Endoscopic approach to colloid cyst: what is the optimal entry point and trajectory?

Abstract

Object. An optimal entry point and trajectory for endoscopic colloid cyst (ECC) resection helps to protect important neurovascular structures. There is a large discrepancy in the entry point and trajectory in the neuroendoscopic literature.Methods. Trajectory views from MRI or CT scans used for cranial image guidance in 39 patients who had undergone ECC resection between July 2004 and July 2010 were retrospectively evaluated. A target point of the colloid cyst was extended out to the scalp through a trajectory carefully observed in a 3D model to ensure that important anatomical structures were not violated. The relation of the entry point to the midline and coronal sutures was established. Entry point and trajectory were correlated with the ventricular size.Results. The optimal entry point was situated 42.3 ± 11.7 mm away from the sagittal suture, ranging from 19.1 to 66.9 mm (median 41.4 mm) and 46.9 ± 5.7 mm anterior to the coronal suture, ranging from 36.4 to 60.5 mm (median 45.9 mm). The distance from the entry point to the target on the colloid cyst varied from 56.5 to 78.0 mm, with a mean value of 67.9 ± 4.8 mm (median 68.5 mm). Approximately 90% of the optimal entry points are located 40-60 mm in front of the coronal suture, whereas their perpendicular distance from the midline ranges from 19.1 to 66.9 mm. The location of the "ideal" entry points changes laterally from the midline as the ventricles change in size.Conclusions. The results suggest that the optimal entry for ECC excision be located at 42.3 ± 11.7 mm perpendicular to the midline, and 46.9 ± 5.7 mm anterior to the coronal suture, but also that this point differs with the size of the ventricles. Intraoperative stereotactic navigation should be considered for all ECC procedures whenever it is available. The entry point should be estimated from the patient's own preoperative imaging studies if intraoperative neuronavigation is not available. An estimated entry point of 4 cm perpendicular to the midline and 4.5 cm anterior to the coronal suture is an acceptable alternative that can be used in patients with ventriculomegaly.

Three-dimensional, computer simulated navigation in endoscopic neurosurgery

“…There is substantial evidence to support the utility of neuronavigation in preoperative planning of burr hole placement 6–9 and trajectory selection 2,6–12 in a variety of neurosurgical cases, including third ventriculostomy, 2,6,12,13 brain biopsy, 9 colloid cyst aspiration, 8,13 and arachnoid cyst fenestration 2 (Table 1). Based on these studies, it appears that stereotactic navigation may be most useful for entrance site selection and pre-selection of trajectories in cases using multiple entry sites, 7 and in endoscopic colloid cyst surgery due to the variability of the optimal entry point.…”

“…Based on these studies, it appears that stereotactic navigation may be most useful for entrance site selection and pre-selection of trajectories in cases using multiple entry sites, 7 and in endoscopic colloid cyst surgery due to the variability of the optimal entry point. 8 In surgeries demonstrating an advantage for stereotactic navigation in pre-operative planning, neuronavigation was of less utility intra-operatively. 11 For example, when optic navigation was performed in combination with continuous navigation of the endoscope, this resulted in a difficulty in establishing a line-of-sight.…”

Outcome of Endoscopic Excision of the Third Ventricular Colloid Cyst

“…Neuroendoscopic resection of the colloid cyst can reliably accomplish complete removal of the tumor with a high patient satisfaction level. The principal advantages of endoscopic colloid cyst aspiration are the short operating time, minimally invasive, lower complication rate due to the small cortical incision so no injury to cingulate gyrus or pericallosal arteries, lower risk of a seizure disorder and can be achieved in comparatively less dilated ventricles [17] . Continued advancement of endoscopic methods and instruments with good long-term outcome in endoscopically treated colloid cysts have established the endoscopic cyst resection as a reasonable alternative to microsurgical methods [18] .…”

Endoscope-assisted resection of cavernous angioma at the foramen of Monro: a case report

“…If intraoperative neuronavigation is not available, the entry point should be estimated from the preoperative imaging studies. An estimated entry point of 4.0 cm perpendicular to the midline and 4.5 cm anterior to the coronal suture is an acceptable alternative that can be used in patients with ventriculomegaly (Rangel-Castilla et al 2014 ). Current navigation systems use either optical or electromagnetic tracking.…”