A silent collapse, and the slow journey back
In 2023, my life changed suddenly. A high fever struck, and within a few days, I lost the ability to walk, speak clearly, maintain balance, and see properly. I was hospitalized for a month. Every possible test was done, but no clear diagnosis was made. An MRI showed a temporary lesion in the cerebellum, which disappeared within days. Lithium toxicity was considered—but dismissed because my serum level was only 1.19 mmol/L, within the “normal” range. At the time, no one could name what I had. But later, I found a possible explanation: SILENT syndrome.
Before dive into the SILENT, let's learn about lithium first.
What is Lithium?
Lithium is a naturally occurring element (atomic number 3) and one of the most effective mood stabilizers used in psychiatry. It has been a cornerstone treatment for bipolar disorder since the 1950s, helping prevent both manic and depressive episodes. It is also used to treat epilepsy.
However, lithium has a narrow therapeutic window — meaning the difference between an effective dose and a toxic dose is very small. Even when blood levels are considered “normal,” lithium may still accumulate in the brain and affect sensitive regions such as the cerebellum, potentially leading to neurotoxicity.
What is SILENT Syndrome?
SILENT stands for:
Syndrome of Irreversible Lithium-Effectuated Neurotoxicity.
It is a rare condition that can occur in individuals undergoing long-term lithium treatment. Notably, it may develop even when lithium blood levels are within therapeutic range. This is really important as almost no doctor knows this (as I see). There are a few case studies I found which shows that even therapeutic range, lithium toxication can occur. For instance;
"In our case, persistent cerebellar syndrome developed despite serum lithium levels being within the therapeutic range."
— Şahingöz & Dağıstanlı, Journal of Mood Disorders, 2013 [1]
“This case suggests that chronic cerebellar degeneration can occur even at non-toxic lithium levels, especially after episodes of hyperthermia.”
— Terao et al., 2017, Neuropsychiatric Disease and Treatment [2]
“Most cases of reversible lithium neurotoxicity occurred at therapeutic serum lithium levels (≤1.5 mEq/L), with daily doses below 2,000 mg.”
— Netto & Phutane, 2012, The Primary Care Companion for CNS Disorders [3]
Common symptoms include:
- Ataxia (loss of balance and coordination)
- Dysarthria (slurred or slowed speech)
- Tremor
- Nystagmus (involuntary eye movements)
- Cognitive impairment
- Muscle weakness
How Does It Develop?
The core issue in SILENT syndrome lies in the cerebellum and basal ganglia, brain regions particularly sensitive to lithium’s effects. Lithium tends to linger in the cerebrospinal fluid, meaning its neurotoxic effects can emerge even after blood levels normalize. Dehydration, heat, infection, or kidney impairment can increase the risk by disrupting lithium balance in the body.
Why Is It Called “SILENT”?
Because it often starts quietly and insidiously. Diagnosis is difficult, especially when serum lithium appears normal. Yet, the effects can be serious—and sometimes irreversible. It’s a silent, hidden threat.
"Clinically and heuristically, it is important to raise the awareness of this syndrome so that clinicians are able to avoid it. A precise definition, operational diagnostic criteria, and a descriptive name will aid in the early identification and prevention of SILENT." Adityanjee et al. (2005). Syndrome of irreversible lithium-effectuated neurotoxicity (SILENT) [4]
My Journey
I was on lithium for 8 years. After the crisis, I couldn't walk, speak, or maintain balance. Months of physical and speech therapy followed. Generally, the damage to the cerebellum is permanent and symptoms remain.However, in some cases, it is reversible:
"Lithium neurotoxicity may be reversible or irreversible. Reversible lithium neurotoxicity has been defined as cases of lithium neurotoxicity in which patients recovered without any permanent neurologic sequelae, even after 2 months of an episode of lithium toxicity. Cases of reversible lithium neurotoxicity differ in clinical presentation from those of irreversible lithium neurotoxicity and have important implications in clinical practice."
"There are no typical clinical features to clearly identify a case of reversible lithium neurotoxicity. The clinical features of irreversible lithium toxicity are permanent and easier to detect, whereas reversible lithium neurotoxicity is transitory and difficult to evaluate. There are reviews on irreversible lithium neurotoxicity but none on reversible lithium neurotoxicity." [3]
Today, I can walk again and communicate better. Recovery is slow and requires deep patience. So, I believe my case is very very rare.
What I deeply angry at... No one knew that lithium can damage even in therapeutic levels. Maybe they could save me from this. That's why I want everyone to know that this medicine can do it. Actually, ataxia is listed as a side effect in the leaflet. But I guess it's easier to look away.
I visited a few psychiatrists and told my case. They didn't believe me. They said "your lithium was not high". It was 1.19.
:)
Scientific References
- Şahingöz & Dağıstanlı, Journal of Mood Disorders, 2013
- Rossi FH, Rossi EM, Hoffmann M, Liu W, Cruz RR, Antonovich N, Rezaei A, Gonzalez E, Franco MC, Estevez A, Thomas F. Permanent Cerebellar Degeneration After Acute Hyperthermia with Non-toxic Lithium Levels: a Case Report and Review of Literature. Cerebellum. 2017 Dec;16(5-6):973-978. doi: 10.1007/s12311-017-0868-3. PMID: 28593454.
- Netto I, Phutane VH. Reversible lithium neurotoxicity: review of the literatur. Prim Care Companion CNS Disord. 2012;14(1):PCC.11r01197. doi: 10.4088/PCC.11r01197. PMID: 22690368; PMCID: PMC3357580.
- Adityanjee, Munshi KR, Thampy A. The syndrome of irreversible lithium-effectuated neurotoxicity. Clin Neuropharmacol. 2005 Jan-Feb;28(1):38-49. doi: 10.1097/01.wnf.0000150871.52253.b7. PMID: 15714160.
