Abstract： Objective To evaluate the value of image fusion neuronavigation in transsphenoidal microsurgery for pituitary adenomas of recurrence or associated with poorly pneumatized sphenoid sinus (PPSS). Method During a four - year period, neuronavigation - guided transsphenoidal microsurgery was performed for selected twenty - four patients with pituitary adenoma. Among them, eighteen cases underwent repeat transsphenoidal surgery;six cases associated with PPSS received primary operation. The fused images of magnetic resonance imaging(MRI) and computed tomography(CT) were utilized for preoperative planning and introperative guidance. The extent of tumor removal was determined by the comparative analysis of preand post - operative radiological materials. Results All lesions were accurately oriented and approached with the aid of neuronavigation. Fused images allowed simultaneous visualization of the bony structures (sphenoid wall and cavity,sellar floor) and soft tissue( tumor, internal carotid artery,cavernous sinus) as well as the relationship between them. Total tumor removal was achieved in 20 patients, subtotal and part tumor removal in 2 patients respectively. There was no intracranial hemorrhage and infection. Postoperative transient diabetes insipidus occurred in 7 patients, cerebrospinal fluid leakage and occulomotor palsy in 1 patient respectively. No recurrence was found in the 22 patients with total or subtotal tumor removal during an average 17.6 months follow - up period. ConclusionsImage fusion neuronavigation is beneficial to transsphenoidal microsurgical removal of either recurrent pituitary adenomas or pituitary adenomas associated with PPSS. It may provide accurate guidance for the procedure, avoid complications due to misdirection and achieve a more radical tumor removal.