(Es)ketamine in functional neurological disorder: a systematic review

Area of Science:

• Neuroscience
• Psychiatry

Background:

• Functional neurological disorder (FND) is a prevalent and debilitating condition with limited effective treatments.
• Clinical outcomes in FND are variable, especially in chronic or comorbid cases.
• Ketamine and esketamine are increasingly utilized for various neuropsychiatric conditions.

Purpose of the Study:

• To systematically review and synthesize existing evidence on the use of ketamine and esketamine in patients with FND.
• To evaluate the reported clinical outcomes and adverse effects of (Es)ketamine treatment for FND.

Main Methods:

• A systematic literature search was conducted across PubMed, PsycINFO, and Google Scholar up to December 2025.
• Included studies reported clinical outcomes following (Es)ketamine administration in patients with functional neurological symptoms.
• Due to heterogeneity, findings were synthesized narratively.

Main Results:

• Thirteen studies, mostly case reports and small series, were identified.
• Some patients experienced improvements in functional motor symptoms and dissociative seizures.
• Interpretation is limited by uncontrolled designs, diagnostic heterogeneity, and potential biases. Adverse effects were generally transient.

Conclusions:

• The current evidence base is insufficient to establish (Es)ketamine efficacy for FND.
• Reported symptom improvements may stem from direct effects, psychiatric benefits, or non-specific factors.
• Prospective controlled trials are necessary to determine the role of (Es)ketamine in FND treatment.