Focal cortical transient preceding myoclonus during lithium and tricyclic antidepressant therapy

Myoclonus is often observed in tricyclic antidepressant (TCA) overdose but is uncommon at therapeutic dosages.1 Myoclonus has also been described in patients treated with lithium, both at toxic and therapeutic dosages,2 as well as in combined lithium–TCA treatment.3 The cortical origin for TCA-induced myoclonus is suggested, but not confirmed, by the finding of enlarged somatosensory evoked potentials (SEPs).4 A 65-year-old man complained of a 6-month history of shakiness and jerking of both hands during activity, particularly with holding the newspaper and with handwriting. He denied seizure activity or change in walking, balance, or speech. He was diagnosed 13 years before presentation with bipolar disorder and had been treated with lithium (900 mg/day) and doxepin (200 mg/day) since then. One year before presentation, he decreased the lithium to 450 mg/day. About 6 months before presentation, the patient increased the dose of lithium to 900 mg/day and within a few weeks developed shaking …