From the Research
Patients with SILENT syndrome should avoid lithium therapy whenever possible to minimize the risk of permanent neurological damage, and if lithium must be used, extremely close monitoring is essential with serum lithium levels checked at least weekly initially, then monthly once stable, as supported by the most recent study 1. The Syndrome of Irreversible Lithium-Effectuated Neurotoxicity (SILENT) is a rare but concerning neurological complication resulting from lithium intoxication, with persistent cerebellar dysfunction being the most commonly reported sequela, often in combination with other sequelae such as cognitive problems, parkinsonism, choreoathetosis, tardive dyskinesia, and peripheral neuropathy 1.
Key Considerations
- Target lithium levels should be kept at the lower end of the therapeutic range (0.6-0.8 mEq/L rather than 0.8-1.2 mEq/L) to minimize the risk of toxicity, as suggested by the available evidence 2, 1.
- Signs of lithium toxicity include tremor, confusion, ataxia, slurred speech, and seizures, and any neurological symptoms in a patient on lithium should prompt immediate lithium level testing and possible discontinuation 3, 1.
- Patients with renal impairment, dehydration, sodium depletion, or those taking NSAIDs, ACE inhibitors, or diuretics have increased risk of lithium toxicity, and should be closely monitored 4, 1.
Clinical Implications
- SILENT syndrome occurs because lithium can accumulate in brain tissue and disrupt normal neuronal function, particularly affecting cerebellar and brainstem regions, which explains the characteristic neurological symptoms that may persist even after lithium discontinuation 2, 1.
- Comprehensive, high-quality research in a systematic and standardized manner is therefore urgently needed to better understand this phenomenon and to raise awareness about SILENT, which remains crucial to avoid deleterious neurological consequences 1.