To describe a case of autopsy-proven corticobasal degeneration (CBD) who presented with auditory hallucination, an unusual non-motor symptom in CBD.

CBD is a rare disease with constellations of symptoms and signs resulting from cortical and subcortical tauopathy, including alien hand phenomenon, limb apraxia, agraphesthesia, and parkinsonism. Auditory hallucination (AH), although commonly associated with psychiatric disorders, is rarely seen in neurodegenerative diseases.

Chart review.

A 70-year-old woman presented with insidious onset of progressively worsening balance and difficulty walking up and downstairs, attributed to reduced ability to manipulate her right leg for ambulation. Three years later, she developed slow, non-purposeful, and uncontrollable movement of the right upper extremity, described as “the hand has the mind of its own.” There were no intermanual conflicts. The involuntary movement was partially suppressible by her will or left hand. In the meantime, she developed AH. The trigger of the AH appeared to be from external rather than internal. The content of AH was always some family members calling out to her. She did not have paranoid thoughts, and the AH did not cause any self-injurious behaviors, including suicidal ideation. On exam, right hand ideomotor apraxia and a constant mirroring of her right hand on the repetitive tasks performed by the left-sided extremities was noted. AH lasted for 4 years with increasing frequency until she deceased. Other hallucinations never occurred. Her brain autopsy showed pronounced tauopathic burden involving the paracentral frontal and parietal region, and to a lesser extent the entorhinal cortex, parahippocampal, and occipitotemporal gyri. No Lewy-body containing neurons were found. The neuropathologic diagnosis is consistent with CBD.

The extra and atypical involvement of the astroglial tau pathology in the mesial temporal structure might further explain the unusual presentation of AH in CBD, which could be related to the interpretation error of the external stimuli.