To synthesize existing evidence regarding the use of (Es)ketamine in treating functional neurological disorder (FND).
Approach:
Systematic Review: A systematic review of PubMed, PsycINFO, and Google Scholar was conducted up to December 2025, focusing on studies reporting clinical outcomes following (Es)ketamine administration in functional neurological symptoms.
Key Findings:
Thirteen studies were identified, predominantly comprising case reports and small case series.
Some patients reported improvement in functional motor symptoms and dissociative seizures after (Es)ketamine administration, but findings are limited by uncontrolled evidence and heterogeneity.
Adverse effects were variably reported but generally transient in supervised settings.
Interpretation:
The current evidence base is insufficient to establish the efficacy of (Es)ketamine for FND, with unclear mechanisms behind reported improvements.
Limitations:
Predominantly uncontrolled and heterogeneous studies.
Variability in diagnoses and outcomes across studies.
Potential publication and expectancy bias.
Conclusion:
Further investigation is justified, and prospective controlled trials are needed to clarify the potential role of (Es)ketamine in FND.
