Labyrinthitis case with cochlear high signal and enhancement

Timothy C. Hain, MD  • Page last modified: April 3, 2023

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A man in his 20's presented to the clinic with a 1 month history of dizziness, imbalance, and a hearing disturbance. The dizziness came on suddenly, preceded by a minor head injury about 1 week ago. One week later, hearing deteriorated on the right side, accompanied by tinnitus, a headache and ear pain. Over the last two weeks, hearing improved.

On examination (at about 1 month post onset), there was a low amplitude left-beating spontaneous nystagmus. This nystagmus was greatly increased by head-shaking and vibration. Hearing was reduced on the right side.

Test results

Audiometry showed a high frequency sensorineural reduction on the right side.	MRI (T2, 3 tesla study) showed high signal of the right cochlea (left side of this image). Gadolinium also showed enhancement.

Audiometry is asymmetrical in persons with labyrinthitis. This is classic picture.

OAE's were absent on the right in this patient. OAE's should be absent when the hearing loss is greater than 30db. This provides objective confirmation. OAE's may be present when the hearing loss is being simulated or exaggerated, or when there is an auditory neuropathy causing the hearing loss.

The VEMP test in this patient was absent on the right. VEMP's are variable in labyrintitis. In severe cases, VEMP's are reduced. VEMP's are usually present in vestibular neuritis.

Overall:

This is a non-classic presentation of labyrinthitis. The unusual aspects are the cochlear enhancement on the MRI, and the one-week delay in onset of hearing symptoms.

Cochlear abnormalities in labrinthitis on MRI are rare. Stookroos et al (1998) found it in only 1/27 cases. While there is a general agreement that MRI is useful to exclude the presence of tumors in persons with unilateral hearing loss, a careful consideration of the cost-benefit ratio in persons with sudden hearing loss (such as is the case in labyrinthitis), to our knowledge, has not been done. In our practice in Chicago Illinois, we commonly do obtain a 3T MRI with contrast in any person with an unexplained substantial, sensorineural hearing loss. We prefer the higher resolution study (3T) compared to the lower and more usual resolution of 1.5 T, as the cochlea is a very small structure and small changes can be hard to see even on a very good MRI scan.

The one week delay in onset of hearing symptoms suggests that there was progression of the disease process in this case over a week. This is not usual in either labyrinthitis or vestibular neuritis, but might occur due to spread of the infection, or other pathologic mechanisms such as poor circulation to the inner ear.

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References:

Stokroos, R. J., F. W. Albers, et al. (1998). "Magnetic resonance imaging of the inner ear in patients with idiopathic sudden sensorineural hearing loss." Eur Arch Otorhinolaryngol 255(9): 433-6.