A 7-year-old girl with chronic otitis media develops severe retro-orbital pain and double vision worse on looking to the left. Examination shows failure of abduction of the left eye. Inflammation has spread from the petrous apex to compress which nerve at which site?
- A Oculomotor nerve in the cavernous sinus
- B Optic nerve in the optic canal
- C Abducens nerve in Dorello's canal ✓
- D Trigeminal nerve at Meckel's cave
Correct answer: C. Abducens nerve in Dorello's canal
Explanation
This is Gradenigo syndrome: petrous apicitis causing ipsilateral sixth nerve palsy, retro-orbital pain from trigeminal involvement, and otorrhoea. The abducens nerve crosses the petrous apex beneath the petrosphenoidal ligament within Dorello's canal before entering the cavernous sinus, making it the nerve most vulnerable to petrous apex inflammation. The oculomotor nerve lies further forward in the lateral wall of the cavernous sinus and produces ptosis with a down and out eye, not isolated abduction failure.
Reference: Snell's Clinical Neuroanatomy, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.