Differentials
Functional tic-like behaviours
SIGNS / SYMPTOMS
Rapid onset of tic-like behaviours over hours to days; rapid progression of tic-like behaviours from simple to complex; age of onset after 12 years; predominance of complex tics including large-amplitude arm movements, complex vocalisations, and context dependent tic-like behaviours; co-occurring psychosocial stressors, anxiety, or mood disorder.
INVESTIGATIONS
Diagnosis is based on history and physical examination.
Obsessive-compulsive disorder (OCD)
SIGNS / SYMPTOMS
Although compulsions are also usually associated with feelings of inner anxiety, they are characterised by ritualistic behaviours (checking, touching, arranging, etc.) and the need to repeat them in the same manner. Obsessions are closely linked and are defined as recurrent, often undesired, intrusive thoughts.
INVESTIGATIONS
Diagnosis is based on history and physical examination.
Stereotypies
SIGNS / SYMPTOMS
Movements are repetitive, stereotyped, and purposeless, elicited by excitement, anxiety, and occasionally boredom. The characteristics of the movements change little in quality over time.
Typical movements include hand flapping, rocking, or chewing, and often have a rhythmic quality.
Stereotypies are common in children with autism or learning difficulties, although may be present in children with no other conditions.[1][3]
Typically do not start in the face or neck.
Usually starts at a younger age, such as in the first 1 to 2 years of life, with 90% of cases reporting onset before age 3 years.[38]
INVESTIGATIONS
Diagnosis is usually based on history and physical examination.
Seizures
SIGNS / SYMPTOMS
If the patient experiences alteration of consciousness, or if the movements cannot be temporarily suppressed or controlled, the patient may be experiencing focal motor seizures or myoclonic seizures and not motor tics.[1][3]
INVESTIGATIONS
If the history does not differentiate tics from seizures, an electroencephalogram is indicated.
Paediatric auto-immune neuropsychiatric disorders associated with streptococcal infection (PANDAS)/paediatric acute-onset neuropsychiatric syndrome (PANS)/childhood acute neuropsychiatric symptoms (CANS)
SIGNS / SYMPTOMS
Group A streptococcal exposure has been linked to tic disorders.[34] This disorder is characterised by tic disorders or obsessive-compulsive disorder (OCD) and is termed paediatric auto-immune neuropsychiatric disorders associated with streptococcal infections (PANDAS). The PANDAS criterion has been modified to eliminate specific aetiological factors (i.e., streptococcal infection) and focus on the initial presentation of symptoms. This expanded clinical entity is termed paediatric acute-onset neuropsychiatric syndrome (PANS) due to increasing evidence showing that rapid changes in personality are not just linked to streptococcal infections but may include many physiological stressors. The term 'childhood acute neuropsychiatric symptoms' (CANS) refers to this phenotype as well, but has a broader diagnostic scope to include symptoms associated with infectious, post-infectious, drug-induced, auto-immune, metabolic, traumatic, psychogenic, and other factors. Furthermore, tics have now been removed from the diagnostic criteria for PANS.[36][37]
INVESTIGATIONS
Positive throat culture for group A streptococci associated in time with an exacerbation of tic symptoms.
Anti-streptolysin O (ASO) titres and antiDNase B may be elevated if symptoms have been present for >1 week.[34][41]
Demonstrating a rise in titres from tic onset or dramatic flare and at 4 to 6 weeks later provides some support for group A streptococci as an inciting event. However, the presence of elevated ASO titres only identifies prior infections and does not demonstrate causality or support an active infection. Other respiratory infections (e.g., influenza, Mycoplasma pneumonia) should be considered.
Abrupt, dramatic onset of OCD symptoms or restricted food intake is the primary diagnostic criterion for PANS.
No specific laboratory testing is recommended for PANS/CANS; however, the nature of co-occurring symptoms may dictate the course of further diagnostic tests, such as MRI scans, ECGs, N-methyl-D-aspartate receptor antibodies, etc.
Dystonia
SIGNS / SYMPTOMS
Repetitive twisting and sustained involuntary movements that may be slow or rapid.
Movements are not preceded by any premonitory sensation, although patients with blepharospasm often report abnormal sensations in the eyes. They are unable to be temporarily suppressed.[1][3]
INVESTIGATIONS
Diagnosis is usually based on history and physical examination.
Myoclonus
SIGNS / SYMPTOMS
Movements are generally more rapid than the brief movement of most tics.
Myoclonus is not suppressible.
The condition may be physiological (such as sleep myoclonus) or pathological (such as seen with myoclonic epilepsies).[1][3]
INVESTIGATIONS
Diagnosis is usually based on history and physical examination.
An electroencephalogram (EEG) may be helpful to distinguish myoclonic that is epileptic, but sub-cortical myoclonus will not have EEG changes.
Tremor
Chorea
SIGNS / SYMPTOMS
Continuous, involuntary, rapid, random movements that are not predictable or stereotyped movements.
Acute onset of chorea in children is most commonly due to Sydenham's chorea (one of the clinical manifestations of acute rheumatic fever).[1][3] Anti-N-methyl-D-aspartate receptor encephalitis is another cause of childhood onset chorea, but will have associated seizure or encephalopathy.
INVESTIGATIONS
Diagnosis is usually based on history and physical examination.
Ballismus
Athetosis
Dyskinesia
SIGNS / SYMPTOMS
Involuntary choreoathetoid movements, often involving head and trunk.
Can occur spontaneously such as paroxysmal nocturnal dyskinesia, but can occur in context of longer term dopamine blockers (tardive dyskinesia) and serotonergic agents, or upon withdrawal of these medications (withdrawal dyskinesia).
The Abnormal Involuntary Movement Scale should be administered at baseline and follow-up when using dopamine blockers.
INVESTIGATIONS
Diagnosis is usually based on history and physical examination.
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