Dysprosody

Dysprosody, which may manifest as pseudo-foreign accent syndrome, refers to a disorder in which one or more of the prosodic functions are either compromised or eliminated completely.

Prosody refers to the variations in melody, intonation, pauses, stresses, intensity, vocal quality, and accents of speech. As a result, prosody has a wide array of functions, including expression on linguistic, attitudinal, pragmatic, affective and personal levels of speech. People diagnosed with dysprosody most commonly experience difficulties in pitch or timing control. Essentially, people diagnosed with the disease can comprehend language and vocalize what they intend to say, however, they are not able to control the way in which the words come out of their mouths. Since dysprosody is the rarest neurological speech disorder discovered, not much is conclusively known or understood about the disorder. The most obvious expression of dysprosody is when a person starts speaking in an accent which is not their own. Speaking in a foreign accent is only one type of dysprosody, as the disease can also manifest itself in other ways, such as changes in pitch, volume, and rhythm of speech. It is still very unclear as to how damage to the brain causes the disruption of prosodic function. The only form of effective treatment developed for dysprosody is speech therapy.

The first documented occurrence of dysprosody was described by Pierre Marie, a French neurologist, in 1907. Marie described the case of a Frenchman who started speaking in an Alsatian accent after suffering from a cerebrovascular accident which caused right hemiplegia.

The next documented report of dysprosody occurred in 1919 by Arnold Pick, a German neurologist. He noticed a 29-year-old Czechoslovakian had started speaking in a Polish accent following a stroke. Pick's patient also suffered from right hemiparesis, a lesser version of hemiplegia, and aphasia after the stroke. Pick noticed that not only was the accent altered, but the timing of the speech was slower, and the patient spoke with uncharacteristic grammatical mistakes. Pick later wanted to follow up on his research but was not able to, since the patient had died with no autopsy performed.

...
Wikipedia