Endoscopic Approach for Colloid Cyst Resection

Summary

This protocol details a minimally invasive endoscopic technique for the removal of third ventricular colloid cysts. It provides a comprehensive overview of preoperative preparations, surgical steps, and postoperative outcomes, emphasizing reduced recovery time, minimal complications, and total cyst removal. This approach is a safe and effective alternative to traditional microsurgery.

Abstract

This protocol describes a minimally invasive endoscopic technique for the removal of colloid cysts located in the third ventricle. These cysts are a rare type of intracranial lesion that can obstruct cerebrospinal fluid flow. If left untreated, they may cause hydrocephalus or, in severe cases, even sudden death. The objective of this approach is to provide a safe and effective alternative to traditional microsurgical methods. It does so by reducing postoperative pain, surgical morbidity, and hospital stays. The protocol delineates meticulous preoperative preparations, encompassing patient positioning and equipment setup, followed by a systematic step-by-step guide to the endoscopic surgical procedure. This protocol involves the use of intraoperative ultrasound guidance for precise navigation, incision of the cyst wall, aspiration of cyst contents, and meticulous hemostasis. Special care is taken to minimize damage to surrounding neural structures, ensuring complete cyst removal while reducing the risk of complications. The efficacy of this minimally invasive approach is substantiated by the observation that it is associated with reduced operation times, minimal neurological deficits, and rapid postoperative recovery. Typically, patients are able to resume mobilization the day after surgery and are discharged within two days. This protocol serves as a comprehensive guide for neurosurgeons aiming to enhance surgical precision while maximizing patient outcomes. The successful utilization of this protocol is dependent on meticulous preoperative planning, advanced intraoperative navigation techniques, and the employment of specialized endoscopic instruments.

Introduction

Colloid cysts of the third ventricle are rare intracranial lesions, constituting about 0.5%-2% of all intracranial tumors^1,2,3. Their estimated occurrence is around 3.2 cases per million people annually⁴. The cyst is lined by simple epithelium, squamous epithelium, or stratified ciliated columnar cuboidal⁵. Colloid cysts originate from the roof of the third ventricle, near the foramen of Monro. They frequently block the flow of cerebrospinal fluid (CSF), which can lead to hydrocephalus and, in some instances, may cause sudden death^2,6.

Most colloid cysts are discovered incidentally during brain imaging performed for unrelated reasons². When symptomatic, they often cause non-communicating hydrocephalus, leading to symptoms such as headaches, nausea, vomiting, lethargy, and in severe cases, coma or sudden death¹. In cases where hydrocephalus progresses slowly, patients might experience more subtle symptoms such as difficulty walking, frequent falls, changes in mental status, memory problems, and urinary incontinence⁷.

The optimal management of colloid cysts remains a subject of debate, and there is no consensus on the optimal surgical technique. Various treatment approaches have been explored, including microsurgical resection, endoscopic resection, endoscopic-assisted microscopic resection, stereotactic aspiration, and the placement of ventriculoperitoneal (VP) shunts^8,9. Each method has its advantages and limitations in terms of safety, effectiveness, and recovery time.

In recent years, minimally invasive endoscopic removal has gained popularity due to its advantages of reduced postoperative pain, lower surgical morbidity, and shorter hospital stays compared to traditional surgical methods. This technique enables precise cyst removal with minimal disruption to surrounding neural structures, making it an appealing option for neurosurgeons¹⁰.

This study outlines a detailed protocol for the endoscopic resection of third ventricular colloid cysts, emphasizing its safety, efficacy, and postoperative outcomes. By providing a comprehensive step-by-step guide, this protocol aims to enhance surgical precision and improve patient recovery.

Protocol

The Institutional Review Board of Istanbul University, Istanbul Faculty of Medicine approved the study. The patients gave written consent prior to the surgical procedure.

1. Preoperative procedure

1. Use the following criteria to select patients: Individuals presenting colloid cysts that lead to hydrocephalus, either symptomatic or asymptomatic, obstructive hydrocephalus, or intermittent clinical manifestations such as headaches; patients with cysts located in proximity to critical neuroanatomical structures. Exclude patients who do not align with the criteria.
2. Perform the procedure under general anesthesia to ensure the patient is unconscious and fully relaxed during the surgery. Ensure the necessary endoscopic and optical instruments are prepared in the operating theater, ensuring that all equipment, including the 25° angled endoscope, working channels, light conductor system, and surgical tools, are sterile and ready for use prior to the procedure.
3. Ensure that the following tools are available for the procedure: endoscope with a 25° angled endoscope (outer diameter of 5.9 mm), a working channel (outer diameter of 6.9 mm), the optical lens system, a light conductor system, and a channel for continuous irrigation. Forceps, scissors, dissectors, and bipolar are introduced from the working channel.

2. Surgical procedure

1. Position the patient and prepare the surgical field as described below.
   1. Place the patient in a supine position with a soft head support to position the patient's head in 10° flexion.
   2. Identify the coronal suture through palpation of the skull. By gently palpating the patient's scalp, locate the suture at the junction of the frontal and parietal bones.Shave and disinfect the right frontal area using iodine or 10% chlorhexidine, covering an area 4 cm lateral to the midline and 5 cm anterior to the coronal suture.
   3. Place a waterproof surgical drape over the operative field to maintain a sterile environment.
2. Perform endoscopy as described below.
   1. Set the 20° rigid endoscope system and manually adjust the endoscope screens according to the surgeon's preferred position. Adjust white balancing and camera focus settings.
   2. Make a 4 cm curvilinear incision centered at the 4 cm lateral to the midline and 5 cm anterior to the coronal suture and in the right frontal area using a #20 scalpel.
   3. Utilize bipolar cautery to achieve hemostasis and perform dissection of the skin and subcutaneous tissue.
   4. Insert automated skin retractor. Use an Adson periosteal elevator to scrape the periosteum.
   5. Use a high-speed perforator to create a 14 mm burr hole slightly lateral to the Kocher point. Expand the burr-hole towards the medial side with Kerrison rongeur as much as the trocar introducer and burr-hole probe of ultrasound can fit. Periodically apply saline to the burr hole using a syringe to improve imaging clarity.
   6. Carefully remove the thin bone layer over the dura with a dissector. Utilize an intraoperative ultrasound puncture probe to visualize the lateral ventricles, the Foramen of Monro, and the third ventricle.
   7. Make a cross-shaped incision in the dura using a #11 scalpel. Coagulate the pia mater underneath using bipolar cautery. Establish the trajectory from the Foramen of Monro to the floor of the third ventricle using intraoperative ultrasound for guidance. Carefully visualize the anatomical landmarks and plan the path to ensure accurate and safe navigation.
   8. Attach the intraoperative ultrasound puncture probe to the endoscope's trocar introducer. Under intraoperative ultrasound guidance, insert the endoscope trocar introducer into the brain tissue. Observe cerebrospinal fluid exiting the endoscope sheath as it enters the lateral ventricle.
   9. While stabilizing the endoscope sheath, remove both the trocar introducer and the intraoperative ultrasound puncture probe. Insert the endoscope into the sheath of the endoscope sheath.
   10. Inside the lateral ventricle, identify key structures such as the lateral ventricular cavity, Foramen of Monro, choroid plexus, thalamostriate vein, and septal vein.
   11. Under direct visualization, visualize the colloid cyst and approach it through the foramen of Monro. Incise the cyst wall carefully and aspirate the contents using an 8F pediatric suction cannula.
       NOTE: Before excising the cyst wall, it is advised to aspirate the cyst contents. Failing to do so could lead to cyst rupture, which may impair vision and result in incomplete removal of the cyst wall.
   12. After aspirating cyst contents, coagulate components of the cyst. Grasp cyst wall firmly with small forceps and rotational movements. Control bleeding by coagulation and irrigation.
       NOTE: If there is concern about insufficient hemostasis, a ventricular catheter may be inserted.
   13. Complete the surgery by removing the endoscopic system after hemostasis in the operation area.

Results

This study describes the successful application of a minimally invasive endoscopic approach for the treatment of colloid cysts in a 20-year-old female patient with no known comorbidities (Figure 1 and Figure 2). The procedure lasted approximately 60 min. No drainage was necessary. No hematoma formation was observed. No neurological deficits were observed postoperatively. The pati...

Discussion

Endoscopic intraventricular surgery has undergone remarkable advancements over the past century, driven by both technological progress and clinical experience. The technique's roots date back to the early 20th century, when Walter Dandy pioneered neuroendoscopy in 1922¹¹, utilizing an endoscope to address hydrocephalus. In 1923, William Mixter further advanced the field by performing the first endoscopic third ventriculostomy (ETV), marking a significant milestone in its development

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Adson periosteal elevator	Ruggles-Redmond (Redmond, USA)	RO263	Semi-sharp, 5 mm, curved 6-3/8, length 164 mm
Automatic skin retractors	Integra (Princeton, USA)	372245	Heiss Automatic Skin Retractor, Length - Overall (mm): 102; Tip/Jaw (mm): 8
Balloon catheter	Edwards Fogarty (Irvine, USA)	120804FP	Length (cm): 80; Catheter size (F): 4; Inflated balloon diameter (mm): 9
Biopsy Forceps	Karl Storz (Tuttlingen, Germany)	28164 LE	Rotating, dismantling, single-action jaws; diameter 2.7 mm; working length 30 cm
Bipolar coagulation electrode	Karl Storz (Tuttlingen, Germany)	28161 SF	Diameter 1.3 mm; working length 30 cm
Bisturi	Beybi (Istanbul, Turkey)	2402502	Beybi Bisturi Tip No. 20 and No. 11
High-speed drill	Medtronic Midas Rex (Minneapolis, USA)	MR8 EM850	Perforator tip used
Kerrison Rongeur	Aesculap (Melsungen, Germany)	FK950B	Length (cm): 7; Jaw Size width: 3.0 mm; Jaw opening: 10.0 mm
Operating sheath	Karl Storz (Tuttlingen, Germany)	28164 LSB	Graduated, rotating; outer diameter 6.8 mm; working length 13 cm
Trocar	Karl Storz (Tuttlingen, Germany)	28164 LLO	Use with Operating Sheaths for ventricular puncture
Ultrasound	BK (Peabody, USA)	bk5000	Use via N11C5s Transducer (9063) for ventricular puncture
Ventriculoscope	Karl Storz (Tuttlingen, Germany)	28164 LAB	Wide-angle telescope 30°, angled eyepiece; outer diameter 6.1 mm; length 18 cm