A 55-year-old male had a diagnosis of schizoaffective disorder at the age of 51. He was initially diagnosed with bipolar I disorder at the age of 30, and mainly treated with a combination of lithium and valproic acid from age 30 to 51. At the age of 51, he was observed to have a manic episode concurrent with persecutory delusions and auditory hallucination. These psychotic symptoms persisted for more than 3 weeks after his manic symptoms had subsided. Later, a combination of lithium and olanzapine 5 to 15 mg/day were given as the main treatment. In addition, he had history of type 2 diabetes mellitus and hyperlipidemia for more than 10 years. He did not have any substance use or neurological disorder before. This time, after poor drug adherence for 4 months, he was admitted to our ward at the age of 53, due to symptoms including elevated mood, increased goal-directed activity, talkativeness, decreased need for sleep, and grandiose delusion lasting for 1 week.
Lithium 600 mg/day and olanzapine 10 mg/day were initially prescribed, and the dosages were titrated to 900 mg/day and 20 mg/day, respectively, over 1 week. His lithium serum level was reported to be 0.60 mEq/L (day 4) and 0.58 mEq/L (day 14). Because of poor blood sugar control, intramuscular injection of risperidone 25 mg was prescribed for switching antipsychotic agent on day 15. Olanzapine was discontinued and risperidone 4.5 mg/day was started on days 22 to 24. However, on day 27, the patient presented slurred speech, muscle rigidity, delirium (confused consciousness, inattention, and disorientation), and decreased urine output. At the same time, he did not present fever, focal neurological signs, or gastrointestinal symptoms. Laboratory data showed: blood urea nitrogen (BUN; 24 mg/dL), creatinine (1.33 mg/dL), serum lithium (1.42 mEq/L) on day 28, and creatine kinase (975 U/L) on day 29, compared with BUN (8 mg/dL) and creatinine (0.8 mg/dL) on admission. All medications were discontinued and he was treated with normal saline hydration. The delirium and abnormal laboratory data were fully recovered within 2 days, as follows: BUN (12 mg/dL), creatinine (0.82 mg/dL), and serum lithium (0.82 mEq/L). Lithium 600 mg/day and risperidone 3 mg/day were re-administered on day 32. But symptoms of delirium and elevated BUN (29 mg/dL), creatinine (1.36 mg/dL), serum lithium (1.54 mEq/L), and creatine kinase (90 U/L) were noted on day 35. All drugs were discontinued again and fluid hydration was given. One day later, the delirium resolved and abnormal data returned to normal: BUN (16 mg/dL), creatinine (0.88 mg/dL), and serum lithium (1.06 mEq/L). Finally, risperidone 2 mg/day monotherapy was given on day 38. The patient was discharged in a stable condition on day 42. He was kept regular treatment with risperidone 2 to 3 mg/day, and no episode of neurotoxicity and nephrotoxicity appeared in the following 2 years.