A modified retrosigmoid approach for direct exposure of the fundus of the internal auditory canal for hearing preservation in acoustic neuroma surgery.
OBJECTIVE
This is a clinical report on a modified retrosigmoid approach with direct exposure of the fundus of the internal auditory canal for hearing preservation in acoustic neuroma surgery.


METHODS
Retrospective case review.


METHODS
Tertiary referral center of an ear, nose, and throat department in a public hospital.


METHODS
One hundred fifty consecutive procedures were reviewed, including 61 males and 89 females with an age range of 13 to 69 years and a mean age of 47 years. There were 15 patients with tumor occupying solely the internal auditory canal and 135 patients with extension into the cerebellopontine angle with an extrameatal diameter of up to 52 mm and a mean of 11.5 mm.


METHODS
The retrosigmoid approach included a wide craniotomy, a perimeatal petrous bone removal up to the blue line of the labyrinth, and a direct exposure of the fundus at the orifices of the facial and cochlear nerves. The quadrant of the superior vestibular nerve remained unexposed.


METHODS
Hearing was measured according to the American Academy of Otolaryngology-Head and Neck Surgery criteria for reporting results of hearing preservation and by comparison with the preoperative level. Facial nerve function was measured using the House-Brackmann grading. The radicality of tumor removal was investigated with mid- to long-term magnetic resonance imaging (MRI).


RESULTS
Measurable hearing was preserved in 45.3%, and in 32.4% of these cases, it was within 15 dB/15% discrimination. Grade 1 or 2 facial function was preserved in 85.3%. MRI follow-up revealed a 3.3% tumor residual or regrowth in the complete series. No residual tumor was found at the 3-year MRI in the last series of patients operated on with direct control of the fundus.


CONCLUSIONS
This modified retrosigmoid approach permits the direct exposure of the facial and cochlear quadrants of the fundus. This allows tumor dissection under direct visual control. Removing the tumor from the vestibular quadrant of the fundus is done blindly in a minority of cases and carries a minimal risk of residual tumor. This technique requires only conventional equipment and skills of neurotology.
Mazzoni
A
A
O.R.L. Department, Ospedali Riuniti, Bergamo, Italy.
Calabrese
V
V
Danesi
G
G
D000293:Adolescent; D000328:Adult; D000368:Aged; D007758:Ear, Inner / Q000601:surgery; D005260:Female; D006309:Hearing / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000000981:diagnostic imaging / Q000601:surgery*; D013506:Otologic Surgical Procedures / Q000379:methods*; D010579:Petrous Bone / Q000000981:diagnostic imaging / Q000601:surgery*; D011182:Postoperative Care; D011300:Preoperative Care; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed