Nagy N. N. Naguib MSc, Presenter: Nothing to Disclose

Nour-Eldin Abdelrehim Nour-Eldin MD, MSc, Abstract Co-Author: Nothing to Disclose

Tatjana Gruber-Rouh, Abstract Co-Author: Nothing to Disclose

Constanze Hey, Abstract Co-Author: Nothing to Disclose

Thomas Lehnert MD, Abstract Co-Author: Nothing to Disclose

Renate Maria Hammerstingl MD, Abstract Co-Author: Nothing to Disclose

Thomas Josef Vogl MD, PhD, Abstract Co-Author: Nothing to Disclose

To test the feasibility of using the intracanalicular facial nerve as a reference for assessment of the cochlear nerve size in patients with longstanding hearing loss using multiplanar reconstruction (MPR) of the high resolution MRI sequence.

The study was retrospectively performed on 86 patients (47 males & 39 females) with a mean age of 51.6 year. The study group (Group 1) consisted of 53 patients with longstanding bilateral hearing loss. The control group (Group 2) consisted of 33 patients not suffering from hearing loss & referred for other reasons. MRI was performed using a T2-weighted SPACE sequence with 0.6 mm slice thickness. MPR reconstruction was bilaterally performed using 3D Application. The size of the cochlear nerve & facial nerve were measured by drawing a region of interest around the cross-sectional circumference of the nerve. The size ratio was obtained by dividing the cochlear nerve size on the facial nerve size. The differences between the study and control groups were tested using the Wilcoxon-Mann-Whitney U-Test. 

In group 1 the ratio cochlear to facial showed a mean of 0.992 (SD:0.296, Range:0.52-1.86) & 1.119 (SD:0.352, Range:0.34-2.3) for the right & left sides respectively. In group 2 the mean was 1.179 (SD:0.232, Range:0.78-1.71) & 1.248 (SD:0.248, Range: 0.85-1.94) for the right & left sides respectively. In group 1 the mean cross sectional surface area of the right cochlear nerve was 1.29 mm2 & 1.34 mm2 for the facial nerve. On the left side the mean was 1.29 mm2 and 1.22 mm2 for cochlear & facial nerves respectively. In two patients the cochlear nerve was absent on the left side. In group 2 the mean was 1.51 mm2 and 1.33 mm2 for cochlear & facial nerves respectively. On the left side the mean was 1.53 mm2 & 1.27 mm2 for cochlear & facial nerves respectively. No significant difference (p=0.735) between both groups was noted regarding the size of the facial nerve. A statistically significant difference (p=0.0001) was noted between both groups regarding the cochlear to facial size ratio.  

The facial nerve can be used as a reference for assessment of the cochlear nerve size in patients with longstanding hearing loss. The cochlear to facial ratio is significantly lower in patients with hearing loss.     

The facial nerve can be added as an imaging reference parameter for assessment of the cochlear nerve in patients with longstanding hearing loss. 

Naguib, N, Nour-Eldin, N, Gruber-Rouh, T, Hey, C, Lehnert, T, Hammerstingl, R, Vogl, T, Assessment of the Cochlear Nerve to Facial Nerve Size Ratio Using High Resolution MR Multiplanar Reconstruction of the Internal Auditory Canal in Patients Presenting with Longstanding Hearing Loss.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12031954.html