MRI of endolymphatic hydrops in patients with Meniere’s disease: a case-controlled study with a simplified classification based on saccular morphology

In vivo imaging of saccular hydrops in humans reflects sensorineural hearing loss rather than Meniere's disease symptoms

OBJECTIVES

A case-controlled imaging study demonstrated that saccular hydrops was specific to Meniere's disease (MD), but only present in a subset of patients. Here, we compared patients with definite MD, vertigo and sensorineural hearing loss (SNHL) to elucidate the relationship between saccular hydrops and extent of SNHL.

METHODS

In this prospective study, we performed 3D-FLAIR sequences between 4.5 and 5.5 h after contrast media injection in patients with MD (n=20), SNHL (n=20), vertigo (n=20) and 30 healthy subjects. Two radiologists independently graded saccular hydrops. ROC analysis was performed to determine the hearing loss threshold to differentiate patients with saccular hydrops.

RESULTS

Saccular hydrops was found in 11 of 20 MD patients, 10 of 20 SNHL patients and in none of the vertigo patients and healthy subjects. In SNHL patients, 45 dB was the threshold above which there was a significant association with saccular hydrops, with sensitivity of 100 % and specificity of 90 %. In MD patients, 40 dB was the threshold above which there was a significant association with saccular hydrops, with sensitivity of 100 % and specificity of 44 %.

CONCLUSIONS

Our results indicate saccular hydrops as a feature of worse than moderate SNHL rather than MD itself.

KEY POINTS

• MRI helps clinicians to assess patients with isolated low-tone sensorineural hearing loss. • Saccular hydrops correlates with sensorineural hearing loss at levels above 40 dB. • Vertigo patients without sensorineural hearing loss do not have saccular hydrops. • Saccular hydrops is described in patients without clinical diagnosis of Meniere's disease.

Imaging of the saccule for the diagnosis of endolymphatic hydrops in Meniere disease, using a three-dimensional T2-weighted steady state free precession sequence: accurate, fast, and without contrast material intravenous injection

BACKGROUND

Endolymphatic hydrops can be studied on magnetic resonance imaging (MRI) using images acquired 4 h after intravenous injection of Gd-chelate. Our aim was to compare high-resolution T2-weighted images of the saccule in normal subjects with histological sections from cadavers and to identify its changes in Meniere disease, compared to healthy volunteers.

METHODS

Sixty-four healthy volunteers without any otologic disease and 64 patients who fulfilled all the criteria for unilateral Meniere disease underwent 3 T MRI using a T2-weighted steady state free precession (SSFP) sequence, without contrast material injection. Images of healthy volunteers were compared with histological sections of normal inner ears from premature foetuses and compared with volunteers.

RESULTS

The normal saccule was easily visible on T2-weighted images in volunteers, with a normal maximal height of 1.6 mm (1.4 ± 0.1 mm, mean ± standard deviation) and a good correlation with reference histological sections, while in Meniere disease the saccule was dilated in 52/62 patients (84%), with a saccular height greater than 1.6 mm (1.69 ± 0.24 mm, p = 0.001), found in 45/52 patients (86%). An associated increased width (greater than 1.4 mm) was found in 23/52 patients (44%). A round shape or the non-visualisation of the saccule were also found in 2/52 (4%) and in 5/62 patients (8%), respectively.

CONCLUSIONS

A T2-weighted sequence is an easy method to diagnose Meniere disease. Saccular abnormalities were found in 84% of the cases: elongation (height > 1.6 mm) in 86%, increased saccular width in 44%, or a missing saccule in 8%.