What is the difference between tic symptoms and extrapyramidal symptoms (EPS) in a pediatric patient with a tic disorder?

Distinguishing Tics from Extrapyramidal Symptoms (EPS)

Tics are voluntary suppressible movements with premonitory sensations that wax and wane over time, while EPS are involuntary drug-induced movement disorders without suppressibility or premonitory urges.

Core Distinguishing Features of Tics

Tics have five cardinal features that fundamentally differentiate them from EPS:

• Suppressibility: Patients can temporarily suppress tics voluntarily, though this is followed by intensification of the premonitory sensation 1, 2
• Distractibility: Tics diminish when attention is diverted elsewhere 3, 2
• Suggestibility: Tics can be modified by suggestion 3, 2
• Variability: The repertoire of tics changes over time with a characteristic waxing-waning pattern that fluctuates over weeks to months 1, 2
• Premonitory sensation: Over 80% of tic patients experience distinct sensory experiences or urges that precede the tic movement 4

Core Features of Extrapyramidal Symptoms (EPS)

EPS are medication-induced movement disorders that lack the volitional control seen in tics:

• Non-suppressible: EPS cannot be voluntarily suppressed by the patient 5
• Drug-related onset: EPS occur as side effects of dopamine-blocking medications (haloperidol, pimozide, risperidone) 5, 4
• No premonitory sensation: EPS lack the characteristic urge or sensory experience that precedes tics 4
• Persistent pattern: EPS do not demonstrate the waxing-waning pattern characteristic of tics 1
• Acute presentations: EPS can manifest as acute dystonia, oculogyric crisis, akathisia, or parkinsonism 5

Clinical Presentation Differences

Tic Characteristics:

• Simple motor tics: Eye blinking, facial grimacing, head jerking, shoulder shrugging 1, 2
• Simple phonic tics: Throat clearing, sniffing, grunting, coughing, squeaking, barking 1, 2
• Complex tics: Stereotyped movements involving multiple muscle groups 2
• Sleep pattern: Tics are markedly diminished during sleep 4
• Stress response: Tics are exacerbated by anger or stress 4

EPS Characteristics:

• Acute dystonia: Sustained muscle contractions causing abnormal postures 5
• Oculogyric crisis: Involuntary upward deviation of eyes 5
• Akathisia: Subjective restlessness with inability to sit still 5
• Drug-emergent: Symptoms appear after initiation or dose increase of neuroleptic medications 5

Critical Diagnostic Algorithm

Step 1: Assess for suppressibility and premonitory sensation

• If present → strongly suggests tics 1, 2
• If absent → consider EPS or other movement disorder 5

Step 2: Evaluate medication history

• Recent neuroleptic use (haloperidol, pimozide, risperidone) → suspect EPS 5, 4
• No dopamine-blocking medication → more likely tics 1

Step 3: Observe temporal pattern

• Waxing-waning over weeks/months → characteristic of tics 1
• Persistent since medication initiation → suggests EPS 5

Step 4: Test voluntary control

• Patient can briefly suppress movements → tics 1, 2
• Cannot suppress despite effort → EPS 5

Common Diagnostic Pitfalls

Avoid misdiagnosing tics as "habit behaviors" or "psychogenic symptoms," as this leads to inappropriate interventions and delays proper treatment 1, 2. The CHEST guidelines specifically recommend against using terms like "habit cough" or "psychogenic cough" and instead using "tic cough" to align with DSM-5 classification 3.

Do not perform excessive medical testing for tics, as diagnosis is primarily clinical and unnecessary testing causes iatrogenic harm 1. However, when EPS is suspected, the medication history is essential 5.

Be aware that antiepileptic drugs can cause tics in children, making it important to review all medications 6.

Age and Gender Considerations

• Tics typically onset around age 7 years, with boys affected more commonly than girls (approximately 1 per 1,000 male children) 1, 2
• Nearly half of tic patients experience spontaneous remission by age 18 1
• EPS can occur at any age when exposed to dopamine-blocking medications 5

Treatment Response Differences

For tics, treatment focuses on behavioral interventions first, with neuroleptics reserved for severe cases 7, 4. The irony is that the same medications used to treat severe tics (haloperidol, pimozide) can cause EPS 5, 4.

For EPS, the primary intervention is reducing or discontinuing the offending medication, or adding anticholinergics like benzhexol 5. Switching to atypical antipsychotics with lower EPS risk (quetiapine, olanzapine) may be necessary 5, 4.