Acute and reversible dyskinesias secondary to lithium toxicity: case report and literature review.

Background: Lithium can cause several neurological side effects, including altered consciousness, delirium, cerebellar symptoms, parkinsonism, and seizures. Also, dyskinesias can be a possible manifestation of lithium intoxication. The clinical picture of dyskinesias secondary to lithium intoxication is still unclear.

Case presentation: We here describe the case of a 75-year-old woman who developed acute and reversible dyskinesia manifesting as generalised chorea because of lithium intoxication. The patient had a medical history of bipolar disorder type 2 and at least 20 years of continuous lithium monotherapy (150 mg, 1 tablet 3 times/day). Dyskinesias were associated with a high serum lithium level of 2.15 mEq/L. Imaging and EEG showed no relevant abnormalities. On the sixth day after admission, dyskinesias faded away when the lithium serum level decreased to 0.4 mmol/L. When critically reviewing the existing literature, we found a total of 33 cases, with an average age of 59.7 years, predominantly female. In these cases, the average lithium peak at the onset of dyskinesia was 2.25 mEq/L, with symptoms typically appearing 4.2 days after reaching peak lithium levels.

Discussion: Lithium toxicity, even at therapeutic serum concentrations, may induce abrupt-onset dyskinesia in susceptible individuals, likely mediated by reversible functional disturbances within the basal ganglia.