A Systematic Review of Oral Vertical Dyskinesia ("Rabbit" Syndrome)

Area of Science:

• Neurology
• Psychiatry
• Pharmacology

Background:

• Rabbit syndrome (RS) is a rare, drug-induced movement disorder characterized by vertical rhythmic dyskinetic movements of the jaw, mouth, and lips.
• Limited evidence exists on the specific clinical features, epidemiological profile, and management strategies for RS.
• Understanding RS is critical for accurate diagnosis and appropriate therapeutic interventions in psychiatric patients.

Purpose of the Study:

• To conduct a comprehensive literature review on rabbit syndrome (RS).
• To evaluate the clinical-epidemiological characteristics, underlying pathological mechanisms, and effective management approaches for RS.
• To differentiate RS from other movement disorders, particularly tardive dyskinesia (TD).

Main Methods:

• Systematic literature search across six databases from 1972 to 2024, without language restrictions.
• Inclusion and assessment of relevant articles by two independent reviewers.
• Analysis of 85 articles reporting a total of 146 cases of RS.

Main Results:

• RS occurred in 1.2% of adult psychiatric hospital patients, predominantly in females (63.6%) with a mean age of 49.2 years.
• Schizophrenia (47.6%) was the most common comorbidity; haloperidol and risperidone were the most frequently associated medications.
• RS was associated with drug-induced parkinsonism (DIP) in 27.4% of cases and showed good response to antipsychotic modification and anticholinergic drugs.

Conclusions:

• Rabbit syndrome is a distinct drug-induced syndrome, primarily linked to antipsychotic use.
• Differentiating RS from TD is essential due to differing treatment strategies.
• RS may represent a spectrum of DIP, sharing similar pathophysiology and treatment outcomes.