Intraventricular migration of fourth ventricular neurocysticercosis: an unusual complication during endoscopic surgery

Abstract

A boy in his middle childhood presented with intermittent episodes of headache with vomiting for 6 months. Plain CT of the head and MRI of the brain revealed fourth ventricular cysticercal cyst with acute obstructive hydrocephalus. Endoscopic excision of the cyst was done along with endoscopic third ventriculostomy and septostomy with external ventricular drain placement. Although we were able to decompress the cysticercal cyst, unfortunately, the cyst got slipped from the grasper leaving the grasped cyst wall in the tooth of the grasper. Through this case report, we want to highlight that such a complication could also happen during neuroendoscopic cysticercal cyst removal and how we dealt with it. Our patient was discharged neurologically intact and was symptom free on follow-up.

Background

Neurocysticercosis (NCC) is the most frequently observed parasitic infection of the central nervous system (CNS) worldwide caused by larval stage of Taenia solium tapeworm. Also, it is the most common preventable cause of acquired epilepsy in the world. NCC is endemic in many regions of Central and South America, sub-Saharan Africa, India and Asia.^1–3 Intraventricular involvement occurs in 7%–30% of cases, and the fourth ventricle is the most frequent site.⁴ Large intraventricular NCC (IVNCC), with their free movement in the ventricular system, can lead to intermittent acute occlusion of the foramen of Monro or aqueduct of Sylvius due to ball valve mechanism leading to development of acute life-threatening hydrocephalus, which is also known as Bruns syndrome.^5–7

Herein we report a case of fourth ventricular NCC with obstructive hydrocephalus for which we did endoscopic removal but unfortunately faced an unusual complication of cyst slippage and migration during surgery. A rescue endoscopic third ventriculostomy (ETV) with septostomy was performed. There is no case reported to date mentioning such an intraoperative incidence. Such complications should be highlighted so that they can be avoided in future.

Case presentation

A boy in his middle childhood presented with intermittent episodes of headache with vomiting since 6 months. On examination, he was conscious and oriented with Glasgow Coma Scale E4V5M6 and bilateral pupils were normal in size and normal reacting. The rest of the neurological examination was unremarkable. He had no history of fever and seizures in the past. CT of the head of the patient done on admission showed hydrocephalus with grossly dilated lateral and third ventricle with an ill-defined cystic lesion in the fourth ventricle (figure 1A and D). MRI of the brain revealed a well-defined cystic lesion in the fourth ventricle with hydrocephalus. The lesion was hypointense on T1, hyperintense on T2 and suppressed on T2 FLAIR sequence. Moreover, an eccentric enhancing nodule (scolex) was seen in the periphery of the lesion, which is shown in SWAN sequence of MRI (figure 2A–E). Based on the radiological findings, a diagnosis of fourth ventricular NCC with obstructive hydrocephalus was made; hence, we planned for the endoscopic removal of the neurocysticercal cyst along with ETV to deal with both the condition, the hydrocephalus and the intraventricular cyst.

Figure 1.

(A) Preoperative plain CT of the head axial section showing cystic lesion in the fourth ventricle with small hyperdense nodule (marked with white arrow); (B) immediate postoperative plain CT of the head axial section showing collapsed cysticercal cyst in the posterior part of the third ventricle (marked with red arrow) and tip of external ventricular drain (marked with yellow arrow); (C) axial section of plain CT of the head done after 2 weeks showing cysticercal cyst migrating to proximal part of the fourth ventricle (marked with white arrow); (D) preoperative plain CT of the head sagittal section showing cystic lesion in the fourth ventricle with small hyperdense nodule (marked with white arrow); (E) immediate postoperative plain CT of the head sagittal section showing collapsed cysticercal cyst in the posterior part of the third ventricle (marked with red arrow); (F) sagittal section of plain CT of the head done after 2 weeks showing the cyst in the proximal part of the fourth ventricle (marked with white arrow).

Figure 2.

(A) Preoperative magnetic resonance T2 sagittal image showing dilated lateral and third ventricle with cysticercal cyst in the fourth ventricle (marked with yellow arrow); (B) preoperative magnetic resonance T2 FLAIR axial image showing cysticercal cyst in the fourth ventricle with hyperintense peripheral scolex (marked with white arrow); (C) preoperative magnetic resonance T1 axial image showing cysticercal cyst in the fourth ventricle with hyperintense peripheral scolex (marked with yellow arrow); (D) preoperative magnetic resonance SWAN sequence axial image showing cystic lesion in the fourth ventricle with an eccentric scolex (marked with red arrow); (E) preoperative magnetic resonance T1C (contrast) axial image showing isointense cysticercal cyst in the fourth ventricle with minimal peripheral contrast uptake (marked with blue arrow).

Surgical technique

After shifting the patient to OT (operation theatre), general anaesthesia was given and the patient was placed supine with head slightly flexed and fixed on three-pin Mayfield head fixation system. A pre-coronal 3×3 cm ‘mini-craniotomy’ was done 3 cm lateral to midline and 1 cm anterior to coronal suture. In comparison with a burr hole, mini-craniotomy allows for a wide range of manipulation of the endoscope to perform ETV and cysticercal cyst removal together, and also the dura can be sutured watertight to prevent postoperative cerebrospinal fluid (CSF) leakage. After opening the dura with a curvilinear incision, a 4 mm rigid 0° endoscope (Aesculap, Germany) with its sheath was navigated to the floor of the third ventricle, and ETV was performed (figure 3A). CSF was collected and sent for ELISA. After completion of the ETV, we navigated the endoscope to the posterior third ventricle to visualise the aqueduct of Sylvius. The aqueduct of Sylvius was dilated and a pearly white cystic lesion mimicking a ‘full moon’ was seen embedded in the proximal part of the fourth ventricle (figure 3B). After fixing the endoscope in a stable position, we increased the flow of the irrigation to dislodge the cyst from the fourth ventricle. Due to the irrigation flow, the cyst started migrating upward into the aqueduct and we grasped the cyst with the grasper and brought upward near the tip of the endoscope. Then, before finally removing the grasped cyst along with the whole endoscope assembly, the cyst got dislodged leaving the grasped part of the cystic wall between the tooth of the grasper (figure 3C). We navigated the endoscope again into the third ventricle and aqueduct of Sylvius, but the cyst could not be visualised. It possibly migrated to the pineal recess of the third ventricle, which could not be accessed using rigid endoscope. So we decided to do septostomy to look into the left lateral ventricle if the cyst has migrated there through the foramen of Monro. But after navigating the endoscope to all possible parts of the ventricular system, we could not visualise the cyst. Finally, we decided to place an external ventricular drain (EVD) to avoid any acute postoperative hydrocephalus. After the completion of the procedure, a piece of rolled gel foam was placed in the corticectomy tract. The dura is closed watertight and the bone flap replaced back and fixed with silk sutures to the adjacent bone.

Figure 3.

(A) Intraoperative image during neuroendoscopy showing the external third ventriculostomy at the floor of the third ventricle (marked with black arrow), infundibular recess (marked with white arrow), mammillary bodies (marked with yellow arrow) and optic chiasm (marked with blue arrow); (B) intraoperative image of neuroendoscopy showing ‘full moon’-shaped cysticercal cyst in the fourth ventricle (marked with black arrow); (C) intraoperative image during neuroendoscopy showing the clinched part of the capsule by the grasper in the foramen of Monro.

Outcome and follow-up

Postoperatively, we started dexamethasone 12 mg/day, tapered over 1 week, and albendazole (15 mg/kg/day) for 4 weeks. We did CT of the head in the postoperative period, which showed the cyst in the posterior third ventricle with no hydrocephalus. We removed the EVD thereafter and the patient was discharged neurologically intact on fifth postoperative day. CT of the head done 2 weeks later showed cyst migration in the proximal part of the fourth ventricle with no hydrocephalus. The patient did not present with any further symptom in 3 months and is kept in follow-up.

Discussion

NCC is the most frequently observed parasitic infection of the CNS worldwide caused by larval stage of T. solium tapeworm. Also, it is the most common preventable cause of acquired epilepsy in the world. NCC is endemic in many regions of Central and South America, sub-Saharan Africa, India and Asia.^1–3 NCC can be classified into two forms as extraparenchymal or intraparenchymal. Brain parenchyma is involved via haematogenous route. Extraparenchymal forms involve the ventricles, the subarachnoid spaces and the cisterns which are seeded by dissemination through choroid plexus. Intraventricular involvement occurs in 7%–30% of cases and most commonly involves the fourth ventricle (43%–70%) followed by the lateral (11%–43%) and third (1%–29%) ventricles with a minority in the aqueduct (7%–9%).^{4 8} The fourth ventricle is involved mostly as the cyst tends to migrate to the fourth ventricle because of gravity and CSF flow pattern.

Intraventricular NCC presents most commonly as obstructive hydrocephalus with signs and symptoms of raised intracranial pressure caused by obstruction of the CSF pathway at the foramen of Monro, posterior part of the third ventricle, aqueduct of Sylvius or the fourth ventricle. Our patient also presented with headache and projectile vomiting suggestive of raised intracranial pressure due to development of acute hydrocephalus. Large IVNCC with their free movement in the ventricular system can lead to intermittent episodes of acute hydrocephalus due to mechanical obstruction of the foramen of Monro or aqueduct of Sylvius due to ball valve mechanism, which is also known as Bruns syndrome.^5–7 Cases of sudden death have been reported in the literature by abrupt onset of hydrocephalus due to ball valve movement of third ventricular and fourth ventricular cysts.^{5 9–11} Therefore, it becomes essential to diagnose such life-threatening conditions early and start management accordingly.

The diagnosis of NCC involves a multimodality approach including clinical features, serology and radiological imaging. Although several serological tests like ELISA and electroimmunotransfer blot (ETIB) are available for diagnosis of NCC, they have a poor sensitivity and specificity. Serological tests allow for detection of specific antigens or antibodies to T. solium in blood, CSF or urine. Nowadays, the ETIB, using partially purified antigenic extracts, has become the serological assay of choice. It has a specificity of around 100% and a sensitivity of around 94%–98% for patients with two or more cystic lesions. But sensitivity drops to 60%–70% in cases of calcified cysts or single intracranial cyst.^{12 13} So, serology has a limited role in cases of emergency due to variable sensitivity and specificity. In our case, the ELISA test for NCC was also reported negative. So, our diagnosis of IVNCC was based on MRI findings which revealed the cystic lesion with peripheral eccentric ‘scolex’. Nowadays, the neuroimaging is considered the gold standard for the diagnosis of NCC. Del Brutto et al revised their diagnostic criteria for NCC in 2017, to include neuroimaging for the definitive diagnosis of NCC, to avoid false-positive serological tests in endemic areas and to increase the diagnosis in non-endemic areas where NCC is often missed.^{14 15} The IVNCC cysts are poorly defined on CT of the brain, so MRI is routinely used for diagnosis. But CT is an important tool in cases of emergency for diagnosing the hydrocephalus. Visualising the eccentric scolex in MRI helps in differentiating NCC from other cystic lesions. However, sometimes, routine MRI may also not be able to identify the nature of lesion, so newer imaging modalities like constructive interference in steady-state three-dimensional, spoiled gradient recalled echo sequence and fast imaging employing steady-state acquisition sequence are used for detection of IVNCC. Visualising the eccentric scolex helps in differentiating neurocysticercal cysts from other types of intraventricular cysts.¹⁶

Treatment options in NCC include managing the seizures, headache, hydrocephalus and the infection itself. In active intraparenchymal disease, antihelminthic medication has shown to prevent seizures and reduce the disease burden. The recent guidelines by the Infectious Diseases Society of America and the American Society of Tropical Medicine and Hygiene recommend albendazole monotherapy (15 mg/kg/day divided into two daily doses) for 10–14 days in case of one or two active parenchymal cysticerci. When more than two viable lesions are present, a combined treatment with albendazole (15 mg/kg/day) and praziquantel (50 mg/kg/day) is preferred for the same period.¹⁷ The antihelminthic drugs are supplemented with tapering dose of steroids. However, in cases of IVNCC, medical management has no active role. IVNCC usually presents with life-threatening obstructive hydrocephalus with signs and symptoms of raised intracranial pressure. Emergency procedure such as ventriculoperitoneal shunt, EVD placement, ETV along with endoscopic cyst removal or microsurgery are necessary.

Microsurgery for NCC removal needs craniotomy, more brain invasion, increases operative time and blood loss, and increases morbidity and hospital stay. Ventriculoperitoneal shunt surgery is associated with high failure rates and repeated shunt surgeries.^{8 18 19} During the last two decades, neuroendoscopy has overcome the microsurgery for managing the intraventricular cysts including fourth ventricular cysts.²⁰ Because of its minimal invasive nature and less brain injury, less operative time and blood loss, endoscopic surgery is now the preferred modality for IVNCC. By using endoscope, one has the benefit of removing the cysts as well as doing ETV to manage and prevent the hydrocephalus in the postoperative period.^{19 21} Even in emergency, endoscopy plays a role in intraoperative diagnosis of these lesions with their distinct features like ‘full moon’ sign. Ramos-Zúñiga et al reported the specific features and consistent correlation between macroscopic endoscopic view of the intraventricular vesicular stage NCC and appearance of the ‘full moon’.²¹ Endoscopic excision of third and fourth ventricular cysts along with ETV has many advantages. It decreases the chances of delayed hydrocephalus due to stenosis of aqueduct or fourth ventricular outlet following microsurgery. Also, ETV provides an alternate pathway for CSF diversion in cases of residual cyst obstructing the normal CSF pathway.²² By doing ETV, we can avoid placing an external hardware system into the patient’s body. Kaif et al, in their study on 30 patients with NCC who underwent endoscopic management, reported that ETV in cases of NCC is feasible and is associated with high success rate apart from providing a long-term cure.²³ Konar et al, in their study, concluded that endoscopic procedure for IVNCC is a safe and effective option, avoiding an indwelling external hardware like ventriculoperitoneal shunt system. They also reported that ETV should be considered for patients with IVNCC and hydrocephalus.²⁴ Proaño et al reported a favourable outcome with endoscopic approach in comparison with open surgical approach at 6-month follow-up.¹¹ Our patient also presented with signs and symptoms of increased hydrocephalus and radiology was suggestive of intraventricular NCC, so we also planned for endoscopic excision along with ETV to deal with the hydrocephalus and cyst simultaneously.

One of the emerging procedures for fourth ventricular NCC is stereotactic surgery. Saavendra et al successfully treated two patients with fourth ventricular NCC with stereotactic surgery via suboccipital transcerebellar approach.²⁵ Stereotactic surgery provides a less invasive and alternate option for microsurgery and endoscopic surgery. Also, it remains the gold standard for locating deep lesions <10 mm with high level of precision.

Although neuroendoscopic surgery has several advantages, it is also associated with some unique complications. Some of the potential and known complications include intraventricular bleeding, hypothermia, pneumocephalus, intraoperative bradycardia, fornix injury, hypothalamic injury, intraoperative cyst rupture leading to ventriculitis and arachnoiditis, postoperative CSF leaking, non-functioning of ETV, subdural hygroma, etc.

In our case, we used mini-craniotomy instead of a burr hole. Similar technique was used by Sharma et al in their case series of five patients with NCC.²⁶ It allows for a wide range of angulation of the endoscope. Also, it permits the watertight closure of the dura, thus avoiding the complication of postoperative CSF leakage.

Apart from such known complications, one complication occurred in our case, which is not mentioned in any literature in the past. Although we were able to decompress the cysticercal cyst, unfortunately, the cyst got slipped from the grasper leaving the grasped cyst wall in the tooth of the grasper. It has been mentioned in the past literature that the cyst rupture or partial removal does not effect the outcome of the patient.²² We did ETV along with septostomy to overcome any possible hydrocephalus due to occlusion of the aqueduct of Sylvius or foramen of Monro from migrating the cysticercal cyst. Through this case report, we want to highlight that such a complication could also happen during neuroendoscopic cysticercal cyst removal and how we dealt with it. Our patient was discharged neurologically intact and was symptom free on follow-up.

Patient’s perspective.

I am father of the above described patient. My son was having severe vomiting and so I got my son admitted in the hospital. After admitting I was explained about the disease of my son and the doctors there said that my son needs an emergency operation. Initially I was very much tensed and then I took decision to get my son operated. Soon after surgery my son got relieved of headache and vomiting. I am thankful to the whole team of doctors for saving my son. I come every month for follow up. My son is doing fine now.

Learning points.

• Intraventricular neurocysticercosis (NCC) is a rare disease and if left untreated can lead to life-threatening consequences.

• The endoscopic approach is becoming the modality of choice as it helps in diagnosis of intraventricular NCC with distinct features like ‘full moon’ appearance along with providing the adequate treatment by allowing the cyst removal and simultaneously addressing the hydrocephalus by doing endoscopic third ventriculostomy.

• Apart from many known complications of neuroendoscopic surgery, through this case report, we want to highlight an unusual but possible complication which could occur during endoscopic removal of intraventricular NCC.

Ethics statements

Patient consent for publication

Parental/guardian consent obtained.