Ears of the lynx sign (brain)

The ears of the lynx sign refers to abnormal T2/FLAIR cone-shaped hyperintensity at the tip of the frontal horn of the lateral ventricles in the region of forceps minor which resembles the tufts of hair crowning the ears of a lynx.

This sign is seen in hereditary spastic paraplegia with thin corpus callosum (HSP-TCC), the commonest form of which is spastic paraplegia 11 (SPG11), a form of hereditary spastic paraplegia associated with mutations of the identically-named spastic paraparesis gene 11 (SPG11) on chromosome 15 which codes for spatacsin ^1,2.

The sign may also be seen in:

• SPG15, another cause of "hereditary spastic paraplegia with thin corpus callosum", which is caused by a mutation in the zinc finger five domain-containing protein 26 (ZFYVE26) gene, encoding spastizin
• Marchiafava-Bignami disease ³

Differential diagnosis

• ependymitis granularis
  • an anatomic variant, commonly seen
  • can appear similar but is usually less pronounced