Case: Midbrain Hearing loss with Musical Tinnitus

Timothy C. Hain, MD • Page last modified: February 13, 2022

see also: Hearing Page• Central hearing loss • Brainstem Strokes

After a pedestrian vs. automobile collision, a woman lost consciousness. On awakening she was weak on the right side and completely deaf. Her bilateral deafness gradually improved over many months. As her hearing slowly recovered, she developed a tinnitus and in particular, she hears music in her head all of the time. She can change the tune of her tinnitus by simply thinking about another song. This type of tinnitus could also reasonably be called a musical hallucination.

She also has hyperacusis, and any auditory stimulus worsens her symptoms, such as for example, "clashing in the kitchen". She can no longer sing in the choir. Loud noises make her tinnitus worse. She tried a hearing aid, but returned it.

She also has double vision (horizontally). Speech had abnormal prosody, although she previously sang in the choir, her singing of "Mary had a little lamb" is very flat. There is no palatal myoclonus. The left pupil reacts sluggishly to light. There is a full ocular range but she sees double due to a exotropia (eye deviated out, suggesting damage to control circuits for convergence or medial eye movement in midbrain).

OAEs were present on both sides, showing both that the cochlea is intact as well as that the "conductive" hearing loss is not real. Cochlear microphonics were also present. ABRs were normal as well.

Discussion:

This patient has midbrain damage associated with bilateral deafness, musical hallucinations, and diplopia. It is likely due to interruption of ascending central hearing pathways that go through the inferior colliculus. These cases are rare but there are similar case reports (Hoistad and Hain 2003; Jani, Laureno et al. 1991, Blagoveshchenskaia and Kapitanov 1994, Musiek, Charette et al. 2004; Woo et al, 2014).

ABRs are usually normal in lesions at this level (Vitte, Tankere et al. 2002). In some cases, a functional hearing loss is suspected until further investigation is made. (Jani, Laureno et al. 1991) Musical hallucinations are reportedly more common in "female elderly adults ..with mood disorders) (Rocha et al, 2015) Musical hallucinations are also a reasonably well known consequence of auditory deprivation (Sanchez, Rocha et al. 2011).

The repetition of auditory input is called palinacousis.

References:

• Blagoveshchenskaia, N. S. and Kapitanov, D. N. (1994). "[Vestibulocochlear syndrome in lesions of the midbrain]." Vestn Otorinolaringol(3): 5-8.
• Hoistad, D. L. and Hain, T. C. (2003). "Central hearing loss with a bilateral inferior colliculus lesion." Audiol Neurootol 8(2): 111-113.
• Jani, N. N., Laureno, R., Mark, A. S. and Brewer, C. C. (1991). "Deafness after bilateral midbrain contusion: a correlation of magnetic resonance imaging with auditory brain stem evoked responses." Neurosurgery 29(1): 106-108; discussion 108-109.
• Musiek, F. E., Charette, L., Morse, D. and Baran, J. A. (2004). "Central deafness associated with a midbrain lesion." J Am Acad Audiol 15(2): 133-151; quiz 172-133.
• Rocha, S. C., et al. (2015). "Multidisciplinary assessment of patients with musical hallucinations, tinnitus and hearing loss." Psychopathology 48(4): 251-255.
• Sanchez, T. G., Rocha, S. C., Knobel, K. A., Kii, M. A., Santos, R. M. and Pereira, C. B. (2011). "Musical hallucination associated with hearing loss." Arq Neuropsiquiatr 69(2B): 395-400.
• Vitte, E., Tankere, F., Bernat, I., Zouaoui, A., Lamas, G. and Soudant, J. (2002). "Midbrain deafness with normal brainstem auditory evoked potentials." Neurology 58(6): 970-973.
• Woo, P. Y., et al. (2014). "Monoaural musical hallucinations caused by a thalamocortical auditory radiation infarct: a case report." J Med Case Rep 8: 400.