<prompt> Unilateral proptosis with bilateral VIth nerve palsy,diagnosis is -Graves diseaseRetinoblastomaPseudotumour of orbitCavernous sinus thrombosis  <response>: Unilateral proptosis and bilateral 6th nerve polsy suggest the diagnosis of CST.Bilateral 6th nerve palsy suggests the involvement of opposite side cavernous sinus. In more than 50 of the patients of CST opposite side is involved. 6th nerve is earliest to be involvement. 