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.
|Early audiogram from this patient showing profound bilateral hearing loss, but with bone better than air (suggesting conductive). Tymps were normal.||MRI image from shortly after her accident show high signal in the dorsal midbrain and a focus of low signal on the left side of the midbrain, adjacent to the L inferior colliculus|
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.
This patient clearly has midbrain damage associated with bilateral deafness, musical hallucinations, and diplopia. 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).
Musical hallucinations are a reasonably well known consequence of auditory deprivation (Sanchez, Rocha et al. 2011). 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)
The repetition of auditory input is called palinacousis.