Obstructive Hydrocephalus Caused by Tumefactive Perivascular Spaces: A Case Report.

BACKGROUND Perivascular spaces (PS), often called Virchow-Robin spaces, are fluid-filled regions surrounding the brain's blood vessels, typically benign and detected incidentally on MRI scans. However, their enlargement, termed tumefactive PS, is rare and poses significant diagnostic challenges, potentially mimicking severe intracranial conditions. Accurate identification is critical, as these expanded spaces can lead to serious clinical outcomes like hydrocephalus or brain herniation. Misinterpretation of imaging can result in incorrect diagnoses and unwarranted procedures. This case report highlights a rare instance where tumefactive PS caused obstructive hydrocephalus, underscoring the necessity for precise diagnosis. CASE REPORT We report a case involving a 66-year-old Hispanic female with a complex medical history, including insulin-dependent diabetes, prior stroke, and post-Whipple's procedure for pancreatic cancer, who was admitted with progressive somnolence. Initial evaluations indicated encephalopathy. Advanced imaging with CT and MRI identified significantly enlarged PS near the third and fourth ventricles, causing obstructive ventriculomegaly. Differential diagnoses considered cystic tumors and infections, yet MRI findings - cerebrospinal fluid (CSF) isointensity and lack of contrast enhancement - confirmed tumefactive PS. A ventriculoatrial shunt was considered, but the patient's condition rapidly worsened due to sepsis and an intraperitoneal abscess, culminating in multi-organ failure and death before surgery. CONCLUSIONS Although rare, tumefactive PS can mimic serious intracranial diseases, necessitating careful MRI evaluation to differentiate these benign spaces from more severe pathologies. Key MRI indicators include alignment with penetrating vessels, absence of enhancement, and CSF signal intensity. Misdiagnosis can lead to unnecessary surgical interventions, emphasizing the importance of accurate imaging interpretation. In symptomatic cases, usually due to mass effect, surgical intervention might be required. Prompt and precise diagnosis is crucial for managing symptomatic tumefactive PS effectively.