Related Subjects:
|Brain tumour s
|Astrocytomas
|Brain Metastases
|Tuberous sclerosis
|Turcot's syndrome
|Lhermitte Duclos Disease
|Oligodendroglioma
|Acute Hydrocephalus
|Intracranial Hypertension
|Primary CNS Lymphoma (PCNSL)
|Colloid cyst in the third ventricle
🧠 Colloid Cyst in the Third Ventricle: Rare, benign brain lesions that can have life-threatening consequences. Symptomatic cases require urgent neurological and neurosurgical assessment.
📌 About
- Developmental cystic abnormality, lined by a single layer of cuboidal/columnar epithelium.
- Contents: gelatinous, viscous, often PAS-positive material.
- Represents ~0.5–1% of primary brain tumours.
- Classically located in the anterior third ventricle, at the foramen of Monro.
- Typical age: 20–50 years; no gender bias.
- Though histologically benign, their location can cause CSF obstruction → acute hydrocephalus.
🧬 Aetiology & Pathophysiology
- Arise from embryonic endodermal remnants or abnormal neuroepithelial development.
- Symptoms due to:
- Obstruction of CSF flow at the foramen of Monro → ventricular enlargement.
- Acute ICP rise if blockage is sudden → collapse or coma.
- Compression of nearby structures (e.g. fornix) → memory/cognitive deficits.
- Rare reports of sudden death from acute obstruction or brain herniation.
🩺 Clinical Features
- Asymptomatic: Incidental finding on neuroimaging.
- Intermittent Hydrocephalus:
- Positional headaches (worse lying flat).
- Nausea, vomiting, blurred vision.
- Raised ICP: Headache, vomiting, papilloedema, visual obscurations, collapse/coma.
- Neuropsychiatric: Memory loss, apathy, hypomania.
- Seizures: Rare, from raised ICP or secondary irritation.
🔬 Investigations
- Clinical: Episodic symptoms + neurological exam for ICP signs.
- CT: Hyperdense, spherical lesion in anterior 3rd ventricle; ventricular dilatation if obstructed.
- MRI:
- T2 hyperintense, sometimes with central hypointensity (viscous content).
- Non-enhancing; FLAIR hyperintense if proteinaceous.
- ❌ Lumbar puncture: Contraindicated if raised ICP (risk of herniation).
⚠️ Complications
- Acute obstructive hydrocephalus.
- Brain herniation → fatal if untreated.
- Permanent cognitive deficits from fornix compression.
- Rare cases of sudden death in young adults.
📊 Risk Stratification
- Mortality in symptomatic cases ~3%.
- Higher risk if:
- Age <65 years.
- Symptomatic with headaches/ICP features.
- Cyst ≥7 mm diameter.
- Hyperintense on FLAIR MRI.
💊 Management
- Observation:
- Asymptomatic small lesions → serial MRI + clinic follow-up.
- Symptomatic Treatment: Analgesics for headache; ICP-lowering measures.
- Definitive Surgery:
- Endoscopic resection – minimally invasive, first-line in many centres.
- Craniotomy – reserved for complex or inaccessible lesions.
- Ventriculoperitoneal shunt – for persistent/refractory hydrocephalus.
- Postoperative Care: Infection/bleeding monitoring; repeat imaging to check resection and CSF flow.
🌟 Prognosis
- Excellent if treated promptly.
- Symptomatic relief common after resection.
- Incomplete resections may require long-term monitoring.
