Interhemispheric transcallosal transforaminal approach and its variants to colloid cyst of third ventricle: Technical issues based on a single institutional experience of 297 cases

Abstract

Context: Colloid cysts are benign intracranial lesions that usually involve the anterior third ventricle with varying appearance on imaging studies. The number of articles debating the origin of this tumor is surpassed by papers proposing the best modality available for its treatment.

Aim: The purpose of this study is to analyze the clinical presentation and surgical outcome of colloid cysts surgically managed over a period of thirty-two years and evaluate the technical issues based on our experience.

Study design: This is a retrospective case series study.

Materials and methods: This is a retrospective case series study on 297 consecutive patients with colloid cysts who were operated. The case records of all the patients were evaluated to record the clinical symptoms and signs, imaging findings, surgical procedure, complications and follow-up data.

Results: There were 178 (60%) males and 119 (40%) females, their age ranging from 9 to 66 years with a mean age of 28 years. The mean duration of symptoms was 1.8 months. Raised intracranial pressure headache was the most common initial presenting symptom followed by visual blurring, memory disturbance and drop attacks with gait unsteadiness. The tumor was an incidental imaging finding in five patients (2%). While an interhemispheric transcallosal approach was used in 275 (92.6%) patients, it was trans-cortical in 22 (7.4%). Twenty-two patients required emergency surgery in view of worsening sensorium. Postoperative complications included memory impairment, limb weakness and seizures. Despite documented complete excision of the tumor in 6 cases, 8 patients had recurrence of tumor during follow-up.

Conclusion: Colloid cysts are potential life threatening but benign lesions that can be removed safely with low morbidity and mortality through the interhemispheric transcallosal approach and its variants. The possibility for recurrence warrants, close imaging follow-up after surgery. It is essential for neurosurgeons to be familiar with the different transcallosal approaches to reach the third ventricle especially for a posteriorly situated cyst and a narrow foramen of Munro.

Keywords: Colloid cyst; hydrocephalus; intraventricular tumor; transcallosal surgery.

Figure 1

(a) Typical anterior third ventricle colloid cyst expanding the foramen of Munro and causing obstructive hydrocephalus. The preoperative axial CT (b) Shows a hyperdense cyst, appearing isointense with a central area of hypointensity on T2-weighted axial; (c) Coronal; (d) MRI. On axial FLAIR sequence; (e) The lesion is hyperintense with evidence of periventricular CSF seepage. Post-contrast axial T1-weighted MRI; (f) Demonstrates a hypointense cyst without any enhancement. This tumor was operated through a transcallosal transforaminal approach and excised completely as evidenced by the postoperative CT image

Figure 2

The patient was referred following a right VP shunt at a local hospital for hydrocephalus. The axial CT shows a hyperdense colloid cyst located posterior to the foramen. During surgery the foramen was narrow and the cyst could not be visualized. A subchoroidal approach through the velum interpositum helped in locating and resecting the tumor

Figure 3

Axial CT (a) and T2-weighted MRI; (b) Large colloid cyst in a young patient with features of obstructive hydrocephalus. Though this tumor was seen at the foramen of Munro, a suprachoroidal approach was required to completely excise the tumor