Lithium-induced Paradoxical Neurotoxicity-a Risk Factor

Though lithium-induced neurotoxicity usually occurs when serum lithium exceeds 2.0 mEq/1, reports and reviews document its occurence with serum lithium within the therapeutic range (Strayhorn and Nash 1977; Hansen and Amidsen 1978; Speirs and Hirsch 1978; West and Meltzer 1979). Neurotoxicity has even been described with serum lithium between 0.4 and 0.5 mEq/l (Hansen and Amidsen 1978). Many hypotheses have been suggested to explain this paradoxical neurotoxicity. These include: interactions with other drugs such as haloperidol and diuretics (Strayhorn and Nash 1977), diphenylhydantoin (Speirs and Hirsch 1978) and phenothiazines (Spring 1979); tissue retention (Strayhorn and Nash 1977); seizure diathesis (Strayhorn and Nash 1977); high pretoxic global ratings of psychotic symptomatology and anxiety (West and Meltzer 1979); old age (Van der Velde 1971); schizophrenia (Shopsin and Gershon 1973); intercurrent medical illness (Shopsin and Gershon 1973; Strayhorn and Nash 1977).