Definition and Diagnostic Controversy
- "Dandy-Walker variant" refers to posterior fossa anomalies that partially fulfill criteria for Dandy-Walker Malformation (DWM) but lack classical features.
- Typically applied when:
- Vermian hypoplasia or agenesis is present.
- Normal-sized posterior fossa (unlike classic DWM).
- Cystic enlargement of fourth ventricle with rotation of the vermis.
- Normal position of torcular Herophili and tentorium cerebelli.
Issues with the Term
- The term "Dandy-Walker variant" is controversial:
- Used inconsistently, leading to confusion and ambiguity.
- Frequently a "default diagnosis" for varied posterior fossa lesions involving fluid spaces.
- Its broad and ambiguous application has led to difficulties in classification and prognostication.
- Expert groups discourage using this term.
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