Overview
Persistent or Chronic Motor or Vocal Tic Disorder is a type of tic disorder characterized by the presence of either:
- Motor Tics: sudden, rapid physical movements such as blinking or making gestures
- Vocal Tics: sudden vocalizations such as grunting or saying words and phrases
Tics are generally compartmentalized as simple tics, lasting for a few milliseconds, or complex tics, lasting for a few seconds.
While Persistent Motor or Vocal Tics are classified as a separate diagnosis than Touretteโs Syndrome, considerable literature has been generated that questions this segregation and proposes placing tic disorders on a spectrum.
While individuals with mild forms of tics may not experience any distress or impairment, severe manifestation of symptoms can have a considerable implication in the daily lives of individuals, including social isolation, issues with interpersonal relationships, difficulties in academic or occupational aspects, and a lower quality of life.
There is a male predominance in the occurrence of tic disorders. The onset of the disorder typically occurs in childhood, and while tics generally improve with age, a small amount of people may experience heightened severity of symptoms as they age.
Genetic, neurological, and environmental factors make up the etiology of the disorder. The most common comorbidities are OCD (Obsessive-Compulsive Disorder) and ADHD (Attention-Deficit/Hyperactivity Disorder).
The preferred mode of treatment for tic disorders is behavioral intervention. Pharmacological intervention strategies are also available.
Signs and Symptoms
Tics are sudden physical movements or vocalizations that occur recurrently, rapidly, and do not follow a particular rhythm. They may be simple, lasting for a few milliseconds (including blinking, throat clearing, shrugging) or complex, lasting for seconds and appearing as a combination of simple tics.
Complex tics may appear offensive or obscene, may present in the way of mirroring movements of someone else, repeating oneโs own words, uttering obscene words or phrases, and so on.
Some common simple tics are:
- Eye blinking
- Shrugging shoulder
- Turning head
- Throat clearing
- Sniffing
- Grunting
Varieties of complex tics have been specified according to their nature:
- Echopraxia: imitation of someoneโs movements
- Copropraxia: sexual or obscene gestures
- Palialia: repeating oneโs own sounds or words
- Echolalia: repeating last-heard words or sounds
- Coprolalia: uttering socially unacceptable words including obscenities and slurs
The signs and symptoms of Persistent Motor or Vocal Tic Disorder include:
- Experiencing either motor or vocal tics
Risk Factors
A male preponderance is observed in the prevalence of tic disorders, though no sex-based differences are present in the type of tics manifested.
Females with the disorder have been speculated to have a higher likelihood of experiencing anxiety and depressive symptoms along with tic disorders. T
he age of onset is typically between 4-6 years of age, with a peak of severity of symptoms occurring between ages 10-12. While the severity of symptoms tends to reduce with age in most cases, the opposite may be true for a minority of individuals with the disorder.
A significant genetic risk is associated with tic disorders. The likelihood of Persistent Motor or Vocal Tic Disorder is higher among first-degree relatives of those with the disorder.
There has been an overlap observed in the bases of Obsessive-Compulsive Disorder and tic disorders, and the two often co-occur among individuals. This is attributable to shared genetic and environmental etiological factors.
Environmental factors such as adversity during pregnancy, as well as maternal smoking during pregnancy have been associated with Persistent Motor or Vocal Tic Disorder. These factors also contribute to a higher severity of tics.
It has also been reported that observing others make particular gestures and sounds can trigger a tic within an individual with the disorder, leading to echopraxia or echolalia tics. Tics are also often worsened by emotional arousal, including excitement and anxiety, or due to exhaustion.
Stress may exacerbate the occurrence of tics.
Diagnosis
The diagnosis of Persistent Motor or Vocal Tic Disorder is largely based on the observation of symptoms as well as a detailed history of behavior.
Family history is a significant factor determining the assessment. This process may also be the first stage of psychoeducation with regards to helping patients understand and attribute their behavior to the presence of pathology.
Interviews and rating scales may be used during this time, including clinician, informant (including parents, caregivers or other close overseers), and patient rated tools.
These are helpful in assessing the type and severity of tics that are being exhibited, and may be used to determine and inform intervention strategies during the stage of treatment.
The Yale Global Tic Severity Scale and the Shapiro Tic Severity Scale are two clinical rating scales that may be used.
Besides differences in severity, the main difference between Touretteโs Disorder and Persistent Motor or Vocal Tic Disorder is that the latter presents with either motor or vocal tics, but not both.
The DSM-5 provides the following diagnostic criteria for Persistent Motor or Vocal Tic Disorder:
- Single or multiple motor or vocal tics have been present during the illness, but not both motor and vocal.
- The tics may wax and wane in frequency but have persisted for more than 1 year since first tic onset.
- Onset is before age 18 years.
- The disturbance is not attributable to the physiological effects of a substance (e.g., cocaine) or another medical condition (e.g., Huntingtonโs disease, post-viral encephalitis).
- Criteria have never been met for Touretteโs disorder.
A specification is made with regards to whether motor or vocal tics are exhibited.
Treatment
Management of tic disorders is informed greatly by the severity of tics and understanding how they are causing impairment to the life of the individual.
The onus of making decisions with regards to whether or not to actively seek treatment for the symptoms experienced falls on the patient, and it is the responsibility of the clinician to guide them through their possible options and their implications.
Certain behavioral interventions have been optimized for the management of tics, and the first-line treatment in this context is Comprehensive Behavioral Intervention for Tics, or CBIT.
The focal point of CBIT is habit reversal, which can begin by forming awareness about the tics. Competing response training is imparted in order to control tic behavior, and follows the act of carrying out voluntary behaviors that are incompatible with the tic behavior.
Pharmacological treatment is typically carried out when psychosocial intervention proves to be ineffective, or the severity of the tics persists in spite of behavioral intervention.
Antipsychotics are the mainstay of pharmacological intervention for tics, and have proven efficacy as observed through randomized control trials. Drugs such as haloperidol, pimozide, risperidone, aripiprazole, ziprasidole, tiapride, and metoclopramide have been effective.
It is important to take into consideration that the use of antipsychotic medication can lead to potential adverse side effects, including drug-induced movement disorders, and metabolic and hormonal effects.
A thorough briefing with regards to the effectiveness and adversity associated with the drug must be understood prior to use, and this process must be facilitated by the clinician.
Alpha agonists are also commonly used as a first line treatment for tic disorders, as they are considered to have more favorable side effects in comparison to antipsychotic medication.
The use of clonidline and guanfacine has been supported by trials, and may also be effective when comorbid ADHD is involved.
While alpha antagonists have shown less serious side effects than antipsychotics, they may still be cause of concern, and can include bradycardia (decreased heart rate), sedation, and hypotension.
The use of botulinum toxin (Botox) has also shown efficacy in helping to manage simple motor tics that occur in the facial region or in the neck or shoulder areas.
Differential Diagnosis
1. Abnormal movements that may accompany other medical conditions and stereotypic movement disorder: Abnormal movements can be differentiated from tics based on the former’s earlier age at onset, prolonged duration, constant repetitive fixed form and location, lack of a premonitory urge, and cessation with distraction.
2. Substance-induced and paroxysmal dyskinesias: Paroxysmal dyskinesias usually occur as dystonie or choreoathetoid movements that are precipitated by voluntary movement or exertion and less commonly arise from normal background activity.
3. Myoclonus: Myoclonus is characterized by a sudden unidirectional movement that is often nonrhythmic. It may occur during sleep. Myoclonus is differentiated from tics by its rapidity, lack of suppressibility, and absence of a premonitory urge.
4. Obsessive-compulsive and related disorders: Differentiating obsessive-compulsive behaviors from tics may be difficult. Clues pointing towards an obsessive-compulsive behavior include a cognitive-based drive and the need to perform the action in a particular manner a certain number of times. Impulse-control problems and other repetitive behaviors, including persistent hair pulling, skin picking, and nail biting, appear more goal directed and complex than tics.
Comorbidity
Many medical and psychiatric conditions are comorbid with tic disorders. ADHD and obsessive-compulsive and related disorders being common.
Specialist
Primary care physicians are likely to recognize symptoms of tic disorders based on observation and a brief history, and the assessment may further be carried out by a specialist such as a neurologist, psychiatrist or clinical psychologist.
Based on the treatment method, practitioners trained in behavioral intervention may be involved in management.
