Objective Complications after transsphenoidal surgery for pituitary adenoma have been well documented in the literatures, but the occurrence of delayed sudden sensorineural hearing loss (SNHL) after pituitary adenoma resection is extremely rare. In this study three cases who developed sudden SNHL 3 to 7 days after pituitary adenoma surgery without experiencing cerebrospinal fluid leak or meningitis were presented, and the possible causes of SNHL were discussed.
Methods Three cases with sudden hearing loss after transsphenoidal surgery for pituitary adenoma were reviewed. The past medical history, onset of sudden hearing loss, accompanying symptoms such as headache, tinnitus, dizziness and aural fullness, and the post-operative MRI images, therapy, and hearing results were reported.
Results Three cases developed profound sudden SNHL on the 3rd to 7th post-operative day, all accompanied by prior headache, tinnitus and dizziness. One patient developed episodic vertigo, ear fullness accompanying with fluctuating hearing loss in the first post-operative month. Two patients had past medical history of arteriosclerosis and coronary heart disease or cerebral infarction. Two of three demonstrated obstructive hydrocephalus on MRI on the first post-operative day. Under treatment with prednisone orally, dexamethasone intratympanic injection, neurotrophic and vasodilatation drugs for 3 to 8 months, hearing of all three improved partially. Obstructive hydrocephalus and ischemia might be responsible for the hearing loss.
Conclusion Post-operative obstructive hydrocephalus and ischemia of labyrinthine arteries might lead to the delayed SNHL after transsphenoidal surgery for pituitary adenoma.

Key words: transsphenoidal surgery for pituitary adenoma, obstructive hydrocephalus, ischemia of internal auditory arteries, sudden sensorineural hearing loss, tinnitus