Neuroscience · Year 2 · from Neuroscience
Case 2: Obstructive Hydrocephalus from Colloid Cyst
Patient Presentation
Demographics: 42-year-old female
Chief Complaint: Sudden severe headache with nausea and transient loss of consciousness
History of Present Illness: The patient was at work when she suddenly developed an extremely severe headache, "the worst of her life." She became nauseated and vomited twice. Coworkers noted she appeared confused and then briefly lost consciousness for approximately 30 seconds. She was responsive when EMS arrived but complained of persistent severe headache and photophobia. She has no significant past medical history. Her mother died suddenly at age 47 from a "brain problem" - specific details unknown.
Physical Examination:
- Vital signs: BP 172/98, HR 58, T 37.2C
- General: Eyes closed, prefers dark room, holding her head
- Neurological:
- Mental status: Alert but slow to respond; oriented to person and place but not date
- Cranial nerves: Pupils equal and reactive but sluggish; fundoscopic exam shows early papilledema bilaterally; no other cranial nerve deficits
- Motor: 5/5 throughout; moves all extremities
- Reflexes: 2+ and symmetric
- Neck: Supple (no meningismus)
Workup:
- CT head without contrast: Markedly dilated lateral ventricles bilaterally; third ventricle not visualized; round hyperdense lesion at the foramen of Monro measuring 1.5 cm; no blood in subarachnoid spaces
- MRI brain: Well-circumscribed cystic lesion at the foramen of Monro with high T1 and T2 signal (proteinaceous content), consistent with colloid cyst; bilateral lateral ventricular dilatation; third ventricle collapsed
- Lumbar puncture: Deferred given obstructive hydrocephalus and risk of herniation
Diagnosis: Obstructive hydrocephalus secondary to third ventricular colloid cyst
Treatment:
- Urgent neurosurgical consultation
- Dexamethasone for cerebral edema
- External ventricular drain (EVD) placed emergently for ICP management
- Endoscopic surgical resection of colloid cyst performed on hospital day 2
Clinical Course: Following EVD placement, the patient's headache improved significantly. Surgical resection was successful with complete removal of the cyst. The EVD was weaned and removed on post-operative day 3. Repeat imaging showed decompressed ventricles. At 2-week follow-up, she was asymptomatic with normal neurological examination.
Clinical Pearl: Colloid cysts are benign, slow-growing lesions that arise in the anterior third ventricle at the foramen of Monro. They can cause sudden obstruction of CSF flow (ball-valve mechanism), leading to acute obstructive hydrocephalus with rapid rise in ICP. The sudden onset of severe headache with obtundation can mimic subarachnoid hemorrhage. Acute presentation can be fatal if not recognized and treated emergently. Positional changes may precipitate symptoms as the cyst moves within the ventricle.