Approach
The diagnosis of tic disorders is made on the basis of the history and an otherwise normal physical examination. No further investigations are necessary unless the presentation and clinical findings suggest other possible differential diagnoses that need to be ruled out.
History
The history may reveal the presence of risk factors strongly associated with tic disorders, such as age <18 years, male sex, family history of tics, and presence or family history of obsessive-compulsive disorder (OCD), ADHD, or depression.
Tics need to be classified, based on the following features:
Duration of symptoms
Type: motor, vocal, or a combination.
Tics may be of any of the following types:
Simple motor tics. These may involve grimacing, blinking, head jerking, shoulder shrugging, abdominal tensing, or kicking.
Simple vocal tics. These may involve sniffing, grunting, throat clearing, barking, snorting, or coughing.
Complex motor tics. These may involve head shaking, finger cracking, touching; jumping, rubbing, echopraxia (imitating others' gestures), or copropraxia (performing obscene gestures).
Complex vocal tics. These may involve whistling, belching, unintelligible or nonsensical words, changes in pitch or volume of speech, coprolalia (uttering obscenities or profanities), echolalia (repeating others' words or phrases), or palilalia (repeating one's own words, particularly the last syllable).
Tourette's syndrome (Tourette's disorder) is diagnosed based on the history and a normal physical examination. Onset is before 18 years of age.[38] It is defined as motor and vocal tics that may wax and wane in frequency, but must have persisted for >1 year since first onset and that cannot be explained by other medical conditions.[3][38]
It is important to determine from the history:
The time course of the tics
Sensations associated with the tics
Exacerbating and ameliorating factors
Behavioural and mood issues.
Tics most commonly start in childhood, although adults may rarely present with new-onset tic disorders. The most common cause of tics in adults is the re-emergence of childhood tics, which may or may not have been recognised or diagnosed in childhood. Adult-onset tic disorders are usually more severe, with greater social morbidity. Rarely, pregnant women may present with new-onset tic disorders. Up to 80% of all patients describe an inner urge or a local premonitory sensation, which is then relieved by performing the tic.[3] This is more common for adults than for children.[2]
Tics occur with variable frequency, and are often described to wax and wane over time. Generally they occur more frequently in situations associated with increased levels of stress, anxiety, transitions, or excitement.[1][2] They may become less frequent if the person is distracted by other mental tasks.[1][2] People with tics are able to temporarily control or suppress them for short periods of time, a feature that helps to differentiate tics from focal seizures (which patients cannot control).[1][2][3]
The history (or physical examination) may reveal or suggest the presence of an associated condition. People with tic disorders, especially those with Tourette's syndrome, may have comorbidities, most notably ADHD and OCD.[3][46] One lifetime prevalence study found that girls were more likely to have comorbid OCD and boys were more likely to have comorbid ADHD.[46]
Family history of psychiatric disorders may also be questioned due to the association of parental psychiatric diagnoses with Tourette's syndrome/chronic tic disorder in offspring.[42][43]
Physical examination
If the tics are not witnessed during the examination, the physician can ask the patient or the parents to provide a video for evaluation. Neurological examination is typically normal, except for observed tics. However, there may be minimal signs, including slight difficulties with coordination and fine motor tasks, distraction, and restlessness.[2]
If there is an abnormal neurological examination (e.g., increased tone, spasticity, rigidity, or weakness), an abrupt onset of tics associated with other neurological symptoms, an unusual pattern of tics (unilateral or associated with dystonia), or an onset in adulthood, the tics may be secondary to another condition. The patient should be referred to a neurologist.[3]
Assessment of secondary and other neurological causes
Tic disorders are diagnosed based on clinical history and no specific test is recommended. However, if a secondary tic disorder is suspected, or if the diagnosis is unclear, further tests may be pursued.
Secondary causes include:
Infections (e.g., encephalitis, Creutzfeldt-Jakob disease, and Sydenham's chorea)
Drugs (stimulants, e.g., cocaine, metamfetamine; or antipsychotics, e.g., tardive tics)
Toxins (e.g., carbon monoxide)
Head trauma
Non-specific cerebral insults, such as hypoxia or ischaemia.
Neurological disorders that may present with tics include:[3]
Static encephalopathy
Autistic spectrum disorders
Neuroacanthocytosis
Huntington's disease
Wilson's disease
Pantothenate-kinase associated neurodegeneration
Hyperthyroidism
N-methyl D-aspartate encephalitis
Systemic lupus erythematosus
Stroke.
Evaluation for these causes usually begins with magnetic resonance imaging (MRI) of the brain, with and without intravenous contrast. MRI is not indicated in patients with a normal neurological examination.[23]
If the patient has an altered level of consciousness while the tic is occurring, or if movements cannot be controlled, focal motor or myoclonic seizures should be considered as an alternate diagnosis. An electroencephalogram is required to help confirm the diagnosis.
Patients presenting with fever, altered mental status, and abrupt onset of a tic disorder may have encephalitis and require a lumbar puncture with cerebrospinal fluid studies, including total protein, glucose, cell count and differential, Gram stain, bacterial culture, and viral culture. A neurologist should be consulted.
In cases of abrupt onset tics, where there are no other neurological symptoms such as chorea or encephalitis, a throat culture, serum anti-streptolysin O, and antiDNase B titres may be recommended. The disorder of paediatric auto-immune neuropsychiatric disorders associated with streptococcal infection (PANDAS) has been modified to describe an expanded clinical entity with less emphasis on preceding infections, paediatric acute-onset neuropsychiatric syndrome (PANS), which is no longer tied to the presence of tics as the primary presenting symptom. The terms PANS or childhood acute neuropsychiatric symptoms (CANS) are now often used instead of PANDAS.[36][37]
The use of antibiotic prophylaxis is most appropriate for presentations that most resemble Sydenham's chorea or that are associated with global behavioural, academic, and functional impairment. The risks and benefits of prophylactic antibiotics for tics needs further study and they should be reserved for documented infections (which may exacerbate tics).
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