EVALUATION OF ENDOLYMPHATIC HYDROPS ON MAGNETIC RESONANCE IMAGING IN PATIENTS WITH OTOSCLEROSIS

Tsutomu Nakashima,1 Tohru Mukaida,1 Tadao Yoshida,1 Masaaki Teranishi,1 Michihiko Sone,1 Shinji Naganawa2

1Department of Otorhinolarygology, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan; 2Department of Radiology, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan

Introduction

In otosclerosis surgery, post-operative vertigo occasionally occurs though it is usually transient. Profound sensorineural hearing loss after otosclerosis surgery has been reported in about two percent of the patients.1 The mechanism of the inner ear disturbance is unknown. Short distance between the stapes footplate and endolymphatic space may be associated with the post-operative vertigo or sensorineural hearing loss. We attempted to evaluate the distance between the stapes footplate and the endolymphatic space with the endo-lymphatic space size.

Methods

In four patients with otosclerosis, magnetic resonance imaging (MRI) was taken four hours after intravenous gadolinium (Gd) injection using a 3-tesla MR unit. We applied heavily T2-weighted 3D fluid attenuated inversion recovery (3D-FLAIR),2,3 3D-inversion recovery sequence with real reconstruction (3D-real IR),4 positive endolymphatic imaging (PEI)5 and HYbriD of Reversed image Of Positive endolymph signal and native image of positive perilymph Signal (HYDROPS).6

Heavily T2-weighted 3D-FLAIR after intravenous standard-dose Gd administration was reported to achieve the visualization of endolymphatic hydrops.2,3 On 3D-FLAIR, perilymph with Gd distribution shows a high signal and endolymph without Gd distribution shows a low signal similar to that of surrounding bone. The sensitivity of this technique to low Gd concentration is better than that of the 3D-real IR.7 However, the 3D-real IR at 3 tesla makes it possible to separately visualize endolymph, perilymph and bone using a single-pulse sequence.4 In PEI, optimal shortening of the inversion time in 3D-FLAIR suppressed the signal of the Gd-containing perilymph and instead gave a high signal for the endolymph that contains no Gd.5 HYDROPS images allowed a 3D-real IR-like image presentation even after intravenous standard-dose Gd administration.6

Results

Endolymphatic hydrops was frequently observed in both the cochlea and vestibule. The distance between the stapes footplate and the endolymphatic space in the vestibule could be evaluated in all patients.

An example of MRI is shown in Figure 1 A-C. In this patient, endolymphatic hydrops was observed in both the cochlea and vestibule on the right side.

The endolymphatic space size in the right ear was clearly larger than that in the left ear. The hearing level was not different between the right and left ears. Stapedotomy was performed on the left side in which the distance between the stapes footplate and the endolymphatic space was larger than that in the other side.

image

Fig. 1A. Endolymphatic hydrops in the right vestibule (arrows) in a 48-year-old female with otosclerosis (3D real IR).

image

Fig. 1B. Endolymphatic hydrops in the right cochlea (arrows) in a 48-year-old female with otosclerosis (left side image; 3D real IR, right side image; heavily T2-weighted 3D FLAIR).

image

Fig. 1C. Endolymphatic space in the left vestibule (arrows) in a 48-year-old female. The space size is smaller than that in the right vestibule shown in Fig. 1A.

Discussion

Endolymphatic hydrops can be visualized by MRI after intra-tympanic or intravenous Gd injection. In general, the intra-tympanic method has higher enhancement of the perilymph and better ability to predict intra-tympanic drug transition to the inner ear. The intravenous method is less invasive and enables stable bilateral observation of the condition of the cochlea.

We reported many cases with asymptomatic endolymphatic hydrops using advanced techniques of MRI.8 Although the mechanism is not clear, endolymphatic hydrops was often recognized in temporal bone specimens in patients with otosclerosis.9,10 Accordingly, it was felt that evaluation of endolymphatic space size with use of MRI is important even if the patients had no sensorineural hearing loss.

It has been postulated that otosclerosis may produce vertigo by several mechanisms. One mechanism is by causing endolymphatic hydrops.9,10 To investigate the anatomic relationship between utricle, saccule, and stapes footplate, and adapt the stapes prosthesis tip to reduce post-operative vertigo, temporal bones were serially sectioned and stained, and the distance from the inner lining of stapes footplate to saccule and utricle, respectively, were measured.11 Based on these measurements, the Fisch prosthesis was modified with a slope of 45 degrees at its tip to adapt to the anatomic configuration of the vestibule. Post-operative vertigo was significantly reduced when the modified prosthesis was inserted.11

Endolymphatic hydrops may be associated with pre-operative and post-operative vertigo in patients with otosclerosis. There is a possibility that the distance between the stapes footplate and the vestibular endolymphatic space is also related to the occurrence of post-operative sensorineural hearing loss. Because the endolymphatic space imaging is now possible after intravenous standard-dose Gd administration, the imaging is expected to contribute to elucidation of the mechanism of pre- and post-operative sensorineural hearing loss and vertigo.

Conclusions

It is now possible to evaluate endolymphatic space size in patients with otosclerosis after intravenous standard-dose Gd injection using 3-tesla MRI. The MRI may contribute to prevention and treatment of the inner ear disorders in patients with otosclerosis.

References

1.Mann WJ, Amedee RG, Fuerst G, Tabb HG. Hearing loss as a complication of stapes surgery. Otolaryngol Head Neck Surg 115:324–328, 1996

2.Naganawa S, Yamazaki M, Kawai H, Bokura K, Sone M, Nakashima T. Visualization of endolymphatic hydrops in Meniere’s disease with single-dose intravenous gadolinium-based contrast media using heavily T(2)-weighted 3D-FLAIR. Magn Reson Med Sci 9:237–242, 2010

3.Sano R, Teranishi M, Yamazaki M, Isoda H, Naganawa S, Sone, M, Hiramatsu M, Yoshida T, Suzuki H, Nakashima T. Contrast enhancement of the inner ear in magnetic resonance images taken at 10 minutes or 4 hours after intravenous gadolinium injection. Acta Otolaryngol 132:241–246, 2012

4.Naganawa S, Satake H, Kawamura M, Fukatsu H, Sone M, Nakashima, T. Separate visualization of endolymphatic space, perilym-phatic space and bone by a single pulse sequence; 3D-inversion recovery imaging utilizing real reconstruction after intratympanic Gd-DTPA administration at 3 Tesla. Eur Radiol 18:920–924, 2008

5.Naganawa S, Yamazaki M, Kawai H, Bokura K, Sone M, Nakashima, T. Imaging of Endolymphatic and Perilymphatic Fluid after Intravenous Administration of Single-dose Gadodiamide. Magn Reson Med Sci 11:145–150, 2012

6.Naganawa S, Yamazaki M, Kawai H, Bokura K, Sone M, Nakashima T. Imaging of Ménière’s disease after intravenous administration of single dose gadodiamide: Utility of subtraction image. Magn Reson Med Sci 11(3):213–219, 2012

7.Nakashima T, Naganawa S, Katayama N, Teranishi M, Nakata S, Sugiura M, Sone M, Kasai S, Yoshioka M, Yamamoto, M. Clinical significance of endolymphatic imaging after intratympanic gadolinium injection. Acta Otolaryngol 129(Suppl 560):9–14, 2009

8.Nakashima T, Sone M, Teranishi M, Yoshida T, Terasaki H, Kondo M, Yasuma T, Wakabayashi T, Nagatani T, Naganawa S. A perspective from magnetic resonance imaging findings of the inner ear: Relationships among cerebrospinal, ocular and inner ear fluids. Auris Nasus Larynx 39:345–355, 2012

9.Liston SL, Paparella MM, Mancini F, Anderson JH. Otosclerosis and endolymphatic hydrops. Laryngoscope 94:1003–1007, 1984

10.Paparella MM, Cureoglu S, Shao W, Schachern PA. Otosclerosis and associated otopathologic conditions. Adv Otorhinolaryngol 65:31–44, 2007

11.Wang ZM, Chi FL, Dai CF. Modified stapes prothesis to limit postoperative vertigo. Otolaryngol Head Neck Surg 132:50–54, 2005


Address for correspondence: Tsutomu Nakashima, tsutomun@med.nagoya-u.ac.jp

Cholesteatoma and Ear Surgery – An Update, pp. 25–28

Edited by Haruo Takahashi

2013 © Kugler Publications, Amsterdam, The Netherlands