What causes Boomerang sign in the splenium of the corpus callosum?
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Answer: A transient, reversible hyperintense lesion in the splenium of the corpus callosum seen on T2/FLAIR MRI sequences, typically associated with mild encephalitis/encephalopathy.
This appearance is referred to as the Boomerang sign on brain MRI.
Why is it called so?:
Named for the curved, boomerang-shaped morphology of the high signal intensity in the splenium, which resembles the throwing tool.
Pathophysiology:
The exact pathophysiology is unclear but is hypothesized to involve transient intramyelinic edema or inflammation associated with MERS (Mild Encephalitis/Encephalopathy with a Reversible Splenial lesion). It is commonly triggered by viral infections (like Influenza or Rotavirus), seizures, or drug withdrawal, and typically resolves completely without permanent damage.
References
- Starkey J, Kobayashi N, Numaguchi Y, Moritani T. Cytotoxic Lesions of the Corpus Callosum That Show Restricted Diffusion: Mechanisms, Causes, and Manifestations. RadioGraphics. 2017.
- Malhotra HS, Garg RK, Vidhate MR, Sharma PK. Boomerang sign: Clinical significance of transient lesion in splenium of corpus callosum. Ann Indian Acad Neurol. 2012.
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