A Case of Acquired Speech-to-Color Synesthesia following Traumatic Brain Injury.
Vasundhra Mahendra1, Alexandra Parashos1, Mark Wagner1, Ezequiel Gleichgerrcht1
1Department of Neurology, Medical University of South Carolina
Background:
Synesthesia is a unique subjective phenomenon where one sensory modality elicits a perceptual experience in an unrelated sensory modality. Chromesthesia is a specific sound-to-color form of synesthesia where auditory stimuli void of color information induce color perception. Knowledge regarding the neurobiology of synesthesia is limited, posing challenges for its detection and management, thereby creating a need for greater lesion-symptom exploration.
Design/Methods:
We report the case of a 71-year-old previously healthy left-handed woman who developed synesthesia after suffering a traumatic head injury with subsequent holocephalic subdural haemorrhage requiring craniotomy. The course was complicated by focal status epilepticus with imaging showing cortical edema. Soon after discharge, patient reported symptoms of seeing colors projecting out of people’s mouth during oral speech, suggestive of chromesthesia. The colors were vivid in intensity at onset but would rapidly dissipate into vapour appearance. During neuropsychological testing, patient described that specific colors were associated with different words and were repeatable. For example, the word “the” was associated with color blue. Interestingly, her symptoms were specific to expressive language and not reproducible with music, singing or other non-verbal sounds such as dogs barking. Viewing videos of people speaking would trigger color but not if the videos contained music, singing or other non-verbal sounds. Patient reported listening to music as a therapeutic intervention when surrounded by multiple conversations in a crowded environment.
Results:
The case shows acquired chromesthesia presenting with word-specific color changes induced solely by oral speech elicited by others and not by other non-verbal sounds, including music.
Conclusions:
We report the first case of acquired human oral speech-to-color synesthesia following Traumatic Brain Injury. Acquired forms of synesthesia tend to result from drug intoxication or neurological disorders, including injury. We discuss our patient’s acquired form of chromesthesia in the context of multiple theories associated with multimodal integration in the adult brain.