Colloid cysts are benign intracranial tumors usually occurring in the the roof of the third ventricle.
A study included 163 colloid cysts, more than half of which were discovered incidentally. More than half of the incidental cysts (58%) were followed with surveillance neuroimaging (mean follow-up 5.1 years). Five patients with incidental cysts (8.8%) progressed and underwent resection. No patient with an incidental, asymptomatic colloid cyst experienced acute obstructive hydrocephalus or sudden neurological deterioration in the absence of antecedent trauma. Nearly half (46.2%) of symptomatic patients presented with hydrocephalus. Eight patients (12.3%) presented acutely, and there were 2 deaths due to obstructive hydrocephalus and herniation. Beaumont et al identified several factors that were strongly correlated with the 2 outcome variables and defined third ventricle risk zones where colloid cysts can cause obstructive hydrocephalus. No patient with a lesion outside these risk zones presented with obstructive hydrocephalus. The Colloid Cyst Risk Score (CCRS) had significant predictive capacity for symptomatic clinical status (area under the curve [AUC] 0.917) and obstructive hydrocephalus (AUC 0.845). A CCRS ≥ 4 was significantly associated with obstructive hydrocephalus (p < 0.0001, RR 19.4).
Patients with incidentally discovered colloid cysts can experience both lesion enlargement and symptom progression or less commonly, contraction and symptom regression. Incidental lesions rarely cause acute obstructive hydrocephalus or sudden neurological deterioration in the absence of antecedent trauma. Nearly one-half of patients with symptomatic colloid cysts present with obstructive hydrocephalus, which has an associated 3.1% risk of death. The CCRS is a simple 5-point clinical tool that can be used to identify symptomatic lesions and stratify the risk of obstructive hydrocephalus. External validation of the CCRS will be necessary before objective surgical indications can be established. Surgical intervention should be considered for all patients with CCRS ≥ 4, as they represent the high-risk subgroup 1).
During this 25-year interval, 162 patients with colloid cysts were examined and cared for at our center. Sixty-eight patients (42%) were thought to be asymptomatic with regard to their colloid cyst and observation with serial neuroimaging was recommended. The mean patient age was 57 years at the time of diagnosis (range 7-88 years) and the mean cyst size was 8 mm (range 4-18 mm). Computerized tomography scanning revealed a hyperdense cyst in 49 (84%) of 58 patients. Three patients were excluded from the study because they died of unrelated causes within 6 months of scanning and seven patients were lost to follow-up review. Clinical follow-up evaluation was available at a mean of 79 months (range 7-268 months) in the remaining 58 patients. The numbers of patients who participated in follow-up review at 2, 5, and 10 years after diagnosis were 40, 28, and 14, respectively. The incidences of symptomatic progression related to the cyst were 0%, 0%, and 8% at 2, 5, and 10 years, respectively. No patient died suddenly during the follow-up interval. Two (6%) of 34 patients in whom follow-up imaging was performed either exhibited cyst growth (one patient) or experienced hydrocephalus (one patient) at a mean of 41 months after diagnosis (range 4-160 months).
Patients in whom asymptomatic colloid cysts are diagnosed can be cared for safely with observation and serial neuroimaging. If a patient becomes symptomatic, the cyst enlarges, or hydrocephalus develops, prompt neurosurgical intervention is necessary to prevent the occurrence of neurological decline from these benign tumors 2).
see Fatal colloid cyst.
Imaging (MRI or CT) demonstrates the tumor usually located in the anterior 3rd ventricle
Here, it often blocks both foramina of Monro causing almost pathognomonic hydrocephalus involving only the lateral ventricles (sparing the 3rd and 4th).
basilar artery aneurysms, hamartomas, primary or secondary neoplasm, and xanthogranulomas.
MRI: usually the optimal imaging technique. However, there are cases where cysts are isointense on MRI and CT is superior (scrutinize the midline T1WI MRI images). When the lesion is identifiable, MRI clearly demonstrates the location of the cyst and its relation to nearby structures, usually obviating an angiogram. MRI appearance: variable. Usually hyperintense on T1WI, hypointense on T2WI. Some data suggest that symptomatic patients are more likely to display T2 hyperintense cysts on MRI, indicating higher water content which may reflect a propensity for continued cyst expansion.
Enhancement: minimal, sometimes involving only a capsule.
CT scan: findings are variable. Most are hyperdense (however, iso- and hypodense colloid cysts occur), and about half enhance slightly. Density may correlate with the viscosity of contents; hyperdense cysts were harder to drain percutaneously.49 CT is usually not quite as good as MRI, especially with isodense cysts. These tumors calcify only rarely.
✖ LP: contraindicated prior to placement of shunt due to risk of herniation.
A young, pregnant woman who presented to the emergency department after cardiac arrest with return of spontaneous circulation in the prehospital setting. She was found to have acute obstructive hydrocephalus on NCHCT, which was later confirmed to be due to a previously undiagnosed colloid cyst of the third ventricle. This acute obstruction resulted in myocardial stunning and, ultimately, cardiac arrest. Although outcomes are often dismal when the cause of arrest is secondary to neurologic catastrophe, this patient survived with completely intact neurologic function. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Although acute obstructive hydrocephalus due to a colloid cyst adjacent to the third ventricle is a rare condition, it is a potentially reversible neurologic cause of out-of-hospital cardiac arrest. However, positive outcomes depend on obtaining the diagnosis rapidly with neurologic imaging and advocating for neurosurgical intervention. This case supports the recommendation that emergency physicians should strongly consider post-cardiac arrest neurologic imaging when another cause is not immediately obvious 3).
Alshuaylan RN, Alismail AA, Haobani FM, Alfulayw MR, Abu Maghayed AY, Khashoggi AA, Al-Mahdi SA, AlKishi SA, Alnaqaa JH, Alwazzan SB, Alshammari M. Colloid Cyst: A Potentially Life-Threatening Etiology of Severe Headache in a Patient With Migraine. Cureus. 2021 Oct 1;13(10):e18424. doi: 10.7759/cureus.18424. Retraction in: Cureus. 2024 Jan 25;16(1):r84. PMID: 34733596; PMCID: PMC8557790.
A 15-year-old girl had undergone a right frontal craniotomy and excision of a third ventricle colloid cyst using the transcallosal approach. Ten days after the operation, she was readmitted for progressive symptoms of behavioral disinhibition. Postoperative magnetic resonance imaging of the brain showed mild-to-moderate bilateral edematous changes along the operative bed, with no other significant findings.
This is the first report in literature to describe behavioral disinhibition occurring as a sequelae to a surgical procedure involving callosotomy 4).
An unusual case of a patient who underwent resection of a colloid cyst and then presented 6 weeks postoperatively with obstructive hydrocephalus. There appear to be no prior reports of such a delayed complication after colloid cyst resection.
A 50-year-old Caucasian woman underwent resection of a colloid cyst with an uncomplicated perioperative course. Postoperative imaging demonstrated complete resection of the cyst. She was discharged home on postoperative day 4 but presented 6 weeks later with symptoms of obstructive hydrocephalus resulting in poor neurologic outcome and ultimately death.
Patients presenting with symptoms of hydrocephalus after resection of a colloid cyst should be followed closely, and timely placement of an external ventricular drain may be critical 5).
Dorsch and Leonardo describe the case of a 42-year-old man who was found to have a colloid cyst of the third ventricle while undergoing evaluation for a dural arteriovenous fistula. They highlight the rotational, or “swiveling,” method for extraction of the colloid cyst 6).
Alshuaylan RN, Alismail AA, Haobani FM, Alfulayw MR, Abu Maghayed AY, Khashoggi AA, Al-Mahdi SA, AlKishi SA, Alnaqaa JH, Alwazzan SB, Alshammari M. Colloid Cyst: A Potentially Life-Threatening Etiology of Severe Headache in a Patient With Migraine. Cureus. 2021 Oct 1;13(10):e18424. doi: 10.7759/cureus.18424. Retraction in: Cureus. 2024 Jan 25;16(1):r84. PMID: 34733596; PMCID: PMC8557790.
22-year-old male childhood with asthma, presented to the emergency department with a syncopal episode, severe headache, and vomiting. Examination revealed a Glasgow Coma Scale (GCS) score of 15, intact visual fields, extraocular movements, and cranial nerves.
Magnetic Resonance Imaging (MRI) revealed a hyperintense nodular lesion in the anterior region of the third ventricle causing hydrocephalus. Colloid cyst causing hydrocephalus with an Evans index of 0.38. Surgical Plan: Craniotomy and resection of the colloid cyst.
Surgical Approach: Right frontal craniotomy. Procedure: Excision of colloid cyst. Postoperative Imaging: Reduction in hydrocephalus with the appearance of intraventricular hemorrhage.
Ventricular Shunt: Inserted through right frontal trephine, with the distal end placed in the lateral ventricle. Complications: Minor intraparenchymal hematoma related to catheter placement. Postoperative Imaging: MRI confirms successful cyst resection and reduction in hydrocephalus. Persistent intraventricular blood and hemosiderin remnants noted. Clinical Course: Stable postoperative course, GCS 15. Follow-up Imaging: No significant complications noted, slight dilation of lateral ventricles (Evans 0.32).
This case highlights the successful surgical intervention for a colloid cyst of the third ventricle resulting in a significant reduction in hydrocephalus. Despite minor complications, the patient showed an uneventful recovery, emphasizing the importance of meticulous surgical technique and postoperative monitoring in managing such cases. Long-term follow-up is crucial to monitor for any potential complications and ensure optimal patient outcomes.