Tourette Syndrome
This 15-year-old girl's involuntary movements preceded by an irresistible "itch" sensation that worsens with suppression are pathognomonic for Tourette syndrome, making it the correct answer among the choices provided.
Key Diagnostic Features Present in This Case
The clinical presentation demonstrates the hallmark characteristics of tics in Tourette syndrome:
Premonitory urge ("itch" sensation): The somatosensory urge preceding the tic is a defining feature of Tourette syndrome, with most children becoming aware of these nearly irresistible urges by age 10 years 1
Suppressibility with worsening urge: The ability to temporarily suppress tics (holding arms still) followed by intensification of the premonitory sensation is a core clinical feature that distinguishes tics from other movement disorders 2
Momentary relief after tic completion: The relief she experiences after touching her nose is characteristic, as a momentary sense of relief typically follows tic completion 1
Repetitive, stereotyped movements: The involuntary touching of nose and chin represents simple motor tics—brief, repetitive movements involving discrete muscle groups 2, 3
Why Other Options Are Incorrect
Huntington disease: Presents with chorea (flowing, dance-like movements) without premonitory urges, typically has adult onset, and involves progressive cognitive decline—none of which fit this presentation
Subthalamic nucleus infarct: Causes hemiballismus (violent flinging movements of one side), not bilateral repetitive touching movements with premonitory sensations
Opsoclonus-myoclonus-ataxia: Characterized by chaotic eye movements, myoclonic jerks, and ataxia—completely different phenomenology from this patient's tics
Restless legs syndrome: The key distinguishing feature is that this patient has no worsening around bedtime, which rules out restless legs syndrome that characteristically worsens in the evening and at rest
Clinical Context Supporting Tourette Syndrome
Age and demographics: The patient is 15 years old, consistent with Tourette syndrome which typically has prepubertal onset with symptoms peaking between ages 8-12 years 1
Two-year duration: The chronic nature (2 years) fits with chronic tic disorder or Tourette syndrome rather than transient tic disorder, which resolves within one year 2, 3
Core tic features present: This case demonstrates all five core clinical features of tics: suppressibility, variability, presence of premonitory sensation, and the characteristic waxing-waning pattern 2
Important Clinical Considerations
When evaluating for Tourette syndrome, screen for common comorbidities that may require separate treatment:
- ADHD: Present in 50-75% of children with Tourette syndrome 3, 4
- Obsessive-compulsive behaviors: Present in 30-60% of cases 3, 4
The diagnosis is primarily clinical based on history and observation; excessive medical testing can cause iatrogenic harm and should be avoided 3