<prompt> Gradenigo;s triad is caused due to the involvement ofAbducent nerveFacial nerveOptic nerveOcculomotor nerve  <response>: Gradenigo syndrome is the classical presentation and consists of a triad of i external rectus palsy VIth nerve palsy,ii deep-seated ear or retro-orbital pain Vth nerve involvement and iii persistent ear dischargeDue to petrositis in CSOM.Spread of infection from middle ear and mastoid to the petrous pa of the temporal bone is called petrositis.Dhingra 6e pg: 79 