The Syndrome of Irreversible Lithium-Effectuated Neurotoxicity: A Scoping Review

The Syndrome of Irreversible Lithium-Effectuated Neurotoxicity (SILENT) is a rare but concerning neurological complication resulting from lithium intoxication. Despite being reported since the 1960s, SILENT remains poorly understood and previous reviews on this topic commonly have been narrative. We therefore conducted a scoping review to assess the nature and scope of the research literature on the long-term neurological sequelae of lithium toxicity and determine the current knowledge of SILENT. A comprehensive and systematic literature search, using the MEDLINE, Embase, and Web of Science databases (from inception to July 2023), was conducted for English and Dutch articles, assessing the long-term neurological sequelae of lithium intoxication. Key information concerning clinical manifestations, risk factors, therapeutic approaches, or preventive measurements was extracted. We reviewed 91 articles, extracting information from 117 cases of SILENT. The prevailing outcome observed was persistent cerebellar dysfunction (77% of cases), often in combination with other sequelae. Other common sequelae included cognitive problems, parkinsonism, choreoathetosis, tardive dyskinesia, and peripheral neuropathy. The most common (61.4%) acute neurological symptom in the development of SILENT is an altered level of consciousness ranging from confusion to comatose states. Cerebellar sequelae were mentioned in 77% of cases as most common persistent sequelae. Antipsychotic use was mentioned in 59% of cases and fever was reported in 37.6% of cases. Scientific knowledge about this phenomenon has not advanced much since its initial reports in the 1960s and 1970s. While the use of lithium has become much more stringent than it had been in years past, and the occurrence of SILENT is rather exceptional, raising awareness about SILENT nevertheless remains crucial to avoid deleterious neurological consequences. Comprehensive, high-quality research in a systematic and standardized manner is therefore urgently needed to better understand this phenomenon.