Remission of functional motor symptoms following esketamine administration in a patient with treatment-resistant depression: a single-case report.

Functional movement disorders (FMD) involve a broad range of abnormal involuntary movements not consistent with neurological diseases. These conditions often occur in combination with mood and anxiety disorders and are associated with poor clinical outcomes. We report the case of a 57-year-old woman diagnosed with treatment-resistant depression (TRD) and comorbid FMD treated with weekly intranasal administrations of esketamine over a six-month follow-up period. A comprehensive clinical and psychometric assessment was carried out at different time points. After 2 months of treatment, a complete remission of motor and axial functional disturbances (athetosis, trunk torsion and genuflections) was detectable, along with a progressive improvement in depressive symptoms during follow-up until full remission. According to novel lines of evidence, glutamatergic transmission might play a role in the pathophysiology of FMD through aberrant limbic-motor interactions. We report that treatment with esketamine, a noncompetitive N-methyl-d-aspartate glutamatergic receptor antagonist, was associated with remission of FMD symptoms in a patient with TRD. Pharmacological compounds modulating brain glutamatergic activity may be of potential benefit in the clinical management of FMD.