Anil Khosla MD, Presenter: Nothing to Disclose

Laboratory testing and MR imaging are used to look for retro-cochlear pathology in asymmetric sensorineural hearing loss (ASNHL). The aim of this study is to evaluate the role of MR (Magnetic Resonance) imaging in older patients with ASNHL for screening prior to hearing aids.

This is a retrospective analysis of 250 consecutively investigated patients (mostly males with mean age of 56 years) between 2001-2004.Results of pure-tone audiogram, auditory brainstem evoked response (ABER) and MR Imaging was reviewed with clinical findings. MR Imaging included- T1, T2 FSE (fast spin echo) in axial and coronal plane and 3D T2 volumetric imaging with multiplanar reconstruction. Additional axial and coronal T1 weighted images after intravenous gadolinium injection was also obtained in some patients. The examination concluded in average 40 minutes.

Most of the patients had asymmetrical hearing loss in high frequency range. ABER (n=39) was equivocal in 90%. ABER was definitely abnormal in 3 patients only. Vestibular schwannoma (smallest-3mm) was detected in 7 patients on MRI. Other findings that could be related to as a possible cause for ASNHL were- Dehiscent Jugular Bulb in one, vascular loop near root entry zone in ten, pontine infarct in two, cerebellar infarction five, and mastoiditis in seven patients. In this particular age group the yield of MR imaging to detect retro-cochlear pathology is low. On analysis of individual sequences- T2 weighted 3D Volume imaging with reconstructions detected 95% of the findings and had excellent anatomic demonstration of the nerves.The vestibular schwannoma was clearly seen on 3D volume images.Less than 4% of the 3D volume studies were technically poor due to motion artifacts.

In low probability for vestibular schwannoma group such as older patients with ASNHL being screened for hearing aids, a T2-3D volumetric imaging is adequate in excluding retro-cochlear pathology. In high probability group detailed evaluation including post contrast studies should be obtained.

Khosla, A, 3D MR Imaging: A Screening Tool for Patients with Asymmetrical Sensory Neural Hearing Loss (ASHNL) in Pre-evaluation for Hearing Aids.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4408296.html