and safety using fibrin glue and absorbable hemostats for packing the endoscopic tract in a pediatric population in the prevention of subdural fluid collections after endoscopic third ventriculostomy.

MATERIALS AND METHODS

Twenty-one endoscopic third ventriculostomies were performed in 20 hydrocephalic children with a mean age of 22 months over a 4-year period using uniformly this technique. Six children, with age ranged 6 days to 22 months (mean 9 months), had severe ventriculomegaly with thin brain mantle less than 10 mm. There was no mortality and no permanent morbidity related to the endoscopic procedure. One child developed an asymptomatic collection, which could be managed conservatively and was most likely attributed to the young age of the child and the assumed poor cerebrospinal fluid absorption ability. Lost compliance of the brain parenchyma may play an additional role, which was not related to the thickness of the brain mantle. No adverse effects regarding the material used for sealing were observed over a mean follow-up of 23 months.

CONCLUSIONS

Subdural fluid collections could be prevented in 20 out of 21 procedures by using this technique regardless of the thickness of the brain mantle, the application of mixture of fibrin glue and hemostatic agents seems to be safe, and we consider this technique effective in reducing the risk of this potential complication.

Neuroprotection against surgically induced brain injury

BACKGROUND

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

METHODS/RESULTS

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

CONCLUSION

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

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

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

Neurofiberscopic biopsy of tumors of the pineal region and posterior third ventricle: indications, technique, complications, and results

OBJECTIVE

Evaluation of results of the neurofiberscopic biopsy of tumors of the pineal region and posterior third ventricle.

METHODS

From 2001 to 2004, 23 patients (mean age, 30.6 yr) with tumors located in the pineal region or posterior third ventricle underwent neurofiberscopic biopsy with simultaneous third ventriculostomy. The procedure was indicated for verification of the histological diagnosis of the neoplasm, which was planned to be treated by radiotherapy and/or chemotherapy without open surgery (eight patients), establishment of the pathological diagnosis for further choice of the most appropriate treatment strategy (11 patients), differentiation of the recurrent neoplasm and radiation necrosis (two patients), and decompression of the large tumor-associated cyst (two patients). In six previously shunted patients, substitution of the ventriculoperitoneal shunt on the third ventricle stoma was performed.

RESULTS

There was no postoperative mortality or permanent morbidity. In all cases, the obtained tissue sample was sufficient for pathological diagnosis. Transient postoperative complications included fever (15 patients), nausea and vomiting (three patients), and diplopia (one patient). On the long-term follow-up, delayed third ventricular stoma failure caused by tumor regrowth and scar formation was found in one patient, and dissemination of the malignant glioma through the subarachnoid space was found in another patient.

CONCLUSION

Neurofiberscopic biopsy represents a useful method for sampling of tumors of the pineal region and posterior third ventricle, which can be effectively used in both previously shunted and shunt-free patients.

Endoscopic third ventriculostomy

Among patients with idopathic aqueductal stenosis or impedance of cerebrospinal fluid (CSF) flow in the posterior fossa due to tumour, endoscopic fenestration of the floor of the third ventricle creates an alternative route for CSF flow to the subarachnoid space via the prepeduncular cistern. By reestablishing CSF flow, this procedure dissipates any pressure gradient on midline structures. This may obviate the need for traditional CSF shunt diversion techniques in such settings. Currently, endoscopic third ventriculostomy is indicated in approximately 25% of patients with hydrocephalus and can be performed instead of shunt placement. Appropriate patients are those with aqueductal stenosis (10%), obstructive tumours (10%), and obstructive cysts (5%). Additional recent data suggest the favorability of third ventriculostomy over shunt implantation in additional patient cohorts. Operative technique is discussed.

Endoscopic third ventriculostomy for obstructive hydrocephalus

The indications for neuroendoscopy are not only constantly increasing, but even the currently accepted indications are constantly being adjusted and tailored. This is also true for one of the most frequently used neuroendoscopic procedures, the endoscopic 3rd ventriculostomy (ETV) for obstructive hydrocephalus. ETV has gained popularity and widespread acceptance during the past few years, but little attention has been paid to the techniques of the procedure. After a short introduction describing the history of ETV, an overview is given of all the different techniques that have been and still are employed to open the floor of the 3rd ventricle. The spectrum of indications for ETV has been widely enlarged over the last years. Initially, the use of this procedure was restricted to patients older than 2 years, to patients with an obvious triventricular hydrocephalus, and to those with a bulging, translucent floor of the 3rd ventricle. Nowadays, indications include all kinds of obstructive hydrocephalus but also communicating forms of hydrocephalus. The results of endoscopic procedures in treating these pathologies are given under special consideration of shunt technologies. In summary, from the review of the publications since the first ETV performed by Mixter in 1923, this technique is the treatment of choice for obstructive hydrocephalus caused by different etiologies and is an alternative to cerebrospinal fluid shunt application.

Long-term complications and definition of failure of neuroendoscopic procedures

OBJECTS

A lot has been published about neuroendoscopic procedures over the last decade. Most of these publications are about the effectiveness of endoscopic third ventriculostomy, the most frequently performed neuroendoscopic procedure. Little is published about the effectiveness of other, less frequently performed neuroendoscopic procedures. Over the years more reports about the complications of endoscopic procedures are published, but again most of these publications are about endoscopic third ventriculostomy and only a little is presented about the complications of all other neuroendoscopic procedures. Furthermore, most reports are about intraoperative and immediate postoperative complications; only a few reports evaluated the long-term complications of neuroendoscopic procedures. There are also a few publications that analyse the failures of neuroendoscopic procedures but a good definition of failure is not given. The reports mention, again, mainly endoscopic third ventriculostomy procedures, and are mostly directed at the short-term failure rates, defined as the need for a shunt to be placed. Less attention is paid to the effects of the endoscopic procedures in the longer term. Looking at longer terms emphasises the need for a better definition of failure.

METHODS

To get more insight into the long-term complications and failures of neuroendoscopic procedures, we reviewed the literature and evaluated our own series of 485 different cranial endoscopic procedures. With the information gathered we tried to answer the questions mentioned above.

CONCLUSIONS

Most of the complications of neuroendoscopic procedures are transient, either spontaneously or by medical intervention. Only a few permanent complications are known, in our series 1.6%, and most of them are not typically related to the endoscopic procedure itself but are due to the ventricular approach necessary for and the management of the endoscopy. Mortality rates are less than 1%. A uniform definition of failure cannot be given for all neuroendoscopic procedures, because the procedures are too heterogeneous and the indications are widespread. Failures are mainly diagnosed within a few months of the procedure but neurosurgeons must be aware of failure in the longer term, because if not diagnosed they can give rise to increased morbidity and probably mortality.