Coprolalia

# Overview
Coprolalia is involuntary swearing or the involuntary utterance of obscene words or socially inappropriate and derogatory remarks. Coprolalia comes from the Greek  meaning "feces" and  meaning "babbling, meaningless talk", from lalein, "to talk". The term is often used as a clinomorphism, with 'compulsive profanity' inaccurately referred to as being Tourette syndrome.
Related terms are copropraxia, performing obscene or forbidden gestures, and coprographia, making obscene writings or drawings.

# Characteristics
Coprolalia encompasses words and phrases that are culturally taboo or generally unsuitable for acceptable social use, when used out of context.  The term is not used to describe contextual swearing.  It is usually expressed out of social or emotional context, and may be spoken in a louder tone or different cadence or pitch than normal conversation. It can be a single word, or complex phrases.  A person with coprolalia may repeat the word mentally rather than saying it out loud; these subvocalizations can be very distressing.
Coprolalia is an occasional but rare characteristic of Tourette syndrome, although it is not required for a diagnosis of Tourette's. In Tourette syndrome, compulsive swearing can be uncontrollable and undesired by the person uttering the phrases.  Involuntary outbursts, such as racial or ethnic slurs in the company of those most offended by such remarks, can be particularly embarrassing. The phrases uttered by a person with coprolalia do not necessarily reflect the thoughts or opinions of the person.
Coprolalia is also a rare symptom of other psychiatric disorders, such as Lesch-Nyhan syndrome.

# Prevalence
According to the Tourette Syndrome Association, fewer than 15% of Tourette syndrome patients exhibit coprolalia, but it tends to attract more attention than any other symptom.   There is a paucity of epidemiological studies of Tourette syndrome; ascertainment bias affects clinical studies.  Studies on people with Tourette's often "came from tertiary referral samples, the sickest of the sick".  Further, the criteria for a diagnosis of Tourette's were changed in 2000, when the impairment criteria was removed from the DSM-IV-TR for all tic disorders, resulting in increased diagnoses of milder cases.  Further, many clinical studies suffer from small sample size.  These factors combine to render older estimates of coprolaliabiased towards clinical populations of the more severe casesoutdated.  An international, multi-site database of 3,500 individuals with Tourette syndrome drawn from clinical samples found 14% of patients with Tourette's accompanied by comorbid conditions had coprolalia, while only 6% of those with uncomplicated ("pure") Tourette's had coprolalia.  The same study found that the chance of having coprolalia increased linearly with the number of comorbid conditions:  patients with four or five other conditionsin addition to ticswere four to six times more likely to have coprolalia than persons with only Tourette's.  One study of a general pediatric practice found an 8% rate of coprolalia in children with Tourette syndrome, while another study found 60% in a tertiary referral center (where typically more severe cases are referred).  A more recent Brazilian study of 44 patients with Tourette syndrome found a 14% rate of coprolalia; a Costa Rican study of 85 subjects found 20% had coprolalia; a Chilean study of 70 patients found an 8.5% rate of coprolalia; older studies in Japan reported a 4% incidence of coprolalia; and a still older clinical study in Brazil found 28% of 32 patients had coprolalia.  Considering the methodological issues affecting all of these reports, the consensus of the Tourette Syndrome Association is that the actual number is below 15 percent.

# Treatment
Some patients have been treated by injecting botulinum toxin (botox) near the vocal cords. This does not prevent the vocalizations, but the partial paralysis that results helps to control the volume of any outbursts.  Surprisingly, botox injections result in more generalized relief of tics than the focal relief expected.