**2.1.2 Secondary tic disorders**

A secondary cause for tics should be considered if it is accompanied by other movement disorders or neurologic abnormalities. Tics often indicate the presence of a global brain developmental disorder in conditions like mental retardation, autism and pervasive developmental disorder. Similarly, a variety of genetic and neurodegenerative conditions can cause tics, including Wilson disease, neuroacanthocytosis8 9, neurodegeneration with brain iron accumulation10 11and Huntington disease12.Other potential causes of tics include lesions involving frontal-subcortical circuits like trauma13, carbon monoxide poisoning14, hypoxic-ischemic encephalopathy and stroke15; central nervous system (CNS) infections (neuroborreliosis16, viral encephalitis17) and central nervous system immune disorders (like antiphospholipid antibody syndrome18, Sydenham'schorea19). Tics can be a manifestation of neuroleptic drug-related tardive dyskinesia20 or withdrawal emergent syndrome21. Induction or exacerbation of tics has been reported with antiepileptic drugs22 23, cocaine24, caffeine25and stimulants26.

meeting the definition of a tic. Common examples include picking, tapping, gesturing, mimicking the gestures of others (echopraxia), repeating one's own speech (palilalia), mimicking the speech of others (echolalia) and the production of inappropriate words or

Tics comprise a group of movement disorders. Thus, transient tics, the most common form of the disorder, consists of single or multiple motor and/or vocal tics that occur for at last four weeks but no longer than 12 months. GTS has onset before 18 years of age, characterized by motor and vocal tics over more than a year, there is never a tic-free period of more than 3 consecutive months, not produced by Huntington disease neither viral encephalitis and produces a negative personal impact. The disorder is called chronic motor tics if the criteria of GTS are present but vocal tics are absent. By contrast, if there are vocal

Simple motor tics may need to be differentiated from myoclonic jerks, which are not typically repetitive in the same body part like tics. Tics are commonly associated with premonitory sensations and suppressibility. Complex motor tics need to be distinguished from stereotypies that are longer lasting, more stereotyped movements (*eg*, body rocking, head nodding, and hand/wrist flapping) or sounds (eg, moaning, yelling) that occur over and over again in a more continuous, less paroxysmal fashion. Stereotypies are typically seen in patients with autism, mental retardation, Down syndrome, Rett syndrome,

Some tics are slow or twisting in character resembling dystonia and are termed ''dystonic tics". Contrary to dystonic tics, dystonia *per se* tends to beslower and leads to more sustained disturbances in posture of a limb, the neck, or trunk. Compulsions frequently occur in association with tics, can sometimes be difficult to distinguish from complex motor tics but typically differ by being done in response to an obsession, being performed to avoid future problems or being done according to ritualistic rules5 6 With very high comorbidity rates of both ADHD and OCD, GTS may represent a multifaceted developmental

A secondary cause for tics should be considered if it is accompanied by other movement disorders or neurologic abnormalities. Tics often indicate the presence of a global brain developmental disorder in conditions like mental retardation, autism and pervasive developmental disorder. Similarly, a variety of genetic and neurodegenerative conditions can cause tics, including Wilson disease, neuroacanthocytosis8 9, neurodegeneration with brain iron accumulation10 11and Huntington disease12.Other potential causes of tics include lesions involving frontal-subcortical circuits like trauma13, carbon monoxide poisoning14, hypoxic-ischemic encephalopathy and stroke15; central nervous system (CNS) infections (neuroborreliosis16, viral encephalitis17) and central nervous system immune disorders (like antiphospholipid antibody syndrome18, Sydenham'schorea19). Tics can be a manifestation of neuroleptic drug-related tardive dyskinesia20 or withdrawal emergent syndrome21. Induction or exacerbation of tics has been reported with antiepileptic drugs22 23, cocaine24,

tics but no motor tics the disorder is called chronic vocal tics4.

psychosis, or congenital blindness and deafness.

sentences.

**2.1.1 Differential diagnosis** 

neuropsychiatric brain disorder7.

**2.1.2 Secondary tic disorders** 

caffeine25and stimulants26.
