The Interhemispheric Transgenual Approach for Microsurgical Removal of Third Ventricle Colloid Cysts. Technical Note

Balloon-Assisted Corpus Callosotomy. Reducing the Impact of Transcallosal Approaches

BACKGROUND

The interhemispheric transcallosal approach is widely used to remove intraventricular lesions. Corpus callosotomy gives immediate access to the ventricular chambers but is invasive in nature. Loss of callosal fibers, although normally tolerate, may cause disturbances ranging from a classical disconnection syndrome up to minor neuropsychological changes.

OBJECTIVE

To open an operative window in the corpus callosum through separation rather than disconnection of the white matter fibers.

METHODS

In 7 patients undergoing the interhemispheric transcallosal approach for intraventricular lesions, lying around or below the foramen of Monro, a stoma was created within the corpus callosum by using a 4F Fogarty catheter. The series included 3 colloid of the third ventricle, 2 thalamic cavernomas, 1 subependymoma, and 1 ependymoma of the foramen of Monro. We illustrate the technique and the clinico-radiological outcome, focusing on the size of callosotomy as seen on postoperative MRI.

RESULTS

The balloon-assisted corpus callosotomy provided a circular, smooth-walled access to the ventricular chambers, which allowed uncomplicated removal of the lesions. On postoperative MRI, the size of the callosotomy shrinked compared with surgery (2.8-6.4 mm at follow-up vs 6-9 mm as measured intraoperatively). No signs of disconnection syndrome or new permanent deficits were observed in this series.

CONCLUSION

The balloon-assisted technique produces a small callosotomy, without clinical consequences, showing a self-closing trend on postoperative MRI. This technique is a rewarding tool to reduce the impact of callosotomy while keeping the advantages of microsurgical interhemispheric approaches.

Practical, Stereotactic, Low-Profile Technique for Transcortical/Transventricular Colloid Cyst Removal Independent of Ventricular Size: Technical Note and Analysis of Approaches

BACKGROUND

In the presence of a dilated foramen of Monro, a transcortical, transforaminal approach is considered the safest and simplest approach for resection of colloid cysts. However, in the presence of small or normal frontal horns, numerous microsurgical approaches and, often complicated, variations have been described, invariably employing forms of stereotactic navigation.

OBJECTIVE

To report an alternative, accurate, microsurgical stereotactic low-profile technique.

METHODS

The small frontal horn is stereotactically targeted as previously described. Routine equipment is used to accurately create a novel, rigid, atraumatic surgical corridor.

RESULTS

After a 7-mm corticotomy, a peel-away catheter carrying the AxiEM stylet engages the target set as the frontal horn. All joints of the endoscope holder are locked, allowing only catheter advancement (y axis) while lateral (x axis) or anteroposterior (z axis) movements are secure. Two, 7-mm retractor blades are inserted. The extremely consistent anatomy of the foramen of Monro allows en bloc microsurgical removal without unnecessary coagulation of cyst wall or choroid plexus.

CONCLUSION

Despite a plethora of approaches to the rostral third ventricle, in the presence of normal or small frontal horns, including creation of transcallosal/interforniceal, suprachoroidal (or transchoroidal), and sub-choroidal, colloid cyst resection does not necessarily need to be convoluted. Technical nuances of an accurate, practical, minimally invasive technique are described.

Structural Brain Network Reorganization Following Anterior Callosotomy for Colloid Cysts: Connectometry and Graph Analysis Results

Introduction:

The plasticity of the neural circuits after injuries has been extensively investigated over the last decades. Transcallosal microsurgery for lesions affecting the third ventricle offers an interesting opportunity to investigate the whole-brain white matter reorganization occurring after a selective resection of the genu of the corpus callosum (CC).

Method

Diffusion MRI (dMRI) data and neuropsychological testing were collected pre- and postoperatively in six patients with colloid cysts, surgically treated with a transcallosal-transgenual approach. Longitudinal connectometry analysis on dMRI data and graph analysis on structural connectivity matrix were implemented to analyze how white matter pathways and structural network topology reorganize after surgery.

Results

Although a significant worsening in cognitive functions (e.g., executive and memory functioning) at early postoperative, a recovery to the preoperative status was observed at 6 months. Connectometry analysis, beyond the decrease of quantitative anisotropy (QA) near the resection cavity, showed an increase of QA in the body and forceps major CC subregions, as well as in the left intra-hemispheric corticocortical associative fibers. Accordingly, a reorganization of structural network topology was observed between centrality increasing in the left hemisphere nodes together with a rise in connectivity strength among mid and posterior CC subregions and cortical nodes.

Conclusion

A structural reorganization of intra- and inter-hemispheric connective fibers and structural network topology were observed following the resection of the genu of the CC. Beyond the postoperative transient cognitive impairment, it could be argued anterior CC resection does not preclude neural plasticity and may subserve the long-term postoperative cognitive recovery.

Giant Colloid Cyst

Giant colloid cysts are defined as cysts of more than 3 cm in maximal diameter. Few cases of giant colloid cysts have been reported in the literature. We herein describe a giant colloid cyst. A 15-year-old female presented with headache, blurred vision, and episodic behavioral changes for three months. Neurological examination was limited due to agitation and confusion. Fundoscopy was notable for bilateral papilledema. Brain CT revealed a giant third-ventricular lesion, causing obstructive hydrocephalus. The patient underwent urgent ventriculoperitoneal shunt insertion initially and then cyst excision. The histopathological sections of the lesion were compatible with a colloid cyst. Five years following surgical resection, a brain MRI did not demonstrate any evidence of residual or cyst recurrence. To our knowledge, giant colloid cysts have been rarely reported and pose a management dilemma in the literature. The present article highlights the symptomatology, radiological findings, and outcome of a giant colloid cyst.

Endoscopic versus Open Microsurgical Excision of Colloid Cysts: A Comparative Analysis and State-of-the-Art Review of Neurosurgical Techniques

BACKGROUND

The surgical approaches of colloid cysts commonly include endoscopy or open microsurgery. Each approach carries its own challenges, feasibility, and complications. The aim of the current study is to compare endoscopic versus open microsurgical excision of third ventricular colloid cysts.

METHODS

A retrospective cohort study was conducted to compare the surgical outcomes of endoscopic versus open microsurgical (transcortical-transventricular and transcallosal approaches) excision of colloid cyst of the third ventricle at a tertiary-care medical institute. All patients with a neuroradiologic diagnosis of colloid cyst who subsequently underwent surgical management between January 2003 and June 2020 were included. The neurologic outcome was assessed at the last follow-up visit.

RESULTS

A total of 32 patients with colloid cysts were included in the study. The mean age was 35.8 ± 18.3 years (range, 4-75 years). Female patients slightly outnumbered male patients (n = 17; 53.1%). A total of 21 patients (65.6%) underwent endoscopic resection of the colloid cyst. Complications were encountered in 7 patients (endoscopic, n = 3; microsurgery, n = 4; P = 0.151). Recurrence was identified in 4 patients (endoscopic, n = 3; microsurgery, n = 1; P = 0.673). Most patients improved neurologically on follow-up visits to the clinic (endoscopic, n = 19; microsurgery, n = 9; P = 0.482).

CONCLUSIONS

Both endoscopic and microsurgical approaches provide favorable surgical outcomes in colloid cyst resection. The complication rates between both approaches is statistically insignificant. The optimal surgical approach for colloid cyst resection remains controversial.