[A patient with acoustic neuroma--The reason for the functional disorder of his inner ear?].

BACKGROUND

Acoustic neuroma is one of the classic causes of retrocochlear hearing disorders. Auditory brainstem response (ABR) testing with a sensitivity of about 90 % in the diagnosis of acoustic neuroma plays an important role as a screening method.

CASE REPORT: A patient suffering from an acute, unilateral sensorineural hearing loss with tinnitus recovered for a short period of time after being treated with low density lipoprotein (LDL-) apheresis improving hemorheology. Surprisingly, the reason for the sudden hearing loss was a tumor in the cerebellopontine angle with a maximum diameter of 2 cm, which was detected by magnetic resonance imaging (MRI). Auditory brainstem response testing (ABR), audiovestibular tests and other standard tests were negative concerning this diagnosis. There was no previous evidence for an acoustic neuroma in all investigations of cochlear disfunction except MRI.

CONCLUSIONS

The acoustic neuroma caused a compression of the labyrinthine artery in the inner auditory canal resulting in an acute unilateral hearing loss with tinnitus. Low Density Lipoprotein-apheresis was able to achieve a short term improvement of blood supply to the inner ear. Thus the compression of the labyrinthine artery caused by an acoustic neuroma could be compensated for the duration of about one week. Within this time the effect of LDL-apheresis decreased more and more. After a sudden unilateral hearing loss an acoustic neuroma must be ruled out even if the retrocochlear testing by ABR primarily shows no prolonged interpeak latency.