Hearing loss and changes in transient evoked otoacoustic emissions after gamma knife radiosurgery for acoustic neurinomas.
OBJECTIVE
To evaluate the neuro-otological effects of gamma knife radiosurgery in patients with acoustic neurinoma.


METHODS
Prospective study.


METHODS
University hospital in Milan, Italy.


METHODS
Thirty consecutive patients with acoustic neurinoma who underwent gamma knife radiosurgery.


METHODS
Gamma knife radiosurgery.


METHODS
Results of neuro-otological tests, including pure-tone audiometry, auditory brainstem responses, and transient evoked otoacoustic emissions, during a 2-year follow-up.


RESULTS
Three patients showed slight tumor growth, 1 complained of a transient facial disturbance, and 5 complained of mild trigeminal disturbances. Seven of the 26 patients with a measurable threshold before radiosurgery experienced a 2-year decrease of more than 20 dB in at least 1 hearing level, and 2 of these became deaf in the affected ear. The analysis of auditory brainstem responses showed no significant increase in mean wave V latency after radiosurgery, but intensity of transient evoked otoacoustic emissions worsened in 9 of the 12 patients who had them before treatment. A statistically significant correlation was found between the 2-year decrease in low-tone average, pure-tone average, and high-tone average hearing levels and the 2-year decrease in transient evoked oacoustic emissions (P<.001, P =.008, and P<.001, respectively), and between the 2-year decrease in high-tone average hearing and the maximal cochlear dose (P =.03).


CONCLUSIONS
Although most patients had only a slight fluctuation of their hearing threshold after gamma knife radiosurgery, several experienced a remarkable hearing worsening. Hearing impairment was found to be mainly due to cochlear irradiation and maximal cochlear dose, which was correlated to hearing loss.
Ottaviani
Francesco
F
Department of Otolaryngology, University of Milan, Italy.
Neglia
Cesare Bartolomeo
CB
Ventrella
Laura
L
Giugni
Enrico
E
Motti
Enrico
E
D000328:Adult; D000368:Aged; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold; D005260:Female; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000175:diagnosis / Q000601:surgery*; D017084:Otoacoustic Emissions, Spontaneous; D011183:Postoperative Complications; D011336:Probability; D011379:Prognosis; D011446:Prospective Studies; D016634:Radiosurgery / Q000009:adverse effects* / Q000295:instrumentation; D018570:Risk Assessment; D018709:Statistics, Nonparametric