Management of pediatric colloid cysts of anterior third ventricle: A review of five cases.

OBJECT: Colloid cysts are congenital benign lesions, associated with more aggressive clinical and radiological picture in children than in adults. We present our experience in management of five pediatric patients with colloid cyst of the anterior third ventricle. They have an excellent chance of surgical cure, or they can be devastating and even fatal, if not recognized on time and treated.
MATERIALS AND METHODS: Five pediatric patients (aged 16 years or less) who were surgically treated for a colloid cyst, between 1987 and 2011 were analyzed. The clinical features included raised intracranial pressure in all five cases, of which one patient was brought unconscious with decerebrate posturing. Computed Tomography (CT) scan of the brain was done in all patients. The density of the lesion, enhancement with contrast and the presence of hydrocephalus were analyzed. Four patients underwent a detailed postoperative neurological assessment.
RESULTS: Three patients underwent the transcallosal-transforaminal approach and total excision of the lesion. One patient underwent revision of the pre-existing ventriculoperitoneal shunt. One patient who was brought in an unconscious state, an external ventricular drain was inserted and she was ventilated. She died 4 hours after the admission. On follow-up, none of the three patients who underwent the transcallosal-transforaminal approach had disconnection syndromes or behavioral disturbances.
CONCLUSION: Colloid cysts in children are rarer and more aggressive than their adult counterparts. It is surgically curable. Early detection and total excision of the lesion is a permanent cure with minimum morbidity, when compared with the natural history of the disease. The limited anterior callosotomy does not result in disconnection syndromes or behavioral disturbance.

Introduction

Colloid cysts account for 0.2–2.0% of all brain tumors. In 1858 Wallmann[1] published the first description of a colloid cyst, which was found on autopsy. In 1910 Sjovall proposed that the cyst originated from the paraphysi.[2] Since then there have been various theories regarding the origin of these surgically challenging lesions.[13-5] These are more common in the third and fifth decade. Their occurrence in the pediatric age group is less commonly seen. These pediatric colloid cysts have aggressive and varied behavior than in adults.

Materials and Methods

We are presenting our experience in the management of five cases of pediatric colloid cysts, of which three were treated by the transcallosal-transforaminal approach.

The various variables of the patients are summarized in Table 1.

Table 1

Characteristics of cases

Case I

A 13-year-old female presented with headache and vomiting of 10 days duration. On examination her fundus was normal and she had no neurological deficits. At the age of 9 years she was diagnosed to have a colloid cyst for which bilateral ventriculoperitoneal shunts were done at another hospital. Her computed tomography (CT) scan of the brain showed a hyperdense, contrast enhancing anterior third ventricle lesion, causing obstructive hydrocephalus. Bilateral shunt tubes were seen in the lateral ventricles. She underwent bilateral shunt revisions, and was relieved of her symptoms. On 1 year follow-up she continues to be asymptomatic.

Case II

A 16-year-old male presented with episodic headache, vomiting, and double vision of 15 days duration. His fundus revealed papilloedema and he had a left sixth cranial nerve paresis. He had no other deficits. CT scan of the brain showed a hyperdense, nonenhancing lesion in the anterior third ventricle causing hydrocephalus. The patient underwent, initially a right ventriculoperitoneal shunt followed 1 week later by a right frontoparietal craniotomy, transcallosal-transforaminal approach, and total excision of a colloid cyst [Figure 1]. Postoperatively he had no deficits. On 4 years 3 months follow up he was asymptomatic, his memory was normal with no deficits.

Figure 1

(a, b) CT scan of the brain showed a enhancing lesion in the anterior third ventricle causing hydrocephalus (c) Postoperative CT scan brain showing complete excision of the lesion and resolving hydrocephalus. Right VP shunt tube is seen in situ

Case III

A 16-year-old female presented with episodic headache and vomiting of 3 years duration, with blurring of vision, impaired memory, and unsteadiness of gait for 10 days. On examination her fundus showed papilloedema. She had no other neurological deficits. CT scan of the brain revealed a hyperdense, contrast enhancing lesion causing obstructive hydrocephalus [Figure 2]. She underwent craniotomy, transcallosal-transforaminal approach and total excision of a colloid cyst. Postoperatively she had relief of her headache, with improvement in memory and gait. On 14 months follow-up, she continues to be asymptomatic with no deficits

Figure 2

(a, b) CT scan of the brain revealed a hyperdense, contrast enhancing lesion in the third ventricle causing obstructive hydrocephalus (c) Postoperative MRI scan of the brain coronal section at the level of third ventricle showing complete excision of the lesion. The craniotomy defect can be seen

Case IV

A 16-year-old female was brought to the emergency room in altered sensorium, and decerebrate posturing, with history of episodic headache and vomiting of 1 month duration. She was deeply unconscious, with her fundus revealing grade IV papilledema and pupils were unreactive to light. Her CT scan of the brain showed a hyperdense, contrast enhancing anterior third ventricle lesion causing gross hydrocephalus. She was intubated, ventilated, and shifted to the operation theatre where a right frontal burr hole and an external ventricular drain was inserted. The cerebral spinal fluid (CSF) was under high pressure, 32 cm H2O. Postoperatively, she was managed with ventilation, and controlled CSF drainage, but expired 4 hours later.

Case V

A 12-year-old female presented with episodic headache and vomiting of 3 months duration. On examination she had papilledema with no other neurological deficits. Her CT scan of the brain showed a hyperdense lesion in the anterior third ventricle region; causing obstructive hydrocephalus. She underwent craniotomy, transcallosal-transforaminal approach, and total excision of the lesion. She was relieved of her symptoms and on 16 months follow-up she had no deficits [Figure 3].

Figure 3

(a, b) CT scan of the brain showed a hyperdense, lesion in the anterior third ventricle region, causing obstructive of the foramen of Monro and hydrocephalus

Results

Of the total cases (n = 5), four were females and one male with a sex ratio of 4:1. The youngest was 12 years. The mean age of presentation was 14.6 years. The most common symptom, which our patients presented, was headache and vomiting. One patient presented in altered sensorium and decerebrate rigidity, she also had headache and vomiting for 1 month and developed sudden deterioration in her neurological status. On examination, papilloedema was seen in four patients (n = 4) and one patient had no deficits.

CT scan of the brain with contrast study was done in all the five patients. The lesion was hyperdense in all the five cases, enhancing in three patients and nonenhancing in two patients. Hydrocephalus was seen in all the five patients.

One patient underwent bilateral shunt revision and was reviewed with repeat imaging. Craniotomy and transcallosal- transforaminal approach and complete excision of the lesion was done in three patients. In one patient who was brought in altered sensorium external ventricular drain was kept, but patient expired after 4 hours.

The mean follow-up was 23.25 months and all the patients were doing well. None of the four patients had recurrence of the lesion.

Discussion

Colloid cysts are nonneoplastic true epithelium lined cysts of the central neuraxis. They generally present in the third to fifth decade but they can present at both extremes of ages. Colloid cysts have always provoked interest in neurosurgeons because of their controversial origin, benign histology, dramatic clinical presentations and the variety of possible treatment options. Pediatric colloid cysts have rarely been reported. We report five cases of pediatric colloid cysts below the age of 16 years.

Epidemiology

Kumar et al. reported a mean age of presentation of 13.8 years.[6] Our patients ranged from 12 to 16 years with a mean age at presentation of 14.6 years. No case was found below the age of 10 years in our series though the youngest reported case was an infant aged 2 months.[7] In our series we had a female sex predominance (4/5 patients). Most major published series by Mathiesen et al.,[8] Nitta and Symon,[9] Little et al.,[10] Masqood et al.[11] indicate a male predilection. The rate of growth of the cyst is uncertain and whether these cysts eventually become symptomatic is unclear.

Symptoms

The most common presentation was headache and vomiting associated with papilloedema suggestive of raised intracranial pressure. Similar features were reported by many authors.[6912-15] The headaches are classically intermittent, episodic, sometimes intense and severe. This headache typically decreases on lying down, which is unusual for a headache due to an intracranial space occupying lesion. As stated by Kelly et al.[13] though the above symptoms were not specific for colloid cyst, as any midline mass may present similarly, these are a strong indication of a colloid cyst and high clinical suspicion is warranted. Associated symptoms include vertigo, memory deficit, diplopia, and behavioral disturbances.

These can present with varied clinical presentation being asymptomatic or occasional unnoticed headaches to rapid deterioration in sensorium, herniation, and death. One patient presented with altered sensorium and decorticate rigidity. This patient in-spite of treatment expired after 4 hours. Such rapid deterioration of symptoms were previously reported.[16-18] The exact mechanism of sudden death in colloid cyst patients was poorly understood[19] . This could be due to sudden block at the foramen of Monro leading to development of acute hydrocephalus or at times due to hemorrhage into the cyst cavity.[20] Pollock et al.[21] analyzed the symptomatic and asymptomatic patients with colloid cyst and stated that the younger age at presentation is a risk factor. Halmat et al.[22] hypothesized that sudden deterioration could be possibly initiated by sudden increase in sagittal sinus pressure, provoking acute brain swelling and ultimately a series of events leading to death. Byard[23] confirmed that the cause of sudden death could be due to sudden obstruction at foramen of Monro and associated prominent cerebral edema. Ryder et al. postulated that the reflex effects involving the cardiovascular centers near the third ventricle might also contribute to the sudden death.[24]

Radiology

All the patients had a preoperative CT scan plain and contrast study. On CT scan these lesions can be clearly identified as round homogenous masses in the anterior third ventricle region of the foramen of Munro. The lesion was hyperdense to brain in all the patients. On contrast administration contrast enhancement was seen in 3 (60%) and no enhancement was seen in 2 (40%) of the patients. The hyperdense appearance was previously attributed to the amount of calcium deposits within the cyst mucin.[25] Later analysis by Maeder et al.[26] found no difference in the amount of calcium contained within hypo- and hyperdense cysts and contributed the viscosity to cholesterol content of the cyst. Urso et al.[27] postulated that the state of hydration of the cyst contents may correlate with CT density. The rapid development of clinical manifestations in children compared with adults may be related to rapid enlargement of cyst due to higher water content within them. Similar finding of the hyperdensity and the aggressive radiological feature was reported by Alnaghmoosh.[28]

Hydrocephalus was present in all of our patients. A pre-craniotomy ventricular peritoneal shunt was done in one patient to reduce the intracranial pressure as retracting a tense brain may cause retraction injury and edema. Moreover, despite complete removal of the lesion, there may be persistent hydrocephalus due to edema or formation of a blood clot at the foramen of Munro causing occlusion of the foramen. However, this was being done in the initial years, and we no longer insert shunts for preoperative hydrocephalus.

Management

Historically, three approaches have been used to reach the anterior third ventricle: the transcortical-transventricular approach going through the frontal lobe, the transcallosal transventricular approach, and the subfrontal approach through the lamina terminalis. In 1921, Dandy was the first neurosurgeon who successfully removed a colloid cyst from the third ventricle through a posterior transcallosal approach.[29] The anterior transcallosal approach was suggested by George Ehni.[30]

Three patients underwent a right fronto parietal midline craniotomy and anterior transcallosal-transforaminal approach. Apuzzo et al.[31] reviewed 100 angiograms and studied the distribution of the parasagittal venous complex in the region of the coronal sulcus. Seventy percent of these venous tributaries entered the superior sagittal sinus within the sector 2 cm posterior to the coronal suture, whereas 30% were in the anterior 2 cm region. Hence the importance of proper planning of the dural flap and by mobilizing rather than sacrificing the cortical veins as a 2 cm long corridor at the midline is all that is necessary.[32] The corpus callosum is incised in the midline between the pericallosal arteries for a length for 1.5 –2.5 cm in the sagittal plane in the anterior corpus callosum, exposing the ventricular system. An incision of up to 2.5 cm in the anterior body of the corpus callosum is all that is necessary for the exposure of the ventricular system and does not cause any disconnection syndromes.[3133] Hernesniemi J[19] has found that the far lateral corpus callosal incision has been especially valuable in avoiding memory disturbances.

Foramen of Munro was identified, which was dilated in all the three cases. Total excision of the lesion was possible in all the three patients. There was no damage to the fornix or the thalamostriate veins during the surgical procedure. External ventricular drainage was kept in situ for 3 days for draining of postoperative blood, which might get collected in the ventricle.

One patient had bilateral shunting procedures done elsewhere, which has been described, with the assumption that the cyst occludes both foramen of Munro. He presented with shunt failure for which bilateral shunt revisions were performed and he improved well. The postoperative period was uneventful in four patients and one patient died after 4 hours of surgery. No postoperative complications were seen in our patients, though transient memory impairment and mutism can occur due to damage to adjacent structures such as cingulate gyrus, wall of the anterior III ventricle, floor of the lateral ventricle and damage to the dominant supplementary motor cortex. This is supported by Nakasu et al.,[34] who stated that a partial callosotomy alone may not be responsible for post-op mutism.

Follow up and outcome

Four patients were followed up from a period of 1 year to 4 years 3 months with a mean follow up of 23.2 months. Of the three patients who underwent the transcallosal-transforaminal excision of the lesion, none had disconnection syndromes or behavior disturbances on 6 months review. The patient who underwent shunt revision was also asymptomatic with no deficits and did not develop another episode of hydrocephalus. There was no recurrence of the tumor on repeat imaging during this follow-up period. Although it is found that sudden neurological deterioration is rare in patients with colloid cysts who do not have preceding symptoms, reports of such fatal outcome continue even during this modern neuroimaging era[33536] as reported in case 4.

Conclusion

Pediatric colloid cysts are rare lesions compared with adults. These present with aggressive behavior due to their rapid growth of tumor, late detection, and rapid development of the manifestations. Early detection and total excision of the lesion is a permanent cure with minimum morbidity. The transcallosal-transforaminal approach is a ‘gold standard’ approach and gives excellent results. There are no major permanent deficits in memory or disconnection syndromes with the limited anterior callosotomy.