Fourth ventricle neurocysticercosis with hydrocephalus: A case report and literature review

Abstract

BACKGROUND

Neurocysticercosis (NCC) is the most common parasitic infection of the central nervous system and remains an important cause of neurological morbidity worldwide. Intraventricular NCC may lead to obstructive hydrocephalus and often requires surgical management. The fourth ventricle is the most frequently involved intraventricular location but poses specific diagnostic and therapeutic challenges.

CASE SUMMARY

A 60-year-old woman presented with persistent headache, dizziness, and recent onset nausea and vomiting. Brain magnetic resonance imaging revealed obstructive hydrocephalus caused by a cystic lesion in the fourth ventricle with an eccentrically located scolex suggestive of NCC. Serological testing confirmed the diagnosis. An endoscopic third ventriculostomy was initially performed to treat hydrocephalus and avoid shunt placement. Although the patient initially improved, she returned 5 weeks later with recurrent symptoms, and imaging revealed cyst enlargement. Therefore, a suboccipital craniotomy with a telovelar approach was performed, allowing complete en bloc removal of the lesion. Histopathology confirmed Taenia solium cysticercosis. The postoperative course was uneventful and antiparasitic therapy was not administered. At the 1-year follow-up, the patient remained asymptomatic with no radiological recurrence.

CONCLUSION

Fourth ventricle NCC may require direct surgical removal when cerebrospinal fluid diversion alone is insufficient. Microsurgical excision remains an effective treatment option.

Key Words: Neurocysticercosis; Fourth ventricle; Hydrocephalus; Endoscopic third ventriculostomy; Telovelar approach; Cyst; Case report

Core Tip: Intraventricular neurocysticercosis (NCC) may present with obstructive hydrocephalus requiring urgent management. Although endoscopic third ventriculostomy can relieve hydrocephalus, it may not address the underlying obstruction caused by the cyst. This case highlights the management dilemma between cerebrospinal fluid diversion and definitive cyst removal in fourth ventricle NCC. When symptoms persist or the lesion enlarges, microsurgical excision through a suboccipital telovelar approach remains a safe and effective treatment strategy.

INTRODUCTION

Neurocysticercosis (NCC) is the most common parasitic infection affecting the human central nervous system (CNS) and is caused by larvae of the pork tapeworm Taenia solium[1,2]. CNS NCC disease may be classified as intraparenchymal or extra-parenchymal. The extra-parenchymal type can be further categorized as intraventricular, subarachnoid, and spinal. Among the intraventricular CNS NCC, the fourth ventricle is the most frequent location, followed by the lateral and third ventricles. Consequently, this type of CNS NCC is usually associated with subacute onset of headache, visual impairment, and other signs or symptoms related to increased intracranial pressure and hydrocephalus.

In this paper, we describe a patient with an extra-parenchymal NCC in the fourth ventricle who underwent both an endoscopic third ventriculostomy (ETV) and microsurgical cyst removal. We discuss the treatment strategies and surgical indications for the rare condition of fourth ventricle NCCs.

CASE PRESENTATION

Chief complaints

A 60-year-old woman presented with persistent headache, dizziness, and recent onset nausea and vomiting.

History of present illness

She presented with a 5-month history of progressive headache and dizziness, followed by the recent onset of nausea and vomiting, prompting admission to the emergency department. No other neurological symptoms were reported.

History of past illness

No special notes.

Personal and family history

No special notes.

Physical examination

Neurological examination was unremarkable at initial presentation.

Laboratory examinations

Blood tests revealed the presence of anti-Taenia solium antibodies, supporting the suspected diagnosis; notably, lumbar puncture was not performed due to the risk of herniation for a fourth ventricular lesion.

Imaging examinations

Magnetic resonance imaging (MRI) of the brain with gadolinium revealed a well-defined fourth ventricular cystic lesion, leading to tri-ventricular hydrocephalus (Figure 1). A small blurred-enhancing nodular component (5 mm) was observed within the cyst, adjacent to the right margin of the thickened cystic wall. A cerebral catheter angiogram was then performed to rule out a posterior fossa hemangioblastoma, initially considered in the differential diagnosis.

Figure 1 Preoperative magnetic resonance imaging. A-D: The initial magnetic resonance imaging (MRI) revealed a cystic lesion within the fourth ventricle, characterized by an eccentrically positioned scolex and minimal contrast enhancement. The lesion is indicated by an orange arrow; E-H: A subsequent MRI, performed 5 weeks later, demonstrated a marked increase in the cyst size (A and E: Axial T2-weighted sequences; C and G: Sagittal T2-weighted sequences; B and F: Axial post-contrast sequences; D and H: Sagittal post-contrast sequences).

The MRI scans were carefully reviewed, and the radiological features—particularly the eccentrically located scolex within a thin-walled cyst—were highly suggestive of NCC in the vesicular stage.

MULTIDISCIPLINARY EXPERT CONSULTATION

An endoscopic third ventriculostomy (ETV) was first performed to treat hydrocephalus. The postoperative course was uneventful and, after multidisciplinary discussion, the patient was discharged without any anti-parasitic medication, as it was believed that such treatment could worsen cyst-related inflammation and swelling.

However, 5 weeks later, the patient was readmitted with recurrent headaches, vomiting, and gait ataxia. A repeat brain MRI demonstrated a significant increase in the size of the fourth ventricular cystic lesion (Figure 1).

A new multidisciplinary discussion with infectious disease specialists was conducted, and surgical removal of the lesion was considered the most appropriate treatment strategy to both excise the cyst and resolve the obstructive hydrocephalus.

FINAL DIAGNOSIS

En bloc surgical resection of the lesion allowed definitive diagnosis of fourth ventricular neurocysticercosis (Taenia solium cyst) in the vesicular stage causing obstructive hydrocephalus.

TREATMENT

The patient was placed in a prone position and a suboccipital telovelar approach was performed to reach the fourth ventricle. The cyst was identified and microsurgically dissected from the ependyma, allowing en bloc removal without any rupture (Figure 2). Cerebrospinal fluid (CSF) flow was successfully restored. Perioperative corticosteroid therapy was administered to reduce the inflammatory response.

Figure 2 Intra-operative images. A: Posterior fossa open approach; B: The cyst (*) was identified in the fourth ventricle and dissected from the ependyma; C and D: En bloc removal of the cyst without rupture. PICA: Posterior inferior cerebellar artery.

Postoperative MRI showed a gross total removal of the ventricular NCC and a marked reduction in ventricular size (Figure 3). Histopathological analysis confirmed the lesion as a Taenia solium cyst in the vesicular stage. After consultation with infectious disease specialists, antiparasitic therapy was withheld due to the lack of evidence supporting its benefit for solitary intraventricular cysts.

Figure 3 Postoperative magnetic resonance imaging. The postoperative magnetic resonance imaging demonstrated complete cyst resection without complications. A: Axial T2-weighted sequence; B: Sagittal T2-weighted sequence; C: Axial post-contrast sequence.

OUTCOME AND FOLLOW-UP

The postoperative course was uneventful, and the patient was discharged on postoperative day 8 without any neurological deficit. At the 1-year follow-up, the patient was neurologically intact, with no radiological evidence of recurrence.

DISCUSSION

NCC is the most common parasitic infection affecting the CNS and remains a major cause of neurological morbidity worldwide[3-5]. It results from infection by pork tapeworm Taenia solium larvae and is typically acquired through ingestion of contaminated food or water[1].

NCC can be classified according to its anatomical location as parenchymal or extra-parenchymal disease. The extra-parenchymal form includes intraventricular, subarachnoid, and spinal involvement and is generally associated with more severe clinical manifestations, such as hydrocephalus, arachnoiditis, and ventriculitis[6,7]. Among intraventricular locations, the fourth ventricle represents the most frequent site (43%-70%), followed by the lateral and third ventricles[2]. In this setting, hydrocephalus is common and may result from direct obstruction of CSF pathways or inflammatory processes leading to aqueductal stenosis[8].

Intraventricular lesions may occasionally cause Bruns’ syndrome, characterized by intermittent obstruction of CSF flow due to a mobile intraventricular mass[9,10]. Although this condition can also be associated with tumors or other cystic lesions, it has been historically described in patients with fourth ventricle NCC[11].

Radiological findings play a crucial role in diagnosis. MRI typically demonstrates a cystic lesion with an eccentrically located scolex, which is highly suggestive of NCC in the vesicular stage. Nevertheless, differential diagnosis of cystic lesions within the fourth ventricle includes infectious conditions such as tuberculomas or hydatid cysts, as well as neoplastic and nonneoplastic lesions, including ependymomas, subependymomas, arachnoid cysts, or Blake’s pouch cysts[12-17]. Clinical history and epidemiological context can therefore help guide the diagnosis.

Management of intraventricular NCC remains challenging and often requires surgical intervention, particularly when hydrocephalus is present[18]. Treatment strategies aim to relieve CSF obstruction and, when feasible, remove the causative lesion. Historically, ventriculoperitoneal shunting has been commonly used for NCC-associated hydrocephalus; however, shunt malfunction and infection rates are relatively high, often requiring multiple revisions[2,19]. For this reason, ETV has been proposed as an alternative strategy for CSF diversion. Some series have reported success rates exceeding 90% with endoscopic CSF diversion procedures[20,21].

In our case, ETV was initially performed to treat obstructive hydrocephalus and to avoid permanent shunt placement. Although the patient initially improved, she returned 5 weeks later with recurrent symptoms and radiological evidence of cyst enlargement. This situation illustrates an important management dilemma in intraventricular NCC: While CSF diversion may provide temporary symptomatic relief, it does not eliminate the underlying obstructive lesion, and definitive cyst removal may ultimately be required.

Endoscopic removal has increasingly become the preferred approach for intraventricular cysts, particularly in the lateral and third ventricles[20,22]. However, removal of fourth ventricle cysts may be technically demanding depending on the anatomy of the aqueduct, the size of the cyst, and its potential adherence to the ependymal surface[23]. In these situations, a posterior fossa microsurgical approach remains a reliable and effective alternative.

Medical treatment of NCC remains a matter of debate. Anthelminthic therapy has demonstrated benefits in patients with active parenchymal disease by reducing viable cysts and preventing seizure recurrence[24-26]. Current guidelines from the Infectious Diseases Society of America and the American Society of Tropical Medicine and Hygiene recommend albendazole-based therapy depending on the number of parenchymal lesions[27]. However, in cases of intraventricular NCC, particularly when the cyst can be safely removed, surgical treatment remains the preferred option[22,27].

Moreover, some studies have discouraged the use of antiparasitic therapy before surgery because it may induce inflammatory changes or cyst rupture, potentially complicating surgical removal[27]. Corticosteroids are often administered to reduce the inflammatory response associated with cyst degeneration or antiparasitic therapy[1,28]. In the present case, the intact cyst was removed and antiparasitic therapy was not administered. The patient remained asymptomatic with no evidence of recurrence at the 1-year follow-up.

The suboccipital telovelar approach allows direct access to the fourth ventricle while avoiding splitting of the cerebellar vermis and provides adequate visualization for safe dissection of the cyst from surrounding structures. Several articles have discussed the risk factors and etiology of the disease[29,30], and many case series have reported favorable outcomes using this technique[31-35]. In our patient, microsurgical removal allowed complete en bloc resection of the cyst and restoration of CSF circulation.

CONCLUSION

Management of intraventricular NCC requires addressing both hydrocephalus and the obstructing lesion. Although ETV can effectively relieve hydrocephalus, it may not provide definitive treatment when the cyst continues to obstruct CSF pathways. This case highlights the clinical decision-making dilemma between cerebrospinal fluid diversion and definitive cyst removal in fourth ventricle NCC. When symptoms persist or the lesion enlarges, microsurgical excision through a suboccipital telovelar approach remains a safe and effective treatment option.