Lithium carbonate therapy, uncomplicated by other factors, can give rise to a deep coma even if the serum levels of lithium are within the desired range. A patient with manic depressive disease, having been treated with lithium carbonate for less than a year, developed progressive impairment of consciousness. A few days after the medication was discontinued, the patient had a slow but complete recovery. Lithium accumulation in the brain is postulated.
Herrero FA. Lithium Carbonate Toxicity. JAMA. 1973;226(9):1109-1110. doi:10.1001/jama.1973.03230090033007