Lithium can have toxic effects on the central nervous system (CNS) that can be both acute and chronic. The syndrome of irreversible lithium-effectuated neurotoxicity (SILENT) was suggested in the 1980s to describe lithium intoxication-induced persistent neurological sequelae. In this article, we report a 61-year-old patient with bipolar disorder who had developed expressive aphasia, ataxia, cogwheel rigidity, and fine tremors after acute on chronic lithium toxicity. These neurological symptoms remained for four months after discontinuation of lithium, confirming the persistence of CNS signs and symptoms, which makes this case meets the SILENT syndrome criteria. Although rare, our report - which shows a severe and disabling form of SILENT syndrome - highlights the need for additional caution when treating patients with lithium and the need to perform strict control of the putative risk factors argued to be associated with the development of this syndrome.