CSF-like Extra-Axial Fluid Collection



CSF-like Extra-Axial Fluid Collection


Yoshimi Anzai, MD, MPH

Judy Tan, MD



DIFFERENTIAL DIAGNOSIS


Common



  • Aging Brain, Normal


  • Enlarged Subarachnoid Spaces


  • Mega Cisterna Magna


  • Subdural Hematoma, Chronic


  • Subdural Hygroma


Less Common



  • Subdural Effusion


  • Dandy-Walker Continuum


  • Arachnoid Cyst


  • Intracranial Hypotension


Rare but Important



  • Extra-Axial Empyema


  • Cephalocele/Meningocele


  • Epidermoid Cyst (Mimic)


ESSENTIAL INFORMATION


Key Differential Diagnosis Issues



  • Absence of mass effect & veins traversing subarachnoid space suggests normal variant


Helpful Clues for Common Diagnoses



  • Aging Brain, Normal



    • Decreased brain volume; mild low density/high intensity periventricular rim


    • No mass effect


  • Enlarged Subarachnoid Spaces



    • Physiologic enlargement of subarachnoid spaces


    • Benign macrocephaly of infancy


    • Head circumference > 95%


  • Mega Cisterna Magna



    • Cisterna magna measuring > 10 mm


    • Vermis intact


  • Subdural Hematoma, Chronic



    • Hypodense subdural collection; may be hyperdense to CSF & have septations


  • Subdural Hygroma



    • Results from tear in arachnoid; CSF density


Helpful Clues for Less Common Diagnoses



  • Subdural Effusion



    • Sterile CSF-like collection associated with meningitis


  • Dandy-Walker Continuum



    • Large posterior fossa with big CSF cyst


    • 4th ventricle appears contiguous with cyst


  • Arachnoid Cyst



    • CSF density/intensity ± bone remodeling


  • Intracranial Hypotension



    • Characteristic postural headache related to reduced intracranial CSF pressure


    • Subdural collections in 15%


    • “Slumping midbrain”, low tonsils, dural enhancement


Helpful Clues for Rare Diagnoses

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Aug 7, 2016 | Posted by in NEUROLOGY | Comments Off on CSF-like Extra-Axial Fluid Collection

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